From c965112c50153a488c06370ad1211b949fdbf6e6 Mon Sep 17 00:00:00 2001
From: Matthias Kaemmer <m.kaemmer@sotec.eu>
Date: Tue, 1 Aug 2023 15:49:06 +0200
Subject: [PATCH] [#19] Enhance device communication API * added support for
 device states * added automatic Pub/Sub tenant topic & subscription creation
 and deletion * added automatically sending of a config in case a config is
 requested or a new one created * extended config table with error field

Signed-off-by: Matthias Kaemmer <m.kaemmer@sotec.eu>
---
 .../api/DeviceCommunicationHttpServer.java    |  31 +-
 .../api/config/ApiCommonConstants.java        |  36 ++
 .../api/config/DeviceConfigsConstants.java    |  13 +-
 .../api/config/DeviceStatesConstants.java     |  42 ++
 .../communication/api/data/DeviceConfig.java  |   2 -
 .../api/data/DeviceConfigEntity.java          |  29 +-
 .../data/DeviceConfigInternalResponse.java    | 121 ++++++
 .../communication/api/data/DeviceState.java   | 106 +++++
 .../api/data/DeviceStateEntity.java           | 107 +++++
 .../api/data/ListDeviceStatesResponse.java    |  90 ++++
 .../api/handler/ConfigTopicEventHandler.java  |  43 ++
 .../api/handler/DeviceConfigsHandler.java     |  12 +-
 .../api/handler/DeviceStatesHandler.java      |  70 ++++
 .../api/handler/StateTopicEventHandler.java   |  35 ++
 .../api/mapper/DeviceStateMapper.java         |  59 +++
 .../api/repository/DeviceStateRepository.java |  48 +++
 .../repository/DeviceStateRepositoryImpl.java | 173 ++++++++
 .../api/service/DeviceConfigServiceImpl.java  |  84 ----
 .../VertxHttpHandlerManagerService.java       |  10 +-
 .../InternalTopicManager.java}                |  14 +-
 .../InternalTopicManagerImpl.java             | 187 +++++++++
 .../{ => config}/DeviceConfigService.java     |  21 +-
 .../config/DeviceConfigServiceImpl.java       | 284 +++++++++++++
 .../DatabaseSchemaCreatorImpl.java            |  28 +-
 .../api/service/state/DeviceStateService.java |  37 ++
 .../service/state/DeviceStateServiceImpl.java | 101 +++++
 .../core/app/DatabaseConfig.java              |  12 +
 .../core/utils/StringValidateUtils.java       |  44 ++
 .../api/hono-device-communication-v1.yaml     |  79 +++-
 .../src/main/resources/api/hono-endpoint.yaml |  77 +++-
 .../resources/db/migration/V1.0__create.sql   |  11 -
 ...g_table.sql => v1_create_config_table.sql} |   8 +-
 .../resources/db/v1_create_state_table.sql    |  28 ++
 .../communication/api/ApplicationTest.java    |   2 -
 .../DeviceCommunicationHttpServerTest.java    |  33 +-
 .../api/handler/DeviceConfigsHandlerTest.java |  44 +-
 .../api/handler/DeviceStatesHandlerTest.java  | 150 +++++++
 .../service/DeviceConfigServiceImplTest.java  | 127 ------
 .../InternalTopicManagerImplTest.java         | 157 +++++++
 .../config/DeviceConfigServiceImplTest.java   | 388 ++++++++++++++++++
 .../DatabaseSchemaCreatorImplTest.java        |  27 +-
 .../DatabaseServiceImplTest.java              |   9 +-
 .../state/DeviceStateServiceImplTest.java     | 152 +++++++
 .../core/utils/StringValidateUtilsTest.java   |  38 ++
 44 files changed, 2828 insertions(+), 341 deletions(-)
 create mode 100644 device-communication/src/main/java/org/eclipse/hono/communication/api/config/ApiCommonConstants.java
 create mode 100644 device-communication/src/main/java/org/eclipse/hono/communication/api/config/DeviceStatesConstants.java
 create mode 100644 device-communication/src/main/java/org/eclipse/hono/communication/api/data/DeviceConfigInternalResponse.java
 create mode 100644 device-communication/src/main/java/org/eclipse/hono/communication/api/data/DeviceState.java
 create mode 100644 device-communication/src/main/java/org/eclipse/hono/communication/api/data/DeviceStateEntity.java
 create mode 100644 device-communication/src/main/java/org/eclipse/hono/communication/api/data/ListDeviceStatesResponse.java
 create mode 100644 device-communication/src/main/java/org/eclipse/hono/communication/api/handler/ConfigTopicEventHandler.java
 create mode 100644 device-communication/src/main/java/org/eclipse/hono/communication/api/handler/DeviceStatesHandler.java
 create mode 100644 device-communication/src/main/java/org/eclipse/hono/communication/api/handler/StateTopicEventHandler.java
 create mode 100644 device-communication/src/main/java/org/eclipse/hono/communication/api/mapper/DeviceStateMapper.java
 create mode 100644 device-communication/src/main/java/org/eclipse/hono/communication/api/repository/DeviceStateRepository.java
 create mode 100644 device-communication/src/main/java/org/eclipse/hono/communication/api/repository/DeviceStateRepositoryImpl.java
 delete mode 100644 device-communication/src/main/java/org/eclipse/hono/communication/api/service/DeviceConfigServiceImpl.java
 rename device-communication/src/main/java/org/eclipse/hono/communication/api/service/{DeviceCommandService.java => communication/InternalTopicManager.java} (66%)
 create mode 100644 device-communication/src/main/java/org/eclipse/hono/communication/api/service/communication/InternalTopicManagerImpl.java
 rename device-communication/src/main/java/org/eclipse/hono/communication/api/service/{ => config}/DeviceConfigService.java (69%)
 create mode 100644 device-communication/src/main/java/org/eclipse/hono/communication/api/service/config/DeviceConfigServiceImpl.java
 rename device-communication/src/main/java/org/eclipse/hono/communication/api/service/{ => database}/DatabaseSchemaCreatorImpl.java (70%)
 create mode 100644 device-communication/src/main/java/org/eclipse/hono/communication/api/service/state/DeviceStateService.java
 create mode 100644 device-communication/src/main/java/org/eclipse/hono/communication/api/service/state/DeviceStateServiceImpl.java
 create mode 100644 device-communication/src/main/java/org/eclipse/hono/communication/core/utils/StringValidateUtils.java
 delete mode 100644 device-communication/src/main/resources/db/migration/V1.0__create.sql
 rename device-communication/src/main/resources/db/{create_device_config_table.sql => v1_create_config_table.sql} (73%)
 create mode 100644 device-communication/src/main/resources/db/v1_create_state_table.sql
 create mode 100644 device-communication/src/test/java/org/eclipse/hono/communication/api/handler/DeviceStatesHandlerTest.java
 delete mode 100644 device-communication/src/test/java/org/eclipse/hono/communication/api/service/DeviceConfigServiceImplTest.java
 create mode 100644 device-communication/src/test/java/org/eclipse/hono/communication/api/service/communication/InternalTopicManagerImplTest.java
 create mode 100644 device-communication/src/test/java/org/eclipse/hono/communication/api/service/config/DeviceConfigServiceImplTest.java
 rename device-communication/src/test/java/org/eclipse/hono/communication/api/service/{ => database}/DatabaseSchemaCreatorImplTest.java (75%)
 rename device-communication/src/test/java/org/eclipse/hono/communication/api/service/{ => database}/DatabaseServiceImplTest.java (90%)
 create mode 100644 device-communication/src/test/java/org/eclipse/hono/communication/api/service/state/DeviceStateServiceImplTest.java
 create mode 100644 device-communication/src/test/java/org/eclipse/hono/communication/core/utils/StringValidateUtilsTest.java

diff --git a/device-communication/src/main/java/org/eclipse/hono/communication/api/DeviceCommunicationHttpServer.java b/device-communication/src/main/java/org/eclipse/hono/communication/api/DeviceCommunicationHttpServer.java
index fdfe6925..0e1dd8e0 100644
--- a/device-communication/src/main/java/org/eclipse/hono/communication/api/DeviceCommunicationHttpServer.java
+++ b/device-communication/src/main/java/org/eclipse/hono/communication/api/DeviceCommunicationHttpServer.java
@@ -22,9 +22,10 @@
 
 import javax.inject.Singleton;
 
-import org.eclipse.hono.communication.api.service.DatabaseSchemaCreator;
-import org.eclipse.hono.communication.api.service.DatabaseService;
 import org.eclipse.hono.communication.api.service.VertxHttpHandlerManagerService;
+import org.eclipse.hono.communication.api.service.communication.InternalTopicManager;
+import org.eclipse.hono.communication.api.service.database.DatabaseSchemaCreator;
+import org.eclipse.hono.communication.api.service.database.DatabaseService;
 import org.eclipse.hono.communication.core.app.ApplicationConfig;
 import org.eclipse.hono.communication.core.app.ServerConfig;
 import org.eclipse.hono.communication.core.http.AbstractVertxHttpServer;
@@ -45,12 +46,12 @@
 import io.vertx.ext.web.openapi.RouterBuilder;
 import io.vertx.ext.web.validation.BadRequestException;
 
-
 /**
  * Vertx HTTP Server for the device communication api.
  */
 @Singleton
 public class DeviceCommunicationHttpServer extends AbstractVertxHttpServer implements HttpServer {
+
     private final Logger log = LoggerFactory.getLogger(DeviceCommunicationHttpServer.class);
     private final String serverStartedMsg = "HTTP Server is listening at http://{}:{}";
     private final String serverFailedMsg = "HTTP Server failed to start: {}";
@@ -58,9 +59,9 @@ public class DeviceCommunicationHttpServer extends AbstractVertxHttpServer imple
 
     private final DatabaseService db;
     private final DatabaseSchemaCreator databaseSchemaCreator;
+    private final InternalTopicManager internalTopicManager;
     private List<HttpEndpointHandler> httpEndpointHandlers;
 
-
     /**
      * Creates a new DeviceCommunicationHttpServer with all dependencies.
      *
@@ -69,26 +70,27 @@ public class DeviceCommunicationHttpServer extends AbstractVertxHttpServer imple
      * @param httpHandlerManager    The http handler manager
      * @param databaseService       The database connection
      * @param databaseSchemaCreator The database migrations service
+     * @param internalTopicManager  The internal topic manager
      */
     public DeviceCommunicationHttpServer(final ApplicationConfig appConfigs,
                                          final Vertx vertx,
                                          final VertxHttpHandlerManagerService httpHandlerManager,
                                          final DatabaseService databaseService,
-                                         final DatabaseSchemaCreator databaseSchemaCreator) {
+                                         final DatabaseSchemaCreator databaseSchemaCreator, final InternalTopicManager internalTopicManager) {
         super(appConfigs, vertx);
         this.httpHandlerManager = httpHandlerManager;
         this.databaseSchemaCreator = databaseSchemaCreator;
         this.httpEndpointHandlers = new ArrayList<>();
         this.db = databaseService;
+        this.internalTopicManager = internalTopicManager;
     }
 
-
     @Override
     public void start() {
-        //Create Database Tables
         databaseSchemaCreator.createDBTables();
 
-        // Create Endpoints Router
+        internalTopicManager.initPubSub();
+
         this.httpEndpointHandlers = httpHandlerManager.getAvailableHandlerServices();
         RouterBuilder.create(this.vertx, appConfigs.getServerConfig().getOpenApiFilePath())
                 .onSuccess(routerBuilder -> {
@@ -97,7 +99,7 @@ public void start() {
                 })
                 .onFailure(error -> {
                     if (error != null) {
-                        log.error("Can not create Router: {}", error.getMessage());
+                        log.error("Can not create Router {}", error.getMessage());
                     } else {
                         log.error("Can not create Router");
                     }
@@ -106,7 +108,6 @@ public void start() {
 
                 });
 
-        // Wait until application is stopped
         Quarkus.waitForExit();
 
     }
@@ -118,7 +119,8 @@ public void start() {
      * @param httpEndpointHandlers All available http endpoint handlers
      * @return The created Router object
      */
-    Router createRouterWithEndpoints(final RouterBuilder routerBuilder, final List<HttpEndpointHandler> httpEndpointHandlers) {
+    Router createRouterWithEndpoints(final RouterBuilder routerBuilder,
+                                     final List<HttpEndpointHandler> httpEndpointHandlers) {
         for (HttpEndpointHandler handlerService : httpEndpointHandlers) {
             handlerService.addRoutes(routerBuilder);
         }
@@ -165,7 +167,6 @@ private void addReadinessHandlers(final Router router, final String readinessPat
         router.get(readinessPath).handler(healthCheckHandler);
     }
 
-
     private void addLivenessHandlers(final Router router, final String livenessPath) {
         log.info("Adding liveness path: {}", livenessPath);
         final HealthCheckHandler healthCheckHandler = HealthCheckHandler.create(vertx);
@@ -190,8 +191,8 @@ void startVertxServer(final Router router) {
                 .listen();
 
         serverCreationFuture
-                .onSuccess(server -> log.info(this.serverStartedMsg, serverConfigs.getServerUrl()
-                        , serverConfigs.getServerPort()))
+                .onSuccess(server -> log.info(this.serverStartedMsg, serverConfigs.getServerUrl(),
+                        serverConfigs.getServerPort()))
                 .onFailure(error -> log.info(this.serverFailedMsg, error.getMessage()));
     }
 
@@ -229,10 +230,8 @@ void addDefault404ExceptionHandler(final RoutingContext routingContext) {
         }
     }
 
-
     @Override
     public void stop() {
-        // stop server custom functionality
         db.close();
 
     }
diff --git a/device-communication/src/main/java/org/eclipse/hono/communication/api/config/ApiCommonConstants.java b/device-communication/src/main/java/org/eclipse/hono/communication/api/config/ApiCommonConstants.java
new file mode 100644
index 00000000..c0b82170
--- /dev/null
+++ b/device-communication/src/main/java/org/eclipse/hono/communication/api/config/ApiCommonConstants.java
@@ -0,0 +1,36 @@
+/*
+ * ***********************************************************
+ *  Copyright (c) 2023 Contributors to the Eclipse Foundation
+ *  <p>
+ *  See the NOTICE file(s) distributed with this work for additional
+ *  information regarding copyright ownership.
+ *  <p>
+ *  This program and the accompanying materials are made available under the
+ *  terms of the Eclipse Public License 2.0 which is available at
+ *  http://www.eclipse.org/legal/epl-2.0
+ *  <p>
+ *  SPDX-License-Identifier: EPL-2.0
+ * **********************************************************
+ *
+ */
+
+package org.eclipse.hono.communication.api.config;
+
+/**
+ * Device constant values.
+ */
+public final class ApiCommonConstants {
+
+    /**
+     * Path parameter name for tenantId.
+     */
+    public static final String TENANT_PATH_PARAMS = "tenantid";
+    /**
+     * Path parameter name for deviceId.
+     */
+    public static final String DEVICE_PATH_PARAMS = "deviceid";
+
+    private ApiCommonConstants() {
+        // avoid instantiation
+    }
+}
diff --git a/device-communication/src/main/java/org/eclipse/hono/communication/api/config/DeviceConfigsConstants.java b/device-communication/src/main/java/org/eclipse/hono/communication/api/config/DeviceConfigsConstants.java
index 86ff6ed2..7122e23b 100644
--- a/device-communication/src/main/java/org/eclipse/hono/communication/api/config/DeviceConfigsConstants.java
+++ b/device-communication/src/main/java/org/eclipse/hono/communication/api/config/DeviceConfigsConstants.java
@@ -21,33 +21,24 @@
  */
 public final class DeviceConfigsConstants {
 
+    public static ApiCommonConstants API_COMMON;
     /**
      * OpenApi GET device configs operation id.
      */
     public static final String LIST_CONFIG_VERSIONS_OP_ID = "listConfigVersions";
-    /**
-     * Path parameter name for tenantId.
-     */
-    public static final String TENANT_PATH_PARAMS = "tenantid";
-    /**
-     * Path parameter name for deviceId.
-     */
-    public static final String DEVICE_PATH_PARAMS = "deviceid";
     /**
      * Path parameter name for number of versions.
      */
     public static final String NUM_VERSION_QUERY_PARAMS = "numVersions";
-
     /**
      * Sql migrations script path.
      */
-    public static final String CREATE_SQL_SCRIPT_PATH = "db/create_device_config_table.sql";
+    public static final String CREATE_SQL_SCRIPT_PATH = "db/v1_create_config_table.sql";
     /**
      * OpenApi POST device configs operation id.
      */
     public static final String POST_MODIFY_DEVICE_CONFIG_OP_ID = "modifyCloudToDeviceConfig";
 
     private DeviceConfigsConstants() {
-        // avoid instantiation
     }
 }
diff --git a/device-communication/src/main/java/org/eclipse/hono/communication/api/config/DeviceStatesConstants.java b/device-communication/src/main/java/org/eclipse/hono/communication/api/config/DeviceStatesConstants.java
new file mode 100644
index 00000000..f70cc710
--- /dev/null
+++ b/device-communication/src/main/java/org/eclipse/hono/communication/api/config/DeviceStatesConstants.java
@@ -0,0 +1,42 @@
+/*
+ * ***********************************************************
+ *  Copyright (c) 2023 Contributors to the Eclipse Foundation
+ *  <p>
+ *  See the NOTICE file(s) distributed with this work for additional
+ *  information regarding copyright ownership.
+ *  <p>
+ *  This program and the accompanying materials are made available under the
+ *  terms of the Eclipse Public License 2.0 which is available at
+ *  http://www.eclipse.org/legal/epl-2.0
+ *  <p>
+ *  SPDX-License-Identifier: EPL-2.0
+ * **********************************************************
+ *
+ */
+
+package org.eclipse.hono.communication.api.config;
+
+/**
+ * Device states constant values.
+ */
+public final class DeviceStatesConstants {
+
+    public static ApiCommonConstants API_COMMON;
+    /**
+     * OpenApi GET device states operation id.
+     */
+    public static final String LIST_STATES_OP_ID = "listStates";
+    /**
+     * Path parameter name for number of states.
+     */
+
+    public static final String NUM_STATES_QUERY_PARAMS = "numStates";
+    /**
+     * Sql migrations script path.
+     */
+    public static final String CREATE_SQL_SCRIPT_PATH = "db/v1_create_state_table.sql";
+
+    private DeviceStatesConstants() {
+        // avoid instantiation
+    }
+}
diff --git a/device-communication/src/main/java/org/eclipse/hono/communication/api/data/DeviceConfig.java b/device-communication/src/main/java/org/eclipse/hono/communication/api/data/DeviceConfig.java
index 47425745..6f24e780 100644
--- a/device-communication/src/main/java/org/eclipse/hono/communication/api/data/DeviceConfig.java
+++ b/device-communication/src/main/java/org/eclipse/hono/communication/api/data/DeviceConfig.java
@@ -21,8 +21,6 @@
 import com.fasterxml.jackson.annotation.JsonInclude;
 import com.fasterxml.jackson.annotation.JsonProperty;
 
-
-
 /**
  * The device configuration.
  **/
diff --git a/device-communication/src/main/java/org/eclipse/hono/communication/api/data/DeviceConfigEntity.java b/device-communication/src/main/java/org/eclipse/hono/communication/api/data/DeviceConfigEntity.java
index 186ccc44..14b4ab5b 100644
--- a/device-communication/src/main/java/org/eclipse/hono/communication/api/data/DeviceConfigEntity.java
+++ b/device-communication/src/main/java/org/eclipse/hono/communication/api/data/DeviceConfigEntity.java
@@ -18,6 +18,8 @@
 
 import java.util.Objects;
 
+import com.fasterxml.jackson.annotation.JsonProperty;
+
 /**
  * The device configuration entity object.
  **/
@@ -31,6 +33,7 @@ public class DeviceConfigEntity {
     private String cloudUpdateTime;
     private String deviceAckTime;
     private String binaryData;
+    private String deviceAckError;
 
 
     /**
@@ -48,47 +51,66 @@ public void setVersion(final int version) {
         this.version = version;
     }
 
+    @JsonProperty("tenantId")
     public String getTenantId() {
         return tenantId;
     }
 
+    @JsonProperty("tenant_id")
     public void setTenantId(final String tenantId) {
         this.tenantId = tenantId;
     }
 
+    @JsonProperty("deviceId")
     public String getDeviceId() {
         return deviceId;
     }
 
+    @JsonProperty("device_id")
     public void setDeviceId(final String deviceId) {
         this.deviceId = deviceId;
     }
 
-
+    @JsonProperty("cloudUpdateTime")
     public String getCloudUpdateTime() {
         return cloudUpdateTime;
     }
 
+    @JsonProperty("cloud_update_time")
     public void setCloudUpdateTime(final String cloudUpdateTime) {
         this.cloudUpdateTime = cloudUpdateTime;
     }
 
+    @JsonProperty("deviceAckTime")
     public String getDeviceAckTime() {
         return deviceAckTime;
     }
 
+    @JsonProperty("device_ack_time")
     public void setDeviceAckTime(final String deviceAckTime) {
         this.deviceAckTime = deviceAckTime;
     }
 
+    @JsonProperty("binaryData")
     public String getBinaryData() {
         return binaryData;
     }
 
+    @JsonProperty("binary_data")
     public void setBinaryData(final String binaryData) {
         this.binaryData = binaryData;
     }
 
+    @JsonProperty("device_ack_error")
+    public String getDeviceAckError() {
+        return deviceAckError;
+    }
+
+    @JsonProperty("device_ack_error")
+    public void setDeviceAckError(final String deviceAckError) {
+        this.deviceAckError = deviceAckError;
+    }
+
 
     @Override
     public String toString() {
@@ -99,6 +121,7 @@ public String toString() {
                 ", cloudUpdateTime='" + cloudUpdateTime + '\'' +
                 ", deviceAckTime='" + deviceAckTime + '\'' +
                 ", binaryData='" + binaryData + '\'' +
+                ", device_ack_error='" + deviceAckError + '\'' +
                 '}';
     }
 
@@ -111,12 +134,12 @@ public boolean equals(final Object o) {
             return false;
         }
         final var that = (DeviceConfigEntity) o;
-        return version == that.version && tenantId.equals(that.tenantId) && deviceId.equals(that.deviceId) && cloudUpdateTime.equals(that.cloudUpdateTime) && Objects.equals(deviceAckTime, that.deviceAckTime) && binaryData.equals(that.binaryData);
+        return version == that.version && tenantId.equals(that.tenantId) && deviceId.equals(that.deviceId) && cloudUpdateTime.equals(that.cloudUpdateTime) && Objects.equals(deviceAckTime, that.deviceAckTime) && binaryData.equals(that.binaryData) && deviceAckError.equals(that.deviceAckError);
     }
 
     @Override
     public int hashCode() {
-        return Objects.hash(version, tenantId, deviceId, cloudUpdateTime, deviceAckTime, binaryData);
+        return Objects.hash(version, tenantId, deviceId, cloudUpdateTime, deviceAckTime, binaryData, deviceAckError);
     }
 
 
diff --git a/device-communication/src/main/java/org/eclipse/hono/communication/api/data/DeviceConfigInternalResponse.java b/device-communication/src/main/java/org/eclipse/hono/communication/api/data/DeviceConfigInternalResponse.java
new file mode 100644
index 00000000..d5a93246
--- /dev/null
+++ b/device-communication/src/main/java/org/eclipse/hono/communication/api/data/DeviceConfigInternalResponse.java
@@ -0,0 +1,121 @@
+/*
+ * ***********************************************************
+ *  Copyright (c) 2023 Contributors to the Eclipse Foundation
+ *  <p>
+ *  See the NOTICE file(s) distributed with this work for additional
+ *  information regarding copyright ownership.
+ *  <p>
+ *  This program and the accompanying materials are made available under the
+ *  terms of the Eclipse Public License 2.0 which is available at
+ *  http://www.eclipse.org/legal/epl-2.0
+ *  <p>
+ *  SPDX-License-Identifier: EPL-2.0
+ * **********************************************************
+ *
+ */
+
+package org.eclipse.hono.communication.api.data;
+
+import java.util.Objects;
+
+import com.fasterxml.jackson.annotation.JsonInclude;
+import com.fasterxml.jackson.annotation.JsonProperty;
+
+/**
+ * Device config response object.
+ */
+@JsonInclude(JsonInclude.Include.NON_NULL)
+public class DeviceConfigInternalResponse {
+
+    private String version;
+    private String tenantId;
+    private String deviceId;
+    private String deviceAckError;
+
+    /**
+     * Creates a new DeviceConfigInternalResponse.
+     */
+    public DeviceConfigInternalResponse() {
+    }
+
+    /**
+     * Creates a new DeviceConfigInternalResponse.
+     *
+     * @param tenantId Tenant id
+     * @param deviceId Device id
+     * @param version Device config version
+     * @param deviceAckError Device acknowledgement error
+     */
+    public DeviceConfigInternalResponse(final String tenantId, final String deviceId, final String version,
+            final String deviceAckError) {
+        this.version = version;
+        this.tenantId = tenantId;
+        this.deviceId = deviceId;
+        this.deviceAckError = deviceAckError;
+    }
+
+    @JsonProperty("version")
+    public String getVersion() {
+        return version;
+    }
+
+    public void setVersion(final String version) {
+        this.version = version;
+    }
+
+    @JsonProperty("tenantId")
+    public String getTenantId() {
+        return tenantId;
+    }
+
+    public void setTenantId(final String tenantId) {
+        this.tenantId = tenantId;
+    }
+
+    @JsonProperty("deviceId")
+    public String getDeviceId() {
+        return deviceId;
+    }
+
+    public void setDeviceId(final String deviceId) {
+        this.deviceId = deviceId;
+    }
+
+    @JsonProperty("device_ack_error")
+    public String getDeviceAckError() {
+        return deviceAckError;
+    }
+
+    public void setDeviceAckError(final String deviceAckError) {
+        this.deviceAckError = deviceAckError;
+    }
+
+    @Override
+    public String toString() {
+        return "DeviceConfigAckResponse{" +
+                "version='" + version + '\'' +
+                ", tenantId='" + tenantId + '\'' +
+                ", deviceId='" + deviceId + '\'' +
+                ", device_ack_error='" + deviceAckError + '\'' +
+                '}';
+    }
+
+    @Override
+    public boolean equals(final Object o) {
+        if (this == o) {
+            return true;
+        }
+        if (o == null || getClass() != o.getClass()) {
+            return false;
+        }
+        final DeviceConfigInternalResponse that = (DeviceConfigInternalResponse) o;
+        return version.equals(that.version) && tenantId.equals(that.tenantId) && deviceId.equals(that.deviceId)
+                && deviceAckError.equals(that.deviceAckError);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(version, tenantId, deviceId, deviceAckError);
+    }
+
+}
diff --git a/device-communication/src/main/java/org/eclipse/hono/communication/api/data/DeviceState.java b/device-communication/src/main/java/org/eclipse/hono/communication/api/data/DeviceState.java
new file mode 100644
index 00000000..1c063272
--- /dev/null
+++ b/device-communication/src/main/java/org/eclipse/hono/communication/api/data/DeviceState.java
@@ -0,0 +1,106 @@
+/*
+ * ***********************************************************
+ *  Copyright (c) 2023 Contributors to the Eclipse Foundation
+ *  <p>
+ *  See the NOTICE file(s) distributed with this work for additional
+ *  information regarding copyright ownership.
+ *  <p>
+ *  This program and the accompanying materials are made available under the
+ *  terms of the Eclipse Public License 2.0 which is available at
+ *  http://www.eclipse.org/legal/epl-2.0
+ *  <p>
+ *  SPDX-License-Identifier: EPL-2.0
+ * **********************************************************
+ *
+ */
+
+package org.eclipse.hono.communication.api.data;
+
+import java.util.Objects;
+
+import com.fasterxml.jackson.annotation.JsonInclude;
+import com.fasterxml.jackson.annotation.JsonProperty;
+
+/**
+ * The device state.
+ **/
+@JsonInclude(JsonInclude.Include.NON_NULL)
+public class DeviceState {
+
+    private String updateTime;
+    private String binaryData;
+
+    /**
+     * Creates a new device state.
+     */
+    public DeviceState() {
+    }
+
+    /**
+     * Creates a new device state.
+     *
+     * @param updateTime Cloud update time
+     * @param binaryData Binary data
+     */
+    public DeviceState(final String updateTime, final String binaryData) {
+        this.updateTime = updateTime;
+        this.binaryData = binaryData;
+    }
+
+    @JsonProperty("updateTime")
+    public String getUpdateTime() {
+        return updateTime;
+    }
+
+    @JsonProperty("update_time")
+    public void setUpdateTime(final String updateTime) {
+        this.updateTime = updateTime;
+    }
+
+    @JsonProperty("binaryData")
+    public String getBinaryData() {
+        return binaryData;
+    }
+
+    @JsonProperty("binary_data")
+    public void setBinaryData(final String binaryData) {
+        this.binaryData = binaryData;
+    }
+
+    @Override
+    public boolean equals(final Object o) {
+        if (this == o) {
+            return true;
+        }
+        if (o == null || getClass() != o.getClass()) {
+            return false;
+        }
+        final DeviceState deviceState = (DeviceState) o;
+        return Objects.equals(updateTime, deviceState.updateTime) &&
+                Objects.equals(binaryData, deviceState.binaryData);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(updateTime, binaryData);
+    }
+
+    @Override
+    public String toString() {
+
+        return "class DeviceState {\n" +
+                "    updateTime: " + toIndentedString(updateTime) + "\n" +
+                "    binaryData: " + toIndentedString(binaryData) + "\n" +
+                "}";
+    }
+
+    /**
+     * Convert the given object to string with each line indented by 4 spaces (except the first line).
+     */
+    private String toIndentedString(final Object o) {
+        if (o == null) {
+            return "null";
+        }
+        return o.toString().replace("\n", "\n    ");
+    }
+}
diff --git a/device-communication/src/main/java/org/eclipse/hono/communication/api/data/DeviceStateEntity.java b/device-communication/src/main/java/org/eclipse/hono/communication/api/data/DeviceStateEntity.java
new file mode 100644
index 00000000..cbf7c976
--- /dev/null
+++ b/device-communication/src/main/java/org/eclipse/hono/communication/api/data/DeviceStateEntity.java
@@ -0,0 +1,107 @@
+/*
+ * ***********************************************************
+ *  Copyright (c) 2023 Contributors to the Eclipse Foundation
+ *  <p>
+ *  See the NOTICE file(s) distributed with this work for additional
+ *  information regarding copyright ownership.
+ *  <p>
+ *  This program and the accompanying materials are made available under the
+ *  terms of the Eclipse Public License 2.0 which is available at
+ *  http://www.eclipse.org/legal/epl-2.0
+ *  <p>
+ *  SPDX-License-Identifier: EPL-2.0
+ * **********************************************************
+ *
+ */
+
+package org.eclipse.hono.communication.api.data;
+
+import java.util.Objects;
+
+import com.fasterxml.jackson.annotation.JsonProperty;
+
+/**
+ * The device state entity object.
+ **/
+public class DeviceStateEntity {
+
+    private String id;
+    private String tenantId;
+    private String deviceId;
+    private String updateTime;
+    private String binaryData;
+
+    public String getId() {
+        return id;
+    }
+
+    public void setId(final String id) {
+        this.id = id;
+    }
+
+    public String getTenantId() {
+        return tenantId;
+    }
+
+    public void setTenantId(final String tenantId) {
+        this.tenantId = tenantId;
+    }
+
+    public String getDeviceId() {
+        return deviceId;
+    }
+
+    public void setDeviceId(final String deviceId) {
+        this.deviceId = deviceId;
+    }
+
+    @JsonProperty("updateTime")
+    public String getUpdateTime() {
+        return updateTime;
+    }
+
+    @JsonProperty("update_time")
+    public void setUpdateTime(final String updateTime) {
+        this.updateTime = updateTime;
+    }
+
+    @JsonProperty("binaryData")
+    public String getBinaryData() {
+        return binaryData;
+    }
+
+    @JsonProperty("binary_data")
+    public void setBinaryData(final String binaryData) {
+        this.binaryData = binaryData;
+    }
+
+    @Override
+    public String toString() {
+        return "DeviceStateEntity{" +
+                "id=" + id +
+                ", tenantId='" + tenantId + '\'' +
+                ", deviceId='" + deviceId + '\'' +
+                ", updateTime='" + updateTime + '\'' +
+                ", binaryData='" + binaryData + '\'' +
+                '}';
+    }
+
+    @Override
+    public boolean equals(final Object o) {
+        if (this == o) {
+            return true;
+        }
+        if (o == null || getClass() != o.getClass()) {
+            return false;
+        }
+        final DeviceStateEntity that = (DeviceStateEntity) o;
+        return id.equals(that.id) && tenantId.equals(that.tenantId) && deviceId.equals(that.deviceId)
+                && updateTime.equals(that.updateTime) && binaryData.equals(that.binaryData);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(id, tenantId, deviceId, updateTime, binaryData);
+    }
+
+}
diff --git a/device-communication/src/main/java/org/eclipse/hono/communication/api/data/ListDeviceStatesResponse.java b/device-communication/src/main/java/org/eclipse/hono/communication/api/data/ListDeviceStatesResponse.java
new file mode 100644
index 00000000..50f36280
--- /dev/null
+++ b/device-communication/src/main/java/org/eclipse/hono/communication/api/data/ListDeviceStatesResponse.java
@@ -0,0 +1,90 @@
+/*
+ * ***********************************************************
+ *  Copyright (c) 2023 Contributors to the Eclipse Foundation
+ *  <p>
+ *  See the NOTICE file(s) distributed with this work for additional
+ *  information regarding copyright ownership.
+ *  <p>
+ *  This program and the accompanying materials are made available under the
+ *  terms of the Eclipse Public License 2.0 which is available at
+ *  http://www.eclipse.org/legal/epl-2.0
+ *  <p>
+ *  SPDX-License-Identifier: EPL-2.0
+ * **********************************************************
+ *
+ */
+
+package org.eclipse.hono.communication.api.data;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Objects;
+
+import com.fasterxml.jackson.annotation.JsonProperty;
+
+/**
+ * A list of a device states.
+ **/
+public class ListDeviceStatesResponse {
+
+    private List<DeviceState> deviceStates = new ArrayList<>();
+
+    /**
+     * Creates a new ListDeviceStatesResponse.
+     */
+    public ListDeviceStatesResponse() {
+    }
+
+    /**
+     * Creates a new ListDeviceStatesResponse.
+     *
+     * @param deviceStates The device states
+     */
+    public ListDeviceStatesResponse(final List<DeviceState> deviceStates) {
+        this.deviceStates = deviceStates;
+    }
+
+    @JsonProperty("deviceStates")
+    public List<DeviceState> getDeviceStates() {
+        return deviceStates;
+    }
+
+    public void setDeviceStates(final List<DeviceState> deviceStates) {
+        this.deviceStates = deviceStates;
+    }
+
+    @Override
+    public boolean equals(final Object o) {
+        if (this == o) {
+            return true;
+        }
+        if (o == null || getClass() != o.getClass()) {
+            return false;
+        }
+        final var listDeviceStatesResponse = (ListDeviceStatesResponse) o;
+        return Objects.equals(deviceStates, listDeviceStatesResponse.deviceStates);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(deviceStates);
+    }
+
+    @Override
+    public String toString() {
+
+        return "class ListDeviceStatesResponse {\n" +
+                "    deviceStates: " + toIndentedString(deviceStates) + "\n" +
+                "}";
+    }
+
+    /**
+     * Convert the given object to string with each line indented by 4 spaces (except the first line).
+     */
+    private String toIndentedString(final Object o) {
+        if (o == null) {
+            return "null";
+        }
+        return o.toString().replace("\n", "\n    ");
+    }
+}
diff --git a/device-communication/src/main/java/org/eclipse/hono/communication/api/handler/ConfigTopicEventHandler.java b/device-communication/src/main/java/org/eclipse/hono/communication/api/handler/ConfigTopicEventHandler.java
new file mode 100644
index 00000000..e547df2e
--- /dev/null
+++ b/device-communication/src/main/java/org/eclipse/hono/communication/api/handler/ConfigTopicEventHandler.java
@@ -0,0 +1,43 @@
+/*
+ * ***********************************************************
+ *  Copyright (c) 2023 Contributors to the Eclipse Foundation
+ *  <p>
+ *  See the NOTICE file(s) distributed with this work for additional
+ *  information regarding copyright ownership.
+ *  <p>
+ *  This program and the accompanying materials are made available under the
+ *  terms of the Eclipse Public License 2.0 which is available at
+ *  http://www.eclipse.org/legal/epl-2.0
+ *  <p>
+ *  SPDX-License-Identifier: EPL-2.0
+ * **********************************************************
+ *
+ */
+
+package org.eclipse.hono.communication.api.handler;
+
+import com.google.cloud.pubsub.v1.AckReplyConsumer;
+import com.google.pubsub.v1.PubsubMessage;
+
+/**
+ * Config topic event handler interface.
+ */
+public interface ConfigTopicEventHandler {
+
+    /**
+     * Handle incoming config send requests.
+     *
+     * @param pubsubMessage The message to handle
+     * @param consumer      The message consumer
+     */
+    void onDeviceConfigRequest(PubsubMessage pubsubMessage, AckReplyConsumer consumer);
+
+    /**
+     * Handle incoming config response message.
+     *
+     * @param pubsubMessage The message to handle
+     * @param consumer      The message consumer
+     */
+
+    void onDeviceConfigResponse(PubsubMessage pubsubMessage, AckReplyConsumer consumer);
+}
diff --git a/device-communication/src/main/java/org/eclipse/hono/communication/api/handler/DeviceConfigsHandler.java b/device-communication/src/main/java/org/eclipse/hono/communication/api/handler/DeviceConfigsHandler.java
index a1649e23..05ac2cc0 100644
--- a/device-communication/src/main/java/org/eclipse/hono/communication/api/handler/DeviceConfigsHandler.java
+++ b/device-communication/src/main/java/org/eclipse/hono/communication/api/handler/DeviceConfigsHandler.java
@@ -22,7 +22,7 @@
 import org.eclipse.hono.communication.api.data.DeviceConfig;
 import org.eclipse.hono.communication.api.data.DeviceConfigRequest;
 import org.eclipse.hono.communication.api.data.ListDeviceConfigVersionsResponse;
-import org.eclipse.hono.communication.api.service.DeviceConfigService;
+import org.eclipse.hono.communication.api.service.config.DeviceConfigService;
 import org.eclipse.hono.communication.core.http.HttpEndpointHandler;
 import org.eclipse.hono.communication.core.utils.ResponseUtils;
 
@@ -31,8 +31,6 @@
 import io.vertx.ext.web.openapi.RouterBuilder;
 
 
-
-
 /**
  * Handler for device config endpoints.
  */
@@ -66,8 +64,8 @@ public void addRoutes(final RouterBuilder routerBuilder) {
      * @return Future of DeviceConfig
      */
     public Future<DeviceConfig> handleModifyCloudToDeviceConfig(final RoutingContext routingContext) {
-        final var tenantId = routingContext.pathParam(DeviceConfigsConstants.TENANT_PATH_PARAMS);
-        final var deviceId = routingContext.pathParam(DeviceConfigsConstants.DEVICE_PATH_PARAMS);
+        final var tenantId = routingContext.pathParam(DeviceConfigsConstants.API_COMMON.TENANT_PATH_PARAMS);
+        final var deviceId = routingContext.pathParam(DeviceConfigsConstants.API_COMMON.DEVICE_PATH_PARAMS);
 
         final DeviceConfigRequest deviceConfig = routingContext.body()
                 .asJsonObject()
@@ -88,8 +86,8 @@ public Future<ListDeviceConfigVersionsResponse> handleListConfigVersions(final R
         final var numVersions = routingContext.queryParams().get(DeviceConfigsConstants.NUM_VERSION_QUERY_PARAMS);
 
         final var limit = numVersions == null ? 0 : Integer.parseInt(numVersions);
-        final var tenantId = routingContext.pathParam(DeviceConfigsConstants.TENANT_PATH_PARAMS);
-        final var deviceId = routingContext.pathParam(DeviceConfigsConstants.DEVICE_PATH_PARAMS);
+        final var tenantId = routingContext.pathParam(DeviceConfigsConstants.API_COMMON.TENANT_PATH_PARAMS);
+        final var deviceId = routingContext.pathParam(DeviceConfigsConstants.API_COMMON.DEVICE_PATH_PARAMS);
 
         return configService.listAll(deviceId, tenantId, limit)
                 .onSuccess(result -> ResponseUtils.successResponse(routingContext, result))
diff --git a/device-communication/src/main/java/org/eclipse/hono/communication/api/handler/DeviceStatesHandler.java b/device-communication/src/main/java/org/eclipse/hono/communication/api/handler/DeviceStatesHandler.java
new file mode 100644
index 00000000..c1c6c8f3
--- /dev/null
+++ b/device-communication/src/main/java/org/eclipse/hono/communication/api/handler/DeviceStatesHandler.java
@@ -0,0 +1,70 @@
+/*
+ * ***********************************************************
+ *  Copyright (c) 2023 Contributors to the Eclipse Foundation
+ *  <p>
+ *  See the NOTICE file(s) distributed with this work for additional
+ *  information regarding copyright ownership.
+ *  <p>
+ *  This program and the accompanying materials are made available under the
+ *  terms of the Eclipse Public License 2.0 which is available at
+ *  http://www.eclipse.org/legal/epl-2.0
+ *  <p>
+ *  SPDX-License-Identifier: EPL-2.0
+ * **********************************************************
+ *
+ */
+
+package org.eclipse.hono.communication.api.handler;
+
+import javax.enterprise.context.ApplicationScoped;
+
+import org.eclipse.hono.communication.api.config.DeviceStatesConstants;
+import org.eclipse.hono.communication.api.data.ListDeviceStatesResponse;
+import org.eclipse.hono.communication.api.service.state.DeviceStateService;
+import org.eclipse.hono.communication.core.http.HttpEndpointHandler;
+import org.eclipse.hono.communication.core.utils.ResponseUtils;
+
+import io.vertx.core.Future;
+import io.vertx.ext.web.RoutingContext;
+import io.vertx.ext.web.openapi.RouterBuilder;
+
+/**
+ * Handler for device state endpoints.
+ */
+@ApplicationScoped
+public class DeviceStatesHandler implements HttpEndpointHandler {
+
+    private final DeviceStateService stateService;
+
+    /**
+     * Creates a new DeviceStatesHandler.
+     *
+     * @param stateService The device states service.
+     */
+    public DeviceStatesHandler(final DeviceStateService stateService) {
+        this.stateService = stateService;
+    }
+
+    @Override
+    public void addRoutes(final RouterBuilder routerBuilder) {
+        routerBuilder.operation(DeviceStatesConstants.LIST_STATES_OP_ID).handler(this::handleListStates);
+    }
+
+    /**
+     * Handles get device states.
+     *
+     * @param routingContext The RoutingContext
+     * @return Future of ListDeviceStatesResponse
+     */
+    public Future<ListDeviceStatesResponse> handleListStates(final RoutingContext routingContext) {
+        final var numStates = routingContext.queryParams().get(DeviceStatesConstants.NUM_STATES_QUERY_PARAMS);
+
+        final var limit = numStates == null ? 0 : Integer.parseInt(numStates);
+        final var tenantId = routingContext.pathParam(DeviceStatesConstants.API_COMMON.TENANT_PATH_PARAMS);
+        final var deviceId = routingContext.pathParam(DeviceStatesConstants.API_COMMON.DEVICE_PATH_PARAMS);
+
+        return stateService.listAll(deviceId, tenantId, limit)
+                .onSuccess(result -> ResponseUtils.successResponse(routingContext, result))
+                .onFailure(err -> ResponseUtils.errorResponse(routingContext, err));
+    }
+}
diff --git a/device-communication/src/main/java/org/eclipse/hono/communication/api/handler/StateTopicEventHandler.java b/device-communication/src/main/java/org/eclipse/hono/communication/api/handler/StateTopicEventHandler.java
new file mode 100644
index 00000000..3c75c101
--- /dev/null
+++ b/device-communication/src/main/java/org/eclipse/hono/communication/api/handler/StateTopicEventHandler.java
@@ -0,0 +1,35 @@
+/*
+ * ***********************************************************
+ *  Copyright (c) 2023 Contributors to the Eclipse Foundation
+ *  <p>
+ *  See the NOTICE file(s) distributed with this work for additional
+ *  information regarding copyright ownership.
+ *  <p>
+ *  This program and the accompanying materials are made available under the
+ *  terms of the Eclipse Public License 2.0 which is available at
+ *  http://www.eclipse.org/legal/epl-2.0
+ *  <p>
+ *  SPDX-License-Identifier: EPL-2.0
+ * **********************************************************
+ *
+ */
+
+package org.eclipse.hono.communication.api.handler;
+
+
+import com.google.cloud.pubsub.v1.AckReplyConsumer;
+import com.google.pubsub.v1.PubsubMessage;
+
+/**
+ * State topic event handler interface.
+ */
+public interface StateTopicEventHandler {
+
+    /**
+     * Handle incoming messages on state topics.
+     *
+     * @param pubsubMessage The message to handle.
+     * @param consumer The message consumer.
+     */
+    void onStateMessage(PubsubMessage pubsubMessage, AckReplyConsumer consumer);
+}
diff --git a/device-communication/src/main/java/org/eclipse/hono/communication/api/mapper/DeviceStateMapper.java b/device-communication/src/main/java/org/eclipse/hono/communication/api/mapper/DeviceStateMapper.java
new file mode 100644
index 00000000..b7d82b38
--- /dev/null
+++ b/device-communication/src/main/java/org/eclipse/hono/communication/api/mapper/DeviceStateMapper.java
@@ -0,0 +1,59 @@
+/*
+ * ***********************************************************
+ *  Copyright (c) 2023 Contributors to the Eclipse Foundation
+ *  <p>
+ *  See the NOTICE file(s) distributed with this work for additional
+ *  information regarding copyright ownership.
+ *  <p>
+ *  This program and the accompanying materials are made available under the
+ *  terms of the Eclipse Public License 2.0 which is available at
+ *  http://www.eclipse.org/legal/epl-2.0
+ *  <p>
+ *  SPDX-License-Identifier: EPL-2.0
+ * **********************************************************
+ *
+ */
+
+package org.eclipse.hono.communication.api.mapper;
+
+import java.time.Instant;
+
+import org.eclipse.hono.communication.api.data.DeviceState;
+import org.eclipse.hono.communication.api.data.DeviceStateEntity;
+import org.mapstruct.Mapper;
+import org.mapstruct.Mapping;
+import org.mapstruct.NullValuePropertyMappingStrategy;
+
+import com.google.pubsub.v1.PubsubMessage;
+
+/**
+ * Mapper for device state objects.
+ */
+@Mapper(componentModel = "cdi", nullValuePropertyMappingStrategy = NullValuePropertyMappingStrategy.IGNORE)
+public interface DeviceStateMapper {
+
+    /**
+     * Convert device state entity to device state.
+     *
+     * @param entity The device state entity
+     * @return The device state
+     */
+    DeviceState deviceStateEntityToDeviceState(DeviceStateEntity entity);
+
+    /**
+     * Convert Pub/Sub message to device state entity.
+     *
+     * @param pubsubMessage The Pub/Sub message.
+     * @return The device state entity.
+     */
+    @Mapping(target = "id", ignore = true)
+    @Mapping(target = "updateTime", expression = "java(getDateTime())")
+    @Mapping(target = "tenantId", expression = "java(pubsubMessage.getAttributesMap().get(\"tenantId\"))")
+    @Mapping(target = "deviceId", expression = "java(pubsubMessage.getAttributesMap().get(\"deviceId\"))")
+    @Mapping(target = "binaryData", expression = "java(pubsubMessage.getData().toStringUtf8())")
+    DeviceStateEntity pubSubMessageToDeviceStateEntity(PubsubMessage pubsubMessage);
+
+    default String getDateTime() {
+        return Instant.now().toString();
+    }
+}
diff --git a/device-communication/src/main/java/org/eclipse/hono/communication/api/repository/DeviceStateRepository.java b/device-communication/src/main/java/org/eclipse/hono/communication/api/repository/DeviceStateRepository.java
new file mode 100644
index 00000000..cb64ba5e
--- /dev/null
+++ b/device-communication/src/main/java/org/eclipse/hono/communication/api/repository/DeviceStateRepository.java
@@ -0,0 +1,48 @@
+/*
+ * ***********************************************************
+ *  Copyright (c) 2023 Contributors to the Eclipse Foundation
+ *  <p>
+ *  See the NOTICE file(s) distributed with this work for additional
+ *  information regarding copyright ownership.
+ *  <p>
+ *  This program and the accompanying materials are made available under the
+ *  terms of the Eclipse Public License 2.0 which is available at
+ *  http://www.eclipse.org/legal/epl-2.0
+ *  <p>
+ *  SPDX-License-Identifier: EPL-2.0
+ * **********************************************************
+ *
+ */
+
+package org.eclipse.hono.communication.api.repository;
+
+import java.util.List;
+
+import org.eclipse.hono.communication.api.data.DeviceState;
+import org.eclipse.hono.communication.api.data.DeviceStateEntity;
+
+import io.vertx.core.Future;
+
+/**
+ * Device state repository interface.
+ */
+public interface DeviceStateRepository {
+
+    /**
+     * Lists all states for a specific device. Result is ordered by version desc
+     *
+     * @param deviceId The device id
+     * @param tenantId The tenant id
+     * @param limit    The number of states to show
+     * @return A Future with a List of DeviceStates
+     */
+    Future<List<DeviceState>> listAll(String deviceId, String tenantId, int limit);
+
+    /**
+     * Creates a new state and deletes the oldest one if the total number of versions in the DB is bigger than the MAX_LIMIT.
+     *
+     * @param entity The instance to insert.
+     * @return A Future of the created DeviceStateEntity.
+     */
+    Future<DeviceStateEntity> createNew(DeviceStateEntity entity);
+}
diff --git a/device-communication/src/main/java/org/eclipse/hono/communication/api/repository/DeviceStateRepositoryImpl.java b/device-communication/src/main/java/org/eclipse/hono/communication/api/repository/DeviceStateRepositoryImpl.java
new file mode 100644
index 00000000..88f9b9cc
--- /dev/null
+++ b/device-communication/src/main/java/org/eclipse/hono/communication/api/repository/DeviceStateRepositoryImpl.java
@@ -0,0 +1,173 @@
+/*
+ * ***********************************************************
+ *  Copyright (c) 2023 Contributors to the Eclipse Foundation
+ *  <p>
+ *  See the NOTICE file(s) distributed with this work for additional
+ *  information regarding copyright ownership.
+ *  <p>
+ *  This program and the accompanying materials are made available under the
+ *  terms of the Eclipse Public License 2.0 which is available at
+ *  http://www.eclipse.org/legal/epl-2.0
+ *  <p>
+ *  SPDX-License-Identifier: EPL-2.0
+ * **********************************************************
+ *
+ */
+
+package org.eclipse.hono.communication.api.repository;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Map;
+import java.util.UUID;
+
+import javax.enterprise.context.ApplicationScoped;
+
+import org.eclipse.hono.communication.api.data.DeviceState;
+import org.eclipse.hono.communication.api.data.DeviceStateEntity;
+import org.eclipse.hono.communication.api.exception.DeviceNotFoundException;
+import org.eclipse.hono.communication.api.service.database.DatabaseService;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import io.vertx.core.Future;
+import io.vertx.sqlclient.RowIterator;
+import io.vertx.sqlclient.SqlConnection;
+import io.vertx.sqlclient.templates.RowMapper;
+import io.vertx.sqlclient.templates.SqlTemplate;
+
+/**
+ * Repository class for making CRUD operations for device state entities.
+ */
+@ApplicationScoped
+public class DeviceStateRepositoryImpl implements DeviceStateRepository {
+
+    private static final Logger log = LoggerFactory.getLogger(DeviceStateRepositoryImpl.class);
+    private static final String SQL_COUNT_STATES_WITH_PK_FILTER = "SELECT COUNT(*) AS total FROM device_status WHERE tenant_id = #{tenantId} AND device_id = #{deviceId}";
+    private static final String SQL_INSERT = "INSERT INTO device_status (id, tenant_id, device_id, update_time, binary_data) "
+            +
+            "VALUES (#{id}, #{tenantId}, #{deviceId}, #{updateTime}, #{binaryData}) RETURNING id";
+    private static final String SQL_LIST = "SELECT update_time, binary_data FROM device_status " +
+            "WHERE device_id = #{deviceId} and tenant_id = #{tenantId} ORDER BY update_time DESC LIMIT #{limit}";
+
+    private static final String SQL_DELETE = "DELETE FROM device_status WHERE device_id = #{deviceId} AND tenant_id = #{tenantId} AND id NOT IN "
+            +
+            "(SELECT id FROM device_status WHERE device_id = #{deviceId} AND tenant_id = #{tenantId} ORDER BY update_time DESC LIMIT 9)";
+    private static final String DEVICE_ID_CAPTION = "deviceId";
+    private static final String TENANT_ID_CAPTION = "tenantId";
+    private static final int MAX_LIMIT = 10;
+    private final DatabaseService db;
+    private final DeviceRepository deviceRepository;
+
+    /**
+     * Creates a new DeviceStateRepositoryImpl.
+     *
+     * @param db The database connection
+     * @param deviceRepository The device repository interface
+     */
+    public DeviceStateRepositoryImpl(final DatabaseService db,
+            final DeviceRepository deviceRepository) {
+        this.db = db;
+        this.deviceRepository = deviceRepository;
+    }
+
+    @Override
+    public Future<List<DeviceState>> listAll(final String deviceId, final String tenantId, final int limit) {
+        final int queryLimit = limit == 0 ? MAX_LIMIT : limit;
+        return db.getDbClient().withConnection(
+                sqlConnection -> deviceRepository.searchForDevice(deviceId, tenantId)
+                        .compose(
+                                counter -> {
+                                    if (counter < 1) {
+                                        throw new DeviceNotFoundException(
+                                                String.format("Device with id %s and tenant id %s doesn't exist",
+                                                        deviceId,
+                                                        tenantId));
+                                    }
+                                    return SqlTemplate
+                                            .forQuery(sqlConnection, SQL_LIST)
+                                            .mapTo(DeviceStateEntity.class)
+                                            .execute(Map.of(DEVICE_ID_CAPTION, deviceId, TENANT_ID_CAPTION, tenantId, "limit",
+                                                    queryLimit))
+                                            .map(rowSet -> {
+                                                final List<DeviceState> states = new ArrayList<>();
+                                                rowSet.forEach(
+                                                        entity -> states.add(new DeviceState(entity.getUpdateTime(),
+                                                                entity.getBinaryData())));
+                                                return states;
+                                            })
+                                            .onSuccess(success -> log.debug(
+                                                    String.format("Listing all states for device %s and tenant %s",
+                                                            deviceId, tenantId)))
+                                            .onFailure(throwable -> log.error("Error: {}", throwable.getMessage()));
+                                }));
+    }
+
+    @Override
+    public Future<DeviceStateEntity> createNew(final DeviceStateEntity entity) {
+        return db.getDbClient().withTransaction(
+                sqlConnection -> deviceRepository.searchForDevice(entity.getDeviceId(), entity.getTenantId())
+                        .compose(
+                                deviceCounter -> {
+                                    if (deviceCounter < 1) {
+                                        throw new DeviceNotFoundException(
+                                                String.format(
+                                                        "Device with id %s and tenant id %s doesn't exist",
+                                                        entity.getDeviceId(),
+                                                        entity.getTenantId()));
+                                    }
+                                    return countStates(entity.getDeviceId(), entity.getTenantId()).compose(
+                                            stateCounter -> {
+                                                if (stateCounter >= 10) {
+                                                    deleteStates(sqlConnection, entity);
+                                                }
+                                                return insert(sqlConnection, entity);
+                                            });
+                                })
+                        .onFailure(error -> log.error(error.getMessage())));
+    }
+
+    private Future<Integer> countStates(final String deviceId, final String tenantId) {
+        final RowMapper<Integer> rowMapper = row -> row.getInteger("total");
+        return db.getDbClient().withConnection(
+                sqlConnection -> SqlTemplate
+                        .forQuery(sqlConnection, SQL_COUNT_STATES_WITH_PK_FILTER)
+                        .mapTo(rowMapper)
+                        .execute(Map.of(DEVICE_ID_CAPTION, deviceId, TENANT_ID_CAPTION, tenantId)).map(rowSet -> {
+                            final RowIterator<Integer> iterator = rowSet.iterator();
+                            return iterator.next();
+                        }));
+    }
+
+    private void deleteStates(final SqlConnection sqlConnection, final DeviceStateEntity entity) {
+        SqlTemplate.forQuery(sqlConnection, SQL_DELETE)
+                .execute(Map.of(DEVICE_ID_CAPTION, entity.getDeviceId(), TENANT_ID_CAPTION, entity.getTenantId()));
+    }
+
+    /**
+     * Inserts a new entity in to the db.
+     *
+     * @param sqlConnection The sql connection instance.
+     * @param entity The instance to insert.
+     * @return A Future of the created DeviceStateEntity.
+     */
+    private Future<DeviceStateEntity> insert(final SqlConnection sqlConnection, final DeviceStateEntity entity) {
+        entity.setId(UUID.randomUUID().toString());
+        return SqlTemplate
+                .forUpdate(sqlConnection, SQL_INSERT)
+                .mapFrom(DeviceStateEntity.class)
+                .mapTo(DeviceStateEntity.class)
+                .execute(entity)
+                .map(rowSet -> {
+                    final RowIterator<DeviceStateEntity> iterator = rowSet.iterator();
+                    if (iterator.hasNext()) {
+                        return entity;
+                    } else {
+                        throw new IllegalStateException(String.format("Can't create device state: %s", entity));
+                    }
+                })
+                .onSuccess(success -> log.debug("Device state created successfully: {}", success))
+                .onFailure(throwable -> log.error(throwable.getMessage()));
+
+    }
+}
diff --git a/device-communication/src/main/java/org/eclipse/hono/communication/api/service/DeviceConfigServiceImpl.java b/device-communication/src/main/java/org/eclipse/hono/communication/api/service/DeviceConfigServiceImpl.java
deleted file mode 100644
index a8abca20..00000000
--- a/device-communication/src/main/java/org/eclipse/hono/communication/api/service/DeviceConfigServiceImpl.java
+++ /dev/null
@@ -1,84 +0,0 @@
-/*
- * ***********************************************************
- *  Copyright (c) 2023 Contributors to the Eclipse Foundation
- *  <p>
- *  See the NOTICE file(s) distributed with this work for additional
- *  information regarding copyright ownership.
- *  <p>
- *  This program and the accompanying materials are made available under the
- *  terms of the Eclipse Public License 2.0 which is available at
- *  http://www.eclipse.org/legal/epl-2.0
- *  <p>
- *  SPDX-License-Identifier: EPL-2.0
- * **********************************************************
- *
- */
-
-package org.eclipse.hono.communication.api.service;
-
-import javax.enterprise.context.ApplicationScoped;
-
-import org.eclipse.hono.communication.api.data.DeviceConfig;
-import org.eclipse.hono.communication.api.data.DeviceConfigRequest;
-import org.eclipse.hono.communication.api.data.ListDeviceConfigVersionsResponse;
-import org.eclipse.hono.communication.api.mapper.DeviceConfigMapper;
-import org.eclipse.hono.communication.api.repository.DeviceConfigsRepository;
-
-import io.vertx.core.Future;
-
-/**
- * Service for device commands.
- */
-
-@ApplicationScoped
-public class DeviceConfigServiceImpl implements DeviceConfigService {
-
-    private final DeviceConfigsRepository repository;
-    private final DatabaseService db;
-    private final DeviceConfigMapper mapper;
-
-    /**
-     * Creates a new DeviceConfigServiceImpl with all dependencies.
-     *
-     * @param repository The DeviceConfigsRepository
-     * @param db         The database service
-     * @param mapper     The DeviceConfigMapper
-     */
-    public DeviceConfigServiceImpl(final DeviceConfigsRepository repository,
-                                   final DatabaseService db,
-                                   final DeviceConfigMapper mapper) {
-
-        this.repository = repository;
-        this.db = db;
-        this.mapper = mapper;
-    }
-
-    @Override
-    public Future<DeviceConfig> modifyCloudToDeviceConfig(final DeviceConfigRequest deviceConfig, final String deviceId, final String tenantId) {
-
-        final var entity = mapper.configRequestToDeviceConfigEntity(deviceConfig);
-        entity.setDeviceId(deviceId);
-        entity.setTenantId(tenantId);
-
-        return db.getDbClient().withTransaction(
-                        sqlConnection ->
-                                repository.createNew(sqlConnection, entity))
-                .map(mapper::deviceConfigEntityToConfig);
-    }
-
-
-    @Override
-    public Future<ListDeviceConfigVersionsResponse> listAll(final String deviceId, final String tenantId, final int limit) {
-        return db.getDbClient().withConnection(
-                sqlConnection -> repository.listAll(sqlConnection, deviceId, tenantId, limit)
-                        .map(
-                                result -> {
-                                    final var listConfig = new ListDeviceConfigVersionsResponse();
-                                    listConfig.setDeviceConfigs(result);
-                                    return listConfig;
-                                }
-                        )
-        );
-
-    }
-}
diff --git a/device-communication/src/main/java/org/eclipse/hono/communication/api/service/VertxHttpHandlerManagerService.java b/device-communication/src/main/java/org/eclipse/hono/communication/api/service/VertxHttpHandlerManagerService.java
index f7909951..ef1b5ac2 100644
--- a/device-communication/src/main/java/org/eclipse/hono/communication/api/service/VertxHttpHandlerManagerService.java
+++ b/device-communication/src/main/java/org/eclipse/hono/communication/api/service/VertxHttpHandlerManagerService.java
@@ -22,6 +22,7 @@
 
 import org.eclipse.hono.communication.api.handler.DeviceCommandHandler;
 import org.eclipse.hono.communication.api.handler.DeviceConfigsHandler;
+import org.eclipse.hono.communication.api.handler.DeviceStatesHandler;
 import org.eclipse.hono.communication.core.http.HttpEndpointHandler;
 
 
@@ -39,11 +40,12 @@ public class VertxHttpHandlerManagerService {
     /**
      * Creates a new  VertxHttpHandlerManagerService with all dependencies.
      *
-     * @param configHandler  The configuration handler
-     * @param commandHandler The command handler
+     * @param configHandler  The configuration handler.
+     * @param commandHandler The command handler.
+     * @param stateHandler The state handler.
      */
-    public VertxHttpHandlerManagerService(final DeviceConfigsHandler configHandler, final DeviceCommandHandler commandHandler) {
-        this.availableHandlerServices = List.of(configHandler, commandHandler);
+    public VertxHttpHandlerManagerService(final DeviceConfigsHandler configHandler, final DeviceCommandHandler commandHandler, final DeviceStatesHandler stateHandler) {
+        this.availableHandlerServices = List.of(configHandler, commandHandler, stateHandler);
     }
 
     public List<HttpEndpointHandler> getAvailableHandlerServices() {
diff --git a/device-communication/src/main/java/org/eclipse/hono/communication/api/service/DeviceCommandService.java b/device-communication/src/main/java/org/eclipse/hono/communication/api/service/communication/InternalTopicManager.java
similarity index 66%
rename from device-communication/src/main/java/org/eclipse/hono/communication/api/service/DeviceCommandService.java
rename to device-communication/src/main/java/org/eclipse/hono/communication/api/service/communication/InternalTopicManager.java
index 316d47b5..91b3b23e 100644
--- a/device-communication/src/main/java/org/eclipse/hono/communication/api/service/DeviceCommandService.java
+++ b/device-communication/src/main/java/org/eclipse/hono/communication/api/service/communication/InternalTopicManager.java
@@ -14,19 +14,15 @@
  *
  */
 
-package org.eclipse.hono.communication.api.service;
-
-import io.vertx.ext.web.RoutingContext;
+package org.eclipse.hono.communication.api.service.communication;
 
 /**
- * Device commands interface.
+ * Internal topic manager interface.
  */
-public interface DeviceCommandService {
+public interface InternalTopicManager {
 
     /**
-     * Post device command.
-     *
-     * @param routingContext The RoutingContext
+     * Initializes topics and subscriptions.
      */
-    void postCommand(RoutingContext routingContext);
+    void initPubSub();
 }
diff --git a/device-communication/src/main/java/org/eclipse/hono/communication/api/service/communication/InternalTopicManagerImpl.java b/device-communication/src/main/java/org/eclipse/hono/communication/api/service/communication/InternalTopicManagerImpl.java
new file mode 100644
index 00000000..62b36dac
--- /dev/null
+++ b/device-communication/src/main/java/org/eclipse/hono/communication/api/service/communication/InternalTopicManagerImpl.java
@@ -0,0 +1,187 @@
+/*
+ * ***********************************************************
+ *  Copyright (c) 2023 Contributors to the Eclipse Foundation
+ *  <p>
+ *  See the NOTICE file(s) distributed with this work for additional
+ *  information regarding copyright ownership.
+ *  <p>
+ *  This program and the accompanying materials are made available under the
+ *  terms of the Eclipse Public License 2.0 which is available at
+ *  http://www.eclipse.org/legal/epl-2.0
+ *  <p>
+ *  SPDX-License-Identifier: EPL-2.0
+ * **********************************************************
+ *
+ */
+
+package org.eclipse.hono.communication.api.service.communication;
+
+import java.util.List;
+
+import javax.enterprise.context.ApplicationScoped;
+
+import org.eclipse.hono.client.pubsub.PubSubBasedAdminClientManager;
+import org.eclipse.hono.client.pubsub.PubSubMessageHelper;
+import org.eclipse.hono.communication.api.config.PubSubConstants;
+import org.eclipse.hono.communication.api.handler.ConfigTopicEventHandler;
+import org.eclipse.hono.communication.api.handler.StateTopicEventHandler;
+import org.eclipse.hono.communication.api.repository.DeviceRepository;
+import org.eclipse.hono.communication.core.app.InternalMessagingConfig;
+import org.eclipse.hono.notification.deviceregistry.LifecycleChange;
+import org.eclipse.hono.notification.deviceregistry.TenantChangeNotification;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import com.fasterxml.jackson.core.JsonProcessingException;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import com.google.cloud.pubsub.v1.AckReplyConsumer;
+import com.google.common.base.Strings;
+import com.google.pubsub.v1.PubsubMessage;
+import com.google.pubsub.v1.SubscriptionName;
+import com.google.pubsub.v1.TopicName;
+
+import io.vertx.core.Vertx;
+
+/**
+ * Internal topic manager interface.
+ */
+@ApplicationScoped
+public class InternalTopicManagerImpl implements InternalTopicManager {
+
+    static ObjectMapper objectMapper = new ObjectMapper();
+    private final Logger log = LoggerFactory.getLogger(InternalTopicManagerImpl.class);
+    private final DeviceRepository deviceRepository;
+    private final ConfigTopicEventHandler configTopicEventHandler;
+    private final StateTopicEventHandler stateTopicEventHandler;
+    private final InternalMessaging internalMessaging;
+    private final InternalMessagingConfig internalMessagingConfig;
+    private final Vertx vertx;
+
+    /**
+     * Creates a new InternalTopicManagerImpl.
+     *
+     * @param deviceRepository        The device repository
+     * @param configTopicEventHandler The config topic event handler.
+     * @param stateTopicEventHandler  The state topic event handler.
+     * @param internalMessaging       The internal messaging interface.
+     * @param internalMessagingConfig The internal messaging config.
+     * @param vertx                   The quarkus Vertx instance.
+     */
+    public InternalTopicManagerImpl(final DeviceRepository deviceRepository,
+                                    final ConfigTopicEventHandler configTopicEventHandler,
+                                    final StateTopicEventHandler stateTopicEventHandler, final InternalMessaging internalMessaging,
+                                    final InternalMessagingConfig internalMessagingConfig, final Vertx vertx) {
+        this.deviceRepository = deviceRepository;
+        this.configTopicEventHandler = configTopicEventHandler;
+        this.stateTopicEventHandler = stateTopicEventHandler;
+        this.internalMessaging = internalMessaging;
+        this.internalMessagingConfig = internalMessagingConfig;
+        this.vertx = vertx;
+    }
+
+    @Override
+    public void initPubSub() {
+        log.info("Initialize tenant topics and subscriptions.");
+        internalMessaging.subscribe(PubSubConstants.TENANT_NOTIFICATIONS, this::onTenantChanges);
+        deviceRepository.listDistinctTenants()
+                .onSuccess(tenants -> {
+                    vertx.executeBlocking(promise -> {
+                        tenants.forEach(tenant -> {
+                            createPubSubResourceForTenant(tenant, PubSubResourceType.TOPIC);
+                            createPubSubResourceForTenant(tenant, PubSubResourceType.SUBSCRIPTION);
+                            subscribeToTenantTopics(tenant);
+                        });
+                        promise.complete();
+                    });
+                    log.info("Initialization of tenant topics and subscriptions completed.");
+                })
+                .onFailure(err -> log.error("Error getting tenants for topic creation: {}", err.getMessage()));
+    }
+
+    /**
+     * Creates Pub/Sub resources (topics or subscriptions) for the provided tenant.
+     *
+     * @param tenantId           The tenant.
+     * @param pubSubResourceType Which Pub Sub resource type should be created (topic or subscription).
+     */
+    private void createPubSubResourceForTenant(final String tenantId, final PubSubResourceType pubSubResourceType) {
+        final String projectId = internalMessagingConfig.getProjectId();
+        if (projectId == null) {
+            log.error("project ID is null");
+            return;
+        }
+        PubSubMessageHelper.getCredentialsProvider()
+                .ifPresentOrElse(provider -> {
+                    final List<String> topics = PubSubConstants.getTenantTopics();
+                    topics.forEach(topic -> {
+                        final var pubSubBasedAdminClientManager = new PubSubBasedAdminClientManager(projectId, provider);
+                        if (pubSubResourceType == PubSubResourceType.TOPIC) {
+                            pubSubBasedAdminClientManager.getOrCreateTopic(topic, tenantId);
+                        } else {
+                            pubSubBasedAdminClientManager.getOrCreateSubscription(topic, tenantId);
+                        }
+                        pubSubBasedAdminClientManager.closeAdminClients();
+                    });
+                    log.info("All {}s created for {}", pubSubResourceType.toString().toLowerCase(), tenantId);
+                }, () -> log.error("credentials provider is empty"));
+    }
+
+    private void subscribeToTenantTopics(final String tenant) {
+        internalMessaging.subscribe(
+                internalMessagingConfig.getEventTopicFormat().formatted(tenant),
+                configTopicEventHandler::onDeviceConfigRequest);
+        internalMessaging.subscribe(
+                internalMessagingConfig.getCommandAckTopicFormat().formatted(tenant),
+                configTopicEventHandler::onDeviceConfigResponse);
+        internalMessaging.subscribe(
+                internalMessagingConfig.getStateTopicFormat().formatted(tenant),
+                stateTopicEventHandler::onStateMessage);
+    }
+
+    /**
+     * Handle incoming tenant CREATE notifications.
+     *
+     * @param pubsubMessage The message to handle
+     * @param consumer      The message consumer
+     */
+    public void onTenantChanges(final PubsubMessage pubsubMessage, final AckReplyConsumer consumer) {
+        consumer.ack();
+        final String jsonString = pubsubMessage.getData().toStringUtf8();
+        final TenantChangeNotification notification;
+        log.info("Handle tenant change notification {}", jsonString);
+        try {
+            notification = objectMapper.readValue(jsonString, TenantChangeNotification.class);
+        } catch (JsonProcessingException e) {
+            log.error("Can't deserialize tenant change notification: {}", e.getMessage());
+            return;
+        }
+        final String tenant = notification.getTenantId();
+        if (notification.getChange() == LifecycleChange.CREATE && !Strings.isNullOrEmpty(tenant)) {
+            log.info("Tenant {} was created. All its topics and subscriptions will be created.", tenant);
+            createPubSubResourceForTenant(tenant, PubSubResourceType.TOPIC);
+            createPubSubResourceForTenant(tenant, PubSubResourceType.SUBSCRIPTION);
+            subscribeToTenantTopics(tenant);
+        } else if (notification.getChange() == LifecycleChange.DELETE && !Strings.isNullOrEmpty(tenant)) {
+            log.info("Tenant {} was deleted. All its topics and subscriptions will be deleted.", tenant);
+            cleanupPubSubResources(tenant);
+        }
+    }
+
+    private void cleanupPubSubResources(final String tenant) {
+        final String projectId = internalMessagingConfig.getProjectId();
+        final List<String> pubSubTopicsToDelete = PubSubConstants.getTenantTopics().stream().map(id -> TopicName.of(projectId, "%s.%s".formatted(tenant, id)).toString()).toList();
+        final List<String> pubSubSubscriptionsToDelete = PubSubConstants.getTenantTopics().stream().map(id -> SubscriptionName.of(projectId, "%s.%s".formatted(tenant, id)).toString()).toList();
+        PubSubMessageHelper.getCredentialsProvider()
+                .ifPresentOrElse(provider -> {
+                    final PubSubBasedAdminClientManager pubSubBasedAdminClientManager = new PubSubBasedAdminClientManager(projectId, provider);
+                    pubSubBasedAdminClientManager.deleteTopics(pubSubTopicsToDelete);
+                    pubSubBasedAdminClientManager.deleteSubscriptions(pubSubSubscriptionsToDelete);
+                    log.info("All topics and subscriptions for tenant {} were deleted successfully.", tenant);
+                    pubSubBasedAdminClientManager.closeAdminClients();
+                }, () -> log.error("credentials provider is empty"));
+    }
+
+    private enum PubSubResourceType {
+        TOPIC, SUBSCRIPTION
+    }
+}
diff --git a/device-communication/src/main/java/org/eclipse/hono/communication/api/service/DeviceConfigService.java b/device-communication/src/main/java/org/eclipse/hono/communication/api/service/config/DeviceConfigService.java
similarity index 69%
rename from device-communication/src/main/java/org/eclipse/hono/communication/api/service/DeviceConfigService.java
rename to device-communication/src/main/java/org/eclipse/hono/communication/api/service/config/DeviceConfigService.java
index cf282858..4907833b 100644
--- a/device-communication/src/main/java/org/eclipse/hono/communication/api/service/DeviceConfigService.java
+++ b/device-communication/src/main/java/org/eclipse/hono/communication/api/service/config/DeviceConfigService.java
@@ -14,14 +14,17 @@
  *
  */
 
-package org.eclipse.hono.communication.api.service;
+package org.eclipse.hono.communication.api.service.config;
 
 
 import org.eclipse.hono.communication.api.data.DeviceConfig;
+import org.eclipse.hono.communication.api.data.DeviceConfigEntity;
+import org.eclipse.hono.communication.api.data.DeviceConfigInternalResponse;
 import org.eclipse.hono.communication.api.data.DeviceConfigRequest;
 import org.eclipse.hono.communication.api.data.ListDeviceConfigVersionsResponse;
 
 import io.vertx.core.Future;
+
 /**
  * Device config interface.
  */
@@ -46,4 +49,20 @@ public interface DeviceConfigService {
      * @return Future of ListDeviceConfigVersionsResponse
      */
     Future<ListDeviceConfigVersionsResponse> listAll(String deviceId, String tenantId, int limit);
+
+
+    /**
+     * Update field deviceAckTime.
+     *
+     * @param config            Device config
+     * @param deviceAckTime     Time of ack
+     */
+    void updateDeviceAckTime(DeviceConfigEntity config, String deviceAckTime);
+
+    /**
+     * Update field error when delivery failure received from the protocol adapter.
+     *
+     * @param configErrorResponse Device config error response
+     */
+    void updateDeviceConfigError(DeviceConfigInternalResponse configErrorResponse);
 }
diff --git a/device-communication/src/main/java/org/eclipse/hono/communication/api/service/config/DeviceConfigServiceImpl.java b/device-communication/src/main/java/org/eclipse/hono/communication/api/service/config/DeviceConfigServiceImpl.java
new file mode 100644
index 00000000..3793decb
--- /dev/null
+++ b/device-communication/src/main/java/org/eclipse/hono/communication/api/service/config/DeviceConfigServiceImpl.java
@@ -0,0 +1,284 @@
+/*
+ * ***********************************************************
+ *  Copyright (c) 2023 Contributors to the Eclipse Foundation
+ *  <p>
+ *  See the NOTICE file(s) distributed with this work for additional
+ *  information regarding copyright ownership.
+ *  <p>
+ *  This program and the accompanying materials are made available under the
+ *  terms of the Eclipse Public License 2.0 which is available at
+ *  http://www.eclipse.org/legal/epl-2.0
+ *  <p>
+ *  SPDX-License-Identifier: EPL-2.0
+ * **********************************************************
+ *
+ */
+
+package org.eclipse.hono.communication.api.service.config;
+
+import java.time.Instant;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.Objects;
+
+import javax.inject.Singleton;
+
+import org.apache.commons.codec.binary.Base64;
+import org.eclipse.hono.communication.api.data.DeviceConfig;
+import org.eclipse.hono.communication.api.data.DeviceConfigEntity;
+import org.eclipse.hono.communication.api.data.DeviceConfigInternalResponse;
+import org.eclipse.hono.communication.api.data.DeviceConfigRequest;
+import org.eclipse.hono.communication.api.data.ListDeviceConfigVersionsResponse;
+import org.eclipse.hono.communication.api.handler.ConfigTopicEventHandler;
+import org.eclipse.hono.communication.api.mapper.DeviceConfigMapper;
+import org.eclipse.hono.communication.api.repository.DeviceConfigRepository;
+import org.eclipse.hono.communication.api.service.DeviceServiceAbstract;
+import org.eclipse.hono.communication.api.service.communication.InternalMessaging;
+import org.eclipse.hono.communication.core.app.InternalMessagingConfig;
+import org.eclipse.hono.communication.core.app.InternalMessagingConstants;
+import org.eclipse.hono.communication.core.utils.StringValidateUtils;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import com.google.cloud.pubsub.v1.AckReplyConsumer;
+import com.google.common.base.Strings;
+import com.google.pubsub.v1.PubsubMessage;
+
+import io.vertx.core.Future;
+import io.vertx.core.Vertx;
+import io.vertx.core.json.JsonObject;
+
+/**
+ * Service for device commands.
+ */
+
+@Singleton
+public class DeviceConfigServiceImpl extends DeviceServiceAbstract
+        implements DeviceConfigService, ConfigTopicEventHandler {
+
+    private static final String TENANT_ID_NOTIFICATION_PROPERTY = "tenantId";
+    private static final String DEVICE_ID_NOTIFICATION_PROPERTY = "deviceId";
+    private static final String SUBJECT = "config";
+    private static final String DEVICE_CONNECTION_TTD = "-1";
+
+    private final Logger log = LoggerFactory.getLogger(DeviceConfigServiceImpl.class);
+    private final DeviceConfigRepository repository;
+    private final DeviceConfigMapper mapper;
+    private final Vertx vertx;
+
+    /**
+     * Creates a new DeviceConfigServiceImpl.
+     *
+     * @param repository The device config repository
+     * @param mapper The device config mapper
+     * @param internalMessagingConfig The internal messaging config
+     * @param internalMessaging The internal messaging interface
+     * @param vertx The vertx instance
+     */
+    public DeviceConfigServiceImpl(final DeviceConfigRepository repository,
+            final DeviceConfigMapper mapper,
+            final InternalMessagingConfig internalMessagingConfig,
+            final InternalMessaging internalMessaging, final Vertx vertx) {
+
+        super(internalMessagingConfig, internalMessaging);
+
+        this.repository = repository;
+        this.mapper = mapper;
+        this.vertx = vertx;
+    }
+
+    /**
+     * Create and publish new device configs.
+     *
+     * @param deviceConfig The device configs
+     * @param deviceId The device id
+     * @param tenantId The tenant id
+     * @return Future of device config
+     */
+    public Future<DeviceConfig> modifyCloudToDeviceConfig(final DeviceConfigRequest deviceConfig, final String deviceId,
+            final String tenantId) {
+
+        if (!StringValidateUtils.isBase64(deviceConfig.getBinaryData())) {
+            return Future
+                    .failedFuture(new IllegalStateException("Field binaryData type should be String base64 encoded."));
+        }
+
+        final var entity = mapper.configRequestToDeviceConfigEntity(deviceConfig);
+        entity.setDeviceId(deviceId);
+        entity.setTenantId(tenantId);
+
+        return repository.createNew(entity)
+                .map(mapper::deviceConfigEntityToConfig)
+                .onSuccess(result -> {
+                    final var topicToPublish = String.format(messagingConfig.getCommandTopicFormat(),
+                            entity.getTenantId());
+                    final var messageAttributes = Map.of(
+                            InternalMessagingConstants.DEVICE_ID, entity.getDeviceId(),
+                            InternalMessagingConstants.TENANT_ID, entity.getTenantId(),
+                            InternalMessagingConstants.CORRELATION_ID, result.getVersion(),
+                            InternalMessagingConstants.SUBJECT, SUBJECT,
+                            InternalMessagingConstants.RESPONSE_REQUIRED, "true");
+                    publish(topicToPublish, result, messageAttributes);
+                });
+    }
+
+    /**
+     * List all device configs.
+     *
+     * @param deviceId The device id
+     * @param tenantId The tenant id
+     * @param limit The limit max=10
+     * @return Future of ListDeviceConfigVersionsResponse
+     */
+    public Future<ListDeviceConfigVersionsResponse> listAll(final String deviceId, final String tenantId,
+            final int limit) {
+        return repository.listAll(deviceId, tenantId, limit)
+                .map(
+                        result -> {
+                            final var listConfig = new ListDeviceConfigVersionsResponse();
+                            listConfig.setDeviceConfigs(result);
+                            return listConfig;
+                        });
+    }
+
+    @Override
+    public void onDeviceConfigResponse(final PubsubMessage pubsubMessage, final AckReplyConsumer consumer) {
+        consumer.ack(); // message was received and processed only once
+
+        final var messageAttributes = pubsubMessage.getAttributesMap();
+
+        if (!isErrorResponse(messageAttributes)) {
+            return;
+        }
+
+        final var deviceId = messageAttributes.get(InternalMessagingConstants.DEVICE_ID);
+        final var tenantId = messageAttributes.get(InternalMessagingConstants.TENANT_ID);
+        final var version = messageAttributes.get(InternalMessagingConstants.CORRELATION_ID);
+        final var status = messageAttributes.get(InternalMessagingConstants.STATUS);
+        final var errorPayload = new JsonObject(pubsubMessage.getData().toStringUtf8());
+        final var error = "error %s: %s".formatted(status, errorPayload.getString("error"));
+
+        final var configErrorResponse = new DeviceConfigInternalResponse(tenantId, deviceId, version, error);
+
+        log.info("Config returned an error: {}", configErrorResponse);
+        updateDeviceConfigError(configErrorResponse);
+
+    }
+
+    private boolean isErrorResponse(final Map<String, String> messageAttributes) {
+        return Objects.equals(messageAttributes.get(messagingConfig.getContentTypeKey()),
+                messagingConfig.getDeliveryFailureNotificationContentType());
+    }
+
+    @Override
+    public void onDeviceConfigRequest(final PubsubMessage pubsubMessage, final AckReplyConsumer consumer) {
+
+        consumer.ack(); // message was received and processed only once
+
+        final var messageAttributes = pubsubMessage.getAttributesMap();
+        final var deviceId = messageAttributes.get(DEVICE_ID_NOTIFICATION_PROPERTY);
+        final var tenantId = messageAttributes.get(TENANT_ID_NOTIFICATION_PROPERTY);
+
+        if (isNotConfigRequest(messageAttributes, tenantId, deviceId)) {
+            return;
+        }
+
+        repository.getDeviceLatestConfig(tenantId, deviceId)
+                .onSuccess(res -> {
+                    final var config = mapper.deviceConfigEntityToConfig(res);
+                    final var topicToPublish = String.format(messagingConfig.getCommandTopicFormat(), tenantId);
+                    final var attributes = new HashMap<String, String>();
+                    attributes.put(InternalMessagingConstants.CORRELATION_ID, config.getVersion());
+                    attributes.put(InternalMessagingConstants.DEVICE_ID, deviceId);
+                    attributes.put(InternalMessagingConstants.TENANT_ID, tenantId);
+                    attributes.put(InternalMessagingConstants.SUBJECT, SUBJECT);
+                    attributes.put(InternalMessagingConstants.RESPONSE_REQUIRED, "true");
+                    log.debug("Handle config request event");
+                    publish(topicToPublish, config, attributes);
+                })
+                .onFailure(err -> log.error("Can't publish configs: {}", err.getMessage()));
+    }
+
+    private boolean isNotConfigRequest(final Map<String, String> messageAttributes, final String tenantId,
+            final String deviceId) {
+        if (Strings.isNullOrEmpty(deviceId) || Strings.isNullOrEmpty(tenantId)) {
+            log.warn("Skip device onConnect event: deviceId or tenantId is empty");
+            return true;
+        }
+        if (!isMqttConfigRequest(messageAttributes) && !isHttpConfigRequest(messageAttributes)) {
+            log.debug("Skip device event");
+            return true;
+        }
+        return false;
+    }
+
+    private boolean isMqttConfigRequest(final Map<String, String> messageAttributes) {
+        return Objects.equals(messageAttributes.get(messagingConfig.getContentTypeKey()),
+                messagingConfig.getEmptyNotificationEventContentType()) &&
+                Objects.equals(messageAttributes.get(messagingConfig.getTtdKey()), DEVICE_CONNECTION_TTD);
+    }
+
+    private boolean isHttpConfigRequest(final Map<String, String> messageAttributes) {
+        return Objects.equals(messageAttributes.get(messagingConfig.getOrigAdapterKey()), "hono-http")
+                && !messageAttributes.get(messagingConfig.getTtdKey()).isBlank()
+                && messageAttributes.get(messagingConfig.getOrigAddressKey()).contains(SUBJECT);
+    }
+
+    private void publish(final String topicToPublish, final DeviceConfig deviceConfig,
+            final Map<String, String> attributes) {
+        final var context = vertx.getOrCreateContext();
+        context.executeBlocking(promise -> {
+            try {
+                final var configPayload = Base64.decodeBase64(deviceConfig.getBinaryData().getBytes());
+                final var tenantId = attributes.get(InternalMessagingConstants.TENANT_ID);
+                final var deviceId = attributes.get(InternalMessagingConstants.DEVICE_ID);
+                final var configVersion = deviceConfig.getVersion();
+
+                resetError(tenantId, deviceId, configVersion);
+                internalMessaging.publish(topicToPublish, configPayload, attributes);
+                log.info("Publish device config {}", configPayload);
+                vertx.setTimer(
+                        messagingConfig.getConfigAckDelay(), id -> configSendSuccess(tenantId, deviceId, configVersion)
+                                .onSuccess(config -> updateDeviceAckTime(config, Instant.now().toString())));
+            } catch (Exception ex) {
+                log.error("Error serialize config {}", deviceConfig);
+            } finally {
+                promise.complete();
+            }
+        });
+    }
+
+    private Future<DeviceConfigEntity> configSendSuccess(final String tenantId, final String deviceId,
+            final String configVersion) {
+
+        return repository.getDeviceConfig(tenantId, deviceId, Integer.parseInt(configVersion))
+                .compose(config -> {
+                    if (config.getDeviceAckError() == null) {
+                        return Future.succeededFuture(config);
+                    } else {
+                        return Future.failedFuture("Config could not successfully be send");
+                    }
+                });
+    }
+
+    private void resetError(final String tenantId, final String deviceId, final String configVersion) {
+        updateDeviceConfigError(new DeviceConfigInternalResponse(tenantId, deviceId, configVersion, null));
+    }
+
+    @Override
+    public void updateDeviceAckTime(final DeviceConfigEntity config, final String deviceAckTime) {
+        repository.updateDeviceAckTime(config, deviceAckTime)
+                .onSuccess(ok -> log.info(
+                        "Successfully updated device acknowledged time for config version {} for device {} in tenant {}",
+                        config.getVersion(), config.getDeviceId(), config.getTenantId()));
+    }
+
+    @Override
+    public void updateDeviceConfigError(final DeviceConfigInternalResponse configErrorResponse) {
+        repository.updateDeviceConfigError(configErrorResponse)
+                .onSuccess(
+                        ok -> log.debug("Successfully updated error for config version {} for device {} in tenant {}",
+                                configErrorResponse.getVersion(), configErrorResponse.getDeviceId(),
+                                configErrorResponse.getTenantId()));
+    }
+}
diff --git a/device-communication/src/main/java/org/eclipse/hono/communication/api/service/DatabaseSchemaCreatorImpl.java b/device-communication/src/main/java/org/eclipse/hono/communication/api/service/database/DatabaseSchemaCreatorImpl.java
similarity index 70%
rename from device-communication/src/main/java/org/eclipse/hono/communication/api/service/DatabaseSchemaCreatorImpl.java
rename to device-communication/src/main/java/org/eclipse/hono/communication/api/service/database/DatabaseSchemaCreatorImpl.java
index d890db0b..f13ebe3a 100644
--- a/device-communication/src/main/java/org/eclipse/hono/communication/api/service/DatabaseSchemaCreatorImpl.java
+++ b/device-communication/src/main/java/org/eclipse/hono/communication/api/service/database/DatabaseSchemaCreatorImpl.java
@@ -14,13 +14,14 @@
  *
  */
 
-package org.eclipse.hono.communication.api.service;
+package org.eclipse.hono.communication.api.service.database;
 
 import java.util.Map;
 
 import javax.enterprise.context.ApplicationScoped;
 
 import org.eclipse.hono.communication.api.config.DeviceConfigsConstants;
+import org.eclipse.hono.communication.api.config.DeviceStatesConstants;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -31,15 +32,15 @@
 import io.vertx.sqlclient.templates.SqlTemplate;
 
 /**
- * Creates all Database tables if they are not exist.
+ * Creates all Database tables if they do not exist.
  */
 
 @ApplicationScoped
 public class DatabaseSchemaCreatorImpl implements DatabaseSchemaCreator {
     private static final Logger log = LoggerFactory.getLogger(DatabaseSchemaCreatorImpl.class);
     private final Vertx vertx;
-    private final String tableCreationErrorMsg = "Table deviceConfig can not be created {}";
-    private final String tableCreationSuccessMsg = "Successfully migrate Table: deviceConfig.";
+    private final String tableCreationErrorMsg = "Table %s can not be created {}";
+    private final String tableCreationSuccessMsg = "Successfully migrate Table: %s.";
     private final DatabaseService db;
 
 
@@ -56,15 +57,20 @@ public DatabaseSchemaCreatorImpl(final Vertx vertx, final DatabaseService db) {
 
     @Override
     public void createDBTables() {
-        createDeviceConfigTable();
+        createTable(DeviceConfigsConstants.CREATE_SQL_SCRIPT_PATH, "device_config");
+        createTable(DeviceStatesConstants.CREATE_SQL_SCRIPT_PATH, "device_status");
     }
 
 
-    private void createDeviceConfigTable() {
-        log.info("Running database migration from file {}", DeviceConfigsConstants.CREATE_SQL_SCRIPT_PATH);
+    private void createTable(final String filePath, final String tableName) {
+        log.info("Running database migration from file {}", filePath);
 
         final Promise<Buffer> loadScriptTracker = Promise.promise();
-        vertx.fileSystem().readFile(DeviceConfigsConstants.CREATE_SQL_SCRIPT_PATH, loadScriptTracker);
+        vertx.fileSystem().readFile(filePath, loadScriptTracker);
+        createTableIfNotExist(loadScriptTracker, tableName);
+    }
+
+    private void createTableIfNotExist(final Promise<Buffer> loadScriptTracker, final String tableName) {
         db.getDbClient().withTransaction(
                         sqlConnection ->
                                 loadScriptTracker.future()
@@ -72,13 +78,11 @@ private void createDeviceConfigTable() {
                                         .compose(script -> SqlTemplate
                                                 .forQuery(sqlConnection, script)
                                                 .execute(Map.of())))
-                .onSuccess(ok -> log.info(tableCreationSuccessMsg))
+                .onSuccess(ok -> log.info(tableCreationSuccessMsg.formatted(tableName)))
                 .onFailure(error -> {
-                    log.error(tableCreationErrorMsg, error.getMessage());
+                    log.error(tableCreationErrorMsg.formatted(tableName), error.getMessage());
                     db.close();
                     Quarkus.asyncExit(-1);
                 });
-
-
     }
 }
diff --git a/device-communication/src/main/java/org/eclipse/hono/communication/api/service/state/DeviceStateService.java b/device-communication/src/main/java/org/eclipse/hono/communication/api/service/state/DeviceStateService.java
new file mode 100644
index 00000000..9308467e
--- /dev/null
+++ b/device-communication/src/main/java/org/eclipse/hono/communication/api/service/state/DeviceStateService.java
@@ -0,0 +1,37 @@
+/*
+ * ***********************************************************
+ *  Copyright (c) 2023 Contributors to the Eclipse Foundation
+ *  <p>
+ *  See the NOTICE file(s) distributed with this work for additional
+ *  information regarding copyright ownership.
+ *  <p>
+ *  This program and the accompanying materials are made available under the
+ *  terms of the Eclipse Public License 2.0 which is available at
+ *  http://www.eclipse.org/legal/epl-2.0
+ *  <p>
+ *  SPDX-License-Identifier: EPL-2.0
+ * **********************************************************
+ *
+ */
+
+package org.eclipse.hono.communication.api.service.state;
+
+import org.eclipse.hono.communication.api.data.ListDeviceStatesResponse;
+
+import io.vertx.core.Future;
+
+/**
+ * Device state interface.
+ */
+public interface DeviceStateService {
+
+    /**
+     * Lists all the states for a specific device.
+     *
+     * @param deviceId Device Id
+     * @param tenantId Tenant Id
+     * @param limit Limit between 1 and 10
+     * @return Future of ListDeviceStatesResponse
+     */
+    Future<ListDeviceStatesResponse> listAll(String deviceId, String tenantId, int limit);
+}
diff --git a/device-communication/src/main/java/org/eclipse/hono/communication/api/service/state/DeviceStateServiceImpl.java b/device-communication/src/main/java/org/eclipse/hono/communication/api/service/state/DeviceStateServiceImpl.java
new file mode 100644
index 00000000..a3afff4b
--- /dev/null
+++ b/device-communication/src/main/java/org/eclipse/hono/communication/api/service/state/DeviceStateServiceImpl.java
@@ -0,0 +1,101 @@
+/*
+ * ***********************************************************
+ *  Copyright (c) 2023 Contributors to the Eclipse Foundation
+ *  <p>
+ *  See the NOTICE file(s) distributed with this work for additional
+ *  information regarding copyright ownership.
+ *  <p>
+ *  This program and the accompanying materials are made available under the
+ *  terms of the Eclipse Public License 2.0 which is available at
+ *  http://www.eclipse.org/legal/epl-2.0
+ *  <p>
+ *  SPDX-License-Identifier: EPL-2.0
+ * **********************************************************
+ *
+ */
+
+package org.eclipse.hono.communication.api.service.state;
+
+import javax.inject.Singleton;
+
+import org.eclipse.hono.communication.api.data.ListDeviceStatesResponse;
+import org.eclipse.hono.communication.api.handler.StateTopicEventHandler;
+import org.eclipse.hono.communication.api.mapper.DeviceStateMapper;
+import org.eclipse.hono.communication.api.repository.DeviceStateRepository;
+import org.eclipse.hono.communication.api.service.DeviceServiceAbstract;
+import org.eclipse.hono.communication.api.service.communication.InternalMessaging;
+import org.eclipse.hono.communication.core.app.InternalMessagingConfig;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import com.google.cloud.pubsub.v1.AckReplyConsumer;
+import com.google.common.base.Strings;
+import com.google.pubsub.v1.PubsubMessage;
+
+import io.vertx.core.Future;
+
+/**
+ * Service for device commands.
+ */
+
+@Singleton
+public class DeviceStateServiceImpl extends DeviceServiceAbstract implements DeviceStateService, StateTopicEventHandler {
+
+    private final Logger log = LoggerFactory.getLogger(DeviceStateServiceImpl.class);
+    private final DeviceStateRepository repository;
+    private final DeviceStateMapper mapper;
+    private final String TENANT_ID_EVENT_PROPERTY = "tenantId";
+    private final String DEVICE_ID_EVENT_PROPERTY = "deviceId";
+
+    /**
+     * Creates a new DeviceStateServiceImpl.
+     *
+     * @param repository The device state repository
+     * @param mapper The device state mapper
+     * @param internalMessagingConfig The internal messaging config
+     * @param internalMessaging The internal messaging interface
+     */
+    protected DeviceStateServiceImpl(final DeviceStateRepository repository, final DeviceStateMapper mapper,
+            final InternalMessagingConfig internalMessagingConfig, final InternalMessaging internalMessaging) {
+        super(internalMessagingConfig, internalMessaging);
+        this.repository = repository;
+        this.mapper = mapper;
+    }
+
+    @Override
+    public Future<ListDeviceStatesResponse> listAll(final String deviceId, final String tenantId, final int limit) {
+        return repository.listAll(deviceId, tenantId, limit)
+                .map(
+                        result -> {
+                            final var listState = new ListDeviceStatesResponse();
+                            listState.setDeviceStates(result);
+                            return listState;
+                        });
+
+    }
+
+    @Override
+    public void onStateMessage(final PubsubMessage pubsubMessage, final AckReplyConsumer consumer) {
+
+        consumer.ack();
+
+        final var messageAttributes = pubsubMessage.getAttributesMap();
+        final var deviceId = messageAttributes.get(DEVICE_ID_EVENT_PROPERTY);
+        final var tenantId = messageAttributes.get(TENANT_ID_EVENT_PROPERTY);
+
+        if (Strings.isNullOrEmpty(deviceId) || Strings.isNullOrEmpty(tenantId)) {
+            log.warn("Skip device state message: deviceId or tenantId is empty");
+            return;
+        }
+
+        final String msg = pubsubMessage.getData().toStringUtf8();
+
+        if (Strings.isNullOrEmpty(msg)) {
+            log.debug("Skip state: payload is empty");
+            return;
+        }
+
+        repository.createNew(mapper.pubSubMessageToDeviceStateEntity(pubsubMessage))
+                .onFailure(err -> log.error("Can't save state in DB: {}", err.getMessage()));
+    }
+}
diff --git a/device-communication/src/main/java/org/eclipse/hono/communication/core/app/DatabaseConfig.java b/device-communication/src/main/java/org/eclipse/hono/communication/core/app/DatabaseConfig.java
index 0819106a..c3c79f83 100644
--- a/device-communication/src/main/java/org/eclipse/hono/communication/core/app/DatabaseConfig.java
+++ b/device-communication/src/main/java/org/eclipse/hono/communication/core/app/DatabaseConfig.java
@@ -42,6 +42,10 @@ public class DatabaseConfig {
     int poolMaxSize;
     @ConfigProperty(name = "vertx.device-registration.table")
     String deviceRegistrationTableName;
+    @ConfigProperty(name = "vertx.tenant.table")
+    String tenantTableName;
+    @ConfigProperty(name = "vertx.tenant.tenant-id-column")
+    String tenantTableIdColumn;
     @ConfigProperty(name = "vertx.device-registration.tenant-id-column")
     String deviceRegistrationTenantIdColumn;
     @ConfigProperty(name = "vertx.device-registration.device-id-column")
@@ -51,6 +55,14 @@ public String getDeviceRegistrationTableName() {
         return deviceRegistrationTableName;
     }
 
+    public String getTenantTableName() {
+        return tenantTableName;
+    }
+
+    public String getTenantTableIdColumn() {
+        return tenantTableIdColumn;
+    }
+
     public String getDeviceRegistrationTenantIdColumn() {
         return deviceRegistrationTenantIdColumn;
     }
diff --git a/device-communication/src/main/java/org/eclipse/hono/communication/core/utils/StringValidateUtils.java b/device-communication/src/main/java/org/eclipse/hono/communication/core/utils/StringValidateUtils.java
new file mode 100644
index 00000000..95e44b45
--- /dev/null
+++ b/device-communication/src/main/java/org/eclipse/hono/communication/core/utils/StringValidateUtils.java
@@ -0,0 +1,44 @@
+/*
+ * ***********************************************************
+ *  Copyright (c) 2023 Contributors to the Eclipse Foundation
+ *  <p>
+ *  See the NOTICE file(s) distributed with this work for additional
+ *  information regarding copyright ownership.
+ *  <p>
+ *  This program and the accompanying materials are made available under the
+ *  terms of the Eclipse Public License 2.0 which is available at
+ *  http://www.eclipse.org/legal/epl-2.0
+ *  <p>
+ *  SPDX-License-Identifier: EPL-2.0
+ * **********************************************************
+ *
+ */
+
+package org.eclipse.hono.communication.core.utils;
+
+import java.util.Base64;
+
+/**
+ * String validation utils.
+ */
+public abstract class StringValidateUtils {
+
+    private StringValidateUtils() {
+        throw new IllegalStateException("Utility class");
+    }
+
+    /**
+     * Checks if a given string is base64 encoded.
+     *
+     * @param stringBase64 String to validate
+     * @return True if string is base64 else False
+     */
+    public static boolean isBase64(final String stringBase64) {
+        try {
+            Base64.getDecoder().decode(stringBase64);
+            return true;
+        } catch (IllegalArgumentException e) {
+            return false;
+        }
+    }
+}
diff --git a/device-communication/src/main/resources/api/hono-device-communication-v1.yaml b/device-communication/src/main/resources/api/hono-device-communication-v1.yaml
index 63764c51..e70c8b5c 100644
--- a/device-communication/src/main/resources/api/hono-device-communication-v1.yaml
+++ b/device-communication/src/main/resources/api/hono-device-communication-v1.yaml
@@ -5,7 +5,7 @@ info:
   version: 1.0.0
   description: Device commands and configs API.
 servers:
-  - url: http://localhost:8080/api/v1
+  - url: http://localhost:8080/v1
 
 paths:
   /commands/{tenantid}/{deviceid}:
@@ -122,6 +122,51 @@ paths:
           type: string
         in: path
         required: true
+  /states/{tenantid}/{deviceid}:
+    summary: Device states
+    description: List states for a specific device
+    get:
+      tags:
+        - STATES
+      parameters:
+        - name: numStates
+          description: "The number of states to list. States are listed in decreasing
+          order of the state id. The maximum number of states saved in Database is
+          10. If this value is zero, it will return all the states available."
+          schema:
+            type: integer
+            minimum: 0
+            maximum: 10
+          in: query
+          required: false
+      responses:
+        "200":
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/ListDeviceStatesResponse'
+          description: Lists the device states
+        "404":
+          description: Device not found
+        "500":
+          description: Internal server error
+      operationId: listStates
+      summary: List the device states
+      description: "Lists the last few states of the device in descending
+        order (i.e.: newest first)."
+    parameters:
+      - name: tenantid
+        description: Unique registry id
+        schema:
+          type: string
+        in: path
+        required: true
+      - name: deviceid
+        description: Unique device id
+        schema:
+          type: string
+        in: path
+        required: true
 components:
   schemas:
     DeviceCommandRequest:
@@ -213,3 +258,35 @@ components:
         cloudUpdateTime: string
         deviceAckTime: string
         binaryData: string
+    ListDeviceStatesResponse:
+      title: Root Type for ListDeviceStatesResponse
+      description: A list of a device states
+      type: object
+      properties:
+        deviceStates:
+          description: List of DeviceState objects
+          type: array
+          items:
+            $ref: '#/components/schemas/DeviceState'
+      example:
+        deviceStates:
+          - object: DeviceState
+    DeviceState:
+      title: Root Type for DeviceState
+      description: The device state.
+      type: object
+      properties:
+        updateTime:
+          description: "String (Timestamp format) [Output only] The time at
+            which this state version was updated. This
+            timestamp is set by the server. Timestamp in 
+            RFC3339 UTC \"Zulu\" format, accurate to nanoseconds. 
+            Example: \"2014-10-02T15:01:23.045123456Z\"."
+          type: string
+        binaryData:
+          description: "string (bytes format) The device state data
+            in string base64-encoded format."
+          type: string
+      example:
+        updateTime: string
+        binaryData: string
\ No newline at end of file
diff --git a/device-communication/src/main/resources/api/hono-endpoint.yaml b/device-communication/src/main/resources/api/hono-endpoint.yaml
index e2e1491b..967451ea 100644
--- a/device-communication/src/main/resources/api/hono-endpoint.yaml
+++ b/device-communication/src/main/resources/api/hono-endpoint.yaml
@@ -7,7 +7,7 @@ info:
   version: 1.0.0
 schemes:
   - http
-basePath: /api/v1
+basePath: /v1
 definitions:
   DeviceCommandRequest:
     description: Command json object structure
@@ -87,7 +87,6 @@ definitions:
     required:
       - binaryData
     type: object
-
   ListDeviceConfigVersionsResponse:
     description: A list of a device config versions
     example:
@@ -101,6 +100,39 @@ definitions:
         type: array
     title: Root Type for ListDeviceConfigVersionsResponse
     type: object
+  DeviceState:
+    description: The device state.
+    example:
+      binaryData: string
+      updateTime: string
+    properties:
+      binaryData:
+        description: >-
+          string (bytes format) The device state data in string
+          base64-encoded format.
+        type: string
+      updateTime:
+        description: >-
+          String (Timestamp format) [Output only] The time at which this
+          state version was updated. This timestamp is
+          set by the server. Timestamp in  RFC3339 UTC "Zulu" format, accurate
+          to nanoseconds.  Example: "2014-10-02T15:01:23.045123456Z".
+        type: string
+    title: Root Type for DeviceState
+    type: object
+  ListDeviceStatesResponse:
+    description: A list of a device states.
+    example:
+      deviceStates:
+        - object: DeviceState
+    properties:
+      deviceStates:
+        description: List of DeviceState objects.
+        items:
+          $ref: "#/definitions/DeviceState"
+        type: array
+    title: Root Type for ListDeviceStatesResponse
+    type: object
 paths:
   "/commands/{tenantid}/{deviceid}":
     parameters:
@@ -202,4 +234,43 @@ paths:
           description: Internal Server error
       summary: Modify cloud to device config
       tags:
-        - CONFIGS
\ No newline at end of file
+        - CONFIGS
+  "/states/{tenantid}/{deviceid}":
+    get:
+      description: >-
+        Lists the last few versions of the device state in descending
+        order (i.e.: newest first).
+      operationId: listStates
+      parameters:
+        - description: >-
+            The number of states to list. States are listed in decreasing
+            order of the state id. The maximum number of states saved in
+            Database is 10. If this value is zero, it will return all the
+            states available.
+          in: query
+          maximum: 10
+          minimum: 0
+          name: numStates
+          required: false
+          type: integer
+      produces:
+        - application/json
+      responses:
+        "200":
+          description: Lists the device states
+          schema:
+            $ref: "#/definitions/ListDeviceStatesResponse"
+      summary: List the device states
+      tags:
+        - STATES
+    parameters:
+      - description: Unique registry id
+        in: path
+        name: tenantid
+        required: true
+        type: string
+      - description: Unique device id
+        in: path
+        name: deviceid
+        required: true
+        type: string
\ No newline at end of file
diff --git a/device-communication/src/main/resources/db/migration/V1.0__create.sql b/device-communication/src/main/resources/db/migration/V1.0__create.sql
deleted file mode 100644
index 69fb9487..00000000
--- a/device-communication/src/main/resources/db/migration/V1.0__create.sql
+++ /dev/null
@@ -1,11 +0,0 @@
-CREATE TABLE IF NOT EXISTS public."deviceConfig"
-(
-    version           INT          not null,
-    "tenantId"        VARCHAR(100) not null,
-    "deviceId"        VARCHAR(100) not null,
-    "cloudUpdateTime" VARCHAR(100) not null,
-    "deviceAckTime"   VARCHAR(100),
-    "binaryData"      VARCHAR      not null,
-
-    PRIMARY KEY (version, "tenantId", "deviceId")
-)
\ No newline at end of file
diff --git a/device-communication/src/main/resources/db/create_device_config_table.sql b/device-communication/src/main/resources/db/v1_create_config_table.sql
similarity index 73%
rename from device-communication/src/main/resources/db/create_device_config_table.sql
rename to device-communication/src/main/resources/db/v1_create_config_table.sql
index ae425132..994c5302 100644
--- a/device-communication/src/main/resources/db/create_device_config_table.sql
+++ b/device-communication/src/main/resources/db/v1_create_config_table.sql
@@ -18,11 +18,13 @@
 CREATE TABLE IF NOT EXISTS device_configs
 (
     version           INT          not null,
-    tenant_id         VARCHAR(100) not null,
-    device_id         VARCHAR(100) not null,
+    tenant_id         VARCHAR(256) not null,
+    device_id         VARCHAR(256) not null,
     cloud_update_time VARCHAR(100) not null,
     device_ack_time   VARCHAR(100),
     binary_data       VARCHAR      not null,
+    device_ack_error  VARCHAR(100),
 
-    PRIMARY KEY (version, tenant_id, device_id)
+    PRIMARY KEY (version, tenant_id, device_id),
+    FOREIGN KEY (tenant_id, device_id) REFERENCES device_registrations (TENANT_ID, DEVICE_ID) ON DELETE CASCADE
 )
\ No newline at end of file
diff --git a/device-communication/src/main/resources/db/v1_create_state_table.sql b/device-communication/src/main/resources/db/v1_create_state_table.sql
new file mode 100644
index 00000000..ce100e41
--- /dev/null
+++ b/device-communication/src/main/resources/db/v1_create_state_table.sql
@@ -0,0 +1,28 @@
+/*
+ * ***********************************************************
+ *  Copyright (c) 2023 Contributors to the Eclipse Foundation
+ *  <p>
+ *  See the NOTICE file(s) distributed with this work for additional
+ *  information regarding copyright ownership.
+ *  <p>
+ *  This program and the accompanying materials are made available under the
+ *  terms of the Eclipse Public License 2.0 which is available at
+ *  http://www.eclipse.org/legal/epl-2.0
+ *  <p>
+ *  SPDX-License-Identifier: EPL-2.0
+ * **********************************************************
+ *
+ */
+
+
+CREATE TABLE IF NOT EXISTS device_status
+(
+    id          VARCHAR(100) not null,
+    tenant_id   VARCHAR(256) not null,
+    device_id   VARCHAR(256) not null,
+    update_time VARCHAR(100) not null,
+    binary_data VARCHAR      not null,
+
+    PRIMARY KEY (id, tenant_id, device_id),
+    FOREIGN KEY (tenant_id, device_id) REFERENCES device_registrations (TENANT_ID, DEVICE_ID) ON DELETE CASCADE
+);
\ No newline at end of file
diff --git a/device-communication/src/test/java/org/eclipse/hono/communication/api/ApplicationTest.java b/device-communication/src/test/java/org/eclipse/hono/communication/api/ApplicationTest.java
index c45b74ed..c0af61c9 100644
--- a/device-communication/src/test/java/org/eclipse/hono/communication/api/ApplicationTest.java
+++ b/device-communication/src/test/java/org/eclipse/hono/communication/api/ApplicationTest.java
@@ -28,10 +28,8 @@
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 
-
 import io.vertx.core.Vertx;
 
-
 class ApplicationTest {
 
     private HttpServer httpServerMock;
diff --git a/device-communication/src/test/java/org/eclipse/hono/communication/api/DeviceCommunicationHttpServerTest.java b/device-communication/src/test/java/org/eclipse/hono/communication/api/DeviceCommunicationHttpServerTest.java
index eee9115b..de3506c5 100644
--- a/device-communication/src/test/java/org/eclipse/hono/communication/api/DeviceCommunicationHttpServerTest.java
+++ b/device-communication/src/test/java/org/eclipse/hono/communication/api/DeviceCommunicationHttpServerTest.java
@@ -17,17 +17,26 @@
 package org.eclipse.hono.communication.api;
 
 import static org.mockito.ArgumentMatchers.any;
-import static org.mockito.Mockito.*;
-
+import static org.mockito.Mockito.anyInt;
+import static org.mockito.Mockito.anyString;
+import static org.mockito.Mockito.doNothing;
+import static org.mockito.Mockito.eq;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.mockStatic;
+import static org.mockito.Mockito.spy;
+import static org.mockito.Mockito.times;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.when;
 
 import java.util.List;
 
 import org.eclipse.hono.communication.api.handler.DeviceCommandHandler;
-import org.eclipse.hono.communication.api.service.DatabaseSchemaCreator;
-import org.eclipse.hono.communication.api.service.DatabaseSchemaCreatorImpl;
-import org.eclipse.hono.communication.api.service.DatabaseService;
-import org.eclipse.hono.communication.api.service.DatabaseServiceImpl;
 import org.eclipse.hono.communication.api.service.VertxHttpHandlerManagerService;
+import org.eclipse.hono.communication.api.service.communication.InternalTopicManager;
+import org.eclipse.hono.communication.api.service.database.DatabaseSchemaCreator;
+import org.eclipse.hono.communication.api.service.database.DatabaseSchemaCreatorImpl;
+import org.eclipse.hono.communication.api.service.database.DatabaseService;
+import org.eclipse.hono.communication.api.service.database.DatabaseServiceImpl;
 import org.eclipse.hono.communication.core.app.ApplicationConfig;
 import org.eclipse.hono.communication.core.app.ServerConfig;
 import org.junit.jupiter.api.AfterEach;
@@ -52,7 +61,6 @@
 import io.vertx.ext.web.openapi.RouterBuilder;
 import io.vertx.ext.web.validation.BadRequestException;
 
-
 class DeviceCommunicationHttpServerTest {
 
     private ApplicationConfig appConfigsMock;
@@ -67,6 +75,7 @@ class DeviceCommunicationHttpServerTest {
     private HttpServerRequest httpServerRequestMock;
     private BadRequestException badRequestExceptionMock;
     private DatabaseSchemaCreator databaseSchemaCreatorMock;
+    private InternalTopicManager internalTopicManager;
     private Route routeMock;
     private JsonObject jsonObjMock;
 
@@ -89,12 +98,13 @@ void setUp() {
         jsonObjMock = mock(JsonObject.class);
         dbMock = mock(DatabaseServiceImpl.class);
         databaseSchemaCreatorMock = mock(DatabaseSchemaCreatorImpl.class);
+        internalTopicManager = mock(InternalTopicManager.class);
         routeMock = mock(Route.class);
         deviceCommunicationHttpServer = new DeviceCommunicationHttpServer(appConfigsMock,
                 vertxMock,
                 handlerServiceMock,
                 dbMock,
-                databaseSchemaCreatorMock);
+                databaseSchemaCreatorMock, internalTopicManager);
 
     }
 
@@ -115,7 +125,7 @@ void tearDown() {
                 dbMock,
                 serverConfigMock,
                 databaseSchemaCreatorMock,
-                routeMock);
+                routeMock, internalTopicManager);
     }
 
 
@@ -178,6 +188,7 @@ void startSucceeded() {
                     verify(routeMock, times(2)).handler(any());
                     verify(routerMock, times(1)).route(anyString());
                     verify(routeMock, times(1)).subRouter(any());
+                    verify(internalTopicManager).initPubSub();
                     quarkusMockedStatic.verify(Quarkus::waitForExit, times(1));
                     routerMockedStatic.verifyNoMoreInteractions();
                     mockedRouterBuilderStatic.verifyNoMoreInteractions();
@@ -213,6 +224,7 @@ void createRouterFailed() {
                 verify(handlerServiceMock, times(1)).getAvailableHandlerServices();
                 verify(appConfigsMock, times(1)).getServerConfig();
                 verify(serverConfigMock, times(1)).getOpenApiFilePath();
+                verify(internalTopicManager).initPubSub();
                 quarkusMockedStatic.verify(() -> Quarkus.asyncExit(-1), times(1));
                 quarkusMockedStatic.verify(Quarkus::waitForExit, times(1));
                 quarkusMockedStatic.verifyNoMoreInteractions();
@@ -245,7 +257,7 @@ void createServerFailed() {
                     when(routeMock.handler(any())).thenReturn(routeMock);
                     when(vertxMock.createHttpServer(any(HttpServerOptions.class))).thenReturn(httpServerMock);
                     when(httpServerMock.requestHandler(routerMock)).thenReturn(httpServerMock);
-                    when(httpServerMock.listen()).thenReturn(Future.failedFuture(new Throwable("Test error on listen()")));
+                    when(httpServerMock.listen()).thenReturn(Future.failedFuture(new Throwable()));
                     when(serverConfigMock.getOpenApiFilePath()).thenReturn("/myPath");
                     when(serverConfigMock.getBasePath()).thenReturn("/basePath");
                     when(routerMock.route(any())).thenReturn(routeMock);
@@ -276,6 +288,7 @@ void createServerFailed() {
                     verify(routeMock, times(2)).handler(any());
                     verify(routeMock, times(1)).subRouter(any());
                     verify(routerMock, times(1)).route(anyString());
+                    verify(internalTopicManager).initPubSub();
                     routerMockedStatic.verify(() -> Router.router(vertxMock), times(1));
                     quarkusMockedStatic.verify(Quarkus::waitForExit, times(1));
                     mockedRouterBuilderStatic.verifyNoMoreInteractions();
diff --git a/device-communication/src/test/java/org/eclipse/hono/communication/api/handler/DeviceConfigsHandlerTest.java b/device-communication/src/test/java/org/eclipse/hono/communication/api/handler/DeviceConfigsHandlerTest.java
index e1a65770..e70a2b92 100644
--- a/device-communication/src/test/java/org/eclipse/hono/communication/api/handler/DeviceConfigsHandlerTest.java
+++ b/device-communication/src/test/java/org/eclipse/hono/communication/api/handler/DeviceConfigsHandlerTest.java
@@ -18,7 +18,12 @@
 
 import static org.mockito.ArgumentMatchers.any;
 import static org.mockito.ArgumentMatchers.anyString;
-import static org.mockito.Mockito.*;
+import static org.mockito.Mockito.anyInt;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.times;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.verifyNoMoreInteractions;
+import static org.mockito.Mockito.when;
 
 import java.util.List;
 
@@ -26,8 +31,8 @@
 import org.eclipse.hono.communication.api.data.DeviceConfig;
 import org.eclipse.hono.communication.api.data.DeviceConfigRequest;
 import org.eclipse.hono.communication.api.data.ListDeviceConfigVersionsResponse;
-import org.eclipse.hono.communication.api.service.DeviceConfigService;
-import org.eclipse.hono.communication.api.service.DeviceConfigServiceImpl;
+import org.eclipse.hono.communication.api.service.config.DeviceConfigService;
+import org.eclipse.hono.communication.api.service.config.DeviceConfigServiceImpl;
 import org.junit.jupiter.api.AfterEach;
 import org.junit.jupiter.api.Assertions;
 import org.junit.jupiter.api.BeforeEach;
@@ -43,7 +48,6 @@
 import io.vertx.ext.web.openapi.Operation;
 import io.vertx.ext.web.openapi.RouterBuilder;
 
-
 class DeviceConfigsHandlerTest {
 
     private final DeviceConfigService configServiceMock;
@@ -113,8 +117,8 @@ void addRoutes() {
 
     @Test
     void handleModifyCloudToDeviceConfig_success() {
-        when(routingContextMock.pathParam(DeviceConfigsConstants.TENANT_PATH_PARAMS)).thenReturn(tenantID);
-        when(routingContextMock.pathParam(DeviceConfigsConstants.DEVICE_PATH_PARAMS)).thenReturn(deviceID);
+        when(routingContextMock.pathParam(DeviceConfigsConstants.API_COMMON.TENANT_PATH_PARAMS)).thenReturn(tenantID);
+        when(routingContextMock.pathParam(DeviceConfigsConstants.API_COMMON.DEVICE_PATH_PARAMS)).thenReturn(deviceID);
         when(routingContextMock.body()).thenReturn(requestBodyMock);
         when(requestBodyMock.asJsonObject()).thenReturn(jsonObjMock);
         when(jsonObjMock.mapTo(DeviceConfigRequest.class)).thenReturn(deviceConfigRequest);
@@ -127,8 +131,8 @@ void handleModifyCloudToDeviceConfig_success() {
         final var results = deviceConfigsHandler.handleModifyCloudToDeviceConfig(routingContextMock);
 
         verify(configServiceMock).modifyCloudToDeviceConfig(deviceConfigRequest, deviceID, tenantID);
-        verify(routingContextMock, times(1)).pathParam(DeviceConfigsConstants.TENANT_PATH_PARAMS);
-        verify(routingContextMock, times(1)).pathParam(DeviceConfigsConstants.DEVICE_PATH_PARAMS);
+        verify(routingContextMock, times(1)).pathParam(DeviceConfigsConstants.API_COMMON.TENANT_PATH_PARAMS);
+        verify(routingContextMock, times(1)).pathParam(DeviceConfigsConstants.API_COMMON.DEVICE_PATH_PARAMS);
         verify(routingContextMock, times(1)).body();
         verify(requestBodyMock, times(1)).asJsonObject();
         verify(jsonObjMock, times(1)).mapTo(DeviceConfigRequest.class);
@@ -139,8 +143,8 @@ void handleModifyCloudToDeviceConfig_success() {
 
     @Test
     void handleModifyCloudToDeviceConfig_failure() {
-        when(routingContextMock.pathParam(DeviceConfigsConstants.TENANT_PATH_PARAMS)).thenReturn(tenantID);
-        when(routingContextMock.pathParam(DeviceConfigsConstants.DEVICE_PATH_PARAMS)).thenReturn(deviceID);
+        when(routingContextMock.pathParam(DeviceConfigsConstants.API_COMMON.TENANT_PATH_PARAMS)).thenReturn(tenantID);
+        when(routingContextMock.pathParam(DeviceConfigsConstants.API_COMMON.DEVICE_PATH_PARAMS)).thenReturn(deviceID);
         when(routingContextMock.body()).thenReturn(requestBodyMock);
         when(requestBodyMock.asJsonObject()).thenReturn(jsonObjMock);
         when(jsonObjMock.mapTo(DeviceConfigRequest.class)).thenReturn(deviceConfigRequest);
@@ -154,9 +158,9 @@ void handleModifyCloudToDeviceConfig_failure() {
         final var results = deviceConfigsHandler.handleModifyCloudToDeviceConfig(routingContextMock);
 
         verify(configServiceMock).modifyCloudToDeviceConfig(deviceConfigRequest, deviceID, tenantID);
-        verify(routingContextMock, times(1)).pathParam(DeviceConfigsConstants.TENANT_PATH_PARAMS);
+        verify(routingContextMock, times(1)).pathParam(DeviceConfigsConstants.API_COMMON.TENANT_PATH_PARAMS);
 
-        verify(routingContextMock, times(1)).pathParam(DeviceConfigsConstants.DEVICE_PATH_PARAMS);
+        verify(routingContextMock, times(1)).pathParam(DeviceConfigsConstants.API_COMMON.DEVICE_PATH_PARAMS);
         verify(routingContextMock, times(1)).body();
         verify(requestBodyMock, times(1)).asJsonObject();
         verify(jsonObjMock, times(1)).mapTo(DeviceConfigRequest.class);
@@ -171,8 +175,8 @@ void handleListConfigVersions_success() {
         final var listDeviceConfigVersionsResponse = new ListDeviceConfigVersionsResponse(List.of(deviceConfig));
         final MultiMap queryParams = MultiMap.caseInsensitiveMultiMap().add(DeviceConfigsConstants.NUM_VERSION_QUERY_PARAMS, String.valueOf(10));
         when(routingContextMock.queryParams()).thenReturn(queryParams);
-        when(routingContextMock.pathParam(DeviceConfigsConstants.TENANT_PATH_PARAMS)).thenReturn(tenantID);
-        when(routingContextMock.pathParam(DeviceConfigsConstants.DEVICE_PATH_PARAMS)).thenReturn(deviceID);
+        when(routingContextMock.pathParam(DeviceConfigsConstants.API_COMMON.TENANT_PATH_PARAMS)).thenReturn(tenantID);
+        when(routingContextMock.pathParam(DeviceConfigsConstants.API_COMMON.DEVICE_PATH_PARAMS)).thenReturn(deviceID);
         when(routingContextMock.response()).thenReturn(httpServerResponseMock);
         when(httpServerResponseMock.setStatusCode(anyInt())).thenReturn(httpServerResponseMock);
         when(httpServerResponseMock.putHeader("Content-Type",
@@ -183,8 +187,8 @@ void handleListConfigVersions_success() {
 
         verify(configServiceMock, times(1)).listAll(deviceID, tenantID, 10);
         verify(routingContextMock, times(1)).queryParams();
-        verify(routingContextMock, times(1)).pathParam(DeviceConfigsConstants.TENANT_PATH_PARAMS);
-        verify(routingContextMock, times(1)).pathParam(DeviceConfigsConstants.DEVICE_PATH_PARAMS);
+        verify(routingContextMock, times(1)).pathParam(DeviceConfigsConstants.API_COMMON.TENANT_PATH_PARAMS);
+        verify(routingContextMock, times(1)).pathParam(DeviceConfigsConstants.API_COMMON.DEVICE_PATH_PARAMS);
 
         verifySuccessResponse(results, listDeviceConfigVersionsResponse);
 
@@ -195,8 +199,8 @@ void handleListConfigVersions_success() {
     void handleListConfigVersions_failed() {
         final MultiMap queryParams = MultiMap.caseInsensitiveMultiMap().add(DeviceConfigsConstants.NUM_VERSION_QUERY_PARAMS, String.valueOf(10));
         when(routingContextMock.queryParams()).thenReturn(queryParams);
-        when(routingContextMock.pathParam(DeviceConfigsConstants.TENANT_PATH_PARAMS)).thenReturn(tenantID);
-        when(routingContextMock.pathParam(DeviceConfigsConstants.DEVICE_PATH_PARAMS)).thenReturn(deviceID);
+        when(routingContextMock.pathParam(DeviceConfigsConstants.API_COMMON.TENANT_PATH_PARAMS)).thenReturn(tenantID);
+        when(routingContextMock.pathParam(DeviceConfigsConstants.API_COMMON.DEVICE_PATH_PARAMS)).thenReturn(deviceID);
         when(routingContextMock.response()).thenReturn(httpServerResponseMock);
         when(httpServerResponseMock.setStatusCode(anyInt())).thenReturn(httpServerResponseMock);
         when(illegalArgumentExceptionMock.getMessage()).thenReturn(errorMsg);
@@ -208,9 +212,9 @@ void handleListConfigVersions_failed() {
 
         verify(configServiceMock, times(1)).listAll(deviceID, tenantID, 10);
         verify(routingContextMock, times(1)).queryParams();
-        verify(routingContextMock, times(1)).pathParam(DeviceConfigsConstants.TENANT_PATH_PARAMS);
+        verify(routingContextMock, times(1)).pathParam(DeviceConfigsConstants.API_COMMON.TENANT_PATH_PARAMS);
 
-        verify(routingContextMock, times(1)).pathParam(DeviceConfigsConstants.DEVICE_PATH_PARAMS);
+        verify(routingContextMock, times(1)).pathParam(DeviceConfigsConstants.API_COMMON.DEVICE_PATH_PARAMS);
         verifyErrorResponse(results);
 
 
diff --git a/device-communication/src/test/java/org/eclipse/hono/communication/api/handler/DeviceStatesHandlerTest.java b/device-communication/src/test/java/org/eclipse/hono/communication/api/handler/DeviceStatesHandlerTest.java
new file mode 100644
index 00000000..a80ef2e0
--- /dev/null
+++ b/device-communication/src/test/java/org/eclipse/hono/communication/api/handler/DeviceStatesHandlerTest.java
@@ -0,0 +1,150 @@
+/*
+ * ***********************************************************
+ *  Copyright (c) 2023 Contributors to the Eclipse Foundation
+ *  <p>
+ *  See the NOTICE file(s) distributed with this work for additional
+ *  information regarding copyright ownership.
+ *  <p>
+ *  This program and the accompanying materials are made available under the
+ *  terms of the Eclipse Public License 2.0 which is available at
+ *  http://www.eclipse.org/legal/epl-2.0
+ *  <p>
+ *  SPDX-License-Identifier: EPL-2.0
+ * **********************************************************
+ *
+ */
+
+package org.eclipse.hono.communication.api.handler;
+
+import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.ArgumentMatchers.anyString;
+import static org.mockito.Mockito.anyInt;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.times;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.when;
+
+import java.util.List;
+
+import org.eclipse.hono.communication.api.config.DeviceStatesConstants;
+import org.eclipse.hono.communication.api.data.DeviceState;
+import org.eclipse.hono.communication.api.data.ListDeviceStatesResponse;
+import org.eclipse.hono.communication.api.service.state.DeviceStateService;
+import org.eclipse.hono.communication.api.service.state.DeviceStateServiceImpl;
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Test;
+
+import io.vertx.core.Future;
+import io.vertx.core.MultiMap;
+import io.vertx.core.http.HttpServerResponse;
+import io.vertx.core.json.Json;
+import io.vertx.core.json.JsonObject;
+import io.vertx.ext.web.RoutingContext;
+import io.vertx.ext.web.openapi.Operation;
+import io.vertx.ext.web.openapi.RouterBuilder;
+
+class DeviceStatesHandlerTest {
+
+    private final RouterBuilder routerBuilderMock;
+    private final RoutingContext routingContextMock;
+    private final Operation operationMock;
+    private final HttpServerResponse httpServerResponseMock;
+    private final IllegalArgumentException illegalArgumentExceptionMock;
+    private final DeviceStateService stateServiceMock;
+    private final DeviceStatesHandler deviceStatesHandler;
+    private final String tenantID = "tenant_ID";
+    private final String deviceID = "device_ID";
+    private final String errorMsg = "test_error";
+    private final DeviceState deviceState = new DeviceState();
+
+    DeviceStatesHandlerTest() {
+        routerBuilderMock = mock(RouterBuilder.class);
+        routingContextMock = mock(RoutingContext.class);
+        operationMock = mock(Operation.class);
+        httpServerResponseMock = mock(HttpServerResponse.class);
+        illegalArgumentExceptionMock = mock(IllegalArgumentException.class);
+        stateServiceMock = mock(DeviceStateServiceImpl.class);
+        deviceStatesHandler = new DeviceStatesHandler(stateServiceMock);
+    }
+
+    @Test
+    void testAddRoutes() {
+        when(routerBuilderMock.operation(anyString())).thenReturn(operationMock);
+        when(operationMock.handler(any())).thenReturn(operationMock);
+
+        deviceStatesHandler.addRoutes(routerBuilderMock);
+
+        verify(routerBuilderMock, times(1)).operation(DeviceStatesConstants.LIST_STATES_OP_ID);
+        verify(operationMock, times(1)).handler(any());
+    }
+
+    @Test
+    void testHandleListStates_success() {
+        final var listDeviceStatesResponse = new ListDeviceStatesResponse(List.of(deviceState));
+        final MultiMap queryParams = MultiMap.caseInsensitiveMultiMap()
+                .add(DeviceStatesConstants.NUM_STATES_QUERY_PARAMS, String.valueOf(10));
+        when(routingContextMock.queryParams()).thenReturn(queryParams);
+        when(routingContextMock.pathParam(DeviceStatesConstants.API_COMMON.TENANT_PATH_PARAMS)).thenReturn(tenantID);
+        when(routingContextMock.pathParam(DeviceStatesConstants.API_COMMON.DEVICE_PATH_PARAMS)).thenReturn(deviceID);
+        when(routingContextMock.response()).thenReturn(httpServerResponseMock);
+        when(httpServerResponseMock.setStatusCode(anyInt())).thenReturn(httpServerResponseMock);
+        when(httpServerResponseMock.putHeader("Content-Type",
+                "application/json")).thenReturn(httpServerResponseMock);
+        when(stateServiceMock.listAll(deviceID, tenantID, 10))
+                .thenReturn(Future.succeededFuture(listDeviceStatesResponse));
+
+        final var results = deviceStatesHandler.handleListStates(routingContextMock);
+
+        verify(stateServiceMock, times(1)).listAll(deviceID, tenantID, 10);
+        verify(routingContextMock, times(1)).queryParams();
+        verify(routingContextMock, times(1)).pathParam(DeviceStatesConstants.API_COMMON.TENANT_PATH_PARAMS);
+        verify(routingContextMock, times(1)).pathParam(DeviceStatesConstants.API_COMMON.DEVICE_PATH_PARAMS);
+
+        verifySuccessResponse(results, listDeviceStatesResponse);
+    }
+
+    @Test
+    void testHandleListStates_failed() {
+        final MultiMap queryParams = MultiMap.caseInsensitiveMultiMap()
+                .add(DeviceStatesConstants.NUM_STATES_QUERY_PARAMS, String.valueOf(10));
+        when(routingContextMock.queryParams()).thenReturn(queryParams);
+        when(routingContextMock.pathParam(DeviceStatesConstants.API_COMMON.TENANT_PATH_PARAMS)).thenReturn(tenantID);
+        when(routingContextMock.pathParam(DeviceStatesConstants.API_COMMON.DEVICE_PATH_PARAMS)).thenReturn(deviceID);
+        when(routingContextMock.response()).thenReturn(httpServerResponseMock);
+        when(httpServerResponseMock.setStatusCode(anyInt())).thenReturn(httpServerResponseMock);
+        when(illegalArgumentExceptionMock.getMessage()).thenReturn(errorMsg);
+        when(httpServerResponseMock.putHeader("Content-Type",
+                "application/json")).thenReturn(httpServerResponseMock);
+        when(stateServiceMock.listAll(deviceID, tenantID, 10))
+                .thenReturn(Future.failedFuture(illegalArgumentExceptionMock));
+
+        final var results = deviceStatesHandler.handleListStates(routingContextMock);
+
+        verify(stateServiceMock, times(1)).listAll(deviceID, tenantID, 10);
+        verify(routingContextMock, times(1)).queryParams();
+        verify(routingContextMock, times(1)).pathParam(DeviceStatesConstants.API_COMMON.TENANT_PATH_PARAMS);
+
+        verify(routingContextMock, times(1)).pathParam(DeviceStatesConstants.API_COMMON.DEVICE_PATH_PARAMS);
+        verifyErrorResponse(results);
+    }
+
+    void verifyErrorResponse(final Future results) {
+        verify(routingContextMock, times(1)).response();
+        verify(httpServerResponseMock).setStatusCode(400);
+        verify(illegalArgumentExceptionMock).getMessage();
+        verify(httpServerResponseMock).putHeader("Content-Type",
+                "application/json");
+        verify(httpServerResponseMock).end(new JsonObject().put("error", errorMsg).encodePrettily());
+        Assertions.assertTrue(results.failed());
+    }
+
+    void verifySuccessResponse(final Future results, final Object responseObj) {
+        verify(routingContextMock, times(1)).response();
+        verify(httpServerResponseMock).setStatusCode(200);
+        verify(httpServerResponseMock).putHeader("Content-Type",
+                "application/json");
+        verify(httpServerResponseMock).end(Json.encodePrettily(responseObj));
+        Assertions.assertTrue(results.succeeded());
+    }
+
+}
diff --git a/device-communication/src/test/java/org/eclipse/hono/communication/api/service/DeviceConfigServiceImplTest.java b/device-communication/src/test/java/org/eclipse/hono/communication/api/service/DeviceConfigServiceImplTest.java
deleted file mode 100644
index 56b767fa..00000000
--- a/device-communication/src/test/java/org/eclipse/hono/communication/api/service/DeviceConfigServiceImplTest.java
+++ /dev/null
@@ -1,127 +0,0 @@
-/*
- * ***********************************************************
- *  Copyright (c) 2023 Contributors to the Eclipse Foundation
- *  <p>
- *  See the NOTICE file(s) distributed with this work for additional
- *  information regarding copyright ownership.
- *  <p>
- *  This program and the accompanying materials are made available under the
- *  terms of the Eclipse Public License 2.0 which is available at
- *  http://www.eclipse.org/legal/epl-2.0
- *  <p>
- *  SPDX-License-Identifier: EPL-2.0
- * **********************************************************
- *
- */
-
-package org.eclipse.hono.communication.api.service;
-
-import static org.mockito.Mockito.*;
-
-import org.eclipse.hono.communication.api.data.DeviceConfig;
-import org.eclipse.hono.communication.api.data.DeviceConfigEntity;
-import org.eclipse.hono.communication.api.data.DeviceConfigRequest;
-import org.eclipse.hono.communication.api.data.ListDeviceConfigVersionsResponse;
-import org.eclipse.hono.communication.api.mapper.DeviceConfigMapper;
-import org.eclipse.hono.communication.api.repository.DeviceConfigsRepository;
-import org.eclipse.hono.communication.api.repository.DeviceConfigsRepositoryImpl;
-import org.junit.jupiter.api.AfterEach;
-import org.junit.jupiter.api.Assertions;
-import org.junit.jupiter.api.Test;
-
-import io.vertx.core.Future;
-import io.vertx.pgclient.PgPool;
-
-
-class DeviceConfigServiceImplTest {
-
-    private final DeviceConfigsRepository repositoryMock;
-    private final DatabaseService dbMock;
-    private final PgPool poolMock;
-    private final DeviceConfigMapper mapperMock;
-    private final DeviceConfigService deviceConfigService;
-
-    private final String tenantId = "tenant_ID";
-    private final String deviceId = "device_ID";
-
-    DeviceConfigServiceImplTest() {
-        this.repositoryMock = mock(DeviceConfigsRepositoryImpl.class);
-        this.dbMock = mock(DatabaseServiceImpl.class);
-        this.mapperMock = mock(DeviceConfigMapper.class);
-        this.poolMock = mock(PgPool.class);
-        this.deviceConfigService = new DeviceConfigServiceImpl(repositoryMock, dbMock, mapperMock);
-    }
-
-
-    @AfterEach
-    void tearDown() {
-        verifyNoMoreInteractions(repositoryMock, mapperMock, dbMock);
-    }
-
-    @Test
-    void modifyCloudToDeviceConfig_success() {
-        final var deviceConfigRequest = new DeviceConfigRequest();
-        final var deviceConfigEntity = new DeviceConfigEntity();
-        final var deviceConfigEntityResponse = new DeviceConfig();
-        when(mapperMock.configRequestToDeviceConfigEntity(deviceConfigRequest)).thenReturn(deviceConfigEntity);
-        when(mapperMock.deviceConfigEntityToConfig(deviceConfigEntity)).thenReturn(deviceConfigEntityResponse);
-        when(dbMock.getDbClient()).thenReturn(poolMock);
-        when(poolMock.withTransaction(any())).thenReturn(Future.succeededFuture(deviceConfigEntity));
-
-
-        final var results = deviceConfigService.modifyCloudToDeviceConfig(deviceConfigRequest, deviceId, tenantId);
-
-        verify(mapperMock, times(1)).configRequestToDeviceConfigEntity(deviceConfigRequest);
-        verify(mapperMock, times(1)).deviceConfigEntityToConfig(deviceConfigEntity);
-        verify(dbMock, times(1)).getDbClient();
-        verify(poolMock, times(1)).withTransaction(any());
-        Assertions.assertTrue(results.succeeded());
-    }
-
-    @Test
-    void modifyCloudToDeviceConfig_failure() {
-        final var deviceConfigRequest = new DeviceConfigRequest();
-        final var deviceConfigEntity = new DeviceConfigEntity();
-        when(mapperMock.configRequestToDeviceConfigEntity(deviceConfigRequest)).thenReturn(deviceConfigEntity);
-        when(dbMock.getDbClient()).thenReturn(poolMock);
-        when(poolMock.withTransaction(any())).thenReturn(Future.failedFuture(new Throwable("test_error")));
-
-
-        final var results = deviceConfigService.modifyCloudToDeviceConfig(deviceConfigRequest, deviceId, tenantId);
-
-        verify(mapperMock, times(1)).configRequestToDeviceConfigEntity(deviceConfigRequest);
-        verify(dbMock, times(1)).getDbClient();
-        verify(poolMock, times(1)).withTransaction(any());
-        Assertions.assertTrue(results.failed());
-    }
-
-    @Test
-    void listAll_success() {
-        final var deviceConfigVersions = new ListDeviceConfigVersionsResponse();
-        when(dbMock.getDbClient()).thenReturn(poolMock);
-        when(poolMock.withConnection(any())).thenReturn(Future.succeededFuture(deviceConfigVersions));
-
-        final var results = deviceConfigService.listAll(deviceId, tenantId, 10);
-
-        verify(dbMock, times(1)).getDbClient();
-        verify(poolMock, times(1)).withConnection(any());
-        Assertions.assertTrue(results.succeeded());
-
-
-    }
-
-
-    @Test
-    void listAll_failed() {
-        when(dbMock.getDbClient()).thenReturn(poolMock);
-        when(poolMock.withConnection(any())).thenReturn(Future.failedFuture(new Throwable("test_error")));
-
-        final var results = deviceConfigService.listAll(deviceId, tenantId, 10);
-
-        verify(dbMock, times(1)).getDbClient();
-        verify(poolMock, times(1)).withConnection(any());
-        Assertions.assertTrue(results.failed());
-
-
-    }
-}
diff --git a/device-communication/src/test/java/org/eclipse/hono/communication/api/service/communication/InternalTopicManagerImplTest.java b/device-communication/src/test/java/org/eclipse/hono/communication/api/service/communication/InternalTopicManagerImplTest.java
new file mode 100644
index 00000000..915780ae
--- /dev/null
+++ b/device-communication/src/test/java/org/eclipse/hono/communication/api/service/communication/InternalTopicManagerImplTest.java
@@ -0,0 +1,157 @@
+/*
+ * ***********************************************************
+ *  Copyright (c) 2023 Contributors to the Eclipse Foundation
+ *  <p>
+ *  See the NOTICE file(s) distributed with this work for additional
+ *  information regarding copyright ownership.
+ *  <p>
+ *  This program and the accompanying materials are made available under the
+ *  terms of the Eclipse Public License 2.0 which is available at
+ *  http://www.eclipse.org/legal/epl-2.0
+ *  <p>
+ *  SPDX-License-Identifier: EPL-2.0
+ * **********************************************************
+ *
+ */
+
+package org.eclipse.hono.communication.api.service.communication;
+
+import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.ArgumentMatchers.anyString;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.mockStatic;
+import static org.mockito.Mockito.times;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.verifyNoMoreInteractions;
+import static org.mockito.Mockito.when;
+
+import java.io.IOException;
+import java.time.Instant;
+import java.util.Optional;
+
+import org.eclipse.hono.client.pubsub.PubSubMessageHelper;
+import org.eclipse.hono.communication.api.handler.ConfigTopicEventHandler;
+import org.eclipse.hono.communication.api.handler.StateTopicEventHandler;
+import org.eclipse.hono.communication.api.mapper.DeviceConfigMapper;
+import org.eclipse.hono.communication.api.repository.DeviceRepository;
+import org.eclipse.hono.communication.core.app.InternalMessagingConfig;
+import org.eclipse.hono.notification.deviceregistry.LifecycleChange;
+import org.eclipse.hono.notification.deviceregistry.TenantChangeNotification;
+import org.junit.jupiter.api.AfterEach;
+import org.junit.jupiter.api.Test;
+import org.mockito.MockedStatic;
+
+import com.fasterxml.jackson.databind.ObjectMapper;
+import com.google.api.gax.core.FixedCredentialsProvider;
+import com.google.cloud.pubsub.v1.AckReplyConsumer;
+import com.google.protobuf.ByteString;
+import com.google.pubsub.v1.PubsubMessage;
+
+import io.vertx.core.Context;
+import io.vertx.core.Vertx;
+
+class InternalTopicManagerImplTest {
+
+    private final DeviceRepository deviceRepositoryMock;
+    private final DeviceConfigMapper mapperMock;
+    private final InternalMessagingConfig communicationConfigMock;
+    private final InternalMessaging internalCommunicationMock;
+    private final String tenantId = "tenant_ID";
+    private final PubsubMessage pubsubMessageMock;
+    private final Context contextMock;
+    private final AckReplyConsumer ackReplyConsumerMock;
+    private final ByteString byteStringMock;
+    private final ConfigTopicEventHandler configTopicEventHandler;
+    private final StateTopicEventHandler stateTopicEventHandler;
+    private final InternalTopicManagerImpl internalTopicManager;
+    private final Vertx vertxMock;
+
+    InternalTopicManagerImplTest() {
+        this.deviceRepositoryMock = mock(DeviceRepository.class);
+        this.mapperMock = mock(DeviceConfigMapper.class);
+        this.communicationConfigMock = mock(InternalMessagingConfig.class);
+        this.internalCommunicationMock = mock(InternalMessaging.class);
+        this.pubsubMessageMock = mock(PubsubMessage.class);
+        this.ackReplyConsumerMock = mock(AckReplyConsumer.class);
+        this.contextMock = mock(Context.class);
+        this.byteStringMock = mock(ByteString.class);
+        this.configTopicEventHandler = mock(ConfigTopicEventHandler.class);
+        this.stateTopicEventHandler = mock(StateTopicEventHandler.class);
+        this.vertxMock = mock(Vertx.class);
+        this.internalTopicManager = new InternalTopicManagerImpl(deviceRepositoryMock, configTopicEventHandler,
+                stateTopicEventHandler, internalCommunicationMock, communicationConfigMock, vertxMock);
+
+    }
+
+    @AfterEach
+    void tearDown() {
+        verifyNoMoreInteractions(deviceRepositoryMock,
+                mapperMock,
+                communicationConfigMock,
+                internalCommunicationMock,
+                pubsubMessageMock,
+                ackReplyConsumerMock,
+                byteStringMock,
+                configTopicEventHandler,
+                stateTopicEventHandler,
+                contextMock,
+                vertxMock);
+    }
+
+    @Test
+    public void testOnTenantChanges_ChangeIsUpdate() throws IOException {
+        final TenantChangeNotification notification = new TenantChangeNotification(LifecycleChange.UPDATE, tenantId,
+                Instant.now(), false, false);
+        when(pubsubMessageMock.getData()).thenReturn(byteStringMock);
+        when(byteStringMock.toStringUtf8()).thenReturn(new ObjectMapper().writeValueAsString(notification));
+
+        internalTopicManager.onTenantChanges(pubsubMessageMock, ackReplyConsumerMock);
+
+        verify(ackReplyConsumerMock).ack();
+        verify(pubsubMessageMock).getData();
+        verify(byteStringMock).toStringUtf8();
+    }
+
+    @Test
+    public void testOnTenantChanges_tenantIdIsEmpty() throws IOException {
+        final TenantChangeNotification notification = new TenantChangeNotification(LifecycleChange.CREATE, "",
+                Instant.now(), false, false);
+        when(pubsubMessageMock.getData()).thenReturn(byteStringMock);
+        when(byteStringMock.toStringUtf8()).thenReturn(new ObjectMapper().writeValueAsString(notification));
+
+        internalTopicManager.onTenantChanges(pubsubMessageMock, ackReplyConsumerMock);
+
+        verify(ackReplyConsumerMock).ack();
+        verify(pubsubMessageMock).getData();
+        verify(byteStringMock).toStringUtf8();
+
+    }
+
+    @Test
+    public void testOnTenantChanges_success() throws IOException {
+        try (MockedStatic<PubSubMessageHelper> mockedPubSubMessageHelper = mockStatic(PubSubMessageHelper.class)) {
+            final var credMock = mock(FixedCredentialsProvider.class);
+            mockedPubSubMessageHelper.when(PubSubMessageHelper::getCredentialsProvider)
+                    .thenReturn(Optional.of(credMock));
+
+            final TenantChangeNotification notification = new TenantChangeNotification(LifecycleChange.CREATE, tenantId,
+                    Instant.now(), false, false);
+            when(pubsubMessageMock.getData()).thenReturn(byteStringMock);
+            when(byteStringMock.toStringUtf8()).thenReturn(new ObjectMapper().writeValueAsString(notification));
+            when(communicationConfigMock.getEventTopicFormat()).thenReturn("%s.event");
+            when(communicationConfigMock.getStateTopicFormat()).thenReturn("%s.event.state");
+            when(communicationConfigMock.getCommandAckTopicFormat()).thenReturn("%s.command_response");
+
+            internalTopicManager.onTenantChanges(pubsubMessageMock, ackReplyConsumerMock);
+
+            verify(ackReplyConsumerMock).ack();
+            verify(pubsubMessageMock).getData();
+            verify(byteStringMock).toStringUtf8();
+            verify(communicationConfigMock).getEventTopicFormat();
+            verify(communicationConfigMock).getStateTopicFormat();
+            verify(communicationConfigMock).getCommandAckTopicFormat();
+            verify(communicationConfigMock, times(2)).getProjectId();
+            verify(internalCommunicationMock, times(3)).subscribe(anyString(), any());
+        }
+    }
+}
diff --git a/device-communication/src/test/java/org/eclipse/hono/communication/api/service/config/DeviceConfigServiceImplTest.java b/device-communication/src/test/java/org/eclipse/hono/communication/api/service/config/DeviceConfigServiceImplTest.java
new file mode 100644
index 00000000..0c06ee85
--- /dev/null
+++ b/device-communication/src/test/java/org/eclipse/hono/communication/api/service/config/DeviceConfigServiceImplTest.java
@@ -0,0 +1,388 @@
+/*
+ * ***********************************************************
+ *  Copyright (c) 2023 Contributors to the Eclipse Foundation
+ *  <p>
+ *  See the NOTICE file(s) distributed with this work for additional
+ *  information regarding copyright ownership.
+ *  <p>
+ *  This program and the accompanying materials are made available under the
+ *  terms of the Eclipse Public License 2.0 which is available at
+ *  http://www.eclipse.org/legal/epl-2.0
+ *  <p>
+ *  SPDX-License-Identifier: EPL-2.0
+ * **********************************************************
+ *
+ */
+
+package org.eclipse.hono.communication.api.service.config;
+
+import static org.mockito.Mockito.any;
+import static org.mockito.Mockito.anyLong;
+import static org.mockito.Mockito.anyString;
+import static org.mockito.Mockito.doAnswer;
+import static org.mockito.Mockito.doNothing;
+import static org.mockito.Mockito.doReturn;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.never;
+import static org.mockito.Mockito.times;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.verifyNoMoreInteractions;
+import static org.mockito.Mockito.when;
+
+import java.time.Instant;
+import java.util.List;
+import java.util.Map;
+import java.util.NoSuchElementException;
+
+import org.eclipse.hono.communication.api.data.DeviceConfig;
+import org.eclipse.hono.communication.api.data.DeviceConfigEntity;
+import org.eclipse.hono.communication.api.data.DeviceConfigRequest;
+import org.eclipse.hono.communication.api.mapper.DeviceConfigMapper;
+import org.eclipse.hono.communication.api.repository.DeviceConfigRepository;
+import org.eclipse.hono.communication.api.repository.DeviceConfigRepositoryImpl;
+import org.eclipse.hono.communication.api.service.communication.InternalMessaging;
+import org.eclipse.hono.communication.core.app.InternalMessagingConfig;
+import org.eclipse.hono.communication.core.app.InternalMessagingConstants;
+import org.junit.jupiter.api.AfterEach;
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Test;
+import org.mockito.ArgumentMatchers;
+
+import com.google.cloud.pubsub.v1.AckReplyConsumer;
+import com.google.protobuf.ByteString;
+import com.google.pubsub.v1.PubsubMessage;
+
+import io.vertx.core.Context;
+import io.vertx.core.Future;
+import io.vertx.core.Handler;
+import io.vertx.core.Promise;
+import io.vertx.core.Vertx;
+
+class DeviceConfigServiceImplTest {
+
+    public static final String CONFIG_BASE_64 = "dGVzdCBjb25maWcgMjIyMjIy";
+    private final DeviceConfigRepository repositoryMock;
+    private final DeviceConfigMapper mapperMock;
+    private final InternalMessagingConfig communicationConfigMock;
+    private final InternalMessaging internalCommunicationMock;
+    private final String tenantId = "tenant_ID";
+    private final String deviceId = "device_ID";
+    private final PubsubMessage pubsubMessageMock;
+    private final Context contextMock;
+    private final AckReplyConsumer ackReplyConsumerMock;
+    private final ByteString byteStringMock;
+    private final DeviceConfigServiceImpl deviceConfigService;
+    private final Vertx vertxMock;
+
+    DeviceConfigServiceImplTest() {
+        this.repositoryMock = mock(DeviceConfigRepositoryImpl.class);
+        this.mapperMock = mock(DeviceConfigMapper.class);
+        this.communicationConfigMock = mock(InternalMessagingConfig.class);
+        this.internalCommunicationMock = mock(InternalMessaging.class);
+        this.pubsubMessageMock = mock(PubsubMessage.class);
+        this.ackReplyConsumerMock = mock(AckReplyConsumer.class);
+        this.contextMock = mock(Context.class);
+        this.byteStringMock = mock(ByteString.class);
+        this.vertxMock = mock(Vertx.class);
+        this.deviceConfigService = createServiceObj();
+    }
+
+    private static <T> Handler<T> anyHandler() {
+        @SuppressWarnings("unchecked")
+        final Handler<T> result = ArgumentMatchers.any(Handler.class);
+        return result;
+    }
+
+    DeviceConfigServiceImpl createServiceObj() {
+        return new DeviceConfigServiceImpl(repositoryMock,
+                mapperMock,
+                communicationConfigMock,
+                internalCommunicationMock,
+                vertxMock);
+    }
+
+    @AfterEach
+    void tearDown() {
+        verifyNoMoreInteractions(repositoryMock,
+                mapperMock,
+                communicationConfigMock,
+                internalCommunicationMock,
+                pubsubMessageMock,
+                ackReplyConsumerMock,
+                byteStringMock,
+                contextMock);
+    }
+
+    @Test
+    void modifyCloudToDeviceConfig_success() throws Exception {
+        final var deviceConfigRequest = new DeviceConfigRequest();
+        deviceConfigRequest.setBinaryData(CONFIG_BASE_64);
+
+        final var deviceConfigEntity = new DeviceConfigEntity();
+
+        final var deviceConfigEntityResponse = new DeviceConfig();
+        deviceConfigEntityResponse.setVersion("1");
+        deviceConfigEntityResponse.setBinaryData(CONFIG_BASE_64);
+
+        when(repositoryMock.createNew(any())).thenReturn(Future.succeededFuture(deviceConfigEntity));
+        when(repositoryMock.updateDeviceConfigError(any())).thenReturn(Future.succeededFuture());
+        when(repositoryMock.getDeviceConfig(tenantId, deviceId, 1))
+                .thenReturn(Future.succeededFuture(deviceConfigEntity));
+
+        when(mapperMock.configRequestToDeviceConfigEntity(deviceConfigRequest)).thenReturn(deviceConfigEntity);
+        when(mapperMock.deviceConfigEntityToConfig(deviceConfigEntity)).thenReturn(deviceConfigEntityResponse);
+        when(mapperMock.configRequestToDeviceConfigEntity(any())).thenReturn(deviceConfigEntity);
+
+        when(communicationConfigMock.getCommandTopicFormat()).thenReturn("%s.config");
+        when(communicationConfigMock.getCommandTopicFormat()).thenReturn("version");
+
+        doAnswer(invocation -> {
+            final Promise<Object> result = Promise.promise();
+            final Handler<Promise<Object>> handler = invocation.getArgument(0);
+            handler.handle(result);
+            return result.future();
+        }).when(contextMock).executeBlocking(any());
+
+        when(vertxMock.getOrCreateContext()).thenReturn(contextMock);
+
+        doAnswer(invocation -> {
+            final Handler<Long> task = invocation.getArgument(1);
+            task.handle(1L);
+            return 1L;
+        }).when(vertxMock).setTimer(anyLong(), anyHandler());
+
+        doNothing().when(internalCommunicationMock).publish(anyString(), any(), any());
+
+        final var results = deviceConfigService.modifyCloudToDeviceConfig(deviceConfigRequest, deviceId, tenantId);
+
+        verify(repositoryMock).createNew(any());
+        verify(repositoryMock).updateDeviceConfigError(any());
+        verify(repositoryMock).getDeviceConfig(tenantId, deviceId, 1);
+        verify(repositoryMock).updateDeviceAckTime(any(), any());
+        verify(mapperMock, times(1)).configRequestToDeviceConfigEntity(deviceConfigRequest);
+        verify(mapperMock, times(1)).deviceConfigEntityToConfig(deviceConfigEntity);
+        verify(communicationConfigMock).getCommandTopicFormat();
+        verify(communicationConfigMock).getConfigAckDelay();
+        verify(contextMock).executeBlocking(any());
+        verify(internalCommunicationMock).publish(anyString(), any(), any());
+        Assertions.assertTrue(results.succeeded());
+    }
+
+    @Test
+    void modifyCloudToDeviceConfig_failure() {
+        final var deviceConfigRequest = new DeviceConfigRequest();
+        deviceConfigRequest.setBinaryData(CONFIG_BASE_64);
+        final var deviceConfigEntity = new DeviceConfigEntity();
+        deviceConfigEntity.setBinaryData(CONFIG_BASE_64);
+
+        when(repositoryMock.createNew(any())).thenReturn(Future.failedFuture(new NoSuchElementException()));
+        when(mapperMock.configRequestToDeviceConfigEntity(deviceConfigRequest)).thenReturn(deviceConfigEntity);
+
+        final var results = deviceConfigService.modifyCloudToDeviceConfig(deviceConfigRequest, deviceId, tenantId);
+
+        verify(mapperMock).configRequestToDeviceConfigEntity(any());
+        verify(repositoryMock).createNew(any());
+        Assertions.assertTrue(results.failed());
+    }
+
+    @Test
+    void modifyCloudToDeviceConfig_failure_noBase64() {
+        final var deviceConfigRequest = new DeviceConfigRequest();
+        deviceConfigRequest.setBinaryData("test 2");
+        final var deviceConfigEntity = new DeviceConfigEntity();
+        deviceConfigEntity.setBinaryData("");
+
+        when(repositoryMock.createNew(any())).thenReturn(Future.failedFuture(new NoSuchElementException()));
+        when(mapperMock.configRequestToDeviceConfigEntity(deviceConfigRequest)).thenReturn(deviceConfigEntity);
+
+        final var results = deviceConfigService.modifyCloudToDeviceConfig(deviceConfigRequest, deviceId, tenantId);
+
+        Assertions.assertTrue(results.failed());
+    }
+
+    @Test
+    void listAll_success() {
+        when(repositoryMock.listAll(deviceId, tenantId, 10))
+                .thenReturn(Future.succeededFuture(List.of(new DeviceConfig())));
+
+        final var results = deviceConfigService.listAll(deviceId, tenantId, 10);
+
+        verify(repositoryMock).listAll(deviceId, tenantId, 10);
+        Assertions.assertTrue(results.succeeded());
+    }
+
+    @Test
+    void listAll_failed() {
+        when(repositoryMock.listAll(deviceId, tenantId, 10)).thenReturn(Future.failedFuture(new RuntimeException()));
+
+        final var results = deviceConfigService.listAll(deviceId, tenantId, 10);
+
+        verify(repositoryMock).listAll(deviceId, tenantId, 10);
+        Assertions.assertTrue(results.failed());
+    }
+
+    @Test
+    void updateDeviceAckTime() {
+        doReturn(Future.succeededFuture()).when(repositoryMock).updateDeviceAckTime(any(), anyString());
+
+        deviceConfigService.updateDeviceAckTime(new DeviceConfigEntity(), Instant.now().toString());
+
+        verify(repositoryMock).updateDeviceAckTime(any(), anyString());
+    }
+
+    @Test
+    void onDeviceConfigResponse_skipIfNoErrorResponse() {
+        when(pubsubMessageMock.getAttributesMap())
+                .thenReturn(Map.of(
+                        "deviceId", "device-123",
+                        "tenantId", "tenant-123",
+                        "configVersion", "12"));
+
+        when(communicationConfigMock.getContentTypeKey()).thenReturn("content-type");
+        when(communicationConfigMock.getDeliveryFailureNotificationContentType()).thenReturn("delivery-failure");
+
+        deviceConfigService.onDeviceConfigResponse(pubsubMessageMock, ackReplyConsumerMock);
+        verify(ackReplyConsumerMock).ack();
+        verify(pubsubMessageMock).getAttributesMap();
+        verify(communicationConfigMock).getContentTypeKey();
+        verify(communicationConfigMock).getDeliveryFailureNotificationContentType();
+        verify(repositoryMock, never()).updateDeviceConfigError(any());
+    }
+
+    @Test
+    void onDeviceConfigResponse() {
+        when(pubsubMessageMock.getAttributesMap())
+                .thenReturn(Map.of(
+                        InternalMessagingConstants.DEVICE_ID, "device-123",
+                        InternalMessagingConstants.TENANT_ID, "tenant-123",
+                        InternalMessagingConstants.STATUS, "500",
+                        InternalMessagingConstants.CORRELATION_ID, "12"));
+        when(pubsubMessageMock.getData())
+                .thenReturn(ByteString.copyFromUtf8("{\"error\": \"test\"}"));
+
+        when(communicationConfigMock.getContentTypeKey()).thenReturn("content-type");
+        doReturn(Future.succeededFuture()).when(repositoryMock).updateDeviceConfigError(any());
+
+        deviceConfigService.onDeviceConfigResponse(pubsubMessageMock, ackReplyConsumerMock);
+        verify(ackReplyConsumerMock).ack();
+        verify(pubsubMessageMock).getAttributesMap();
+        verify(pubsubMessageMock).getData();
+        verify(communicationConfigMock).getContentTypeKey();
+        verify(communicationConfigMock).getDeliveryFailureNotificationContentType();
+        verify(repositoryMock).updateDeviceConfigError(any());
+    }
+
+    @Test
+    public void onDeviceConfigRequest_SkipsIfDeviceIdOrTenantIdIsEmpty() {
+        when(pubsubMessageMock.getAttributesMap())
+                .thenReturn(Map.of(
+                        "deviceId", "",
+                        "tenantId", "tenant-123"));
+        when(pubsubMessageMock.getData()).thenReturn(ByteString.copyFromUtf8("{\"cause\": \"connected\"}"));
+
+        when(communicationConfigMock.getContentTypeKey()).thenReturn("content-type");
+
+        deviceConfigService.onDeviceConfigRequest(pubsubMessageMock, ackReplyConsumerMock);
+
+        verify(pubsubMessageMock).getAttributesMap();
+        verify(ackReplyConsumerMock).ack();
+    }
+
+    @Test
+    public void onDeviceConfigRequest_SkipsEvent() {
+        when(pubsubMessageMock.getAttributesMap())
+                .thenReturn(Map.of(
+                        "deviceId", "device-123",
+                        "tenantId", "tenant-123",
+                        "content-type", "test",
+                        "orig_adapter", "adapter-mqtt"));
+
+
+        when(communicationConfigMock.getContentTypeKey()).thenReturn("content-type");
+        when(communicationConfigMock.getOrigAdapterKey()).thenReturn("adapter-mqtt");
+        when(communicationConfigMock.getEmptyNotificationEventContentType()).thenReturn("skip-content");
+
+        deviceConfigService.onDeviceConfigRequest(pubsubMessageMock, ackReplyConsumerMock);
+
+        verify(pubsubMessageMock).getAttributesMap();
+        verify(communicationConfigMock).getContentTypeKey();
+        verify(communicationConfigMock).getOrigAdapterKey();
+        verify(communicationConfigMock, times(1)).getEmptyNotificationEventContentType();
+
+        verify(ackReplyConsumerMock).ack();
+    }
+
+    @Test
+    public void onDeviceConfigRequest_PublishesDeviceConfig() throws Exception {
+        final String deviceId = "device-123";
+        final String tenantId = "tenant-123";
+
+        final String topic = "tenant-123-config";
+        final byte[] message = "{}".getBytes();
+        final Map<String, String> messageAttributes = Map.of(
+                "deviceId", deviceId,
+                "tenantId", tenantId,
+                "content", "event",
+                "ttd", "-1");
+        final var deviceConfigEntity = new DeviceConfigEntity();
+        final var deviceConfigEntityResponse = new DeviceConfig();
+
+        when(pubsubMessageMock.getAttributesMap()).thenReturn(messageAttributes);
+        when(repositoryMock.getDeviceLatestConfig(tenantId, deviceId))
+                .thenReturn(Future.succeededFuture(deviceConfigEntity));
+        when(mapperMock.deviceConfigEntityToConfig(deviceConfigEntity)).thenReturn(deviceConfigEntityResponse);
+        when(communicationConfigMock.getCommandTopicFormat()).thenReturn("%s-config");
+
+        when(communicationConfigMock.getContentTypeKey()).thenReturn("content");
+        when(communicationConfigMock.getEmptyNotificationEventContentType()).thenReturn("event");
+        when(communicationConfigMock.getTtdKey()).thenReturn("ttd");
+        doNothing().when(internalCommunicationMock).publish(topic, message, messageAttributes);
+        when(vertxMock.getOrCreateContext()).thenReturn(contextMock);
+
+        deviceConfigService.onDeviceConfigRequest(pubsubMessageMock, ackReplyConsumerMock);
+
+        verify(pubsubMessageMock).getAttributesMap();
+        verify(repositoryMock).getDeviceLatestConfig(tenantId, deviceId);
+        verify(mapperMock).deviceConfigEntityToConfig(deviceConfigEntity);
+        verify(communicationConfigMock).getCommandTopicFormat();
+        verify(communicationConfigMock).getContentTypeKey();
+        verify(communicationConfigMock).getEmptyNotificationEventContentType();
+        verify(communicationConfigMock).getTtdKey();
+
+        verify(contextMock).executeBlocking(any());
+
+        verify(ackReplyConsumerMock).ack();
+    }
+
+    @Test
+    public void onDeviceConfigRequest_PublishesDeviceConfig_failed() {
+        final String deviceId = "device-123";
+        final String tenantId = "tenant-123";
+
+        final Map<String, String> messageAttributes = Map.of(
+                "deviceId", deviceId,
+                "content", "event",
+                "tenantId", tenantId,
+                "ttd", "-1");
+
+        when(pubsubMessageMock.getAttributesMap()).thenReturn(messageAttributes);
+        when(repositoryMock.getDeviceLatestConfig(tenantId, deviceId))
+                .thenReturn(Future.failedFuture(new RuntimeException()));
+        when(pubsubMessageMock.getData()).thenReturn(ByteString.copyFromUtf8("{\"cause\": \"connected\"}"));
+
+        when(communicationConfigMock.getContentTypeKey()).thenReturn("content");
+        when(communicationConfigMock.getEmptyNotificationEventContentType()).thenReturn("event");
+        when(communicationConfigMock.getTtdKey()).thenReturn("ttd");
+        when(communicationConfigMock.getCommandAckTopicFormat()).thenReturn("%s.ack");
+
+        deviceConfigService.onDeviceConfigRequest(pubsubMessageMock, ackReplyConsumerMock);
+
+        verify(pubsubMessageMock).getAttributesMap();
+        verify(repositoryMock).getDeviceLatestConfig(tenantId, deviceId);
+        verify(ackReplyConsumerMock).ack();
+
+        verify(communicationConfigMock).getContentTypeKey();
+        verify(communicationConfigMock).getEmptyNotificationEventContentType();
+        verify(communicationConfigMock).getTtdKey();
+    }
+}
diff --git a/device-communication/src/test/java/org/eclipse/hono/communication/api/service/DatabaseSchemaCreatorImplTest.java b/device-communication/src/test/java/org/eclipse/hono/communication/api/service/database/DatabaseSchemaCreatorImplTest.java
similarity index 75%
rename from device-communication/src/test/java/org/eclipse/hono/communication/api/service/DatabaseSchemaCreatorImplTest.java
rename to device-communication/src/test/java/org/eclipse/hono/communication/api/service/database/DatabaseSchemaCreatorImplTest.java
index 24c9cb8d..56f036de 100644
--- a/device-communication/src/test/java/org/eclipse/hono/communication/api/service/DatabaseSchemaCreatorImplTest.java
+++ b/device-communication/src/test/java/org/eclipse/hono/communication/api/service/database/DatabaseSchemaCreatorImplTest.java
@@ -14,11 +14,15 @@
  *
  */
 
-package org.eclipse.hono.communication.api.service;
+package org.eclipse.hono.communication.api.service.database;
 
 import static org.mockito.ArgumentMatchers.any;
 import static org.mockito.ArgumentMatchers.anyString;
-import static org.mockito.Mockito.*;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.times;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.verifyNoMoreInteractions;
+import static org.mockito.Mockito.when;
 
 import org.junit.jupiter.api.AfterEach;
 import org.junit.jupiter.api.BeforeEach;
@@ -29,7 +33,6 @@
 import io.vertx.core.file.FileSystem;
 import io.vertx.pgclient.PgPool;
 
-
 class DatabaseSchemaCreatorImplTest {
 
     private final Vertx vertxMock;
@@ -66,10 +69,10 @@ void createDBTables_success() {
 
         databaseSchemaCreator.createDBTables();
 
-        verify(vertxMock).fileSystem();
-        verify(fileSystemMock).readFile(anyString(), any());
-        verify(dbMock).getDbClient();
-        verify(pgPoolMock).withTransaction(any());
+        verify(vertxMock, times(2)).fileSystem();
+        verify(fileSystemMock, times(2)).readFile(anyString(), any());
+        verify(dbMock, times(2)).getDbClient();
+        verify(pgPoolMock, times(2)).withTransaction(any());
 
     }
 
@@ -83,11 +86,11 @@ void createDBTables_failed() {
 
         databaseSchemaCreator.createDBTables();
 
-        verify(vertxMock).fileSystem();
-        verify(fileSystemMock).readFile(anyString(), any());
-        verify(dbMock).getDbClient();
-        verify(dbMock).close();
-        verify(pgPoolMock).withTransaction(any());
+        verify(vertxMock, times(2)).fileSystem();
+        verify(fileSystemMock, times(2)).readFile(anyString(), any());
+        verify(dbMock, times(2)).getDbClient();
+        verify(dbMock, times(2)).close();
+        verify(pgPoolMock, times(2)).withTransaction(any());
 
     }
 }
diff --git a/device-communication/src/test/java/org/eclipse/hono/communication/api/service/DatabaseServiceImplTest.java b/device-communication/src/test/java/org/eclipse/hono/communication/api/service/database/DatabaseServiceImplTest.java
similarity index 90%
rename from device-communication/src/test/java/org/eclipse/hono/communication/api/service/DatabaseServiceImplTest.java
rename to device-communication/src/test/java/org/eclipse/hono/communication/api/service/database/DatabaseServiceImplTest.java
index 886c2259..792ff408 100644
--- a/device-communication/src/test/java/org/eclipse/hono/communication/api/service/DatabaseServiceImplTest.java
+++ b/device-communication/src/test/java/org/eclipse/hono/communication/api/service/database/DatabaseServiceImplTest.java
@@ -14,9 +14,13 @@
  *
  */
 
-package org.eclipse.hono.communication.api.service;
+package org.eclipse.hono.communication.api.service.database;
 
-import static org.mockito.Mockito.*;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.mockStatic;
+import static org.mockito.Mockito.times;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.verifyNoMoreInteractions;
 
 import org.eclipse.hono.communication.core.app.DatabaseConfig;
 import org.eclipse.hono.communication.core.utils.DbUtils;
@@ -28,7 +32,6 @@
 import io.vertx.core.Vertx;
 import io.vertx.pgclient.PgPool;
 
-
 class DatabaseServiceImplTest {
 
     private final Vertx vertxMock;
diff --git a/device-communication/src/test/java/org/eclipse/hono/communication/api/service/state/DeviceStateServiceImplTest.java b/device-communication/src/test/java/org/eclipse/hono/communication/api/service/state/DeviceStateServiceImplTest.java
new file mode 100644
index 00000000..169345ea
--- /dev/null
+++ b/device-communication/src/test/java/org/eclipse/hono/communication/api/service/state/DeviceStateServiceImplTest.java
@@ -0,0 +1,152 @@
+/*
+ * ***********************************************************
+ *  Copyright (c) 2023 Contributors to the Eclipse Foundation
+ *  <p>
+ *  See the NOTICE file(s) distributed with this work for additional
+ *  information regarding copyright ownership.
+ *  <p>
+ *  This program and the accompanying materials are made available under the
+ *  terms of the Eclipse Public License 2.0 which is available at
+ *  http://www.eclipse.org/legal/epl-2.0
+ *  <p>
+ *  SPDX-License-Identifier: EPL-2.0
+ * **********************************************************
+ *
+ */
+
+package org.eclipse.hono.communication.api.service.state;
+
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.verifyNoMoreInteractions;
+import static org.mockito.Mockito.when;
+
+import java.util.List;
+import java.util.Map;
+
+import org.eclipse.hono.communication.api.data.DeviceState;
+import org.eclipse.hono.communication.api.data.DeviceStateEntity;
+import org.eclipse.hono.communication.api.mapper.DeviceStateMapper;
+import org.eclipse.hono.communication.api.repository.DeviceStateRepository;
+import org.eclipse.hono.communication.api.repository.DeviceStateRepositoryImpl;
+import org.eclipse.hono.communication.api.service.communication.InternalMessaging;
+import org.eclipse.hono.communication.core.app.InternalMessagingConfig;
+import org.junit.jupiter.api.AfterEach;
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Test;
+
+import com.google.cloud.pubsub.v1.AckReplyConsumer;
+import com.google.protobuf.ByteString;
+import com.google.pubsub.v1.PubsubMessage;
+
+import io.vertx.core.Future;
+
+class DeviceStateServiceImplTest {
+
+    private final DeviceStateRepository repositoryMock;
+    private final DeviceStateMapper mapperMock;
+    private final InternalMessagingConfig communicationConfigMock;
+    private final InternalMessaging internalCommunicationMock;
+    private final PubsubMessage pubsubMessageMock;
+    private final AckReplyConsumer ackReplyConsumerMock;
+    private final String tenantId = "tenant_ID";
+    private final String deviceId = "device_ID";
+    private final DeviceStateServiceImpl deviceStateService;
+
+    DeviceStateServiceImplTest() {
+        this.repositoryMock = mock(DeviceStateRepositoryImpl.class);
+        this.mapperMock = mock(DeviceStateMapper.class);
+        this.communicationConfigMock = mock(InternalMessagingConfig.class);
+        this.internalCommunicationMock = mock(InternalMessaging.class);
+        this.pubsubMessageMock = mock(PubsubMessage.class);
+        this.ackReplyConsumerMock = mock(AckReplyConsumer.class);
+        deviceStateService = new DeviceStateServiceImpl(repositoryMock, mapperMock, communicationConfigMock,
+                internalCommunicationMock);
+    }
+
+    @AfterEach
+    void tearDown() {
+        verifyNoMoreInteractions(repositoryMock,
+                mapperMock,
+                communicationConfigMock,
+                internalCommunicationMock,
+                pubsubMessageMock);
+    }
+
+    @Test
+    void testListAll_success() {
+        when(repositoryMock.listAll(deviceId, tenantId, 10))
+                .thenReturn(Future.succeededFuture(List.of(new DeviceState())));
+
+        final var results = deviceStateService.listAll(deviceId, tenantId, 10);
+
+        verify(repositoryMock).listAll(deviceId, tenantId, 10);
+        Assertions.assertTrue(results.succeeded());
+
+    }
+
+    @Test
+    void testListAll_failed() {
+        when(repositoryMock.listAll(deviceId, tenantId, 10)).thenReturn(Future.failedFuture(new RuntimeException()));
+
+        final var results = deviceStateService.listAll(deviceId, tenantId, 10);
+
+        verify(repositoryMock).listAll(deviceId, tenantId, 10);
+        Assertions.assertTrue(results.failed());
+
+    }
+
+    @Test
+    public void testOnStateMessage_SkipsIfDeviceIdOrTenantIdIsEmpty() {
+        when(pubsubMessageMock.getAttributesMap())
+                .thenReturn(Map.of(
+                        "deviceId", "",
+                        "tenantId", "tenant-123"));
+
+
+        deviceStateService.onStateMessage(pubsubMessageMock, ackReplyConsumerMock);
+
+        verify(pubsubMessageMock).getAttributesMap();
+    }
+
+    @Test
+    public void testOnStateMessage_SkipsPayloadEmpty() {
+        when(pubsubMessageMock.getAttributesMap())
+                .thenReturn(Map.of(
+                        "deviceId", "device-123",
+                        "tenantId", "tenant-123"));
+        when(pubsubMessageMock.getData()).thenReturn(ByteString.copyFromUtf8(""));
+
+
+        deviceStateService.onStateMessage(pubsubMessageMock, ackReplyConsumerMock);
+
+        verify(pubsubMessageMock).getAttributesMap();
+        verify(pubsubMessageMock).getData();
+        verify(ackReplyConsumerMock).ack();
+    }
+
+    @Test
+    public void testOnStateMessage_CreatesNewStateEntryInDB() {
+        final String deviceId = "device-123";
+        final String tenantId = "tenant-123";
+
+        final Map<String, String> messageAttributes = Map.of(
+                "deviceId", deviceId,
+                "tenantId", tenantId);
+        final var deviceStateEntity = new DeviceStateEntity();
+
+        when(pubsubMessageMock.getAttributesMap()).thenReturn(messageAttributes);
+        when(pubsubMessageMock.getData()).thenReturn(ByteString.copyFromUtf8("{\"cause\": \"connected\"}"));
+        when(repositoryMock.createNew(deviceStateEntity)).thenReturn(Future.succeededFuture(deviceStateEntity));
+        when(mapperMock.pubSubMessageToDeviceStateEntity(pubsubMessageMock)).thenReturn(deviceStateEntity);
+
+
+        deviceStateService.onStateMessage(pubsubMessageMock, ackReplyConsumerMock);
+
+        verify(pubsubMessageMock).getAttributesMap();
+        verify(pubsubMessageMock).getData();
+        verify(repositoryMock).createNew(deviceStateEntity);
+        verify(mapperMock).pubSubMessageToDeviceStateEntity(pubsubMessageMock);
+        verify(ackReplyConsumerMock).ack();
+    }
+}
diff --git a/device-communication/src/test/java/org/eclipse/hono/communication/core/utils/StringValidateUtilsTest.java b/device-communication/src/test/java/org/eclipse/hono/communication/core/utils/StringValidateUtilsTest.java
new file mode 100644
index 00000000..e15ce066
--- /dev/null
+++ b/device-communication/src/test/java/org/eclipse/hono/communication/core/utils/StringValidateUtilsTest.java
@@ -0,0 +1,38 @@
+/*
+ * ***********************************************************
+ *  Copyright (c) 2023 Contributors to the Eclipse Foundation
+ *  <p>
+ *  See the NOTICE file(s) distributed with this work for additional
+ *  information regarding copyright ownership.
+ *  <p>
+ *  This program and the accompanying materials are made available under the
+ *  terms of the Eclipse Public License 2.0 which is available at
+ *  http://www.eclipse.org/legal/epl-2.0
+ *  <p>
+ *  SPDX-License-Identifier: EPL-2.0
+ * **********************************************************
+ *
+ */
+package org.eclipse.hono.communication.core.utils;
+
+import java.util.Base64;
+
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Test;
+
+class StringValidateUtilsTest {
+
+    @Test
+    public void isBase64_valid_true() {
+        final String string = "This is a test.";
+        final String base64 = Base64.getEncoder().encodeToString(string.getBytes());
+        Assertions.assertTrue(StringValidateUtils.isBase64(base64));
+    }
+
+    @Test
+    public void isBase64_invalid_false() {
+        final String string = "This is a test.";
+        Assertions.assertFalse(StringValidateUtils.isBase64(string));
+    }
+
+}