Add Trigger Error mediator

Add Trigger Error mediator
<triggererror type="string" (errorMessage="string" | expression="expression")/>

modules/core/src/main/java/org/apache/synapse/SynapseConstants.java

@@ -628,4 +628,6 @@ public enum ENDPOINT_TIMEOUT_TYPE { ENDPOINT_TIMEOUT, GLOBAL_TIMEOUT, HTTP_CONNE
 
     public static final String SCATTER_MESSAGES = "SCATTER_MESSAGES";
     public static final String CONTINUE_FLOW_TRIGGERED_FROM_MEDIATOR_WORKER = "CONTINUE_FLOW_TRIGGERED_FROM_MEDIATOR_WORKER";
+
+    public static final String DEFAULT_ERROR_TYPE = "ANY";
 }

modules/core/src/main/java/org/apache/synapse/config/xml/MediatorFactoryFinder.java

@@ -104,7 +104,8 @@ public class MediatorFactoryFinder implements XMLToObjectMapper {
             JSONTransformMediatorFactory.class,
             NTLMMediatorFactory.class,
             VariableMediatorFactory.class,
-            ScatterGatherMediatorFactory.class
+            ScatterGatherMediatorFactory.class,
+            TriggerErrorMediatorFactory.class
     };
 
     private final static MediatorFactoryFinder instance  = new MediatorFactoryFinder();

modules/core/src/main/java/org/apache/synapse/config/xml/MediatorSerializerFinder.java

@@ -78,7 +78,8 @@ public class MediatorSerializerFinder {
             JSONTransformMediatorSerializer.class,
             NTLMMediatorSerializer.class,
             VariableMediatorSerializer.class,
-            ScatterGatherMediatorSerializer.class
+            ScatterGatherMediatorSerializer.class,
+            TriggerErrorMediatorSerializer.class
     };
 
     private final static MediatorSerializerFinder instance = new MediatorSerializerFinder();

modules/core/src/main/java/org/apache/synapse/config/xml/TriggerErrorMediatorFactory.java

@@ -0,0 +1,76 @@
+/*
+ *  Copyright (c) 2024, WSO2 LLC. (http://www.wso2.org) All Rights Reserved.
+ *
+ *  WSO2 LLC. licenses this file to you under the Apache License,
+ *  Version 2.0 (the "License"); you may not use this file except
+ *  in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *  http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing,
+ *  software distributed under the License is distributed on an
+ *  "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ *  KIND, either express or implied. See the License for the
+ *  specific language governing permissions and limitations
+ *  under the License.
+ */
+package org.apache.synapse.config.xml;
+
+import org.apache.axiom.om.OMAttribute;
+import org.apache.axiom.om.OMElement;
+import org.apache.synapse.Mediator;
+import org.apache.synapse.SynapseConstants;
+import org.apache.synapse.SynapseException;
+import org.apache.synapse.mediators.v2.TriggerError;
+import org.jaxen.JaxenException;
+
+import javax.xml.namespace.QName;
+import java.util.Properties;
+
+/**
+ * Creates a trigger error mediator through the supplied XML configuration
+ * <p/>
+ * <pre>
+ * &lt;triggererror type="string" (errorMessage="string" | expression="expression")/&gt;
+ * </pre>
+ */
+public class TriggerErrorMediatorFactory extends AbstractMediatorFactory {
+
+    private static final QName ATT_ERROR_MSG = new QName("errorMessage");
+    private static final QName ATT_TYPE = new QName("type");
+    private static final QName TRIGGER_ERROR_Q
+            = new QName(XMLConfigConstants.SYNAPSE_NAMESPACE, "triggererror");
+
+    @Override
+    protected Mediator createSpecificMediator(OMElement elem, Properties properties) {
+        TriggerError triggerErrorMediator = new TriggerError();
+        OMAttribute type = elem.getAttribute(ATT_TYPE);
+        OMAttribute errorMsg = elem.getAttribute(ATT_ERROR_MSG);
+        OMAttribute expression = elem.getAttribute(ATT_EXPRN);
+
+        if (type == null || type.getAttributeValue().isEmpty()) {
+            triggerErrorMediator.setType(SynapseConstants.DEFAULT_ERROR_TYPE);
+        } else {
+            triggerErrorMediator.setType(type.getAttributeValue());
+        }
+        if (expression != null) {
+            try {
+                triggerErrorMediator.setExpression(SynapsePathFactory.getSynapsePath(elem, ATT_EXPRN));
+            } catch (JaxenException e) {
+                throw new SynapseException("Invalid expression for attribute 'expression' : " +
+                        expression.getAttributeValue());
+            }
+        } else if (errorMsg != null && !errorMsg.getAttributeValue().isEmpty()) {
+            triggerErrorMediator.setErrorMsg(errorMsg.getAttributeValue());
+        } else {
+            triggerErrorMediator.setErrorMsg("Error occurred in the mediation flow");
+        }
+        return triggerErrorMediator;
+    }
+
+    @Override
+    public QName getTagQName() {
+        return TRIGGER_ERROR_Q;
+    }
+}

modules/core/src/main/java/org/apache/synapse/config/xml/TriggerErrorMediatorSerializer.java

@@ -0,0 +1,57 @@
+/*
+ *  Copyright (c) 2024, WSO2 LLC. (http://www.wso2.org) All Rights Reserved.
+ *
+ *  WSO2 LLC. licenses this file to you under the Apache License,
+ *  Version 2.0 (the "License"); you may not use this file except
+ *  in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *  http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing,
+ *  software distributed under the License is distributed on an
+ *  "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ *  KIND, either express or implied. See the License for the
+ *  specific language governing permissions and limitations
+ *  under the License.
+ */
+package org.apache.synapse.config.xml;
+
+import org.apache.axiom.om.OMElement;
+import org.apache.synapse.Mediator;
+import org.apache.synapse.mediators.v2.TriggerError;
+
+/**
+ * <pre>
+ * &lt;triggererror type="string" (errorMessage="string" | expression="expression")/&gt;
+ * </pre>
+ */
+public class TriggerErrorMediatorSerializer extends AbstractMediatorSerializer{
+    @Override
+    protected OMElement serializeSpecificMediator(Mediator m) {
+        if (!(m instanceof TriggerError)) {
+            handleException("Unsupported mediator passed in for serialization : " + m.getType());
+        }
+
+        TriggerError mediator = (TriggerError) m;
+        OMElement triggerError = fac.createOMElement("triggererror", synNS);
+        saveTracingState(triggerError, mediator);
+
+        if (mediator.getType() != null) {
+            triggerError.addAttribute(fac.createOMAttribute("type", nullNS, mediator.getType()));
+        }
+        if (mediator.getExpression() != null) {
+            SynapsePathSerializer.serializePath(mediator.getExpression(), triggerError, "expression");
+        } else if (mediator.getErrorMsg() != null) {
+            triggerError.addAttribute(fac.createOMAttribute("errorMessage", nullNS, mediator.getErrorMsg()));
+        }
+
+        serializeComments(triggerError, mediator.getCommentsList());
+        return triggerError;
+    }
+
+    @Override
+    public String getMediatorClassName() {
+        return TriggerError.class.getName();
+    }
+}

modules/core/src/main/java/org/apache/synapse/mediators/v2/TriggerError.java

@@ -0,0 +1,89 @@
+/*
+ *  Copyright (c) 2024, WSO2 LLC. (http://www.wso2.org) All Rights Reserved.
+ *
+ *  WSO2 LLC. licenses this file to you under the Apache License,
+ *  Version 2.0 (the "License"); you may not use this file except
+ *  in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *  http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing,
+ *  software distributed under the License is distributed on an
+ *  "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ *  KIND, either express or implied. See the License for the
+ *  specific language governing permissions and limitations
+ *  under the License.
+ */
+package org.apache.synapse.mediators.v2;
+
+import org.apache.synapse.MessageContext;
+import org.apache.synapse.SynapseConstants;
+import org.apache.synapse.SynapseException;
+import org.apache.synapse.SynapseLog;
+import org.apache.synapse.config.xml.SynapsePath;
+import org.apache.synapse.mediators.AbstractMediator;
+
+/**
+ * This mediator is used to trigger an error in the mediation flow.
+ */
+public class TriggerError extends AbstractMediator {
+    private String type = null;
+    private String errorMsg = null;
+    private SynapsePath expression = null;
+
+    @Override
+    public boolean mediate(MessageContext synCtx) {
+        if (synCtx.getEnvironment().isDebuggerEnabled()) {
+            if (super.divertMediationRoute(synCtx)) {
+                return true;
+            }
+        }
+
+        SynapseLog synLog = getLog(synCtx);
+        if (synLog.isTraceOrDebugEnabled()) {
+            synLog.traceOrDebug("Start : TriggerError mediator");
+            if (synLog.isTraceTraceEnabled()) {
+                synLog.traceTrace("Message : " + synCtx.getEnvelope());
+            }
+        }
+
+        String desc = null;
+        if (errorMsg != null) {
+            desc =  errorMsg.toString();
+        } else if (expression != null) {
+            desc = expression.stringValueOf(synCtx);
+        }
+
+        synLog.traceOrDebug("End : TriggerError mediator");
+        synCtx.setProperty(SynapseConstants.ERROR_CODE, type);
+        synCtx.setProperty(SynapseConstants.ERROR_MESSAGE, desc);
+        throw new SynapseException(desc, new Throwable(type));
+    }
+
+    @Override
+    public String getType() {
+        return type;
+    }
+
+    public void setType(String type) {
+        this.type = type;
+    }
+
+
+    public SynapsePath getExpression() {
+        return expression;
+    }
+
+    public void setExpression(SynapsePath expression) {
+        this.expression = expression;
+    }
+
+    public String getErrorMsg() {
+        return errorMsg;
+    }
+
+    public void setErrorMsg(String errorMsg) {
+        this.errorMsg = errorMsg;
+    }
+}

modules/core/src/test/java/org/apache/synapse/config/xml/TriggerErrorMediatorFactoryTest.java

@@ -0,0 +1,55 @@
+/*
+ *  Copyright (c) 2024, WSO2 LLC. (http://www.wso2.org) All Rights Reserved.
+ *
+ *  WSO2 LLC. licenses this file to you under the Apache License,
+ *  Version 2.0 (the "License"); you may not use this file except
+ *  in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *  http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing,
+ *  software distributed under the License is distributed on an
+ *  "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ *  KIND, either express or implied. See the License for the
+ *  specific language governing permissions and limitations
+ *  under the License.
+ */
+package org.apache.synapse.config.xml;
+
+import org.apache.axiom.om.OMElement;
+import org.apache.axiom.om.util.AXIOMUtil;
+import org.apache.synapse.mediators.v2.TriggerError;
+import org.junit.Assert;
+import org.junit.Test;
+
+import javax.xml.stream.XMLStreamException;
+
+/**
+ * This is the test class for TriggerErrorMediatorFactory class.
+ */
+public class TriggerErrorMediatorFactoryTest {
+
+    /**
+     * Test create TriggerError with given XML configuration and asserting it is created.
+     *
+     * @throws XMLStreamException - XMLStreamException
+     */
+    @Test
+    public void testTriggerErrorExp() throws XMLStreamException {
+        String inputXML = "<triggererror expression=\"${$.abc}\"/>";
+        OMElement element = AXIOMUtil.stringToOM(inputXML);
+        TriggerErrorMediatorFactory triggerErrorMediatorFactory = new TriggerErrorMediatorFactory();
+        TriggerError triggerError = (TriggerError) triggerErrorMediatorFactory.createSpecificMediator(element,null);
+        Assert.assertNotNull("${$.abc}", triggerError.getExpression().toString());
+    }
+
+    @Test
+    public void testTriggerErrorMsg() throws XMLStreamException {
+        String inputXML = "<triggererror errorMessage=\"abc\"/>";
+        OMElement element = AXIOMUtil.stringToOM(inputXML);
+        TriggerErrorMediatorFactory triggerErrorMediatorFactory = new TriggerErrorMediatorFactory();
+        TriggerError triggerError = (TriggerError) triggerErrorMediatorFactory.createSpecificMediator(element,null);
+        Assert.assertNotNull("abc", triggerError.getErrorMsg());
+    }
+}

modules/core/src/test/java/org/apache/synapse/config/xml/TriggerErrorMediatorSerializerTest.java

@@ -0,0 +1,31 @@
+package org.apache.synapse.config.xml;
+
+import org.apache.axiom.om.OMElement;
+import org.apache.synapse.mediators.v2.TriggerError;
+import org.apache.synapse.util.xpath.SynapseExpression;
+import org.jaxen.JaxenException;
+import org.junit.Assert;
+import org.junit.Test;
+
+import javax.xml.namespace.QName;
+
+public class TriggerErrorMediatorSerializerTest {
+
+    @Test
+    public void testSerializeTriggerErrorMediator() throws JaxenException {
+        TriggerErrorMediatorSerializer triggerErrorMediatorSerializer = new TriggerErrorMediatorSerializer();
+        TriggerError mediator = new TriggerError();
+        String type = "TRANSPORT:TIMEOUT";
+        String err  = "Error occurred";
+        String exp = "${payload.err}";
+        mediator.setExpression(new SynapseExpression(exp));
+        mediator.setType(type);
+        OMElement element = triggerErrorMediatorSerializer.serializeSpecificMediator(mediator);
+        Assert.assertEquals("invalid type", type, element.getAttributeValue(new QName("type")));
+        Assert.assertEquals("invalid expression", exp, element.getAttributeValue(new QName("expression")));
+        mediator.setExpression(null);
+        mediator.setErrorMsg(err);
+        element = triggerErrorMediatorSerializer.serializeSpecificMediator(mediator);
+        Assert.assertEquals("invalid error message", err, element.getAttributeValue(new QName("errorMessage")));
+    }
+}