Added a better documentation to the GsonUtils class that makes clear …

…which method expects the length of a String value and which doesn't. removed the error details property since it is not needed. updated the error reporting classes accordingly.

src/main/java/org/hobbit/core/data/ErrorData.java

@@ -23,19 +23,14 @@ public class ErrorData {
     protected String errorType;
     /**
      * A string that can be used as short label of an error (optional, the error
-     * type label will be used as default)
+     * type label might be used as default)
      */
     protected String label;
     /**
      * A string that can be used as a short description of an error (optional, the
-     * error type description will be used as default).
+     * error type description might be used as default).
      */
     protected String description;
-    /**
-     * A string that contains details about the error, e.g., a stack trace
-     * (optional).
-     */
-    protected String details;
 
     /**
      * @return the containerId
@@ -93,27 +88,12 @@ public void setDescription(String description) {
         this.description = description;
     }
 
-    /**
-     * @return the details
-     */
-    public String getDetails() {
-        return details;
-    }
-
-    /**
-     * @param details the details to set
-     */
-    public void setDetails(String details) {
-        this.details = details;
-    }
-
     @Override
     public int hashCode() {
         final int prime = 31;
         int result = 1;
         result = prime * result + ((containerName == null) ? 0 : containerName.hashCode());
         result = prime * result + ((description == null) ? 0 : description.hashCode());
-        result = prime * result + ((details == null) ? 0 : details.hashCode());
         result = prime * result + ((errorType == null) ? 0 : errorType.hashCode());
         result = prime * result + ((label == null) ? 0 : label.hashCode());
         return result;
@@ -138,11 +118,6 @@ public boolean equals(Object obj) {
                 return false;
         } else if (!description.equals(other.description))
             return false;
-        if (details == null) {
-            if (other.details != null)
-                return false;
-        } else if (!details.equals(other.details))
-            return false;
         if (errorType == null) {
             if (other.errorType != null)
                 return false;
@@ -172,14 +147,13 @@ public static ErrorData createFromException(Exception e, String containerName) {
         ErrorData result = new ErrorData();
         result.containerName = containerName;
         result.errorType = HobbitErrors.UnhandledException.getURI();
-        result.label = e.getClass().getName();
-        result.description = e.getMessage();
+        result.label = e.getMessage();
         // Get the full stack trace
         StringWriter writer = new StringWriter();
         PrintWriter pwriter = new PrintWriter(writer);
         e.printStackTrace(pwriter);
         pwriter.flush();
-        result.details = writer.toString();
+        result.description = writer.toString();
         pwriter.close();
 
         return result;

src/main/java/org/hobbit/core/rabbit/GsonUtils.java

@@ -1,5 +1,7 @@
 package org.hobbit.core.rabbit;
 
+import java.nio.ByteBuffer;
+
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -34,6 +36,34 @@ public static <T> byte[] serializeObjectWithGson(Gson gson, T object) {
         return null;
     }
 
+    /**
+     * Deserialize a Java data object that was received as JSON with a command.
+     * First, the given byte array will be transformed into a String using the
+     * {@link RabbitMQUtils} class, before it will be deserialized using the given
+     * {@link Gson} object.
+     * 
+     * @param <T>            The class that the data object should have.
+     * @param gson           The Gson instance used to deserialize the JSON object.
+     * @param data           The byte array that has been received.
+     * @param clazz          The class that the data object should have.
+     * @param containsLength This flag indicates whether the given byte array
+     *                       contains the data with a preceeded int value containing
+     *                       the length of the next piece of data
+     * @return The deserialized object or null if an error occurred
+     */
+    public static <T> T deserializeObjectWithGson(Gson gson, byte[] data, Class<? extends T> clazz,
+            boolean containsLength) {
+        if (data != null) {
+            if (containsLength) {
+                return deserializeObjectWithGson(gson, ByteBuffer.wrap(data), clazz);
+            } else {
+                String dataString = RabbitMQUtils.readString(data);
+                return deserializeObjectWithGson(gson, dataString, clazz);
+            }
+        }
+        return null;
+    }
+
     /**
      * Deserialize a Java data object that was received as JSON with a command.
      * First, the given byte array will be transformed into a String using the
@@ -42,19 +72,24 @@ public static <T> byte[] serializeObjectWithGson(Gson gson, T object) {
      * 
      * @param <T>   The class that the data object should have.
      * @param gson  The Gson instance used to deserialize the JSON object.
-     * @param data  The byte array that has been received.
+     * @param data  A ByteBuffer containing the data and the length of the data.
      * @param clazz The class that the data object should have.
      * @return The deserialized object or null if an error occurred
      */
-    public static <T> T deserializeObjectWithGson(Gson gson, byte[] data, Class<? extends T> clazz) {
+    public static <T> T deserializeObjectWithGson(Gson gson, ByteBuffer data, Class<? extends T> clazz) {
         if (data != null) {
             String dataString = RabbitMQUtils.readString(data);
-            try {
-                return gson.fromJson(dataString, clazz);
-            } catch (Exception e) {
-                LOGGER.error("Error while parsing JSON data. Returning null.");
-            }
+            return deserializeObjectWithGson(gson, dataString, clazz);
         }
         return null;
     }
+
+    protected static <T> T deserializeObjectWithGson(Gson gson, String dataString, Class<? extends T> clazz) {
+        try {
+            return gson.fromJson(dataString, clazz);
+        } catch (Exception e) {
+            LOGGER.error("Error while parsing JSON data form String \"" + dataString + "\". Returning null.", e);
+            return null;
+        }
+    }
 }

src/main/java/org/hobbit/vocab/Algorithm.java

@@ -22,7 +22,6 @@ public class Algorithm {
     public static final Resource Result = resource("Result");
 
     // Properties sorted alphabetically
-    public static final Property errorDetails = property("errorDetails");
     public static final Property instanceOf = property("instanceOf");
     public static final Property parameter = property("parameter");
     public static final Property produces = property("produces");

src/test/java/org/hobbit/core/rabbit/GsonUtilsTest.java

@@ -1,39 +1,74 @@
 package org.hobbit.core.rabbit;
 
+import java.nio.ByteBuffer;
+import java.util.ArrayList;
+import java.util.List;
+
 import org.hobbit.core.data.ErrorData;
 import org.junit.Assert;
 import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.junit.runners.Parameterized;
+import org.junit.runners.Parameterized.Parameters;
 
 import com.google.gson.Gson;
 
+@RunWith(Parameterized.class)
 public class GsonUtilsTest {
 
-    @Test
-    public void testErrorData() {
-        ErrorData original = new ErrorData();
-        original.setErrorType("http://example.org/generalError");
-        original.setContainerId("123");
+    protected static Gson gson = new Gson();
+
+    protected Object original;
+    protected Class<?> clazz;
 
-        Gson gson = new Gson();
-        ErrorData received;
+    public GsonUtilsTest(Object original, Class<?> clazz) {
+        super();
+        this.original = original;
+        this.clazz = clazz;
+    }
 
-        received = GsonUtils.deserializeObjectWithGson(gson, GsonUtils.serializeObjectWithGson(gson, original),
-                ErrorData.class);
+    @Test
+    public void testDirect() {
+        Object received = GsonUtils.deserializeObjectWithGson(gson, GsonUtils.serializeObjectWithGson(gson, original),
+                ErrorData.class, false);
         Assert.assertEquals(original, received);
+    }
 
-        original.setLabel("Example label");
-        received = GsonUtils.deserializeObjectWithGson(gson, GsonUtils.serializeObjectWithGson(gson, original),
-                ErrorData.class);
+    @Test
+    public void testWithLengthPrefix() {
+        byte[] data = GsonUtils.serializeObjectWithGson(gson, original);
+        ByteBuffer buffer = ByteBuffer.allocate(data.length + 4);
+        buffer.putInt(data.length);
+        buffer.put(data);
+
+        Object received = GsonUtils.deserializeObjectWithGson(gson, buffer.array(),
+                ErrorData.class, true);
         Assert.assertEquals(original, received);
+    }
+
+    @Parameters
+    public static List<Object[]> parameters() {
+        List<Object[]> testCases = new ArrayList<>();
+        ErrorData original;
 
+        original = new ErrorData();
+        original.setErrorType("http://example.org/generalError");
+        original.setContainerId("123");
+        testCases.add(new Object[] {original, original.getClass()});
+
+        original = new ErrorData();
+        original.setErrorType("http://example.org/generalError");
+        original.setContainerId("123");
+        original.setLabel("Example label");
+        testCases.add(new Object[] {original, original.getClass()});
+
+        original = new ErrorData();
+        original.setErrorType("http://example.org/generalError");
+        original.setContainerId("123");
+        original.setLabel("Example label");
         original.setDescription("Some description");
-        received = GsonUtils.deserializeObjectWithGson(gson, GsonUtils.serializeObjectWithGson(gson, original),
-                ErrorData.class);
-        Assert.assertEquals(original, received);
+        testCases.add(new Object[] {original, original.getClass()});
 
-        original.setDetails("A lot of details....");
-        received = GsonUtils.deserializeObjectWithGson(gson, GsonUtils.serializeObjectWithGson(gson, original),
-                ErrorData.class);
-        Assert.assertEquals(original, received);
+        return testCases;
     }
 }