serialization improvements: tests and interfaces

Signed-off-by: Erik Escher <eclipse@erikescher.de>

bom/pom.xml

@@ -34,6 +34,7 @@
 
         <!-- ### Compile dependencies versions -->
         <minimal-json.version>0.9.5</minimal-json.version>
+        <jackson-core.version>2.10.1</jackson-core.version>
         <typesafe-config.version>1.3.4</typesafe-config.version>
         <ssl-config-core.version>0.3.8</ssl-config-core.version>
         <akka.version>2.5.27</akka.version>
@@ -109,6 +110,18 @@
                 <version>${minimal-json.version}</version>
             </dependency>
 
+            <dependency>
+                <groupId>com.fasterxml.jackson.core</groupId>
+                <artifactId>jackson-core</artifactId>
+                <version>${jackson-core.version}</version>
+            </dependency>
+
+            <dependency>
+                <groupId>com.fasterxml.jackson.dataformat</groupId>
+                <artifactId>jackson-dataformat-cbor</artifactId>
+                <version>${jackson-core.version}</version>
+            </dependency>
+
             <dependency>
                 <groupId>com.typesafe</groupId>
                 <artifactId>config</artifactId>

json/pom.xml

@@ -37,6 +37,14 @@
             <groupId>com.eclipsesource.minimal-json</groupId>
             <artifactId>minimal-json</artifactId>
         </dependency>
+        <dependency>
+            <groupId>com.fasterxml.jackson.core</groupId>
+            <artifactId>jackson-core</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>com.fasterxml.jackson.dataformat</groupId>
+            <artifactId>jackson-dataformat-cbor</artifactId>
+        </dependency>
 
         <!-- ### Provided ### -->
         <dependency>

json/src/main/java/org/eclipse/ditto/json/AbstractJsonNumber.java

@@ -89,4 +89,9 @@ public String toString() {
         return value.toString();
     }
 
+    @Override
+    public void writeValue(final SerializationContext serializationContext) {
+        // TODO implement
+        // Does it make more sense to implement this here or should I implement this in the concrete classes?
+    }
 }

json/src/main/java/org/eclipse/ditto/json/ByteBufferOutputStream.java

@@ -0,0 +1,32 @@
+/*
+ * Copyright (c) 2019 Contributors to the Eclipse Foundation
+ *
+ * See the NOTICE file(s) distributed with this work for additional
+ * information regarding copyright ownership.
+ *
+ * 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
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
+
+package org.eclipse.ditto.json;
+
+import java.io.OutputStream;
+import java.nio.ByteBuffer;
+
+public class ByteBufferOutputStream extends OutputStream {
+
+    private final ByteBuffer destinationBuffer;
+
+    ByteBufferOutputStream(ByteBuffer destinationBuffer){
+        this.destinationBuffer = destinationBuffer;
+    }
+
+    @Override
+    public void write(final int b) {
+        // super specifies to ignore everything except the lower 8 bits.
+        destinationBuffer.put((byte) b);
+    }
+}

json/src/main/java/org/eclipse/ditto/json/CborFactory.java

@@ -0,0 +1,62 @@
+/*
+ * Copyright (c) 2019 Contributors to the Eclipse Foundation
+ *
+ * See the NOTICE file(s) distributed with this work for additional
+ * information regarding copyright ownership.
+ *
+ * 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
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
+
+package org.eclipse.ditto.json;
+
+import java.io.Reader;
+import java.nio.ByteBuffer;
+
+//TODO: move these Methods to JsonFactory
+
+public final class CborFactory {
+
+    /*
+     * This utility class is not meant to be instantiated.
+     */
+    private CborFactory(){
+        throw new AssertionError();
+    }
+
+    public static JsonValue readFrom(final byte[] bytes){
+        // TODO implement
+        return null;
+    }
+
+    public static JsonValue readFrom(final byte[] bytes, int offset, int length){
+        // TODO implement
+        return null;
+    }
+
+    public static JsonValue readFrom(ByteBuffer byteBuffer){
+        // TODO implement
+        return null;
+    }
+
+    public static JsonValue readFrom(Reader reader){
+        // TODO implement
+        return null;
+    }
+
+    public static byte[] toByteArray(JsonValue jsonValue){
+        // TODO implement by calling jsonValue.toByteArray with an appropriate Generator
+        return null;
+    }
+
+    public static ByteBuffer toByteBuffer(JsonValue jsonValue){
+        // TODO implement by calling jsonValue.toByteBuffer with an appropriate Generator
+        return null;
+    }
+
+    // TODO: support the equivalent of Reader
+
+}

json/src/main/java/org/eclipse/ditto/json/ImmutableJsonArray.java

@@ -237,6 +237,11 @@ public String toString() {
         return valueList.asJsonArrayString();
     }
 
+    @Override
+    public void writeValue(final SerializationContext serializationContext) {
+        // TODO implement
+    }
+
     @Immutable
     static final class SoftReferencedValueList {
 

json/src/main/java/org/eclipse/ditto/json/ImmutableJsonArrayNull.java

@@ -141,4 +141,9 @@ public String toString() {
         return JsonFactory.nullLiteral().toString();
     }
 
+    @Override
+    public void writeValue(final SerializationContext serializationContext) {
+        // TODO implement test
+    }
+
 }

json/src/main/java/org/eclipse/ditto/json/ImmutableJsonBoolean.java

@@ -79,4 +79,9 @@ public String toString() {
         return String.valueOf(value);
     }
 
+    @Override
+    public void writeValue(final SerializationContext serializationContext) {
+        // TODO implement
+    }
+
 }

json/src/main/java/org/eclipse/ditto/json/ImmutableJsonNull.java

@@ -83,4 +83,9 @@ public String toString() {
         return "null";
     }
 
+    @Override
+    public void writeValue(final SerializationContext serializationContext) {
+        // TODO implement
+    }
+
 }

json/src/main/java/org/eclipse/ditto/json/ImmutableJsonObject.java

@@ -509,6 +509,11 @@ public String toString() {
         return fieldMap.asJsonObjectString();
     }
 
+    @Override
+    public void writeValue(final SerializationContext serializationContext) {
+        // TODO implement
+    }
+
     @Immutable
     static final class SoftReferencedFieldMap {
 

json/src/main/java/org/eclipse/ditto/json/ImmutableJsonObjectNull.java

@@ -192,4 +192,9 @@ public String toString() {
         return JsonFactory.nullLiteral().toString();
     }
 
+    @Override
+    public void writeValue(final SerializationContext serializationContext) {
+        // TODO implement
+    }
+
 }

json/src/main/java/org/eclipse/ditto/json/ImmutableJsonString.java

@@ -84,6 +84,11 @@ public String toString() {
         return result;
     }
 
+    @Override
+    public void writeValue(final SerializationContext serializationContext) {
+        // TODO implement
+    }
+
     private String createStringRepresentation() {
         final JavaStringToEscapedJsonString javaStringToEscapedJsonString = JavaStringToEscapedJsonString.getInstance();
         return javaStringToEscapedJsonString.apply(value);

json/src/main/java/org/eclipse/ditto/json/JsonValue.java

@@ -274,4 +274,13 @@ default String formatAsString() {
         return isString() ? asString() : toString();
     }
 
+    /**
+     * Writes this JsonValue into the provided serialization context.
+     * This is intended to be used by serialization logic only.
+     * Pass this object to the relevant methods in {@link JsonFactory} instead if you want its serialized representation.
+     *
+     * @param serializationContext The context for serialization bundling configuration and state needed for serialization.
+     */
+    void writeValue(SerializationContext serializationContext);
+
 }

json/src/main/java/org/eclipse/ditto/json/SerializationContext.java

@@ -0,0 +1,70 @@
+/*
+ * Copyright (c) 2019 Contributors to the Eclipse Foundation
+ *
+ * See the NOTICE file(s) distributed with this work for additional
+ * information regarding copyright ownership.
+ *
+ * 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
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
+
+package org.eclipse.ditto.json;
+
+import java.io.Closeable;
+import java.io.Flushable;
+import java.io.IOException;
+import java.io.OutputStream;
+import java.nio.ByteBuffer;
+
+import com.fasterxml.jackson.core.JsonFactory;
+import com.fasterxml.jackson.core.JsonGenerator;
+
+/**
+ * A class that bundles State and Configuration for serialization.
+ * It must be recreated for each serialization target.
+ */
+public class SerializationContext implements Closeable, Flushable {
+
+    private JsonGenerator jacksonGenerator;
+
+    /**
+     * Creates a Serialization context that writes to the designated target.
+     * @param jacksonFactory The JsonFactory (from Jackson) to use during serialization. It defines among other things the Format to use.
+     * @param outputStream The stream to write serialized data to. The stream is considered to be borrowed and will not be closed.
+     */
+    public SerializationContext(JsonFactory jacksonFactory, OutputStream outputStream) throws IOException {
+        jacksonGenerator = jacksonFactory.createGenerator(outputStream);
+    }
+
+    /**
+     * Creates a Serialization context that writes to the designated target.
+     * @param jacksonFactory The JsonFactory (from Jackson) to use during serialization. It defines among other things the Format to use.
+     * @param targetBuffer The Buffer to write serialized data to. The Buffer is considered to be borrowed and will not be closed.
+     */
+    public SerializationContext(JsonFactory jacksonFactory, ByteBuffer targetBuffer) throws IOException {
+        this(jacksonFactory, new ByteBufferOutputStream(targetBuffer));
+    }
+
+    JsonGenerator getJacksonGenerator() {
+        return jacksonGenerator;
+    }
+
+    /**
+     * Closes internal objects that need to be closed. Targets will be closed according to the promise during creation.
+     */
+    @Override
+    public void close() throws IOException {
+        jacksonGenerator.close();
+    }
+
+    /**
+     * Flushes everything including targets.
+     */
+    @Override
+    public void flush() throws IOException {
+        jacksonGenerator.flush();
+    }
+}

json/src/test/java/org/eclipse/ditto/json/ByteBufferOutputStreamIT.java

@@ -0,0 +1,40 @@
+/*
+ * Copyright (c) 2019 Contributors to the Eclipse Foundation
+ *
+ * See the NOTICE file(s) distributed with this work for additional
+ * information regarding copyright ownership.
+ *
+ * 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
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
+
+package org.eclipse.ditto.json;
+
+import static org.eclipse.ditto.json.assertions.DittoJsonAssertions.assertThat;
+
+import java.io.IOException;
+import java.nio.ByteBuffer;
+
+import org.junit.Test;
+
+public class ByteBufferOutputStreamIT {
+
+    @Test
+    public void writesThroughToBuffer() throws IOException {
+        final int expectedCount = 11;
+        final ByteBuffer buffer = ByteBuffer.allocate(expectedCount);
+        final ByteBufferOutputStream outputStream = new ByteBufferOutputStream(buffer);
+
+
+        for (int i = 0; i < 5; i++) {
+            outputStream.write(i);
+        }
+        outputStream.write(new byte[]{7,8,9});
+        outputStream.write(new byte[]{10,11,12,13,14}, 1, 3);
+
+        assertThat(buffer.position()).isEqualTo(expectedCount - 1);
+    }
+}