[ECO-5386] Defined LiveObjectSerializer interface

1. Added LiveObjectsHelper for initializing LiveObjects plugin and LiveObjectsSerializer impl.
2. Updated ProtocolMessage to handle msgpack serialization/deserialization for state field
3. Implemented LiveObjectsJsonSerializer for json serialization/deserialization of state field

Author: sacOO7

lib/src/main/java/io/ably/lib/objects/LiveObjectSerializer.java

@@ -0,0 +1,51 @@
+package io.ably.lib.objects;
+
+import com.google.gson.JsonArray;
+import org.jetbrains.annotations.NotNull;
+import org.msgpack.core.MessagePacker;
+import org.msgpack.core.MessageUnpacker;
+
+import java.io.IOException;
+
+/**
+ * Serializer interface for converting between LiveObject arrays and their
+ * MessagePack or JSON representations.
+ */
+public interface LiveObjectSerializer {
+    /**
+     * Reads a MessagePack array from the given unpacker and deserializes it into an Object array.
+     *
+     * @param unpacker the MessageUnpacker to read from
+     * @return the deserialized Object array
+     * @throws IOException if an I/O error occurs during unpacking
+     */
+    @NotNull
+    Object[] readMsgpackArray(@NotNull MessageUnpacker unpacker) throws IOException;
+
+    /**
+     * Serializes the given Object array as a MessagePack array using the provided packer.
+     *
+     * @param objects the Object array to serialize
+     * @param packer the MessagePacker to write to
+     * @throws IOException if an I/O error occurs during packing
+     */
+    void writeMsgpackArray(@NotNull Object[] objects, @NotNull MessagePacker packer) throws IOException;
+
+    /**
+     * Reads a JSON array from the given {@link JsonArray} and deserializes it into an Object array.
+     *
+     * @param json the {@link JsonArray} representing the array to deserialize
+     * @return the deserialized Object array
+     */
+    @NotNull
+    Object[] readFromJsonArray(@NotNull JsonArray json);
+
+    /**
+     * Serializes the given Object array as a JSON array.
+     *
+     * @param objects the Object array to serialize
+     * @return the resulting JsonArray
+     */
+    @NotNull
+    JsonArray asJsonArray(@NotNull Object[] objects);
+}

lib/src/main/java/io/ably/lib/objects/LiveObjectsHelper.java

@@ -0,0 +1,40 @@
+package io.ably.lib.objects;
+
+import io.ably.lib.realtime.AblyRealtime;
+import io.ably.lib.util.Log;
+
+import java.lang.reflect.InvocationTargetException;
+
+public class LiveObjectsHelper {
+
+    private static final String TAG = LiveObjectsHelper.class.getName();
+    private static LiveObjectSerializer liveObjectSerializer;
+
+    public static LiveObjectsPlugin tryInitializeLiveObjectsPlugin(AblyRealtime ablyRealtime) {
+        try {
+            Class<?> liveObjectsImplementation = Class.forName("io.ably.lib.objects.DefaultLiveObjectsPlugin");
+            LiveObjectsAdapter adapter = new Adapter(ablyRealtime);
+            return (LiveObjectsPlugin) liveObjectsImplementation
+                .getDeclaredConstructor(LiveObjectsAdapter.class)
+                .newInstance(adapter);
+        } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | NoSuchMethodException |
+                 InvocationTargetException e) {
+            Log.i(TAG, "LiveObjects plugin not found in classpath. LiveObjects functionality will not be available.", e);
+            return null;
+        }
+    }
+
+    public static LiveObjectSerializer getLiveObjectSerializer() {
+        if (liveObjectSerializer == null) {
+            try {
+                Class<?> serializerClass = Class.forName("io.ably.lib.objects.DefaultLiveObjectSerializer");
+                liveObjectSerializer = (LiveObjectSerializer) serializerClass.getDeclaredConstructor().newInstance();
+            } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | NoSuchMethodException |
+                     InvocationTargetException e) {
+                Log.e(TAG, "Failed to init LiveObjectSerializer, LiveObjects plugin not included in the classpath", e);
+                return null;
+            }
+        }
+        return liveObjectSerializer;
+    }
+}

lib/src/main/java/io/ably/lib/objects/LiveObjectsJsonSerializer.java

@@ -0,0 +1,32 @@
+package io.ably.lib.objects;
+
+import com.google.gson.*;
+import io.ably.lib.util.Log;
+
+import java.lang.reflect.Type;
+
+public class LiveObjectsJsonSerializer implements JsonSerializer<Object[]>, JsonDeserializer<Object[]> {
+    private static final String TAG = LiveObjectsJsonSerializer.class.getName();
+    private final LiveObjectSerializer serializer = LiveObjectsHelper.getLiveObjectSerializer();
+
+    @Override
+    public Object[] deserialize(JsonElement json, Type typeOfT, JsonDeserializationContext context) throws JsonParseException {
+        if (serializer == null) {
+            Log.w(TAG, "Skipping 'state' field json deserialization because LiveObjectsSerializer not found.");
+            return null;
+        }
+        if (!json.isJsonArray()) {
+            throw new JsonParseException("Expected a JSON array for 'state' field, but got: " + json);
+        }
+        return serializer.readFromJsonArray(json.getAsJsonArray());
+    }
+
+    @Override
+    public JsonElement serialize(Object[] src, Type typeOfSrc, JsonSerializationContext context) {
+        if (serializer == null) {
+            Log.w(TAG, "Skipping 'state' field json serialization because LiveObjectsSerializer not found.");
+            return JsonNull.INSTANCE;
+        }
+        return serializer.asJsonArray(src);
+    }
+}

lib/src/main/java/io/ably/lib/realtime/AblyRealtime.java

@@ -1,13 +1,11 @@
 package io.ably.lib.realtime;
 
-import java.lang.reflect.InvocationTargetException;
 import java.util.ArrayList;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
 
-import io.ably.lib.objects.Adapter;
-import io.ably.lib.objects.LiveObjectsAdapter;
+import io.ably.lib.objects.LiveObjectsHelper;
 import io.ably.lib.objects.LiveObjectsPlugin;
 import io.ably.lib.rest.AblyRest;
 import io.ably.lib.rest.Auth;
@@ -74,7 +72,7 @@ public AblyRealtime(ClientOptions options) throws AblyException {
         final InternalChannels channels = new InternalChannels();
         this.channels = channels;
 
-        liveObjectsPlugin = tryInitializeLiveObjectsPlugin();
+        liveObjectsPlugin = LiveObjectsHelper.tryInitializeLiveObjectsPlugin(this);
 
         connection = new Connection(this, channels, platformAgentProvider, liveObjectsPlugin);
 
@@ -185,20 +183,6 @@ public interface Channels extends ReadOnlyMap<String, Channel> {
         void release(String channelName);
     }
 
-    private LiveObjectsPlugin tryInitializeLiveObjectsPlugin() {
-        try {
-            Class<?> liveObjectsImplementation = Class.forName("io.ably.lib.objects.DefaultLiveObjectsPlugin");
-            LiveObjectsAdapter adapter = new Adapter(this);
-            return (LiveObjectsPlugin) liveObjectsImplementation
-                .getDeclaredConstructor(LiveObjectsAdapter.class)
-                .newInstance(adapter);
-        } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | NoSuchMethodException |
-                 InvocationTargetException e) {
-            Log.i(TAG, "LiveObjects plugin not found in classpath. LiveObjects functionality will not be available.", e);
-            return null;
-        }
-    }
-
     private class InternalChannels extends InternalMap<String, Channel> implements Channels, ConnectionManager.Channels {
         /**
          * Get the named channel; if it does not already exist,

lib/src/main/java/io/ably/lib/types/ProtocolMessage.java

@@ -4,6 +4,11 @@
 import java.lang.reflect.Type;
 import java.util.Map;
 
+import com.google.gson.annotations.JsonAdapter;
+import io.ably.lib.objects.LiveObjectSerializer;
+import io.ably.lib.objects.LiveObjectsHelper;
+import io.ably.lib.objects.LiveObjectsJsonSerializer;
+import org.jetbrains.annotations.Nullable;
 import org.msgpack.core.MessageFormat;
 import org.msgpack.core.MessagePacker;
 import org.msgpack.core.MessageUnpacker;
@@ -123,6 +128,13 @@ public ProtocolMessage(Action action, String channel) {
     public AuthDetails auth;
     public Map<String, String> params;
     public Annotation[] annotations;
+    /**
+     * This will be null if we skipped decoding this property due to user not requesting Objects functionality
+     * JsonAdapter annotation supports java version (1.8) mentioned in build.gradle
+     */
+    @Nullable
+    @JsonAdapter(LiveObjectsJsonSerializer.class)
+    public Object[] state;
 
     public boolean hasFlag(final Flag flag) {
         return (flags & flag.getMask()) == flag.getMask();
@@ -147,6 +159,7 @@ void writeMsgpack(MessagePacker packer) throws IOException {
         if(params != null) ++fieldCount;
         if(channelSerial != null) ++fieldCount;
         if(annotations != null) ++fieldCount;
+        if(state != null) ++fieldCount;
         packer.packMapHeader(fieldCount);
         packer.packString("action");
         packer.packInt(action.getValue());
@@ -186,6 +199,15 @@ void writeMsgpack(MessagePacker packer) throws IOException {
             packer.packString("annotations");
             AnnotationSerializer.writeMsgpackArray(annotations, packer);
         }
+        if(state != null) {
+            LiveObjectSerializer liveObjectsSerializer = LiveObjectsHelper.getLiveObjectSerializer();
+            if (liveObjectsSerializer != null) {
+                packer.packString("state");
+                liveObjectsSerializer.writeMsgpackArray(state, packer);
+            } else {
+                Log.w(TAG, "Skipping 'state' field msgpack serialization because LiveObjectsSerializer not found");
+            }
+        }
     }
 
     ProtocolMessage readMsgpack(MessageUnpacker unpacker) throws IOException {
@@ -248,6 +270,15 @@ ProtocolMessage readMsgpack(MessageUnpacker unpacker) throws IOException {
                 case "annotations":
                     annotations = AnnotationSerializer.readMsgpackArray(unpacker);
                     break;
+                case "state":
+                    LiveObjectSerializer liveObjectsSerializer = LiveObjectsHelper.getLiveObjectSerializer();
+                    if (liveObjectsSerializer != null) {
+                        state = liveObjectsSerializer.readMsgpackArray(unpacker);
+                    } else {
+                        Log.w(TAG, "Skipping 'state' field msgpack deserialization because LiveObjectsSerializer not found");
+                        unpacker.skipValue();
+                    }
+                    break;
                 default:
                     Log.v(TAG, "Unexpected field: " + fieldName);
                     unpacker.skipValue();

live-objects/build.gradle.kts

@@ -11,6 +11,7 @@ repositories {
 
 dependencies {
     implementation(project(":java"))
+    implementation(libs.bundles.common)
     implementation(libs.coroutine.core)
 
     testImplementation(kotlin("test"))

live-objects/src/main/kotlin/io/ably/lib/objects/Serialization.kt

@@ -2,9 +2,30 @@ package io.ably.lib.objects
 
 import com.google.gson.Gson
 import com.google.gson.GsonBuilder
+import com.google.gson.JsonArray
+import org.msgpack.core.MessagePacker
+import org.msgpack.core.MessageUnpacker
 
 internal val gson: Gson = createGsonSerializer()
 
 private fun createGsonSerializer(): Gson {
   return GsonBuilder().create() // Do not call serializeNulls() to omit null values
 }
+
+internal class DefaultLiveObjectSerializer : LiveObjectSerializer {
+  override fun readMsgpackArray(unpacker: MessageUnpacker): Array<Any> {
+    TODO("Not yet implemented")
+  }
+
+  override fun writeMsgpackArray(objects: Array<out Any>?, packer: MessagePacker) {
+    TODO("Not yet implemented")
+  }
+
+  override fun readFromJsonArray(json: JsonArray): Array<Any> {
+    TODO("Not yet implemented")
+  }
+
+  override fun asJsonArray(objects: Array<out Any>?): JsonArray {
+    TODO("Not yet implemented")
+  }
+}