A much more straightforward networking system.

src/main/java/net/minecraftforge/common/UsernameCache.java

@@ -19,28 +19,32 @@
 
 package net.minecraftforge.common;
 
-import static com.google.common.base.Preconditions.checkNotNull;
-
-import java.io.File;
+import java.io.BufferedReader;
+import java.io.BufferedWriter;
 import java.io.IOException;
 import java.lang.reflect.Type;
-import java.nio.charset.Charset;
-import java.nio.charset.StandardCharsets;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.util.HashMap;
 import java.util.Map;
+import java.util.Objects;
 import java.util.UUID;
 
 import javax.annotation.Nullable;
 
+import com.google.common.base.Charsets;
+import net.minecraft.world.storage.ThreadedFileIOBase;
+import net.minecraftforge.fml.loading.FMLLoader;
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
 
 import com.google.common.collect.ImmutableMap;
-import com.google.common.collect.Maps;
-import com.google.common.io.Files;
 import com.google.common.reflect.TypeToken;
 import com.google.gson.Gson;
 import com.google.gson.GsonBuilder;
 import com.google.gson.JsonSyntaxException;
+import org.apache.logging.log4j.Marker;
+import org.apache.logging.log4j.MarkerManager;
 
 /**
  * Caches player's last known usernames
@@ -52,19 +56,18 @@ import com.google.gson.JsonSyntaxException;
  */
 public final class UsernameCache {
 
-    private static Map<UUID, String> map = Maps.newHashMap();
+    private static Map<UUID, String> map = new HashMap<>();
 
-    private static final Charset charset = StandardCharsets.UTF_8;
-
-    private static final File saveFile = new File( /* The minecraft dir */(File) FMLInjectionData.data()[6], "usernamecache.json");
+    private static final Path saveFile = FMLLoader.getGamePath().resolve("usernamecache.json");
     private static final Gson gson = new GsonBuilder().setPrettyPrinting().create();
 
-    private static final Logger log = LogManager.getLogger(ForgeVersion.MOD_ID + ".UsernameCache");
+    private static final Logger LOGGER = LogManager.getLogger(UsernameCache.class);
+    private static final Marker USRCACHE = MarkerManager.getMarker("USERNAMECACHE");
 
     private UsernameCache() {}
 
     /**
-     * Set a player's current username
+     * Set a player's current usernamee
      *
      * @param uuid
      *            the player's {@link java.util.UUID UUID}
@@ -73,8 +76,8 @@ public final class UsernameCache {
      */
     protected static void setUsername(UUID uuid, String username)
     {
-        checkNotNull(uuid);
-        checkNotNull(username);
+        Objects.requireNonNull(uuid);
+        Objects.requireNonNull(username);
 
         if (username.equals(map.get(uuid))) return;
 
@@ -91,7 +94,7 @@ public final class UsernameCache {
      */
     protected static boolean removeUsername(UUID uuid)
     {
-        checkNotNull(uuid);
+        Objects.requireNonNull(uuid);
 
         if (map.remove(uuid) != null)
         {
@@ -115,7 +118,7 @@ public final class UsernameCache {
     @Nullable
     public static String getLastKnownUsername(UUID uuid)
     {
-        checkNotNull(uuid);
+        Objects.requireNonNull(uuid);
         return map.get(uuid);
     }
 
@@ -128,7 +131,7 @@ public final class UsernameCache {
      */
     public static boolean containsUUID(UUID uuid)
     {
-        checkNotNull(uuid);
+        Objects.requireNonNull(uuid);
         return map.containsKey(uuid);
     }
 
@@ -155,32 +158,31 @@ public final class UsernameCache {
      */
     protected static void load()
     {
-        if (!saveFile.exists()) return;
+        if (!Files.exists(saveFile)) return;
 
-        try
+        try (final BufferedReader reader = Files.newBufferedReader(saveFile, Charsets.UTF_8))
         {
-
-            String json = Files.toString(saveFile, charset);
-            Type type = new TypeToken<Map<UUID, String>>() { private static final long serialVersionUID = 1L; }.getType();
-
-            map = gson.fromJson(json, type);
+            Type type = new TypeToken<Map<UUID, String>>(){}.getType();
+            map = gson.fromJson(reader, type);
         }
-        catch (JsonSyntaxException e)
+        catch (JsonSyntaxException | IOException e)
         {
-            log.error("Could not parse username cache file as valid json, deleting file", e);
-            saveFile.delete();
-        }
-        catch (IOException e)
-        {
-            log.error("Failed to read username cache file from disk, deleting file", e);
-            saveFile.delete();
+            LOGGER.error(USRCACHE,"Could not parse username cache file as valid json, deleting file {}", saveFile, e);
+            try
+            {
+                Files.delete(saveFile);
+            }
+            catch (IOException e1)
+            {
+                LOGGER.error(USRCACHE,"Could not delete file {}", saveFile.toString());
+            }
         }
         finally
         {
             // Can sometimes occur when the json file is malformed
             if (map == null)
             {
-                map = Maps.newHashMap();
+                map = new HashMap<>();
             }
         }
     }

src/main/java/net/minecraftforge/fml/ModContainer.java

@@ -20,7 +20,6 @@
 package net.minecraftforge.fml;
 
 import net.minecraftforge.fml.language.IModInfo;
-import net.minecraftforge.fml.network.Networking;
 
 import java.util.ArrayList;
 import java.util.HashMap;

src/main/java/net/minecraftforge/fml/common/network/simpleimpl/IMessageHandler.java

@@ -20,10 +20,10 @@
 package net.minecraftforge.fml.common.network.simpleimpl;
 
 
-import net.minecraftforge.fml.network.simple.MessageContext;
+import net.minecraftforge.fml.network.NetworkEvent;
 
 /**
- * A message handler based on {@link IMessage}. Implement and override {@link #onMessage(IMessage, MessageContext)} to
+ * A message handler based on {@link IMessage}. Implement and override {@link #onMessage(IMessage, NetworkEvent.Context)} to
  * process your packet. Supply the class to {@link SimpleNetworkWrapper#registerMessage(Class, Class, int, Side)}
  * to register both the message type and it's associated handler.
  *
@@ -41,5 +41,5 @@ public interface IMessageHandler<REQ extends IMessage, REPLY extends IMessage> {
      * @param message The message
      * @return an optional return message
      */
-    REPLY onMessage(REQ message, MessageContext ctx);
+    REPLY onMessage(REQ message, NetworkEvent.Context ctx);
 }

src/main/java/net/minecraftforge/fml/common/network/simpleimpl/SimpleChannelHandlerWrapper.java

@@ -20,7 +20,7 @@
 package net.minecraftforge.fml.common.network.simpleimpl;
 
 import net.minecraftforge.api.distmarker.Dist;
-import net.minecraftforge.fml.network.simple.MessageContext;
+import net.minecraftforge.fml.network.NetworkEvent;
 
 import net.minecraft.network.INetHandler;
 import net.minecraftforge.fml.common.FMLLog;
@@ -52,7 +52,7 @@ public class SimpleChannelHandlerWrapper<REQ extends IMessage, REPLY extends IMe
     protected void channelRead0(ChannelHandlerContext ctx, REQ msg) throws Exception
     {
         INetHandler iNetHandler = ctx.channel().attr(NetworkRegistry.NET_HANDLER).get();
-        MessageContext context = new MessageContext(iNetHandler, side);
+        NetworkEvent.Context context = new NetworkEvent.Context(iNetHandler, side);
         REPLY result = messageHandler.onMessage(msg, context);
         if (result != null)
         {

src/main/java/net/minecraftforge/fml/common/network/simpleimpl/SimpleNetworkWrapper.java

@@ -80,14 +80,14 @@ import net.minecraftforge.fml.common.network.NetworkRegistry.TargetPoint;
  *  }
  *  // Message1Handler expects input of type Message1 and returns type Message2
  *  public Message1Handler implements IMessageHandler<Message1,Message2> {
- *   public Message2 onMessage(Message1 message, MessageContext ctx) {
+ *   public Message2 onMessage(Message1 message, Context ctx) {
  *    // do something and generate reply message
  *    return aMessage2Object;
  *   }
  *  }
  *  // Message2Handler expects input of type Message2 and returns no message (IMessage)
  *  public Message2Handler implements IMessageHandler<Message2,IMessage> {
- *   public IMessage onMessage(Message2 message, MessageContext ctx) {
+ *   public IMessage onMessage(Message2 message, Context ctx) {
  *    // handle the message 2 response message at the other end
  *    // no reply for this message - return null
  *    return null;

src/main/java/net/minecraftforge/fml/loading/FMLLoader.java

@@ -57,6 +57,7 @@ public class FMLLoader
     private static LoadingModList loadingModList;
     private static ClassLoader launchClassLoader;
     private static RuntimeDistCleaner runtimeDistCleaner;
+    private static Path gamePath;
 
     static void onInitialLoad(IEnvironment environment, Set<String> otherServices) throws IncompatibleEnvironmentException
     {
@@ -124,6 +125,7 @@ public class FMLLoader
             fmlLog.error(CORE, "Incompatible Launch handler found - type {}, cannot continue", launchHandler.get().getClass().getName());
             throw new RuntimeException("Incompatible launch handler found");
         }
+        gamePath = environment.getProperty(IEnvironment.Keys.GAMEDIR.get()).orElse(Paths.get(".").toAbsolutePath());
 
         FMLCommonLaunchHandler commonLaunchHandler = (FMLCommonLaunchHandler)launchHandler.get();
         commonLaunchHandler.setup(environment);
@@ -192,4 +194,9 @@ public class FMLLoader
     {
         return launchClassLoader;
     }
+
+    public static Path getGamePath()
+    {
+        return gamePath;
+    }
 }

src/main/java/net/minecraftforge/fml/network/Network.java

@@ -0,0 +1,45 @@
+/*
+ * Minecraft Forge
+ * Copyright (c) 2018.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation version 2.1
+ * of the License.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ */
+
+package net.minecraftforge.fml.network;
+
+import net.minecraft.network.PacketBuffer;
+
+import java.util.function.BiFunction;
+import java.util.function.Supplier;
+
+public enum Network
+{
+    PLAYSERVER(NetworkEvent.ClientCustomPayloadEvent::new),
+    PLAYCLIENT(NetworkEvent.ServerCustomPayloadEvent::new),
+    LOGINSERVER(NetworkEvent.ClientCustomPayloadEvent::new),
+    LOGINCLIENT(NetworkEvent.ServerCustomPayloadEvent::new);
+
+    private final BiFunction<PacketBuffer, Supplier<NetworkEvent.Context>, NetworkEvent> eventSupplier;
+
+    Network(BiFunction<PacketBuffer, Supplier<NetworkEvent.Context>, NetworkEvent> eventSupplier)
+    {
+        this.eventSupplier = eventSupplier;
+    }
+
+    public NetworkEvent getEvent(final PacketBuffer buffer, final Supplier<NetworkEvent.Context> manager) {
+        return this.eventSupplier.apply(buffer, manager);
+    }
+
+}

src/main/java/net/minecraftforge/fml/network/NetworkEvent.java

@@ -0,0 +1,101 @@
+/*
+ * Minecraft Forge
+ * Copyright (c) 2018.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation version 2.1
+ * of the License.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ */
+
+package net.minecraftforge.fml.network;
+
+import net.minecraft.client.network.NetHandlerPlayClient;
+import net.minecraft.network.INetHandler;
+import net.minecraft.network.NetHandlerPlayServer;
+import net.minecraft.network.NetworkManager;
+import net.minecraft.network.PacketBuffer;
+import net.minecraftforge.eventbus.api.Event;
+
+import java.util.function.Supplier;
+
+public class NetworkEvent extends Event
+{
+    private final PacketBuffer payload;
+    private final Supplier<Context> source;
+
+    private NetworkEvent(PacketBuffer payload, Supplier<Context> source)
+    {
+        this.payload = payload;
+        this.source = source;
+    }
+
+    public PacketBuffer getPayload()
+    {
+        return payload;
+    }
+
+    public Supplier<Context> getSource()
+    {
+        return source;
+    }
+
+    public static class ServerCustomPayloadEvent extends NetworkEvent
+    {
+        ServerCustomPayloadEvent(final PacketBuffer payload, final Supplier<Context> source) {
+            super(payload, source);
+        }
+    }
+    public static class ClientCustomPayloadEvent extends NetworkEvent
+    {
+        ClientCustomPayloadEvent(final PacketBuffer payload, final Supplier<Context> source) {
+            super(payload, source);
+        }
+    }
+
+    /**
+     * Context for {@link NetworkEvent}
+     */
+    public static class Context
+    {
+        /**
+         * The {@link INetHandler} for this message. It could be a client or server handler, depending
+         * on the {@link #side} received.
+         */
+        private final INetHandler netHandler;
+
+        /**
+         * The {@link Network} this message has been received on
+         */
+        private final Network side;
+
+        Context(NetworkManager netHandler, Network side)
+        {
+            this.netHandler = netHandler.getNetHandler();
+            this.side = side;
+        }
+
+        public Network getSide() {
+            return side;
+        }
+
+        public NetHandlerPlayServer getServerHandler()
+        {
+            return (NetHandlerPlayServer) netHandler;
+        }
+
+        public NetHandlerPlayClient getClientHandler()
+        {
+            return (NetHandlerPlayClient) netHandler;
+        }
+    }
+}

src/main/java/net/minecraftforge/fml/network/NetworkHooks.java

@@ -27,7 +27,6 @@ import net.minecraft.network.handshake.client.C00Handshake;
 import net.minecraft.network.play.client.CPacketCustomPayload;
 import net.minecraft.network.play.server.SPacketCustomPayload;
 import net.minecraft.util.ResourceLocation;
-import net.minecraftforge.fml.LogicalSide;
 import net.minecraftforge.fml.common.registry.EntityRegistry;
 
 import java.util.Objects;
@@ -63,22 +62,22 @@ public class NetworkHooks
 
     public static void onServerCustomPayload(final SPacketCustomPayload packet, final NetworkManager manager) {
         NetworkRegistry.findTarget(new ResourceLocation(packet.getChannelName())).
-                ifPresent(ni->ni.dispatch(NetworkInstance.NetworkSide.PLAYSERVER, packet.getBufferData(), manager));
+                ifPresent(ni->ni.dispatch(Network.PLAYSERVER, packet.getBufferData(), manager));
     }
 
     public static void onClientCustomPayload(final CPacketCustomPayload packet, final NetworkManager manager) {
         NetworkRegistry.findTarget(new ResourceLocation(packet.getChannelName())).
-                ifPresent(ni->ni.dispatch(NetworkInstance.NetworkSide.PLAYCLIENT, packet.getBufferData(), manager));
+                ifPresent(ni->ni.dispatch(Network.PLAYCLIENT, packet.getBufferData(), manager));
     }
 
     public static void onServerLoginCustomPayload(final SPacketCustomPayload packet, final NetworkManager manager) {
         NetworkRegistry.findTarget(new ResourceLocation(packet.getChannelName())).
-                ifPresent(ni->ni.dispatch(NetworkInstance.NetworkSide.LOGINSERVER, packet.getBufferData(), manager));
+                ifPresent(ni->ni.dispatch(Network.LOGINSERVER, packet.getBufferData(), manager));
     }
 
     public static void onClientLoginCustomPayload(final CPacketCustomPayload packet, final NetworkManager manager) {
         NetworkRegistry.findTarget(new ResourceLocation(packet.getChannelName())).
-                ifPresent(ni->ni.dispatch(NetworkInstance.NetworkSide.LOGINCLIENT, packet.getBufferData(), manager));
+                ifPresent(ni->ni.dispatch(Network.LOGINCLIENT, packet.getBufferData(), manager));
     }
 
     public static void registerServerChannel(NetworkManager manager, C00Handshake packet)

src/main/java/net/minecraftforge/fml/network/NetworkInstance.java

@@ -26,7 +26,6 @@ import net.minecraftforge.eventbus.api.Event;
 import net.minecraftforge.eventbus.api.IEventBus;
 import net.minecraftforge.eventbus.api.IEventListener;
 
-import java.util.function.BiFunction;
 import java.util.function.Consumer;
 import java.util.function.Predicate;
 import java.util.function.Supplier;
@@ -38,24 +37,6 @@ public class NetworkInstance
         return channelName.toString();
     }
 
-    public enum NetworkSide {
-        PLAYSERVER(NetworkEvent.ServerCustomPayloadEvent::new),
-        PLAYCLIENT(NetworkEvent.ClientCustomPayloadEvent::new),
-        LOGINSERVER(NetworkEvent.ServerCustomPayloadEvent::new),
-        LOGINCLIENT(NetworkEvent.ClientCustomPayloadEvent::new);
-
-        private final BiFunction<PacketBuffer, NetworkManager, NetworkEvent> eventSupplier;
-
-        NetworkSide(BiFunction<PacketBuffer, NetworkManager, NetworkEvent> eventSupplier)
-        {
-            this.eventSupplier = eventSupplier;
-        }
-
-        public NetworkEvent getEvent(final PacketBuffer buffer, final NetworkManager manager) {
-            return this.eventSupplier.apply(buffer, manager);
-        }
-
-    }
     private final ResourceLocation channelName;
     private final Supplier<String> networkProtocolVersion;
     private final Predicate<String> clientAcceptedVersions;
@@ -76,9 +57,9 @@ public class NetworkInstance
 
     }
 
-    public <T extends NetworkEvent> void addListener(Consumer<T> serverEventListener)
+    public <T extends NetworkEvent> void addListener(Consumer<T> eventListener)
     {
-        this.networkEventBus.addListener(serverEventListener);
+        this.networkEventBus.addListener(eventListener);
     }
 
     public void registerObject(final Object object) {
@@ -89,41 +70,10 @@ public class NetworkInstance
         this.networkEventBus.unregister(object);
     }
 
-    void dispatch(final NetworkSide side, final PacketBuffer bufferData, final NetworkManager manager)
+    void dispatch(final Network side, final PacketBuffer bufferData, final NetworkManager manager)
     {
-        this.networkEventBus.post(side.getEvent(bufferData,manager));
+        this.networkEventBus.post(side.getEvent(bufferData,()->new NetworkEvent.Context(manager, side)));
     }
 
 
-    public static class NetworkEvent extends Event {
-        private final PacketBuffer payload;
-        private final NetworkManager source;
-
-        private NetworkEvent(PacketBuffer payload, NetworkManager source)
-        {
-            this.payload = payload;
-            this.source = source;
-        }
-
-        public PacketBuffer getPayload()
-        {
-            return payload;
-        }
-
-        public NetworkManager getSource()
-        {
-            return source;
-        }
-
-        public static class ServerCustomPayloadEvent extends NetworkEvent {
-            ServerCustomPayloadEvent(final PacketBuffer payload, final NetworkManager source) {
-                super(payload, source);
-            }
-        }
-        public static class ClientCustomPayloadEvent extends NetworkEvent {
-            ClientCustomPayloadEvent(final PacketBuffer payload, final NetworkManager source) {
-                super(payload, source);
-            }
-        }
-    }
 }

src/main/java/net/minecraftforge/fml/network/NetworkRegistry.java

@@ -21,6 +21,7 @@ package net.minecraftforge.fml.network;
 
 import io.netty.util.AttributeKey;
 import net.minecraft.util.ResourceLocation;
+import net.minecraftforge.fml.network.event.EventNetworkChannel;
 import net.minecraftforge.fml.network.simple.SimpleChannel;
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
@@ -50,13 +51,21 @@ public class NetworkRegistry
 
 
     public static SimpleChannel newSimpleChannel(final ResourceLocation name, Supplier<String> networkProtocolVersion, Predicate<String> clientAcceptedVersions, Predicate<String> serverAcceptedVersions) {
+        return new SimpleChannel(createInstance(name, networkProtocolVersion, clientAcceptedVersions, serverAcceptedVersions));
+    }
+
+    public static EventNetworkChannel newEventChannel(final ResourceLocation name, Supplier<String> networkProtocolVersion, Predicate<String> clientAcceptedVersions, Predicate<String> serverAcceptedVersions) {
+        return new EventNetworkChannel(createInstance(name, networkProtocolVersion, clientAcceptedVersions, serverAcceptedVersions));
+    }
+    private static NetworkInstance createInstance(ResourceLocation name, Supplier<String> networkProtocolVersion, Predicate<String> clientAcceptedVersions, Predicate<String> serverAcceptedVersions)
+    {
         final NetworkInstance networkInstance = new NetworkInstance(name, networkProtocolVersion, clientAcceptedVersions, serverAcceptedVersions);
         if (instances.containsKey(name)) {
             LOGGER.error(NETREGISTRY, "Network channel {} already registered.", name);
             throw new IllegalArgumentException("Network Channel {"+ name +"} already registered");
         }
         instances.put(name, networkInstance);
-        return new SimpleChannel(networkInstance);
+        return networkInstance;
     }
 
     static Optional<NetworkInstance> findTarget(ResourceLocation resourceLocation)

src/main/java/net/minecraftforge/fml/network/event/EventNetworkChannel.java

@@ -17,9 +17,34 @@
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
  */
 
-package net.minecraftforge.fml.network;
+package net.minecraftforge.fml.network.event;
 
-public class Networking
+import net.minecraftforge.fml.network.NetworkEvent;
+import net.minecraftforge.fml.network.NetworkInstance;
+
+import java.util.function.Consumer;
+
+public class EventNetworkChannel
 {
-    public enum Type { SIMPLE, EVENT, NONE }
+    private final NetworkInstance instance;
+
+    public EventNetworkChannel(NetworkInstance instance)
+    {
+        this.instance = instance;
+    }
+
+    public <T extends NetworkEvent> void addListener(Consumer<T> eventListener)
+    {
+        instance.addListener(eventListener);
+    }
+
+    public void registerObject(Object object)
+    {
+        instance.registerObject(object);
+    }
+
+    public void unregisterObject(Object object)
+    {
+        instance.unregisterObject(object);
+    }
 }

src/main/java/net/minecraftforge/fml/network/simple/IndexedMessageCodec.java

@@ -22,6 +22,7 @@ package net.minecraftforge.fml.network.simple;
 import it.unimi.dsi.fastutil.objects.Object2ObjectArrayMap;
 import it.unimi.dsi.fastutil.shorts.Short2ObjectArrayMap;
 import net.minecraft.network.PacketBuffer;
+import net.minecraftforge.fml.network.NetworkEvent;
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
 import org.apache.logging.log4j.Marker;
@@ -46,9 +47,9 @@ public class IndexedMessageCodec
         private final Optional<BiConsumer<MSG, PacketBuffer>> encoder;
         private final Optional<Function<PacketBuffer, MSG>> decoder;
         private final int index;
-        private final BiConsumer<MSG,Supplier<MessageContext>> messageConsumer;
+        private final BiConsumer<MSG,Supplier<NetworkEvent.Context>> messageConsumer;
         private final Class<MSG> messageType;
-        public CodecIndex(int index, Class<MSG> messageType, BiConsumer<MSG, PacketBuffer> encoder, Function<PacketBuffer, MSG> decoder, BiConsumer<MSG, Supplier<MessageContext>> messageConsumer)
+        public CodecIndex(int index, Class<MSG> messageType, BiConsumer<MSG, PacketBuffer> encoder, Function<PacketBuffer, MSG> decoder, BiConsumer<MSG, Supplier<NetworkEvent.Context>> messageConsumer)
         {
             this.index = index;
             this.messageType = messageType;
@@ -61,13 +62,16 @@ public class IndexedMessageCodec
 
 
     }
-    private static <M> void tryDecode(PacketBuffer payload, Supplier<MessageContext> context, CodecIndex<M> codec)
+    private static <M> void tryDecode(PacketBuffer payload, Supplier<NetworkEvent.Context> context, CodecIndex<M> codec)
     {
         codec.decoder.map(d->d.apply(payload)).ifPresent(m->codec.messageConsumer.accept(m, context));
     }
 
     private static <M> void tryEncode(PacketBuffer target, M message, CodecIndex<M> codec) {
-        codec.encoder.ifPresent(c->c.accept(message, target));
+        codec.encoder.ifPresent(encoder->{
+            target.writeByte(codec.index & 0xff);
+            encoder.accept(message, target);
+        });
     }
     public <MSG> void build(MSG message, PacketBuffer target)
     {
@@ -80,7 +84,7 @@ public class IndexedMessageCodec
         tryEncode(target, message, codecIndex);
     }
 
-    void consume(final PacketBuffer payload, Supplier<MessageContext> context) {
+    void consume(final PacketBuffer payload, Supplier<NetworkEvent.Context> context) {
         short discriminator = payload.readUnsignedByte();
         final CodecIndex<?> codecIndex = indicies.get(discriminator);
         if (codecIndex == null) {
@@ -90,7 +94,7 @@ public class IndexedMessageCodec
         tryDecode(payload, context, codecIndex);
     }
 
-    <MSG> void addCodecIndex(int index, Class<MSG> messageType, BiConsumer<MSG, PacketBuffer> encoder, Function<PacketBuffer, MSG> decoder, BiConsumer<MSG, Supplier<MessageContext>> messageConsumer) {
+    <MSG> void addCodecIndex(int index, Class<MSG> messageType, BiConsumer<MSG, PacketBuffer> encoder, Function<PacketBuffer, MSG> decoder, BiConsumer<MSG, Supplier<NetworkEvent.Context>> messageConsumer) {
         new CodecIndex<>(index, messageType, encoder, decoder, messageConsumer);
     }
 }

src/main/java/net/minecraftforge/fml/network/simple/MessageContext.java

@@ -1,70 +0,0 @@
-/*
- * Minecraft Forge
- * Copyright (c) 2016-2018.
- *
- * This library is free software; you can redistribute it and/or
- * modify it under the terms of the GNU Lesser General Public
- * License as published by the Free Software Foundation version 2.1
- * of the License.
- *
- * This library is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
- * Lesser General Public License for more details.
- *
- * You should have received a copy of the GNU Lesser General Public
- * License along with this library; if not, write to the Free Software
- * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
- */
-
-package net.minecraftforge.fml.network.simple;
-
-import net.minecraft.client.network.NetHandlerPlayClient;
-import net.minecraft.network.INetHandler;
-import net.minecraft.network.NetHandlerPlayServer;
-import net.minecraft.network.NetworkManager;
-import net.minecraftforge.api.distmarker.Dist;
-import net.minecraftforge.fml.common.network.simpleimpl.IMessageHandler;
-import net.minecraftforge.fml.network.NetworkInstance;
-
-/**
- * Context for the {@link IMessageHandler}
- *
- * @author cpw
- *
- */
-public class MessageContext {
-    /**
-     * The {@link INetHandler} for this message. It could be a client or server handler, depending
-     * on the {@link #side} received.
-     */
-    private final INetHandler netHandler;
-
-    /**
-     * The {@link NetworkInstance.NetworkSide} this message has been received on
-     */
-    private final NetworkInstance.NetworkSide side;
-    /**
-     * @param netHandler
-     * @param side
-     */
-    MessageContext(NetworkManager netHandler, NetworkInstance.NetworkSide side)
-    {
-        this.netHandler = netHandler.getNetHandler();
-        this.side = side;
-    }
-
-    public NetworkInstance.NetworkSide getSide() {
-        return side;
-    }
-
-    public NetHandlerPlayServer getServerHandler()
-    {
-        return (NetHandlerPlayServer) netHandler;
-    }
-
-    public NetHandlerPlayClient getClientHandler()
-    {
-        return (NetHandlerPlayClient) netHandler;
-    }
-}

src/main/java/net/minecraftforge/fml/network/simple/SimpleChannel.java

@@ -19,12 +19,11 @@
 
 package net.minecraftforge.fml.network.simple;
 
-import io.netty.buffer.ByteBuf;
 import io.netty.buffer.Unpooled;
 import net.minecraft.client.Minecraft;
-import net.minecraft.network.NetworkManager;
 import net.minecraft.network.PacketBuffer;
 import net.minecraft.network.play.client.CPacketCustomPayload;
+import net.minecraftforge.fml.network.NetworkEvent;
 import net.minecraftforge.fml.network.NetworkInstance;
 
 import java.util.function.BiConsumer;
@@ -40,24 +39,18 @@ public class SimpleChannel
     {
         this.instance = instance;
         this.indexedCodec = new IndexedMessageCodec();
-        instance.addListener(this::serverEventListener);
-        instance.addListener(this::clientEventListener);
+        instance.addListener(this::networkEventListener);
     }
 
-    private void clientEventListener(final NetworkInstance.NetworkEvent.ClientCustomPayloadEvent clientCustomPayloadEvent)
+    private void networkEventListener(final NetworkEvent networkEvent)
     {
-    }
-
-    private void serverEventListener(final NetworkInstance.NetworkEvent.ServerCustomPayloadEvent serverCustomPayloadEvent)
-    {
-        this.indexedCodec.consume(serverCustomPayloadEvent.getPayload(),
-                ()->new MessageContext(serverCustomPayloadEvent.getSource(), NetworkInstance.NetworkSide.PLAYSERVER));
+        this.indexedCodec.consume(networkEvent.getPayload(),networkEvent.getSource());
     }
 
     public <MSG> void encodeMessage(MSG message, final PacketBuffer target) {
         this.indexedCodec.build(message, target);
     }
-    public <MSG> void registerMessage(int index, Class<MSG> messageType, BiConsumer<MSG, PacketBuffer> encoder, Function<PacketBuffer, MSG> decoder, BiConsumer<MSG, Supplier<MessageContext>> messageConsumer) {
+    public <MSG> void registerMessage(int index, Class<MSG> messageType, BiConsumer<MSG, PacketBuffer> encoder, Function<PacketBuffer, MSG> decoder, BiConsumer<MSG, Supplier<NetworkEvent.Context>> messageConsumer) {
         this.indexedCodec.addCodecIndex(index, messageType, encoder, decoder, messageConsumer);
     }
 

src/test/java/net/minecraftforge/debug/item/MapDataTest.java

@@ -51,7 +51,7 @@ import net.minecraftforge.fml.common.event.FMLPreInitializationEvent;
 import net.minecraftforge.eventbus.api.SubscribeEvent;
 import net.minecraftforge.fml.common.network.simpleimpl.IMessage;
 import net.minecraftforge.fml.common.network.simpleimpl.IMessageHandler;
-import net.minecraftforge.fml.network.simple.MessageContext;
+import net.minecraftforge.fml.network.NetworkEvent;
 import net.minecraftforge.fml.common.network.simpleimpl.SimpleNetworkWrapper;
 import net.minecraftforge.fml.common.registry.GameRegistry;
 
@@ -237,7 +237,7 @@ public class MapDataTest
     {
         @Nullable
         @Override
-        public IMessage onMessage(CustomMapPacket message, MessageContext ctx)
+        public IMessage onMessage(CustomMapPacket message, NetworkEvent.Context ctx)
         {
             // Like NetHandlerPlayClient.handleMaps but using our custom type
             Minecraft.getMinecraft().addScheduledTask(new Runnable() {

src/test/java/net/minecraftforge/fml/test/simplenet/SimpleNetHandler1.java

@@ -20,12 +20,12 @@
 package net.minecraftforge.fml.test.simplenet;
 
 import net.minecraftforge.fml.common.network.simpleimpl.IMessageHandler;
-import net.minecraftforge.fml.network.simple.MessageContext;
+import net.minecraftforge.fml.network.NetworkEvent;
 
 public class SimpleNetHandler1 implements IMessageHandler<SimpleNetTestMessage1, SimpleNetTestMessage2>
 {
     @Override
-    public SimpleNetTestMessage2 onMessage(SimpleNetTestMessage1 message, MessageContext context)
+    public SimpleNetTestMessage2 onMessage(SimpleNetTestMessage1 message, NetworkEvent.Context context)
     {
         return null;
     }

src/test/java/net/minecraftforge/fml/test/simplenet/SimpleNetHandler2.java

@@ -20,12 +20,12 @@
 package net.minecraftforge.fml.test.simplenet;
 
 import net.minecraftforge.fml.common.network.simpleimpl.IMessageHandler;
-import net.minecraftforge.fml.network.simple.MessageContext;
+import net.minecraftforge.fml.network.NetworkEvent;
 
 public class SimpleNetHandler2 implements IMessageHandler<SimpleNetTestMessage2, SimpleNetTestMessage1>
 {
     @Override
-    public SimpleNetTestMessage1 onMessage(SimpleNetTestMessage2 message, MessageContext context)
+    public SimpleNetTestMessage1 onMessage(SimpleNetTestMessage2 message, NetworkEvent.Context context)
     {
         return null;
     }