Differences

This shows you the differences between two versions of the page.

--- tutorial:networking [2021/10/01 03:00] – voleil
+++ tutorial:networking [2024/10/26 20:39] (current) – [How do I fix the crash?] double "be" fix skycatminepokie
@@ Line 1: / Line 1: @@
-====== Page Information ======
+**Note: **This page has replaced the old networking page.
-This page has replaced the old networking page.
 It is recommended to use the new networking API described on this page.
 The old page can be [[tutorial:legacy:networking-v0|found here]].
+For the even newer networking API introduced at 1.20.5, read the [[#Networking in 1.20.5 | separate documentation below]].
 ====== Networking ======
@@ Line 15: / Line 15: @@
 Say you had a wand which highlights the block you are looking at to all nearby players.
 <code java [enable_line_numbers="true"]>
-class HighlightingWandItem extends Item {
+public class HighlightingWandItem extends Item {
     public HighlightingWand(Item.Settings settings) {
         super(settings)
@@ Line 51: / Line 51: @@
 [[Minecraft's Logical Sides|{{tutorial:sides.png?700}}]]
-The diagram above shows that the game client and dedicated server art separate systems bridged together using packets. This packet bridge does not only exist between a game client and dedicated server, but also between your client and another client connected over LAN. The packet bridge is also present even in singleplayer! This is because the game client will spin up a special integrated server instance to run the game on. The key difference between the three types of connections that are shown in the table below:
+The diagram above shows that the game client and dedicated server are separate systems bridged together using packets. This packet bridge does not only exist between a game client and dedicated server, but also between your client and another client connected over LAN. The packet bridge is also present even in singleplayer! This is because the game client will spin up a special integrated server instance to run the game on. The key difference between the three types of connections that are shown in the table below:
 ^ Connection Type               ^ Access to game client       ^
@@ Line 58: / Line 58: @@
 | Singleplayer (or LAN host)    | Yes -> Full access          |
-It may seem complicated to have communication with the server in three different ways. However, you don't need to communicate in three different ways with the game client. Since all three connection types communicate with the game client using packets, you only need to communicate with the game client like you are always running on a dedicated server. Connection to a server over LAN or Singleplayer can be also be treated like the server is a remote dedicated server; so your game client cannot directly access the server instance.
+It may seem complicated to have communication with the server in three different ways. However, you don't need to communicate in three different ways with the game client. Since all three connection types communicate with the game client using packets, you only need to communicate with the game client like you are always running on a dedicated server. Connection to a server over LAN or Singleplayer can also be treated like the server is a remote dedicated server; so your game client cannot directly access the server instance.
 ===== An introduction to networking =====
@@ Line 80: / Line 80: @@
 </code>
-Next, we need to send the packet to the game client. First, you need to define an ''Identifier'' used to identify your packet. For this example our Identifier will be ''wiki_example:highlight_block''. In order to send the packet to the game client, you need to specify which player's game client you want to packet to be received by. Since the action is occurring on the logical server, we may upcast the ''player'' to a ''ServerPlayerEntity''.
+Next, we need to send the packet to the game client. First, you need to define an ''Identifier'' used to identify your packet. For this example our Identifier will be ''tutorial:highlight_block''. In order to send the packet to the game client, you need to specify which player's game client you want the packet to be received by. Since the action is occurring on the logical server, we may upcast the ''player'' to a ''ServerPlayerEntity''.
+<code java>
+public class TutorialNetworkingConstants {
+    // Save the id of the packet so we can reference it later
+    public static final Identifier HIGHLIGHT_PACKET_ID = Identifier.of("tutorial", "highlight_block");
+}
+</code>
 To send the packet to the player, we will use some of the methods inside of ''ServerPlayNetworking''. We will use the following method inside of that class:
@@ Line 125: / Line 131: @@
     client.execute(() -> {
         // Everything in this lambda is run on the render thread
-        ClientBlockHighlighting.highlightBlock(client, target);
     });
 });
@@ Line 169: / Line 174: @@
 Firstly sending a packet to the server is done through ''ClientPlayNetworking.send''. Receiving a packet on the server is similar to receiving a packet on the client, using the ''ServerPlayNetworking.registerGlobalReceiver(Identifier channelName, ChannelHandler channelHandler)'' method. The ''ChannelHandler'' for the server networking also passes the ''ServerPlayerEntity'' (player) who sent the packet through the ''player'' parameter.
-===== The concept of tracking and why you only see the highlighted block =====
+===== The concept of tracking and why only you see the highlighted block =====
 Now that the highlighting wand properly uses networking so the dedicated server does not crash, you invite your friend back on the server to show off the highlighting wand. You use the wand and the block is highlighted on your client and the server does not crash. However, your friend does not see the highlighted block. This is intentional with the code that you already have here. To solve this issue let us take a look at the item's use code:
@@ Line 213: / Line 218: @@
 After this change, when you use the wand, your friend should also see the highlighted block on their own client.
-====== Advanced Networking topics ======
-The Networking system Fabric API supplies is very flexible and supports additional features other than just sending and receiving simple packets. As some of these more advanced topics are long, here are links to their specific pages:
+===== Networking in 1.20.5 =====
+Since 1.20.5, the logic of networking has been totally rewritten. In 1.20.5, ''RegistryByteBuf'' is now used in PLAY-phase networking and you have to define a custom ''Payload''. First, define the payload that includes a ''BlockPos'':
-^ Networking Topic ^ Description ^
+<code java>
-| [[tutorial:networking:connection_events|Connection Network connection events]] | Events related to the the lifecycle of a connection to a client or server |
+public record BlockHighlightPayload(BlockPos blockPos) implements CustomPayload {
-| [[tutorial:networking:channel_events|Channel registration events]] | Events related to a server of client declaring the ability to receive a packet on a channel of a specific name |
+    public static final CustomPayload.Id<BlockHighlightPayload> ID = new CustomPayload.Id<>(TutorialNetworkingConstants.HIGHLIGHT_PACKET_ID);
-| [[tutorial:networking:login|Login phase networking]]| Sending requests to a client during login; and allowing delay of login for a short amount of time |
+    public static final PacketCodec<RegistryByteBuf, BlockHighlightPayload> CODEC = PacketCodec.tuple(BlockPos.PACKET_CODEC, BlockHighlightPayload::blockPos, BlockHighlightPayload::new);
-| [[tutorial:networking:dynamic_handlers|Dynamic registration of channel handlers]]| Allowing for a connection to receive a packet with a special handler |
+    // should you need to send more data, add the appropriate record parameters and change your codec:
+    // public static final PacketCodec<RegistryByteBuf, BlockHighlightPayload> CODEC = PacketCodec.tuple(
+    //         BlockPos.PACKET_CODEC, BlockHighlightPayload::blockPos,
+    //         PacketCodecs.INTEGER, BlockHighlightPayload::myInt,
+    //         Uuids.PACKET_CODEC, BlockHighlightPayload::myUuid,
+    //         BlockHighlightPayload::new
+    // );
+    @Override
+    public CustomPayload.Id<? extends CustomPayload> getId() {
+        return ID;
+    }
+}
+</code>
+And then, register the receiver like this:
+<code java>
+// NOTE: PayloadTypeRegistry has 2 functions:
+//       - playS2C is for server -> client communication
+//       - playC2S is for client -> server communication
+// In your common initializer method
+PayloadTypeRegistry.playS2C().register(BlockHighlightPayload.ID, BlockHighlightPayload.CODEC);
+// In your client-only initializer method
+ClientPlayNetworking.registerGlobalReceiver(BlockHighlightPayload.ID, (payload, context) -> {
+    context.client().execute(() -> {
+        ClientBlockHighlighting.highlightBlock(client, payload.blockPos());
+    });
+});
+</code>
+Now, on the server side, you can send the packet to players like this:
+<code java>
+    public TypedActionResult<ItemStack> use(World world, PlayerEntity user, Hand hand) {
+        if (world.isClient()) return super.use(world, user, hand);
+        // ...
+        for (ServerPlayerEntity player : PlayerLookup.tracking((ServerWorld) world, target)) {
+            ServerPlayNetworking.send(player, new BlockHighlightPayload(target));
+        }
+        return TypedActionResult.success(user.getHandStack(hand));
+    }
+</code>