Pre-release protocol

This page documents the changes from the last stable Minecraft release (currently 1.9.2, protocol 109) to the current pre-release (currently 1.9.3-pre2, protocol 110). Note that this page contains bleeding-edge information that may not be completely or correctly documented.

One who wishes to commandeer the merging of this into Protocol when an update is made must be sure to respect any changes that may have occurred to the respective packets there.

Contents

Data types

No changes so far.

Packets

ID	Packet name	Documentation
Handshaking serverbound
0x00	Handshake	Current	Pre
Play clientbound
0x09	Update Block Entity	Current	Pre
0x20	Chunk data	Current	Pre
0x46	Update Sign (clientbound)	Current
0x47 0x46	Sound Effect	Current	(unchanged)
0x48 0x47	Player List Header And Footer	Current	(unchanged)
0x49 0x48	Collect Item	Current	(unchanged)
0x4A 0x49	Entity Teleport	Current	(unchanged)
0x4B 0x4A	Entity Properties	Current	(unchanged)
0x4C 0x4B	Entity effect	Current	(unchanged)

New/modified data types

None so far.

MC|StopSound plugin channel

Used to implement the /stopsound command. Stops a sound that is currently playing on the client.

Field name	Field type	Notes
Sound name	String	A sound effect name. If left empty, all sounds are stopped.
Sound category	String	Should be one of the sound categories used in Named Sound Effect, but if it's invalid or empty then it is (intentionally) treated as all sound categories.

Emptiness of sound category or sound name can be combined, IE a empty sound name but a set sound category will stop all sounds in the given category.

Handshaking

Clientbound

No changes so far.

Serverbound

No changes so far.

Handshake

This causes the server to switch into the target state.

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x00	Handshaking	Server	Protocol Version	VarInt	See protocol version numbers (currently 109 110)
			Server Address	String	Hostname or IP, e.g. localhost or 127.0.0.1, that was used to connect. The Notchian server does not use this information.
			Server Port	Unsigned Short	Default is 25565. The Notchian server does not use this information.
			Next State	VarInt Enum	1 for status, 2 for login

Play

Clientbound

Chunk Data

See also: #Unload Chunk

The server only sends skylight information for chunk pillars in the Overworld, it's up to the client to know in which dimenison the player is currently located. You can also infer this information from the primary bitmask and the amount of uncompressed bytes sent. This also sends all tile entities in the chunk.

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x20	Play	Client	Chunk X	Int	Block coordinate divided by 16, rounded down
			Chunk Z	Int	Block coordinate divided by 16, rounded down
			Ground-Up Continuous	Boolean	This is true if the packet represents all chunk sections in this vertical chunk column, where the Primary Bit Mask specifies exactly which chunk sections are included, and which are air.
			Primary Bit Mask	VarInt	Bitmask with bits set to 1 for every 16×16×16 chunk section whose data is included in Data. The least significant bit represents the chunk section at the bottom of the chunk column (from y=0 to y=15).
			Size	VarInt	Size of Data in bytes, plus size of Biomes in bytes if present
			Data	Array of Chunk Section	The length of the array is equal to the number of bits set in Primary Bit Mask. Chunks are sent bottom-to-top, i.e. the first chunk, if sent, extends from Y=0 to Y=15.
			Biomes	Optional Byte Array	Only if Ground-Up Continuous: biome array, byte per XZ coordinate, 256 bytes total.
			Number of tile entities	VarInt	Length of the following array
			Tile entities	Array of NBT Tag	All tile entities in the chunk. Use the x, y, and z tags in the NBT to determine their positions.

Serverbound

No changes so far.

Status

Clientbound

No changes so far.

Serverbound

No changes so far.

Login

Clientbound

No changes so far.

Serverbound

No changes so far.