Pre-release protocol

Under construction In light of the recent release of Minecraft 1.9, this article still contains some changes between 1.8.9 and 1.9, which are currently being merged into Protocol. If you want to contribute, please coordinate with us in #mcdevs, and ping Fenhl before making any edits.

This page documents the changes from the last stable Minecraft release (currently 1.9, protocol 107) to the current pre-release (currently 1.9.1-pre2, protocol 108). 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
0x23	Join Game	Current	Pre
0x25	Entity Relative Move	Current	Pre
0x26	Entity Look And Relative Move	Current	Pre
0x3A	Attach Entity	Current	Pre
Play serverbound
0x00	Teleport Confirm		Pre
0x01	Tab-Complete	Current	Pre
0x03	Client Status	Current	Pre
0x04	Client Settings	Current	Pre
0x0A	Use Entity	Current	Pre
0x10	Vehicle Move (serverbound)		Pre
0x11	Steer Boat		Pre
0x13	Player Digging	Current	Pre
0x14	Entity Action	Current	Pre
0x19	Update Sign	Current	Pre
0x1A	Animation	Current	Pre
0x1C	Player Block Placement	Current	Pre
0x1D	Use Item		Pre

New/modified data types

None so far.

Handshaking

Clientbound

No changes so far.

Serverbound

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 107 108)
			Server Address	String	hostname or IP, e.g. localhost or 127.0.0.1 (does this support IPv6?)
			Server Port	Unsigned Short	default is 25565
			Next State	VarInt Enum	1 for status, 2 for login

Play

Clientbound

Join Game

See Protocol Encryption for information on logging in.

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x23	Play	Client	Entity ID	Int	The player's Entity ID (EID)
			Gamemode	Unsigned Byte	0: Survival, 1: Creative, 2: Adventure, 3: Spectator. Bit 3 (0x8) is the hardcore flag.
			Dimension	Byte Int Enum	-1: Nether, 0: Overworld, 1: End
			Difficulty	Unsigned Byte	0: peaceful, 1: easy, 2: normal, 3: hard
			Max Players	Unsigned Byte	Used by the client to draw the player list
			Level Type	String	default, flat, largeBiomes, amplified, default_1_1
			Reduced Debug Info	Boolean	If true, a Notchian client shows reduced information on the debug screen.

Entity Relative Move

This packet is sent by the server when an entity moves less then 8 blocks; if an entity moves more than 8 blocks Entity Teleport should be sent instead.

This packet allows at most 8 blocks movement in any direction, because short range is from -32768 to 32767. And 32768/(128*32)=8.

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x15 0x25	Play	Client	Entity ID	VarInt
			Delta X	Byte Short	Change in X position as a Fixed-Point number (currentX * 32 - prevX * 32) * 128
			Delta Y	Byte Short	Change in Y position as a Fixed-Point number (currentY * 32 - prevY * 32) * 128
			Delta Z	Byte Short	Change in Z position as a Fixed-Point number (currentZ * 32 - prevZ * 32) * 128
			On Ground	Boolean

Entity Look And Relative Move

This packet is sent by the server when an entity rotates and moves. Since a short range is limited from -32768 to 32767, and movement is offset of fixed-point numbers, this packet allows at most 8 blocks movement in any direction. (-32768/(32*128) == -8)

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x17 0x26	Play	Client	Entity ID	VarInt
			Delta X	Byte Short	Change in X position as a Fixed-Point number (currentX * 32 - prevX * 32) * 128
			Delta Y	Byte Short	Change in Y position as a Fixed-Point number (currentY * 32 - prevY * 32) * 128
			Delta Z	Byte Short	Change in Z position as a Fixed-Point number (currentZ * 32 - prevZ * 32) * 128
			Yaw	Angle	New angle, not a delta
			Pitch	Angle	New angle, not a delta
			On Ground	Boolean

Attach Entity

This packet is sent when a player has been attached to an entity (e.g. Minecart).

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x1B 0x3A	Play	Client	Entity ID	Int	Attached entity's EID
			Vehicle ID	Int	Vechicle's Entity ID. Set to -1 to detach
			Leash	Boolean	If true leashes the entity to the vehicle

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.