Pre-release protocol

This page documents the changes from the last stable Minecraft release (currently 1.3.2) to the current pre-release (or weekly release).

New packets

-None-

Changed packets

Time Update (0x04)

Server to Client

Time is based on ticks, where 20 ticks happen every second. There are 24000 ticks in a day, making Minecraft days exactly 20 minutes long.

The time of day is based on the timestamp modulo 24000. 0 is sunrise, 6000 is noon, 12000 is sunset, and 18000 is midnight.

The default SMP server increments both by 20 every second.

The 'Time' is the Age of the world. It is not changing on server commands and will increased by 20 every second.

Packet ID	Field Name	Field Type	Example	Notes
0x04	Time	long	45464654	The 'Age of the world', in ticks
	Day Time	long	21321	The world (or region) time, in ticks
Total Size:	17 Bytes

Spawn Named Entity (0x14)

See the change in metadata below. (Under Protocol History, 2012-08-24)

Spawn Dropped Item (0x15)

TODO

It includes a new byte array after the "Damage" field, and before the "X" field if certain conditions are met. If the array does not exist, then the length of the array is "-1".

Spawn Mob (0x18)

See the change in metadata below. (Under Protocol History, 2012-08-24)

Entity Metadata (0x28)

See the change in metadata below. (Under Protocol History, 2012-08-24)

Click Window (0x66)

Client to Server

This packet is sent by the player when it clicks on a slot in a window.

Packet ID	Field Name	Field Type	Example	Notes
0x66	Window id	byte	0	The id of the window which was clicked. 0 for player inventory.
	Slot	short	36	The clicked slot. See below.
	Right-click	byte	1
	Action number	short	12	A unique number for the action, used for transaction handling (See the Transaction packet).
	Shift	boolean	0	This is true if the user was holding keyboard shift when they clicked.
	Clicked item	slot
Total Size:	9 bytes + slot data

Entity Metadata Format

Note that entity metadata is a totally distinct concept from block metadata.

The entity metadata format is quirky dictionary format, where the key and the value's type are packed in a single byte.

To parse, repeat the following procedure:

1. Read an unsigned byte
2. If this byte == 127, stop reading
3. Decompose the byte.
   The bottom 5 bits (0x1F) serve as an identifier (key) for the data to follow.
   The top 3 bits (0xE0) serve as a type.
4. Read and unpack based on the type (below)

Type	Meaning
0	byte
1	short
2	int
3	float
4	string16
5	short, byte, short (slot type) - If first short is empty, no further data is sent.
6	int, int, int (x, y, z)

In Python-like code:

#socket is positioned at the beginning of the metadata array. Also note that the method unpack() doesn't exist in socket
metadata = {}
x = socket.unpack('byte')
while x != 127:
    index = x & 0x1F # Lower 5 bits
    ty    = x >> 5   # Upper 3 bits
    if ty == 0: val = socket.unpack('byte') 
    if ty == 1: val = socket.unpack('short') 
    if ty == 2: val = socket.unpack('int') 
    if ty == 3: val = socket.unpack('float') 
    if ty == 4: val = socket.unpack('string16')
    if ty == 5:
        val = {}
        val["id"] = socket.unpack('short')
        if val["id"] != -1:
            val["count"]  = socket.unpack('byte')
            val["damage"] = socket.unpack('short')
    if ty == 6:
        val = []
        for i in range(3):
            val.append(socket.unpack('int'))
    metadata[index] = (ty, val)
    x = socket.unpack('byte')
return metadata

Removed packets

-None-

Protocol History

2012-10-04

• 12w40a
• Protocol version is now 45
• Packet 0x66 changed

2012-09-06

• 12w36a
• Protocol version is now 42

2012-08-24

• 12w34b
• Protocol version is now 41

• Changed Entity Metadata Format

2012-08-09

• 12w32a
• Protocol version is now 40

• Changed Time Update packet