People very, very often have questions regarding the Minecraft Modern Protocol, so we'll try to address some of the most common ones on this document. If you're still having trouble, join us on IRC, channel #mcdevs on irc.freenode.net.
Is the protocol documentation complete?
Depending on your definition, yes! All packet types are known and their layout documented. Some finer details are missing, but everything you need to make functional programs is present. We have a script that monitors for new versions of the client and notifies us, allowing us to quickly document new packets.
What's the normal login sequence for a client?
See Authentication for communication with minecraft.net
The recommended login sequence looks like this, where C is the client and S is the server:
- Client connects to server
- C->S : Handshake State=2
- C->S : Login Start
- S->C : Encryption Key Request
- (Client Auth)
- C->S : Encryption Key Response
- (Server Auth, Both enable encryption)
- S->C : Login Success
- S->C : Sends chunks and entities
- S->C : Sends spawn position
- S->C : Sends inventory [Need to verify this since inventory changed] (beta 1.1_02: looks like Window items with type=0, then a Set slot with window id = -1 and slot = -1)
- S->C : Tell the client they're ready to spawn by sending a position + look packet.
- C->S : Sends a position + look packet to confirm the spawn position
I think I've done everything right, but…
…my player isn't spawning!
Note that if the following steps are taken, a Minecraft client will spawn the player:
While the above steps are sufficient for Minecraft 1.4.5, it is good form to send PDUs that inform the client about the world around the player before allowing the player to spawn.
…my client isn't receiving complete map chunks!
Main article: How to Write a Client
…all connecting clients spasm and jerk uncontrollably!
For newer clients, your server needs to send 49 chunks ahead of time, not just one. Send a 7x7 square of chunks, centered on the connecting client's position, before spawning them.