Difference between the various XMPP MessageType(s)?

Question

I'm trying to figure out what are the various MessageType in Google App Engine XMPP Implementation. The MessageType JavaDoc is totally lacking, actually many parts of GAE's JavaDocs are very poor.

I've tried googling, but could not find anything. Here is the list of MessageType:

CHAT           
ERROR          
GROUPCHAT           
HEADLINE       
NORMAL

I've seen people's code around using NORMAL, I don't understand what could be the difference between NORMAL and CHAT. Anyone can explain or point me to some good documentation?

Answer 1

From RFC6121 :

Chat :

The message is sent in the context of a one-to-one chat session. Typically an interactive client will present a message of type "chat" in an interface that enables one-to-one chat between the two parties, including an appropriate conversation history. Detailed recommendations regarding one-to-one chat sessions are provided under Section 5.1.

Normal :

The message is a standalone message that is sent outside the context of a one-to-one conversation or groupchat, and to which it is expected that the recipient will reply. Typically a receiving client will present a message of type "normal" in an interface that enables the recipient to reply, but without a conversation history. The default value of the 'type' attribute is "normal".