[JDEV] File Transfer Proposals

Tom Jackson tom at zmbh.com
Fri Feb 15 20:10:38 CST 2002

I have to admit that I have not looked much at the proposals but the
main issue that needs to be addressed is that there is an internal limit
on message size in Jabber. 

For text messages, this limit is more than adequate. However, for a
generic file transfer protocol inside jabber you need to deal with
arbitrary file sizes.

The current max limit is in the xml parser from what I have heard and it
is around 1/2 megabyte. 

This is a buffer limit I think, so a different protocol implimentation
could have a lower limit, and some other part of the system could also
have unanticipated limits that are not specified in the protocol.

What would be most helpful is to have an application level protocol that
would chop up the file and transfer it in less than MTU size chunks,
possibly low enough to support udp. Each packet would have to specify
the byte range, and maybe a sequence number, but I doubt the sending
client would keep track of what packet was what, and would have to
reconstruct based on byte range. 

This would allow arbitrary sized file transfer, but also, it would allow
clients to receive large files while still being able to chat. Otherwise
most clients would probably handle the one large message until it was

--Tom Jackson

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