hmm, intesting response, but please excuse my ignorance again as I drum up
I would like to think that a fault-tolerant architecture, (example, IP
routing), should
have routing information in every message it sent. The assumption that the
connection
would stay alive for days or weeks has a few possible issues
(1) distribute system should be stateless, but if the router replies on the
first message to decide
how to route subseqeunt messages in the session, then that routing info has
to stay in memory
for a long, long time, sounds like a stateful design to me... in contrast, a
stateless approach
will parse XML messages, look for routing info, then route it and garbage
collect memory
and move on to next message..
(2) for connection oriented protocol like TCP, openning a connection for a
few days is also
a bad idea, because TCP maintains states (ties up resources) on both ends...
(3) what if system crashes or the connection resets?
The other potential issue has to do what the big environment...
1. If other XML apps assume every message is a well-formed document (like
AJAX,SOA), they
may not work well with XMPP because of incompatibility to XML stream... so
XMPP would
likely have to live with that, hindering adoption...
2. In the future, XML capability will get built into the network layer, but
if a message is not well-formed
XML, they are less likely to take advantage of those capabilities of network
routers and switches, again
hindering adoption....
----- Original Message -----
From: "Peter Saint-Andre" <[EMAIL PROTECTED]>
To: "Jabber software development list" <[email protected]>
Sent: Friday, May 19, 2006 8:39 PM
Subject: Re: [jdev] Re: VTD-XML version 1.6
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Hash: SHA1
Jimmy Zhang wrote:
Excuse my ignorance, after read your examples a bit more, I had only
more questions...
why not exchanging well-formed XML messages for each request and
response like SIP??
Because SIP sucks?
But seriously, Jabber/XMPP technologies were designed this way from the
very beginning (when Jeremie Miller invented them in 1998). It's a bit
late to change things now.
for some reason this partial conversation style of XMPP looks pretty
unnatural??
Heh, I chatted with Tim Bray about this at a conference a few years ago
and he said "well, I wouldn't have designed it that way" -- i.e., he
would have sent complete documents, rather than dreaming up something
"unnatural" like XML streams. So yes, streaming XML seems unnatural to
people who are used to thinking of XML as a document format. Yet there
is no really good reason why a message should be a full document, is
there?
Why is XMPP this way??
Because. :P
But it turns out that streaming XML has some inherent benefits, one of
which is that you don't have to create a new parser instance every time
you want to send, receive, or route a message.
Peter
- --
Peter Saint-Andre
Jabber Software Foundation
http://www.jabber.org/people/stpeter.shtml
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