I just talked to stpeter IRL (he's all of 10 feet from me; should
have done that first thing this morning!), and made sure he
understood what I was after. I'm replying to Rachel's mail, since it
hits on the two (in my mind) remaining interesting questions, namely:
1) is it necessary to explicitly flag that we're doing hashes?
I like Kevin Smith's suggestion that the receiver should always do
the hash. For old clients, the hash will never match, but it's the
same policy decision to allow old clients as to allow broken senders
that send bad hashes.
2) do we need ext in the hash world?
Rachel makes a good point that without ext, more data has to be
cached, since there will be redundant features associated with
different ver's. I think it's a toss-up; no ext's is considerably
simpler for all involved; no partitioning of features on the sender
side and no unions on the receiving side.
To be clear and explicit, all in one place, here is what I'm
recommending:
<presence from='[EMAIL PROTECTED]/globe'>
<c xmlns='http://jabber.org/protocol/caps'
node='http://psi-im.org/caps'
ver='big-long-hash-goes-here'/>
</presence>
Again, I think simplicity dictates that we pick a single hash
algorithm and stick with it; I'm almost entirely disinterested in
what that algorithm is, as long as it doesn't provide output that has
too many bytes in it.
On Jul 3, 2007, at 10:40 AM, Rachel Blackman wrote:
The XEP could also specify that if a client sets the value of
the 'node' attribute to "$" then it MUST NOT include an 'ext'
attribute.
Not sure about this, it really depends on how ext is actually
used in the wild, as Joe said. I'd be tempted to leave this
somewhat open, at least for now. It could be that we could grow a
set of extensions of commonly co-implemented features, bearing no
actual relation to client plugins, and cut down traffic that way.
But such things require quite a bit of research.
Ext is used in the wild. My initial reaction is that it is still
needed, but on further thought, I can't see why.
If you remove ext, you create MORE separate things to cache, and
thus recreate more network traffic. Because now, client Foo with
plugin Bar installed will have an entirely different hash than
client Foo without Bar installed. With ext, client Foo has the
same capabilities hash in both cases, but one has an additional ext
hash for plugin Bar's capabilities.
