Hi,
On Mar 17, 2008, at 10:11 PM, Peter Saint-Andre wrote:
Pedro Melo wrote:
On Mar 17, 2008, at 3:22 PM, Peter Saint-Andre wrote:
Pedro Melo wrote:
On Mar 11, 2008, at 12:06 AM, Dave Cridland wrote:
On Mon Mar 10 23:45:28 2008, Peter Saint-Andre wrote:
One potential problem: this is not a nice, small, incremental
change.
Now servers and clients must support:
1. The 'sequence' attribute.
2. Roster pushes via message, not IQ.
3. Multiple items in a roster push.
4. Multiple items in a roster set.
The more we change, the less likely it is that clients and
servers
will
add this feature. Then we're back where we started.
"If it ain't broke, don't fix it."
So what's broken?
1. Huge roster gets every time you log in. The 'sequence'
stuff fixes
this.
What's not broken?
2. Roster pushes via IQ.
3. One item per roster push.
4. One item per roster set.
Why are we fixing 2, 3, and 4? Just because we can? Because it
is more
elegant? Or because it really solves a big problem on the
network?
Unless there is a compelling need, I'd vote for changing as
little as
possible.
The problem is that if you go for Joe's concept - which is
certainly
elegant - of having the roster "diff" simply sent as a bunch of
pushes, then these - being sent as <iq/> - need to be
acknowledged.
Now, I appreciate that clients don't always do this, but the
fact is
that they should be doing so. I'm unhappy with suggesting that
clients
quietly ignore RFC 3920 because nobody cares.
So we can fix that simply by using <message/> instead of <iq/>
- it's
a pretty trivial change, and it eliminates the type='result'
reply for
clients on all pushes, so it's inarguably a performance
improvement.
Ok, I must have been missing something because if you want to fix
something, why not just do multiple items per roster push?
Because it's never been done that way.
The argument that diff is complex doesn't play well with me.
Each item
is a replacement item, so no diff required. The usual code for a
client
"foreach item update my model" will work with both.
But clients have never expected multiple items in a roster push.
However, that might be something clients could move to if they
support
sequencing. My question is: will clients do that?
Yes. Basically if I'm a client and I'm telling the server that yes, I
support sequencing and I want to use it, the server is OK to change
previous rules if they are specified in the new XEP.
Yes, I know that client developers *could* add this support, but my
question is: *will* they really do so or will they see this spec
and say
"well this roster sequencing stuff looks nice but &@#$&?^!@ I need to
modify my roster handling code and I haven't touched that in 3 years,
what the heck is the XSF thinking?!?!"
Yes, I understand that.
The whole point about this was saving bandwidth. The current method
of a single item per push would waste a bit in the IQ replies. The
alternatives suggested where re-using messages to deliver roster
pushes, or ignore the IQ replies with a new IQ type "fire-and-
forget" (not the final type of course :) ) or bundle up multiple
roster items in a single push. I might have missed another approach...
Of all this, I think the multiple items per push is the least
intrusive. But if even that is a problem, we could always make it an
option: when we tell the server that we want to use roster sync, tell
him that we support multiple items per push also.
Best regards,
--
Pedro Melo
Blog: http://www.simplicidade.org/notes/
XMPP ID: [EMAIL PROTECTED]
Use XMPP!
