[Opensim-dev] Revising the grid standards (Part II -Implementation details)

Fri Nov 2 22:08:32 UTC 2007

XMPP does presence very well. it does coarse-grained events (especially,
for example, updates of presence) very well. it also has the advantage
that the messages are typed. that means you could extend it to carry
useful VW-specific information like my avatar's current location in
order to implement local chat (or to pass currency or object references
or whatever...). but the current open-source implementations (there's a
great list on www.jabber.org) don't scale well on number of messages per
second. the implementations were designed with IM usages in mind
(potentially a large number of users, very long sessions, and a few
messages per minutes at the most). 

XMPP would clearly be good for IM and possibly local chat. it would work
well for cross-domain user presence (eg send IM's from osgrid to
deepgrid, monitor presence of friends across regions etc). it might
actually work for advertising regions & monitoring region presence. 

most of the server implementations have pluggable authentication. that
would make it possible to separate the identity (and user
authentication) pieces in one service that was shared among regions & IM
& whatever else you want. translation: you could have one identity that
was used to authenticate for regions, assets, and IM. 

i don't believe XMPP (or rather the current server implementations)
would be a good mechanism for distributing assets or for handling
object/scene updates. the current (open source) implementations just
cant handle that volume of traffic. the message formats might be useful,
but i really haven't looked through the list of XMPP extensions to find
ones that would help us.

--mic

________________________________

From: opensim-dev-bounces at lists.berlios.de
[mailto:opensim-dev-bounces at lists.berlios.de] On Behalf Of Michael
Wright
Sent: Friday, November 02, 2007 1:48 PM
To: opensim-dev at lists.berlios.de
Subject: Re: [Opensim-dev] Revising the grid standards (Part II
-Implementation details)

Yeah finding c# jabber/xmpp servers is a problem. There is one (that
doesn't look that complete) but its in c#' 3.0 so not really usable by
us at the moment. There are some c# xmpp client libraries (not
completely sure the licenses) so I guess its most likely a case of
writing our own servers from them. Or taking a java server and porting,
which maybe the easiest thing.

But, I think after reading mic's reply that we should drop the idea of
using XMPP for grid/user, as I think we need to listen to someone who
has had experience of using it. So we should just use it for IM's , as
has been the plan since very early in this project.

Sean Dague <sean at dague.net> wrote: 

	On Fri, Nov 02, 2007 at 07:43:54PM +0000, Michael Wright wrote:
	> When I first mentioned XMPP it was just a throw out idea. But
thinking
	> and looking into it some more I actually think its got some
plus
	> points. But I don't think we should think about it for Assets
(which I
	> think REST is the correct thing for) and maybe not even
inventory. I
	> was thinking more User server and grid server.

	My brain is starting to wrap on this a bit more, and treating
Regions
	and Users as just things with presence via XMPP actually seems
pretty
	interesting.

	Could you sketch out a bit more the way you think that would
work?

	> I really don't think using REST because thats what LL use
makes any
	> difference as when they release specs we are going to have to
have new
	> implementation anyway. Please remember not everyone is
interested in
	> connecting to LL grid, so I think no matter what happens it
most
	> likely will be, that we end up with at least two
implementations; our
	> own and one compatible with their grid.

	Agreed, and understood.

	> I think XMPP most likely will end up as easiest and fastest to
	> implement and it includes a number of things that we wouldn't
need to
	> spend time on. But when it comes down to it, I'm not fixed on
the idea
	> enough to fight strongly for it. So if the general opinion is
for REST
	> for all. Then I'd go with that without a problem. As long as
we are
	> going with it for the right reasons and not the compatible
reason.

	Presumably, regardless of how much XMPP will be in OpenSim (i.e.
just
	messaging or messaging + much more) we'll need XMPP client /
server
	classes in OpenSim anyway. So work in getting that into tree and
	functional would be good regardless.

	Fwiw, XMPP did come up at last office hours re: IM, and steffan
said
	something about there not being nicely licensed library/server
for C#.
	It would be good to make sure we had that before getting on the
XMPP
	bandwagon.

	-Sean

	-- 

__________________________________________________________________

	Sean Dague Mid-Hudson Valley
	sean at dague dot net Linux Users Group
	http://dague.net http://mhvlug.org

	There is no silver bullet. Plus, werewolves make better
neighbors
	than zombies, and they tend to keep the vampire population down.

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