[OSM-dev] TRAPI status

[Brett Henderson]

On Wed, Mar 10, 2010 at 11:21 PM, Bernhard zwischenbrugger <
bz at datenkueche.com> wrote:

> Brett Henderson schrieb:
> > On Wed, Mar 10, 2010 at 7:30 PM, Peter Körner <osm-lists at mazdermind.de
> > <mailto:osm-lists at mazdermind.de>> wrote:
> >
> >     >     I started working on a streaming XML output plugin for
> >     Osmosis. I
> >     >     was intending to take advantage of PuSH/PubSubHub messaging and
> >     >     maybe even XMPP (so that you get a 1-min delayed IM when
> someone
> >     >     changes something in your bbox).
> >     >
> >     >     Anyway, TRAPI could use this same plugin to apply updates to
> >     their
> >     >     database.
> >
> What about a XMPP "groupchat" for changesets?
>
> It's easy:
> ....login...
> <presence to="osm at conference.osm.org/osm"
>
> <message to="osm at conference.osm.org" type="groupchat" id="58">
> <changeset>  ....</changeset>
> </message>
>
> The OSM Server should send all changesets to this groupchat.
> If  somebody wants the changesets he can connect to the groupchat and
> will get the changesets.
> If the  messages get an incrementing serial number, it should be
> possible to load changesets if
> they are missing because of whatever.
>
> I don't know if a jabber server is able to handle the load. But facebook
> also uses ejabberd (free software) and it's working.
>
> If somebody wants to implement pubsub he can use the input from
> groupchat and load it to pubsub. That should be easy.
>

The biggest problem I see with XMPP is keeping in sync.  If a client misses
one or more changesets it has to separately retrieve the missing changesets
from the planet server to "catch up".  In the meantime it has to remain on
the XMPP channel and hold the received changesets locally until it has
caught up and can apply them.

But don't let me dissuade you.  If you think it's a good idea then you can
implement something that feeds off the existing changesets.  If it works
well and people find it useful we can look at ways of incorporating it into
the existing replication setup.

Brett
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