[XESAM] changes in the Xesam XML Query Languae
Mikkel Kamstrup Erlandsen
mikkel.kamstrup at gmail.com
Mon May 21 13:32:33 PDT 2007
2007/5/21, jamie <jamiemcc at blueyonder.co.uk>:
> On Mon, 2007-05-21 at 21:43 +0200, Mikkel Kamstrup Erlandsen wrote:
> > >
> > > 5) And a bigger issue, that is a tough call... Should we use
> > real dbus
> > > objects for sessions/searches? According to Havoc Pennington
> > it
> > > doesn't take a roundtrip to the bus to register a new
> > object, so
> > > spawning lots of search objects shouldn't flood the bus (not
> > with
> > > object-registration requests at least).
> > yes the overhead is negligible - its not like an app is going
> > to
> > construct 100's of search objects all at once
> > I just had seconds thoughts on this. One thing is that the spawning of
> > the Search object on the server doesn't touch the bus, but what about
> > when the client sets up a proxy to it?
> > The current way where only handles are used is guaranteed to not have
> > extra dbus roundtrips and I really think this is an important
> > feature.
> well we can - we only need a unique Id for the session so its one round
> trip max. For each new query we can append queryX where X is an
> incrementing integer to the session object path so no round trip is
This imposes additional tasks for the client. Although this could possibly
be hidden in the toolkit bindings I still think it is a bit inelegant...
Anyway it doesn't save a roundtrip in the current API. The NewSearch call
takes a query_xml that you need to pass over the bus somewhere no matter
About the bus round trip; I was worried that creating the proxy search
object for the search would require a dbus round trip, are anyone certain
> Maybe we wont handle 100's of searches, but I could easily imagine
> > myself doing 50 searches/sec or whatever the engine could pull off.
> > This could fx be in a scenario where I would like to extract
> > meta-information about the index. Such as information clusters.
> can easily reuse existing search query objects for that - no need to
> keep creating new ones?
You can reuse the Session objects, but the Search objects are created for a
specific query. A Search is to be considered a server-side compiled
representation of a query.
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