DBus over the network; clustered machines acting as one; service discovery

[Shawn Rutledge]

On Tue, Apr 8, 2008 at 6:02 PM, Avery Pennarun <apenwarr at gmail.com> wrote:
> On Tue, Apr 8, 2008 at 8:26 PM, Shawn Rutledge
>  <shawn.t.rutledge at gmail.com> wrote:
>  >  Has anybody been running dbus across the network yet, for example to
>  >  bind together a cluster of machines?
>
>  Yes, WvDbusd is an alternative to dbus-daemon which supports DBus over
>  TCP and SSL.  We plan to add Avahi (or some other kind of) service
>  location within the next few months.

Sounds cool.  Google didn't find much though, just some messages about this

http://code.google.com/p/versaplex/

but is wvdbusd usable by itself?  Are you going to spin it off as a
separate project?

>  Note that a very basic way to handle this would be to have a single
>  central bus that everyone connects to.  If you're not going to do
>  that, you'd need to have a bus proxy service of some sort (ie.
>  something to connect two buses to each other).

Yeah that's what I was thinking, one or the other.

> This ought to be
>  fairly easy to do with WvDBusd, although nobody has done it yet.  (The
>  hard part is making sure all the service registration/unregistration
>  messages get handled correctly.)
>
>
>  >  It seems there must be about 3 levels of discovery in general:
>  >  [1] discover the buses (local, remote, IP and non-IP)
>  >  [2] discover the services
>  >  [3] discover the methods that can be called and signals that can be sent
>  >  and received
>
>  [1] could be done by either putting everything on a central bus and
>  discovering with Avahi, or by proxying between buses automatically and
>  discovering *all* of them with Avahi.
>
>  [2] is easy since DBus already does that stuff.
>
>  [3] is sort of easy, as DBus provides optional ways of doing such
>  things, although it's not very useful.  After all, if your app doesn't
>  even know which services are out there, it probably also doesn't know
>  what to do with them if it *did* find them.

Well I found the Introspectable interface, but then you just have to
parse the XML.  It's cool that it is there, though.