Re: Platform

[Shaun McCance <shaunm gnome org>]

On Tue, 2009-05-19 at 01:31 +0300, Felipe Contreras wrote:
> On Tue, May 19, 2009 at 12:52 AM, Ross Burton <ross burtonini com> wrote:
> > On Mon, 2009-05-18 at 22:39 +0300, Stefan Kost wrote:
> >> Now that apple has closed the whole bonjour stack, I would prefer to build on
> >> upnp. We have gupnp, which is actively developed and fitting nicely here.
> >
> > I'm very curious as to what this "closing" of the bonjour stack is: even
> > if they closed their Bonjour implementation the specifications are
> > public (interestingly the Internet Draft expired yesterday):
> >
> > http://files.dns-sd.org/draft-cheshire-dnsext-nbp.txt
> >
> > Whilst I'm a maintainer of GUPnP and think it's the best solution we
> > have for interoperating with other UPnP devices (of which they are many
> > in the wild), I really do think it's an ugly specification which hasn't
> > had any recent development.  I also notice that Windows Vista includes
> > something I've forgotten the name of which they basically call the
> > successor to UPnP...
> >
> > The two technologies are pretty different.
> >
> > mDNS gives you name resolution and by extension (via cunning use of DNS)
> > service lookups, i.e. "what printers are here".  At this point it stops
> > caring and you use application-specific protocols: XMPP for link-local
> > chat, IPP/HTTP for printing, and so on.  Generally mDNS is used to
> > announce an existing service, such as the location of an existing IPP
> > print queue, or SSH server, or HTTP server.  Because mDNS doesn't care
> > what you do after discovery, security is not it's problem.
> >
> > UPnP doesn't do name resolution, but does do service discovery.
> > Introspection of services and invocation of remote method calls is also
> > part of UPnP, invocation is done via everyone's favorite RPC protocol,
> > SOAP.  The UPnP specifications cover a large number of services
> > (internet gateway devices, media servers, scanners, printers, security
> > cameras, lighting and so on) but I've only ever seen IGDs and media
> > servers in the wild.  Security is non-existent, any process (including
> > Flash in a web page) can make UPnP calls and  (say) open ports on your
> > router.
> >
> > Personally speaking, if you want to do basic service
> > announcement/discovery and you already have a good protocol which works
> > (say HTTP or XMPP) then I'd recommend starting with mDNS.  If you want
> > to interoperate with existing devices (such as routers and media
> > servers) then using UPnP is the only solution, because I don't know of a
> > mDNS equivalent for the IGD magic and Apple are working very hard at
> > stopping you from using DAAP/DPAP on a Mac.
> >
> > This mail turned out to be a bit longer and rambling than I was hoping,
> > but the executive summary is this: at present, both are required,
> > depending on the situation.
> 
> Why are we discussing UPnP vs mDNS? Isn't it like discussing USB vs
> Firewire? Ideally both should be supported.

This entire thread is not about what we should be capable
of interacting with.  It's about what we want to present
to third-party developers as our platform.

Say a game developer comes along and wants a way for his
game to find other instances of itself on the local network.
What are we recommending?

I don't have all the answers to these questions.

--
Shaun