Re: Platform

[Felipe Contreras <felipe contreras gmail com>]

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.

-- 
Felipe Contreras