Oh my, WS-Discovery is a Web service spec I might actually use! Horror! 8-)
But there’s not really too much to say about it (at least until I do a detailed review). Link local discovery is a pretty well understood domain, and the authors of this spec seem to grok it at least as well as I do. The use of SOAP/XML is unfortunate, I’d say, because of its bloat; you really need to keep things lean for multicast discovery so as to fit everything in a single datagram. Some kind of binary-encoded SOAP would be useful here.
I sort of wonder why Rendezvous or LLMNR weren’t adopted; the former has a whole lot of support and running code behind it, while the latter has MS and should be published as an RFC shortly. But I suppose that nothing’s really close to critical mass in this space, so I can’t blame them for starting from scratch.
There’s also mention of a “SOAP/UDP” spec, which is “To be published”. That’ll be interesting to see, especially if there’s a compact (but still extensible) binary encoding. What’s suggested in the spec, re “UNICAST_UDP_REPEAT” and “APP_MAX_DELAY”, and comments such as “waiting for timers” suggests that it might be more a case of trying to reinvent parts of TCP rather than embracing the message-per-datagram model which seems to work so well. But my experience there is rather limited, so I’d be happy to be proven wrong.