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Jeffrey Schlimmer's Blog » WS-Discovery Updates

WS-Discovery Updates

BEA, Canon, Intel, and Microsoft are delighted to welcome webMethods as a co-author on an updated version of WS-Discovery.
 
The biggest technical change is to define a baseline protocol for a Discovery Proxy (DP). While a rich DP-specific protocol is intentionally unspecified, feedback from the workshop indicated the community wants a fallback protocol, so
  • A DP now responds to at least (unicast) Probe and Resolve (and probably other, richer DP protocols), and
  • Probe Match has been extended to allow > 1 match for Discovery Proxy, and
  • Resolve has been changed to carry the Target Service Endpoint Reference in the SOAP Body so Resolve can be sent to either the discovery endpoint (multicast) or the DP (unicast)
 
Other workshop feedback addressed includes:
  • Clarified phrase "managed network" in Introduction
  • Cleaned up usage of address terms, i.e., Endpoint Reference, transport address, and IP address
  • Explained usage of a:EndpointReference/a:Address="uuid:..."
  • Added diagram to explain relationship between Probe and Resolve
  • Clarified omitted a:ReplyTo in Probe and Resolve
  • Explained that Clients talk to DP using transport address in DP Hello
  • Revised Security Considerations
 
In addition, feedback from implementations underway suggested the following:
  • Replaced "http:" scheme URI for discovery endpoint with "urn:" scheme URI [RFC 2141] to avoid possible confusion with an actual transport address
  • Replaced d:SoapHttpRequestReplyAddress policy assertion with d:XAddrs to simplify extraction of transport addresses from a Hello, Probe Match, and Resolve Match
  • Refined discovery/rfc2396 and discovery/ldap matching rules
 
Finally, here are some basic hygiene updates:
  • Updated XML namespace and action URIs to 2004/10
  • Removed UNICAST_UDP_REPEAT parameter (duplicate with SOAP over UDP)
  • Moved the compact signature down into WS-Discovery from Devices Profile (to be cut from there)
  • Updated reference to latest SOAP-over-UDP and WS-Addressing
  • Added pointer to normative WSDL
 
Posted Oct 28 2004, 02:39 PM by jeffrey-schlimmer

Comments

Efren wrote re: WS-Discovery Updates
on 02-09-2005 1:03 PM
Jeffrey,

On the SOAP-over-UDP specification, section 4.2.2 says:
...
Note that despite the fact that the [destination] for the message is specified using a URI that uses the http scheme, the message is still transmitted over UDP.
...

This implies that the HTTP server to which this request is sent to most be a UDP server, doesn't it? In other words:

socket(PF_INET, SOCK_DGRAM, 0);
bind();
for (;;)
{
recvfrom();

/* HTTP/1.1 protocol logic */

sendto();
}
/*NOTREACHED!*/

V/R,
Efren
Jeffrey Schlimmer wrote re: WS-Discovery Updates
on 02-09-2005 1:14 PM
No. This example illustrates that the value of the WS-Addressing [destination] property may be just a SOAP address of the intended receiver and not also a network transport and/or network address for the receiver. You can see this more clearly in the examples in WS-Discovery where the [destination] property of a Hello is "urn:schemas-xmlsoap-org:ws:2004:10:discovery". See also Section 2.6 of WS-Discovery.

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