Thursday, July 13, 2006

WS-RM, WS-RX, Reliable Messaging which is what?

I've just been in yet another meeting where the wonder that is the confusion around Web Service Reliable Messaging cause a nice "deer in the headlights" moment with a vendor.

The converstation goes like this :
Vendor : "we are looking at using WS-RM in our next release"
Customer : "do you mean the work of the WS-RM OASIS group specification?"
Vendor : "Yes"
Customer : "So you mean you do WS-Reliability?"
Vendor : "Is that another name? I didn't know that I just thought it was WS-RM"

Much fun can then be had. The problem is simple to describe (sort of) the WS-RM (entitled Web Services Reliable Messaging) expert group, led by Coastin and Fujitsu this produced a specification (in 2004) called WS-Reliability, there was then another group called WS-RX (entitled Web Services Reliable Exchange) started led by IBM (now WS02 after Paul Fremantle left), SAP and... Coastin. This second group as produced two specifications called (wait for it...) WS - Reliable Messaging and WS - Reliable Messaging Policy Assertion, which are abbreviated to WS-RM and WS-RM Policy respectively.

The WS-RX/WS-RM specification actually only mentions that it really is the WS-RM specification on line 121 with the wonderful line

[WS-Addressing], then the action IRI MUST consist of the WS-RM namespace URI concatenated with a
'/', followed by the message element name. For example:

Which is pretty cunning.

So to be clear, WS-RX is the group that is defining what Reliable Messaging will be in the WS-* universe. So when people say WS-RM they should be talking about the specification released by this group. But you never know there might be some vendor out there who has completely muppetted it so its always best to check.

So WS-RX = WS-RM, except where it doesn't, and where it doesn't the person doing it is wrong.

So next time you have a vendor in and you want a bit of sport, just remember the WS-RM mantra and you never know you might find out that they have done the wrong one, but you'll certainly find out how much the guy saying "We are 100% behind the standards" knows what he is talking about.

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