Assigning reply-to EPRs to partner links Was: [wsbpel] Question about se

Subject: Assigning reply-to EPRs to partner links Was: [wsbpel] Question about section 6.2

My question to the TC is: is this view of WS-Addressing accurate?

Since the whole paragraph got removed, the WS-Addressing view issue becomes orthogonal for now. (However, I would be personally interested in discussing this topic in another email thread ...)

The WS-Addressing spec explicitly allows you to use the reply-to address to send reply messages in different operations from the original request (see section 3, second paragraph). So that one statement hints that you can assign the reply-to EPR to the partner link.

With three exceptions:

1. If you send a SOAP request and expect a response on the same HTTP connection, the reply-to address MUST be anonymous (see the SOAP bindings). You can't send messages to anonymous addresses.

2. The reply-to address is OPTIONAL, so a one-way that doesn't have a reply-to address is valid. The default value for the reply-to address is anonymous.

3. An implementation may, and some do, create a temporary address for collecting the response message, and stop receiving messages on that address once it's done. That's a common pattern when the implementation has only understanding of the operation, not the overall process.

So assigning reply-to addresses to partner links is possible, but not interoperable.

Assaf

Thanks!

Regards,
Alex Yiu

Ron Ten-Hove wrote:
I was puzzling over the following text in section 6.2:

References to a WS-BPEL processor initializing the EPR of a partnerRole relate to the infrastructure logic specific to that processor. A typical example is process deployment logic. This is in contrast to EPR initialization mechanisms outside a WS-BPEL processor, such as:

Business logic expressed in the process definition

Auto-assignment of EPR logic in an underlying EPR scheme, such as the reply-to feature in WS-Addressing

The second bullet seems a bit odd. If a wsa:ReplyTo header contains something other than the anonymous URI, then the SOAP processor sends the response to the specified endpoint, as per the W3C recommendation "Web Services Addressing 1.0 - SOAP Binding" (9 May 2006). The second bullet says that a WS-BPEL implementation might elect to make this "sticky", by copying the EPR in the wsa:ReplyTo header to the appropriate partnerLink. I'm not sure this actually complies with the cited recommendation from the W3C, since it calls for SOAP processors to treat lack of a wsa:ReplyTo header as the same as using such a header with the anonymous URI (meaning send the response to the requestor).

It also looks strange since the wsa:ReplyTo header affects responses to received requests. It does not imply a change to the EPR of the partnerRole in the partnerLink (the EPR where request messages for <invoke>s performed by the process on that partnerLink are sent). A request received containing a wsa:RepyTo header is associated with the "myRole" endpoint of the partnerLink.

I realize this part of WS-BPEL isn't normative language, but it seems that we are encouraging implementors to contemplate being non-compliant with another specification, and perhaps promoting confusion about EPRs and partnerLinks.

My question to the TC is: is this view of WS-Addressing accurate? If so, then I suggest we simply strike all the text following the comma in the second bullet ("such as the...").

-Ron

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