Proposal for correlation mechanism in ebBP / WSDL mapping

["Jean-Jacques Dubray" <jeanjadu@Attachmate.com>]

We have made great progress in driving a consensus for mapping ebBP BTAs to web service operations invocations.

 

There is still the issue of specifying a correlation mechanism. WSDL itself does not offer any correlation mechanisms to group a series of operation invocation as a unit of work. I have looked at ASAP and WS-CTX (WS-CAF).

 

It appears to me that architecturally, WS-CTX is a lot closer to what we need for ebBP. ASAP appears to me as a mechanism to deal with asynchronous request / response but not necessarily to deal with a unit of work associated to multiple web services and multiple operation invocations on these web services.

 

Even though, WS-CTX is still a draft, I would recommend that we aligned with the current draft. I would also recommend that we establish the following caveats:

 

-          a BTA mapped to web services can only be initiated by an ebXML capable party. A web service capable party cannot join a MPC. We may allow an exception when the web service capable party initiates the MPC. Otherwise, I don’t see how we can establish a correlation between the collaboration instance and the operation invocation from a WS capable party to an ebXML capable party.

-          Request/Confirm and Information notification may be implemented via a single web service operation invocation. If this operation is synchronous, no further correlation mechanism is necessary.

-          For the moment we will only support an explicit correlation (by value), and will not support a context service (by reference).

 

The end points will have to support this subset of WS-CTX SOAP extensions

 

<context timeout=”BTA timeToPerform”>

            <context-identifier>BTA instance identifier</context-identifier>

            <type>http://www.ebpml.org/ebBP/2004</type>

<participating-services>

<service-ref reference-scheme="http://www.w3.org/2004/04/wsmessagedelivery">

<!--based on my understanding this is used as an addressing mechanism, i.e. replyTo -->

<wsdl:service name="AcmeBuyerService"

wsmd:portType="RN:BuyerService">

<wsdl:port    name="AcmeBuyerPort"

binding="RN:BuyerServiceBinding">

<soapbind:address location="http://acme.com/buyer/impl"/>

</wsdl:port>

</wsdl:service>

<wsdl:service name="AmericanSellerService"

wsmd:portType="RN:SellerService">

<wsdl:port    name="AmericanSellerPort"

binding="RN:SellerServiceBinding">

<soapbind:address location="http://american.com/seller/impl"/>

</wsdl:port>

</wsdl:service>

</service-ref>

</participating-services>

</context>

 

Let me know if this is acceptable.

 

Jean-Jacques