RE: [sca-c-cpp] ISSUE 54: Long Running Operations and C++

An issue came up when revising this document to take an IOU/Future approach to the asynchronous interface. With the introduction of the asynchronous functions, we’ve also introduced the concept of a service proxy class, which I don’t think has been mentioned before. This appears to be a code generated class, based on either the WSDL or C++ interface for the service, and it looks like it will be this class that is returned from the ComponentContext::getService() and presumably the ExternalContext::getService(). This seems like a relatively significant change from what we’ve discussed before, and may have wider reaching implications than just the asynchronous API. For example, if we’re now requiring code generation of a proxy class for all services, then we no longer have a requirement that the ComponentContext::getService() method return a type without a base class. We could require that all generated proxy classes derive from some sort of base Proxy class. This would allow us to provide a type safe mechanism for accessing the proxies, instead of the unsafe mechanism we have today:

oasis::sca::ComponentContextPtr context = oasis::sca::ComponentContext::getCurrent();

MyServiceProxy* proxy = dynamic_cast<MyServiceProxy*>(context->getService(“MyService”));

proxy will be null if the service we get back isn’t a MyServiceProxy. This only works though if all proxies (and all services returned from MyService) inherit from a common base class.

If we are introducing the generation of a proxy concept, we also probably need to expand the current WSDL mapping rules and clarify how we map from a WSDL to a generated proxy.

Thanks.

David.

From: Bryan Aupperle [mailto:aupperle@us.ibm.com]
Sent: Friday, February 06, 2009 12:36 PM
To: sca-c-cpp@lists.oasis-open.org
Subject: [sca-c-cpp] ISSUE 54: Long Running Operations and C++

This is a fairly complete proposal
The one topic that is open is how to deal with operations that have multiple possible WSDL faults. Do we need to define a ServiceBusinessException class that the classes generated from a WSDL document extend?

Bryan Aupperle, Ph.D.
STSM, WebSphere Enterprise Platform Software Solution Architect

Research Triangle Park, NC
+1 919-254-7508 (T/L 444-7508)
Internet Address: aupperle@us.ibm.com

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