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Subject: ISSUE 35: The ServiceReference interface should extend Serializable


Von: Mark Combellack [mailto:mcombellack@avaya.com]
Gesendet: Mittwoch, 9. April 2008 11:49
An: OASIS Java
Betreff: [sca-j] NEW ISSUE: The ServiceReference interface should extend Serializable

RAISER:  Mark Combellack

TARGET:  The ServiceReference interface should extend Serializable


Document references taken from:

Service Component Architecture Java Common Annotations and APIs Specification Version 1.1

Working Draft 28 February 2008




In several locations in the specification, it talks about passing ServiceReference instances around. These include:


Section 6.3 Passing Conversational Services as Parameters contains the following:


268    The service reference which represents a single conversation can be passed as a parameter to

269    another service, even if that other service is remote. This may be used in order to allow one

270    component to continue a conversation that had been started by another.



Section 6.5 Conversation Lifetime Summary contains the following:


325 Continuing conversations

326 The client can continue an existing conversation, by:

327         Holding the service reference that was created when the conversation started

328         Getting the service reference object passed as a parameter from another service, even

329         remotely

330         Loading a service reference that had been written to some form of persistent storage



The standard mechanism used by Java for transporting and persisting objects is to use Serialization. Currently, ServiceReference is not Serializable as it does not extend Serializable as ServiceReference and its parent (CallableReference) do not extend Serializable.



Section 7.3 CallableReference


739 public interface CallableReference<B> {



Section 7.4 ServiceReference


769  public interface ServiceReference<B> extends CallableReference<B>{




Making ServiceReference Serializable will allow:


·        ServiceReferences to be passed over @Remotable interfaces as a parameter

·        ServiceReferences to be returned by methods over @Remotable interfaces

·        Standard approach for persisting ServiceReferences to some form of persistent storage by using the JDK java.io.ObjectOutputStream and java.io.ObjectInputStream classes.

·        Applications that Serialize ServiceReferences will be portable across different vendors SCA Implementations**** (i.e. the Application code will run on both SCA Implementations without modification)



*** Note: I do not mean interoperable. I would not expect a ServiceReference Serialized in Vendor 1 SCA Implementation to be able to be deserialized and used in Vendor 2 SCA Implementation.



There are two possible options. My preferred approach is Option 1.



Option 1 - Make CallableReference extend Serializable


By making CallableReference extend Serializable, this will also make ServiceReference Serializable.


The advantage of this approach is that a Component marked as @Conversational but @Scope(“STATELESS”) can persist the @Callback and use it in subsequent calls.




Option 2- Make just ServiceReference extend Serializable


This would mean that CallableReference is not Serializable and the @Callback cannot be persisted by a Component marked as @Conversational but @Scope(“STATELESS”) can persist the @Callback and use it in subsequent calls.






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