C++ and C Impacts of Event Support - initial view

[Bryan Aupperle <aupperle@us.ibm.com>]

Now that 1.1 is nearing completion, we
need to start understanding what is happening in the Assembly TC towards
V1.2.

Background
One of the major additions to SCA in
V1.2 will be support for events and a pub-sub model of messaging.  This
work started in the OSOA collaboration (much like the V1.0 work) and has
been submitted to the Assembly TC.  Since the submission to the Assembly,
TC, there have been discussions about aspects of the OSOA submission, and
an alternative proposal has been made.  Discussions on the differences
between the two proposal continue.  Additionally, an initial proposal
on the impacts to the Java specs has been submitted.

Initial draft proposal (based on discussions
in OSOA): https://www.oasis-open.org/committees/download.php/36508/sca-assembly-1.2-spec-wd01.doc

Counter draft proposal: https://www.oasis-open.org/committees/download.php/37272/sca-assembly-1.2-spec-wd01-issue-227.doc


Initial proposal for Java extensions:
https://www.oasis-open.org/committees/download.php/33985/Java%20Extensions%20for%20Eventing.doc


Based on the OSOA-based proposal and
the Java proposal, the C++ and C specs will need to add material to deal
with the client and implementation model impacts for EventTypes, Consumers
and Producers.  Brief overviews of these concepts and my preliminary
thoughts on the additions needed are:

EventType
A format of a type of event.  Much
like with WSDL message formats, a form is needed for manipulation by implementation
code.
Defined by:

• Name
• Shape (representable by an XSD type)
• Optional Metadata (not standardized)

C++	C
Primitive type DataObject (potentially static)	Primitive type struct DataObject (potentially static)
Annotation needed	Annotation needed

Consumer
Implementation code to process events.
Defined by:

• One or more EventTypes that can be processed.
• Name (unique within ComponentType)

C++	C
Member function of implementation class Single in-parameter (type is EventType or superclass of EventTypes) DataObjectPtr is superclass for any type of event void return type	Function of implementation Single in-parameter (type is EventType or type compatible with EventTypes) void return type Program-based SCAService returns “Event” SCAOperation returns consumer name Input message is event
Implementation function attribute to designate	Implementation function attribute to designate
Annotation needed	Annotation needed

Producer
Implementation code that can trigger
the generation of events.  Represents and event stream
Defined by:

• Set of EventTypes that can be generated
• Name (unique within ComponentType)

C++	C
ComponentContext::getProducer(std::string) returns a ProducerProxy ProducerProxy for a specific Producer has a member function for each EventType that can be produced Form produce<EventType>(const EventType&) Can use superclasses	SCAGetProducer(wchar_t *) returns a SCAREF SCAProduceEvent(SCAREF, wchar_t *, len, void *) Optional proxy function support SCA_produce<EventType>(SCAREF,  EventType)
Annotation needed	Annotation needed

STSM, WebSphere Enterprise Platform Software Solution Architect
WW Center of Excellence for Enterprise Systems & Banking Center of
Excellence Application Integration Architect

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