NEW ISSUE: Long-Running Request-Response Operations

[Dieter Koenig1 <dieterkoenig@de.ibm.com>]

(Issue originally raised as [BPEL-12] -- the SCA-BPEL TC decided to move it
over to the SCA-Assembly TC)

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References:
Original issue: http://www.osoa.org/jira/browse/BPEL-12

Previous SCA-BPEL email thread:
http://lists.oasis-open.org/archives/sca-bpel/200710/msg00045.html
http://lists.oasis-open.org/archives/sca-bpel/200710/msg00061.html
http://lists.oasis-open.org/archives/sca-bpel/200710/msg00062.html
http://lists.oasis-open.org/archives/sca-bpel/200711/msg00002.html
http://lists.oasis-open.org/archives/sca-bpel/200711/msg00027.html
http://lists.oasis-open.org/archives/sca-bpel/200711/msg00032.html
http://lists.oasis-open.org/archives/sca-bpel/200711/msg00033.html
http://lists.oasis-open.org/archives/sca-bpel/200711/msg00038.html

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TARGET: SCA Assembly Specification - a resolution may affect other SCA
specifications as well.


DESCRIPTION: Consider a WS-BPEL 2.0 process that implements a service
containing a WSDL request-response operation, using an inbound message
activity (<receive> or <pick>/<onMessage> or <eventHandlers>/<onEvent>) and
a corresponding <reply> activity, both referencing this operation.
Furthermore, assume that there are long-running activities between the
inbound message activity and the <reply>.

At this point in time, such long-running implementations of request-res
ponse operations are NOT SUPPORTED by SCA. As a result, the very first
SCA-BPEL goal ("... use any valid WS-BPEL process definition as the
implementation of a component within SCA") is NOT MET.

Many concrete WS-BPEL scenarios involving such long-running
request-response behavior EXIST TODAY - long interrupts may be caused by
timer-driven activities and service invocations bound to asynchronous
protocols or involving user interactions. Many of these long-running
processes expose request-response operations as this is a more convenient
modeling style, for example, when the business logic is structured in
hierarchies of parent and sub-processes. SCA must support using such
processes as implementations of SCA components.

As an example, without loss of generality, consider the following very
simple <sequence> containing a <wait> activity delaying the response by 14
days (of course, real-world processes would do useful work here instead of
calling the <wait> activity :-).

  <sequence>
    <receive ... operation="rrOperation" .../>
    <wait><for>'P14D'</for></wait>
    <reply ... operation="rrOperation" .../>
  </sequence>

The SCA implementation as well as a caller of this operation should be made
aware of the long-running behavior. Note that inspecting the process
implementation is not sufficient as the long-running nature of activities
may not be visible in the process model. Regardless of the structure of the
SCA assembly (component/service directly/transitively wired within/across
composites), an SCA implementation would want to execute calls to this
operation using some asynchronous means internally.


PROPOSAL: (I withdraw my original proposal from SCA-BPEL issue [BPEL-12],
introducing a new intent and implementing long-running request-response
operations like separate one-way operations with one-way callback
operations).

Instead, I would like to "+1" the direction proposed in
http://lists.oasis-open.org/archives/sca-bpel/200711/msg00002.html (
WS-Addressing WS-Policy assertion wsam:NonAnonymousResponses)

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Kind Regards
DK