Issue 193: Clarify why the spec mandates that JoinConditions must always be evaluated only after all source activities complete

["Tony Fletcher" <tony_fletcher@btopenworld.com>]

Title: Message

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Issue 193: Clarify why the spec mandates that JoinConditions must always be evaluated only after all source activities complete

Status: received
Date added: 27 Feb 2005
Categories: State management
Date submitted: 26 February 2005
Submitter: Prasad Yendluri
Document: WS-BPEL Working Draft, December, 2004
Description: This is a follow on to issue 189 which we classified as a new feature request.

The BPEL specification currently requires that a joinCondition on a target activity be evaluated only after all sources activities for the links coming into it are complete, even for an implicit OR <joinCondition> where the status of only one of the incoming links needs to be positive.

This is a major constraint that disables straight-forward modeling of a large class of processes where the target activity needs only one of its source activities to complete successfully. An example scenario is a private auction, where the auction tracking activity needs a bid to be placed by only one of the N bidders possible, to start.

The only text in the specification that speaks to this major constraint is hidden in one sentence in the text in section 12.5.1: "If an activity that is ready to start ..., then it does not start until the status *of all its incoming links has been determined* and the (implicit or explicit) join condition associated with the activity has been evaluated."

Issue 189 called for lifting this constraint but the TC decided to not to address this in this version of the specification. Different justifications for not incorporating the change were alluded to by the TC members during the discussion of issue 189, including increased implementation complexity and the amount of changes needed to the specification.

However since this is a major constraint, the specification must minimally clarify why this constraint is imposed by the specification.
Submitter's proposal: I request that text be added to section 12.5.1 around the area where this constraint is specified.
Changes: 27 Feb 2005 - new issue

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 Best Regards,

Tony                          

	Tony Fletcher Technical Advisor Choreology Ltd. 68, Lombard Street, London EC3V 9L J   UK
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