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Subject: Re: [wsbpel] Issue - R49 - Isolated Scopes


I believe that this issue is the result of a misreading of the spec.  The referenced text says almost exactly what the proposed text does:

existing:

The semantics of isolated scopes ensure that the results would be NO DIFFERENT if all conflicting activities .. were conceptually reordered so that either all such activities within S1 are completed before any in S2 or vice versa.

proposed:

The semantics of isolated scopes ensure that all conflicting activities (read/write and write/write activities) are not executed in parallel. The order of execution is non-deterministic and thus the result is non-deterministic, too.

The difference is only in careful wording in the spec that doesn't come out and say that activities can't execute in parallel, only that the data must be treated as if that were so.  It's a subtle difference, but it allows some implementers to do some fancy tricks.



ws-bpel issues list editor wrote:

This issue has been added to the wsbpel issue list with a status of "received". The status will be changed to "open" if a motion to open the issue is proposed and that motion is approved by the TC. A motion could also be proposed to close it without further consideration. Otherwise it will remain as "received".

The issues list is posted as a Technical Committee document to the OASIS WSBPEL TC pages on a regular basis. The current edition, as a TC document, is the most recent version of the document entitled in the "Issues" folder of the WSBPEL TC document list - the next posting as a TC document will include this issue. The list editor's working copy, which will normally include an issue when it is announced, is available at this constant URL.

Issue - R49 - Isolated Scopes

Status: received
Date added: 23 Jan 2007
Origin: Public comment Oliver Kopp, 23 Jan 2007 (public comment list)
Date submitted: 23 Jan 2007
Submitter: Oliver Kopp
Document: WS-BPEL 2.0 second public review text
Description: Section 12.8 reads:

The isolated attribute of a scope, when set to "yes", provides control of concurrent access to shared resources:
But the explanation reads:

Suppose two concurrent isolated scopes, S1 and S2, access a common set of variables and partner links (external to them) for read or write operations. The semantics of isolated scopes ensure that the results would be NO DIFFERENT if all conflicting activities (read/write and write/write activities) on all shared variables and partner links were conceptually reordered so that either all such activities within S1 are completed before any in S2 or vice versa.

Regard the following example.

Global variable x

Scope S1: sets x to 1 Scope S2: sets x to 2

S1 runs in parallel to S2.

Then the result is not independent from the execution order of S1 and S2.

Is there a mistake in the text?

Should it be something like following?

The semantics of isolated scopes ensure that all conflicting activities (read/write and write/write activities) are not executed in parallel. The order of execution is non-deterministic and thus the result is non-deterministic, too.

Changes: 23 Jan 2007 - new issue

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