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Subject: Issue - 52 - Deadlocks and Internal Messaging
Satish, I'm not 100% sure what you mean when you say that internal messaging causes deadlock. One of my basic assumptions is that any messaging operation that does not complete within a certain period of time will eventually time out. So I'm not clear on how internal messaging could cause deadlocks. What I can see is how one could create a livelock. For example: <flow> <sequence> <while condition="bpws:getVariableData(Success1) <> "done"> <scope> <faultHandlers> <catch faultName="ProprietaryTimeOutFault"><empty/></catch> </faultHandlers> <sequence> <invoke partnerLink="TalkingToSelf" operation="getFoo" inputVariable="FooIn" outputVariable="FooOut"> <assign><copy><from>Done</from><to variable="Success1"/></copy></assign> </sequence> </scope> </while> <!-- Wait to receive a getBar incoming message and then do useful work --> </sequence> <sequence> <while condition="bpws:getVariableData(Success2) <> "done"> <scope> <faultHandlers> <catch faultName="ProprietaryTimeOutFault"><empty/></catch> </faultHandlers> <sequence> <invoke partnerLink="TalkingToSelf" operation="getBar" inputVariable="BarIn" outputVariable="BarOut"> <assign><copy><from>Done</from><to variable="Success2"/></copy></assign> </sequence> </scope> </while> <!-- Wait to receive a getFoo incoming message and then do useful work --> </sequence> </flow> Is this what you meant when you aid deadlock? Yaron -----Original Message----- From: Satish Thatte [mailto:satisht@microsoft.com] Sent: Thursday, September 25, 2003 9:24 PM To: ygoland@bea.com; wsbpel@lists.oasis-open.org Subject: RE: [wsbpel] Issue - 67 - Clarify semantics of serializable scopes Yaron, Perhaps I misspoke. I thought in the context of the discussion on Issue#52, you had commented that deadlocks are already possible in BPEL 1.1, in response to my claim that internal messaging would introduce them for the first time. My apologies if I mistakenly interpreted that to mean serializable scopes in BPEL 1.1 already allow deadlocks because of the locking they imply. Satish _____ From: Yaron Goland [mailto:ygoland@bea.com] Sent: Wednesday, September 24, 2003 3:44 PM To: wsbpel@lists.oasis-open.org Subject: RE: [wsbpel] Issue - 67 - Clarify semantics of serializable scopes I'm not sure what the issue is referring to vis a vis any comments I made. I'm not aware of serializable scopes introducing any new deadlock issues that aren't already in BPEL [1]. After all Serializable scopes are really nothing more than instructions to the thread scheduler. So in theory any behavior you could see as a result of a serializable scope could be reproduced by a sufficiently eccentric thread scheduler. Yaron [1] The use of serializable scopes and links could cause deadlocks. But the authors understood this and so explicitly banned the use of links that cross serialized boundaries in section 12.5. -----Original Message----- From: ws-bpel issues list editor [mailto:peter.furniss@choreology.com] Sent: Wednesday, September 24, 2003 1:28 AM To: wsbpel@lists.oasis-open.org Subject: [wsbpel] Issue - 67 - Clarify semantics of serializable scopes This issue has been added to the wsbpel issue list. The issues list is posted as a Technical Committee document to the OASIS WSBPEL TC <http://www.oasis-open.org/apps/org/workgroup/wsbpel> pages on a regular basis. The current edition, as a TC document, is the most recent document with the title in the "Issues" folder of the WSBPEL <http://www.oasis-open.org/apps/org/workgroup/wsbpel/documents.php> TC document list - the next posting will include this issue. The list editor's working copy, which will normally include an issue when it is announced, is available at this <http://www.choreology.com/external/WS_BPEL_issues_list.html> constant URL. Issue - 67 - Clarify semantics of serializable scopes Status: open Categories: concurrency control Date added: 24 Sep 2003 Submitter: Satish Thatte <mailto:satisht@microsoft.com> Date submitted: 23 September 2003 Champion: Satish Thatte <mailto:satisht@microsoft.com> Document: Language specification, section 13.6 Description: There has been some recent discussion regarding the concurrency control semantics of serializable scopes. Yaron Goland had also raised a question regarding the possibility of deadlock among serializable scopes. This section needs additional wording to clarify these issues. Links: Ron <http://lists.oasis-open.org/archives/wsbpel/200309/msg00169.html> Ten-Hove, 15 Sep 2003 Changes: 24 Sep 2003 - new issue _____ To comment on this issue, please follow-up to this announcement on the wsbpel@lists.oasis-open.org list (replying to this message should automatically send your message to that list), or ensure the subject line as you send it starts "Issue - 67 - [anything]" or is a reply to such a message. To add a new issue, see the issues procedures document. To unsubscribe from this mailing list (and be removed from the roster of the OASIS TC), go to http://www.oasis-open.org/apps/org/workgroup/wsbpel/members/leave_workgroup. php.
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