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Subject: Re: [wsbpel] Issue 135 - Rough draft of a proposal for vote
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Satish, Thanks for bring in a new perspective to the discussion. I agree with you guys in general. The fault notion of forcedTermination does create some confusion. Just few more clarification questions:
Thanks! Regards, Alex Yiu Edwin Khodabakchian wrote: + 1. - Edwin -----Original Message----- From: Satish Thatte [mailto:satisht@microsoft.com] Sent: Thursday, September 02, 2004 11:15 PM To: Alex Yiu; ygoland@bea.com Cc: wsbpeltc Subject: RE: [wsbpel] Issue 135 - Rough draft of a proposal for vote There is no reason to allow catchall to also handle the forcedTermination "fault" since the latter is in fact an external "cancel" signal rather than an internal fault that may be optionally rethrown. We should insist that in order to capture and handle forcedTermination you must have a specific handler, and we shouldn't even need to call it a faultHandler -- call it a cancelHandler instead. The whole forcedTermination "fault" notion is a false economy of concept that causes unnecessary confusion. Didn't Peter make some such proposal at some point? ________________________________ From: Alex Yiu [mailto:alex.yiu@oracle.com] Sent: Thu 9/2/2004 9:13 PM To: ygoland@bea.com Cc: wsbpeltc; Alex Yiu Subject: Re: [wsbpel] Issue 135 - Rough draft of a proposal for vote Hi, Yaron, [ I know you are on vacation now ... Still, I would like to reply this thread. :-) ] Thanks for clarification. Few points to add: * +1 to the part of rename <teminate> activity to <halt> activity. Because, I got a similar confusion between "forcedTermination" fault and <terminate> activity, when I first read the spec. Also, the term "terminate" is used everywhere in the spec. But, the usage of "terminate" has no relation with <terminate> activity. * Regarding to the fault handler part of proposal, * Default fault handler: For clarity, we may want to change the description of default fault handler in Section 13.4.1 as well. Currently, it said: "Rethrow the fault to the next enclosing scope.". I think it should say: "Rethrow the fault to the next enclosing scope, if the fault is not bpws:forcedTermination". * In the case of <catch faultName="bpws:forcedTermination">: We may want to enforce the prohibition <throw> or <rethrow> within this particular kind of <catch> construct by static analysis. * In the case of <catchAll>: I think users should be able to use <catchAll> to catch "bpws:forcedTermination" fault. Because users should be able to specify an explicit fault handler to perform any partial undo operation, no matter which fault is causing the problem. In order to observe "bpws:forcedTermination", I have two alternative proposals to refine catchAll semantics. [A] If a <catchAll> handler exists without a <catch faultName="bpws:forcedTermination"> handler in the same scope, <throw> or <rethrow> will be disallowed in the <catchAll> handler. This restriction can be enforced by static analysis. This restriction will essentially force BPEL developers to have two fault handlers when then want to throw fault in <catchAll>. [Better code clarity; more burden on users] [B] If a <catchAll> get a "bpws:forcedTermination", any <throw> or <rethrow> activity within that <catchAll> fault handler instance will become an NO-OP. [Less code clarity; less burden on users] Thoughts ... ? Particularly for the last item. Thanks! Regards, Alex Yiu Yaron Y. Goland wrote: I am not proposing any functional changes, I am just proposing changing the name of "terminate" to "halt" so as to prevent confusion with the completely unrelated bpws:forcedTermination fault. Thanks, Yaron Alex Yiu wrote: Hi, Yaron, Do you mean to introduce a new activity "halt"? If so, could you highlight again what is the difference between "halt" and "terminate"? Thanks! Regards, Alex Yiu Yaron Y. Goland wrote: Below is a first attempt to creating a proposal for vote for issue 135. Thoughts? Comments? Yaron Proposal Summary: * Change the name of the terminate activity to the Halt activity. * Specify that the bpws:forcedTermination fault cannot be caught by catchAll handlers. Proposed Language Changes: Change all instances of the Terminate activity name to Halt. Change section 14.6 to read: The halt activity can be used to immediately halt the business process instance within which the halt activity is performed. All currently running activities MUST be halted as soon as possible without any fault handling or compensation behavior. <halt standard-attributes> standard-elements </halt> Section 13.4: Current Language: A catchAll clause can be added to catch any fault not caught by a more specific catch handler. Proposed Language: A catchAll clause can be added to catch faults not caught by a more specific catch handler, with the exception of the bpws:forcedTermination fault. Delete the following sentence, it appears twice: Otherwise, the default catchAll handler is selected if present. Add an extra bullet after the existing two bullets in section 13.4 that reads: If the fault is not caught by any of the handler's catch clauses per the previous two rules, the fault is not a bpws:forcedTermination fault, and there is a catchAll handler then the fault MUST be caught by the catchAll handler. Insert the following sentence after the previous bullet: The bpws:forcedTermination fault cannot be caught by the catchAll handler because the environment in which bpws:forcedTermination faults are handled is different than the normal BPEL fault environment and so a dedicated fault handler is needed. If a dedicated bpws:forcedTermination fault handler is not provided then bpws:forcedTermination fault is dropped. Current Language: If there is fault data associated with the fault, the third catch will be selected if and only if the type of the fault's data matches the type of variable "bar", otherwise the default catchall handler will be selected. Finally, a fault with a fault variable whose type matches the type of "bar" and whose name is not "x:foo" will be processed by the second catch. All other faults will be processed by the default catchall handler. Proposed Language: If there is fault data associated with the fault, the third catch will be selected if and only if the type of the fault's data matches the type of variable "bar". Finally, a fault with a fault variable whose type matches the type of "bar" and whose name is not "x:foo" will be processed by the second catch. All other faults, other than the bpws:forcedTermination fault, will be caught by the catchall handler and discarded. 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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