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Subject: Re: [wsbpel] Issue 241 - Proposal for Vote
This suggestion is related to 241 and 204. For more consistency across event handlers and forEach, if we allow variables to be declared in the EH's associated scope: "For cross-reference redundancy and clarity, these variables referenced by variable attribute or <fromPart> element may be optionally declared in the associated scope explicitly. If explicitly declared, variable types used in declaration MUST be exact matches of the correponding definitions in WSDL." then it would make sense to allow the optional explicit declaration of a counter variable (in a scope associated with forEach) as well. Any opinion? Kind Regards DK Alex Yiu <alex.yiu@oracle. com> To wsbpeltc 07.03.2006 05:44 <wsbpel@lists.oasis-open.org> cc Alex Yiu <alex.yiu@oracle.com>, Danny van der Rijn <dannyv@tibco.com>, Mark Ford <mark.ford@active-endpoints.com> Subject [wsbpel] Issue 241 - Proposal for Vote Hi all, Here is the formal proposal for voting for Issue 241: PDF version: (9 page) http://www.oasis-open.org/apps/org/workgroup/wsbpel/download.php/17023/wsbpel-specification-draft.241_proposal_v2b.pdf MS-Word version: (9 page of changes on top of whole spec) http://www.oasis-open.org/apps/org/workgroup/wsbpel/download.php/17024/wsbpel-specification-draft.241_proposal_v2b.doc 90% of changes are same as the draft that I sent out last week with some extra clarification and cleaning up syntax in the direction of voting decision of Issue 242. Please let me know ahead of time, if you guys have any idea of friendly amendments or fine-tuning of wordings. Thanks! Regards, Alex Yiu Alex Yiu wrote: Hi all, Here is the proposal draft for Issue 241. PDF version of 9 pages which contain the changes http://www.oasis-open.org/apps/org/workgroup/wsbpel/download.php/16945/wsbpel-specification-draft.241_proposal_draft.pdf MS-Word version of changes applied to the whole spec text (based on a very recent version from CVS): http://www.oasis-open.org/apps/org/workgroup/wsbpel/download.php/16944/wsbpel-specification-draft.241_proposal.doc Note: [1] One more normative changes we need to make (but not a part of the PDF) is to amend/clarify resolution of Issue 123 in a very minor way as follow: From: "This resolution follows the same scoping rules as variable and correlationSet resolution." To: "This resolution follows the same scoping rules as correlationSet resolution." [2] In this proposal, I did try to clean up some syntactic issue of <onEvent> not directly related to issue 242. (e.g. making variable attribute optional because of <fromPart>). I do intend to come up a consolidated proposal based on the (directional) decision of Issue 242. Because there are a number of places in desc text of <onEvent> (not just syntax) needs to be fine-tuned a bit more after syntactic decisions are made. Here are two syntactic decisions need to be made: [a] moving <correlationSets> "inline" declaration to the associate scope (regardless of decision of [b] below: whether the associated scope is collapse into <onEvent>). [Currently, I tend to say we should move declaration to make the syntax more consistent with other scope-related syntax] [b] core decision for Issue 242: whether to collapse scope syntax into <onEvent> syntax. Namely, we have 3 choices here: (i) Yes, we collapse. The syntax is based XSD extend. Example: --------------------------- <onEvent ... partnerLink="..." variable="..." isolated="..." name="..."> <partnerLinks> ... </partnerLinks> <variables> ... </variables> <correlationSets> ... </correlationSets> ... main activity <correlations> ... </corelations> <fromPart ... />* </onEvent> --------------------------- (ii) Yes, we collapse. Its syntax is NOT derived scope. (That means we need to main a separate, duplicated, different and yet similar grammar rule.) Example: --------------------------- <onEvent ... partnerLink="..." variable="..." isolated="..." name="..."> <correlations> ... </corelations> <fromPart ... />* <partnerLinks> ... </partnerLinks> <variables> ... </variables> <correlationSets> ... </correlationSets> ... main activity </onEvent> --------------------------- (iii) No. We do not collapse. Instead, we choose the "extend-by-containment" approach. Example: --------------------------- <onEvent ... partnerLink="..." variable="..."> <correlations> ... </corelations> <fromPart ... />* <scope ... isolated="..." name="..."> <partnerLinks> ... </partnerLinks> <variables> ... </variables> <correlationSets> ... </correlationSets> ... main activity </scope> </onEvent> --------------------------- Further analysis (from my viewpoint): The main reason that I heard from proponents of collapse seems to be elminiating forward-reference pattern (i.e. a resource is declared after reference in source code order). IMHO, that is a commonly used situation in a lot of programming language. Furthermore, you can see later that this situation cannot be elminated even if we decide to collapse those syntax. The syntax order in (i) just seems very odd and unnatural and make the source code visualization much harder. And, forward-reference still happens for variable and partnerLink. For the syntax in (ii), forward-reference still happens for variable and partnerLink. The interleaving syntax (highlighted blue and brown) make it harder for people to learn and remember what is exactly <onEvent> is about. Moreover, we will be forced to duplicated grammar rule for tScope for no compelling reasons. Make BPEL source code syntax analyser implementation more difficult. For the syntax in (iii), I personally prefer the most. Because, the syntax groups syntax common to <scope> and specific to <onEvent> in a clean and easy-to-learn way. <onEvent> syntax is the outer syntax, while <scope> is the inner syntax. It does not require any XSD grammar rule duplication. And, it makes use of another common and useful design pattern - "extend-by-containment". Ideally, I want to submit a proposal (potentially with Danny) that resolve both Issue 241 and 242. That will minimize any risk inconsistent and "leftover" editing issue in that section. [3] For Issue 245, assuming it is opened. I agree with Danny and Mark there. This proposal draft contains an attempt to clean up Section 12.5.7 which is also a part of "Event Handlers" section. Thanks! Regards, Alex Yiu
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