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Subject: RE: [wsbpel] Issue - 297 - Does correlation require a propertyAlias withmessageType attribute?
+1 to this issue. We've discussed this question while the chapter 15 review, too (in 15.2.2 there is a receive referencing an element-typed variable but there's only a message-typed propertyAlias for the input message of the used operation). The only paragraph we have found which indicates (but does not say it explicitly) that the example is correct, is the one you'd like to add the clarification. It's currently really hard to find this paragraph, because there is no normative MUST regarding the propertyAlias <-> correlation relationship, and additionally it's hard to find out what is meant by the current wording. There are other paragraphs in 7.3 which might be interpreted that an element-typed propertyAlias is expected: "The first bpel:propertyAlias defines a named property tns:taxpayerNumber as an alias for a location in the identification part of the message type txmsg:taxpayerInfoMsg. The second bpel:propertyAlias provides a second definition for the same named property tns:taxpayerNumber but this time as an alias for a location inside of the element txtyp:taxPayerInfoElem. The presence of both aliases means that it is possible to retrieve the social security number from both a variable holding a message of messageType txmsg:taxpayerInfo as well as an element defined using txtyp:taxPayerInfoElem." But the referenced paragraph in 9.2 says that for correlation the message have to be used for retrieving the correlation values and not the variable with which the message is constructed. Therefore it indicates that a message-typed propertyAlias is expected. Your proposal makes this very clear now. The static analysis list should be updated accordingly because violation of this rule can be detected while static analysis. Maybe the proposal can be changed to: Observe that in order to retrieve correlation values from a message, a processor MUST apply a <propertyAlias> with a messageType value that matches the QName of the message. This constraint MUST be statically enforced. In the case in which the application of the <propertyAlias> results in a response that contains anything other than exactly one information item and/or a collection of Character Information Items then a bpel:selectionFailure fault MUST be thrown. Best regards/Mit freundlichen Grüßen, Thomas Schulze "Mark Ford" <mark.ford@active -endpoints.com> To <wsbpel@lists.oasis-open.org> 10.06.2006 18:00 cc Subject RE: [wsbpel] Issue - 297 - Does correlation require a propertyAlias with messageType attribute? I discussed this with Chris Keller last week and he seemed to recall that this was already settled by a previous issue. After doing a little research I found the following issues which touch on this area: Issue 112: Input/Output Elements on Messaging Activities http://www.choreology.com/external/WS_BPEL_issues_list.html#Issue112 -- This issue added support for elements on message activities Issue 145: Properties on Non-Message Variables http://www.choreology.com/external/WS_BPEL_issues_list.html#Issue145 -- This issue added support for propertyAliases for elements and types. It does not discuss correlation. Perhaps it was mentioned during the face to face in Hawthorne? If the intent was to allow elementType propertyAliases for correlation then this has not made it into the spec. Does anyone else recall the discussion or can they point me to another issue that might address this? Lastly, if I missed a part of the spec that covers this I'd appreciate a pointer to it as well. Thanks. From: ws-bpel issues list editor [mailto:peter.furniss@erebor.co.uk] Sent: Saturday, June 10, 2006 11:47 AM To: wsbpel@lists.oasis-open.org Subject: [wsbpel] Issue - 297 - Does correlation require a propertyAlias with messageType attribute? 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 - 297 - Does correlation require a propertyAlias with messageType attribute? Status: received Date added: 10 Jun 2006 Date submitted: 09 June 2006 Submitter: Mark Ford Description: I'd like a clarification as to the use of a propertyAlias for message correlation. My reading is that the spec requires a propertyAlias with a messageType in order to extract values for correlation. In cases where an activity like a <receive> uses an elementType variable for its data the spec explains that an anonymous temporary WSDL message variable is created for the data and its single part is used to populate the element variable on the <receive>. The same wording (anonymous temporary WSDL message variable) is used to explain <fromPart> and <toPart> behavior. If the intent is to allow propertyAlias with elementType then we would need to define which propertyAlias would be used in the case that there was a messageType and an elementType since they could have different queries. If the intent is to require a propertyAlias with messageType then some additional text to Section 9.2 could make this explicit. Submitter's proposal: In Section 9.2, change --- from --- Observe that in order to retrieve correlation values from a message, a processor needs to apply a particular <propertyAlias> to the message. In the case in which the application of the <propertyAlias> results in a response that contains anything other than exactly one information item and/or a collection of Character Information Items then a bpel:selectionFailure fault MUST be thrown. --- to --- Observe that in order to retrieve correlation values from a message, a processor MUST apply a <propertyAlias> with a messageType value that matches the QName of the message. In the case in which the application of the <propertyAlias> results in a response that contains anything other than exactly one information item and/or a collection of Character Information Items then a bpel:selectionFailure fault MUST be thrown. Changes: 10 Jun 2006 - new issue To comment on this issue (including whether it should be accepted), 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 - 297 - [anything]" or is a reply to such a message. If you want to formally propose a resolution to an open issue, please start the subject line "Issue - 297 - Proposed resolution", without any Re: or similar. 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