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Subject: Re: [wsbpel] Issue 197: Un-initializing BPEL variables
Yaron Y. Goland wrote: > Your argument works for text nodes but not elements and who says that > the contents of a static value that contains nothing is a text node? > That certainly isn't defined in the spec today. In fact we have at > least 2 open issues on exactly this kind of problem. I made no such assumption. To assign a value to a text node I need to obtain a string value, but if you read the XPath expression, I can operate on a variety of content models in order to arrive at that string value. Since I consider an empty value to be a valid and useful value, we need a way to disambiguate between un-initializing a variable and expressions that can assign an empty value to a text node. Since we want to keep it simple, let's find an un-initializing mechanism that is not node-type specific, and retain that distinction across all node types. Assaf > > Assaf Arkin wrote: > >> In XML empty is still a content. An empty text node contains zero >> characters. Different from nothing or null. >> >> For example, if I have the expression concat($X,$Y) it is valid for Y >> to be empty, and its reasonable for someone to set it to empty and be >> used. $Y needs to have a value in this case and the expression need >> to evaluate. >> >> Un-initialize will require its own construct, a) to not confuse >> between empty and null, and b) since we currently do not allow null >> to be selected. >> >> Assaf >> >> Tony Fletcher wrote: >> >>> This issue has been added to the wsbpel issue list with a status of >>> "received". The status will be changed to "open" if the TC accepts >>> it as identifying a bug in the spec or decides it should be accepted >>> specially. Otherwise it will be closed without further consideration >>> (but will be marked as "Revisitable") >>> >>> The issues list is posted as a Technical Committee document to the >>> OASIS WSBPEL TC pages >>> <http://www.oasis-open.org/apps/org/workgroup/wsbpel> 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 >>> <http://www.oasis-open.org/apps/org/workgroup/wsbpel/documents.php> >>> - 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 >>> <http://www.choreology.com/external/WS_BPEL_issues_list.html>. >>> >>> >>> ------------------------------------------------------------------------ >>> >>> >>> >>> Issue 197: Un-initializing BPEL variables >>> >>> *Status:* received >>> *Date added:* 12 Mar 2005 >>> *Categories:* Data Handling >>> <http://www.choreology.com/external/WS_BPEL_issues_list.html#category_data_handling> >>> >>> *Date submitted:* 11 March 2004 >>> *Submitter:* Yaron Y. Goland <mailto:ygoland@bea.com> >>> *Description:* Is it legal/possible to un-initialize a variable in >>> BPEL? What happens, for example, if one tries to assign a static >>> from value that is empty? Should we allow for from-spec to be empty >>> and have that mean that the target is uninitialized? >>> *Submitter’s proposal:* Being able to un-initialize variables is a >>> generically useful thing. It makes it clear when a variable doesn't >>> contain a 'useful' value. So I think we should provide a way to >>> un-initialize variables. >>> *Changes:* 12 Mar 2005 - new issue >>> >>> ------------------------------------------------------------------------ >>> >>> Best Regards, >>> >>> Tony/ / >>> >>> / <http://www.choreology.com/>/ >>> >>> >>> Tony Fletcher >>> >>> Technical Advisor >>> Choreology Ltd. >>> 68, Lombard Street, London EC3V 9L J UK >>> >>> Phone: >>> >>> >>> +44 (0) 1473 729537 >>> >>> Mobile: >>> >>> >>> +44 (0) 7801 948219// >>> >>> Fax: >>> >>> >>> +44 (0) 870 7390077 >>> >>> Web: >>> >>> >>> /www.choreology.com <http://www.choreology.com/>/ >>> >>> Cohesions™ >>> >>> Business transaction management software for application coordination >>> >>> Work: tony.fletcher@choreology.com >>> >>> Home: amfletcher@iee.org <mailto:amfletcher@iee.org> >>> >> > >
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