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Subject: Re: [wsbpel] Issue 305

Hi Mark,

I agree that the fourth <to> variant should be an expression instead of a
query, because there is no context. And I agree that then the queryLanguage
attribute can be removed from <process> because with the previous change
queries can't no longer occur in a BPEL process.

The propertyAlias is the only remaining place, but it's outside of the
BPEL. But when removing the queryLanguage attribute from <process> there is
no longer a default. So we need a default (XPath 1.0 I assume) for the
queryLanguage attribute in propertyAlias/query what solves another problem:
If you currently have two processes which want to use the same
property/propertyAlias (no queryLanguage attribute specified in the
propertyAlias/query), but the set queryLanguage is different for both
processes you can't use this propertyAlias in the context of both
processes. You either need to duplicate the property and propertyAlias to
solve the problem or you need to change the set queryLanguage in one
Removing the queryLanguage attribute from <process> and introducing a
default for the queryLanguage attribute in propertyAlias/query would solve
that problem in an elegant way, too.

Best regards/Mit freundlichen Grüßen,

       Thomas Schulze

             "Mark Ford"                                                   
             -endpoints.com>                                            To 
             27.07.2006 18:18                                           cc 
                                       [wsbpel] Issue 305                  

As we discussed this specification internally it became clear that the main
difference between queries and expressions is that queries have a context
while expressions do not. One way of achieving this is to remove
queryLanguage from the process altogether. This is how the issue was
originally framed in the issue description.

Another way of achieving this same goal but with fewer changes would be to
restore the query option in the <from> and <to> variants that had queries
with a variable as the context.

Therefore, I propose the following to restore the distinction between
queries and expressions:

   1. Change existing <to> query variant to match existing <from>
      expression variant.

<to expressionLanguage=”expr-lang”>expr</to>

   2. restore the query option in the <from> and <to> that take variables
      and have them look and behave the same as propertyAlias queries

<from variable=”BPELVariableName” part=”NCName”?>
          <query queryLanguage=”query-lang”?>?

<to variable=”BPELVariableName” part=”NCName”?>
          <query queryLanguage=”query-lang”?>?

I appreciate any feedback on this issue before I embark on submitting a
formal proposal. The proposal will include the current version of the spec
with only the edits for this issue appearing as changes.


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