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From phanlesang <phanles...@gmail.com>
Subject Re: When we need to initialize a variable
Date Thu, 09 Jul 2009 13:36:27 GMT

Hi,
Thank you for your explanation.
 


Bill McCusker wrote:
> 
> Hi,
> 
> Variables need to be initialized before they are assigned from or when 
> assigned to using a query or an expression or if they are used as to 
> input to an invoke or in conditional expressions. If you are just 
> assigning directly to a variable's message part with no query then no 
> initialization is needed. Thats why the second example needs no 
> initialization.
> 
> Bill McCusker
> 
> phanlesang wrote:
>> Hi Everyone!
>> I'm getting confused about when we need to initialize a variable in BPEL
>> 2.0
>> though BPEL 2.0 standard says that every variable must be initialized
>> before
>> using.
>> For example:
>> In the HelloBPELProcess example, I see the variable output is
>> initialized:
>>
>> <bpel:assign validate="no" name="createResponse">
>>             <bpel:copy>
>>                 <bpel:from>
>>                     <bpel:literal
>> xml:space="preserve"><tns:HelloBPELProcessResponse
>> xmlns:tns="http://www.se.uni-hannover.de/soa08/tutorial/HelloBPELProcess"
>> xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
>>   <tns:result></tns:result>
>> </tns:HelloBPELProcessResponse>
>> </bpel:literal>
>>                 </bpel:from>
>>                 <bpel:to variable="output" part="payload"></bpel:to>
>>             </bpel:copy>
>>             <bpel:copy>
>>                 <bpel:from part="payload" variable="input">
>>                     <bpel:query
>> queryLanguage="urn:oasis:names:tc:wsbpel:2.0:sublang:xpath1.0"><![CDATA[tns:input]]></bpel:query>
>>                 </bpel:from>
>>                 <bpel:to part="payload" variable="output">
>>                     <bpel:query
>> queryLanguage="urn:oasis:names:tc:wsbpel:2.0:sublang:xpath1.0"><![CDATA[tns:result]]></bpel:query>
>>                 </bpel:to>
>>             </bpel:copy>
>>         </bpel:assign>
>>
>> But in the SimpleInvokeProcess process, the variable output is not
>> initialized:
>>
>> <bpel:assign validate="no" name="PrepareRandomHelloRequest">
>>             <bpel:copy>
>>                 <bpel:from>
>>                     <bpel:literal xml:space="preserve"><impl:sayHello
>> xmlns:impl="http://randomHelloService.tutorial.soa08.se.unihannover.de"
>> xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
>>   <impl:withSpace></impl:withSpace>
>> </impl:sayHello>
>> </bpel:literal>
>>                 </bpel:from>
>>                 <bpel:to variable="RandomHelloRequest"
>> part="parameters"></bpel:to>
>>             </bpel:copy>
>>             <bpel:copy>
>>                 <bpel:from>
>>                     <bpel:literal
>> xml:space="preserve">true</bpel:literal>
>>                 </bpel:from>
>>                 <bpel:to part="parameters" variable="RandomHelloRequest">
>>                     <bpel:query
>> queryLanguage="urn:oasis:names:tc:wsbpel:2.0:sublang:xpath1.0"><![CDATA[ns1:withSpace]]></bpel:query>
>>                 </bpel:to>
>>             </bpel:copy>
>>         </bpel:assign>
>>         <bpel:invoke name="GetGreeting" partnerLink="RandomHelloPL"
>> operation="sayHello" portType="ns1:RandomHelloService"
>> inputVariable="RandomHelloRequest"
>> outputVariable="RandomHelloResponse"></bpel:invoke>
>>         <bpel:assign validate="no" name="PrepareOutput">
>>             <bpel:copy>
>>                 <bpel:from xmlns:http="urn:http:namesapce">
>>                    
>> <![CDATA[concat(bpel:getVariableData('RandomHelloResponse', 'parameters',
>> '/'), bpel:getVariableData('input', 'payload', '/'))]]>
>>                 </bpel:from>
>>                 <bpel:to variable="output" part="payload"></bpel:to>
>>             </bpel:copy>
>>         </bpel:assign> 
>>
>> Thanks for any help!
>>
>> -----
>> Sang PL  http://www.nabble.com/file/u1501219/20.gif 
>>   
> 
> 
> 


-----
Sang PL
-- 
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