Re: [wsbpel] inputVariable optional on Invoke

[Prasad Yendluri <pyendluri@webmethods.com>]

Ron,

This is only permits zero parts in the wsdl:message or the soap:body 
(binding level) being empty. This does not say the wsdl:message or the 
soap:envelope itself can be totally absent. Hence we can not interpret 
that to imply the inputVariable can be absent. It can be empty or void 
of  payload (body) content and with WSDL 1.1 headers can be present in 
the soap:envelope coming from other wsdl:messages  etc.

Regards, Prasad

Ron Ten-Hove wrote:

>     When faced with the oddities of WSDL 1.1, I usually consult my 
> copy of the WS-I Basic Profile. Even though it is SOAP-centric, it 
> does have a lot to say about service declarations. The BP 1.0 doesn't 
> recognize (and clarify) the contradiction you found (concerning the 
> cardinality of message parts), but I find this:
>
> From section 5.3.1 (Bindings and Parts):
>
>     Use of wsdl:message elements with zero parts is permitted in
>     Document styles to permit operations that can send or receive
>     messages with empty soap:Bodys. Use of wsdl:message elements with
>     zero parts is permitted in RPC styles to permit operations that
>     have no (zero) parameters and/or a return value.
>
>     I'd say we have the WS-I's blessing on leaving the inputVariable 
> as optional. Other implementations of SOAP may have different 
> interpretations, but allowing the inputVariable to be optional is the 
> most general choice, and will cover such implementations as well.
>
> -Ron
>
> Yaron Y. Goland wrote:
>
>> Executive Summary: Antony Miguel, in a private e-mail, pointed out 
>> that the inputVariable attribute on invoke is currently optional. In 
>> BPEL as it now is specified this doesn't make sense as all operations 
>> MUST have a WSDL message associated with them. But if issue 12 passes 
>> then the optional inputVariable makes sense in cases where the 
>> message has no parts. Unfortunately the WSDL 1.1 spec seems to 
>> contradict itself on the legality of partless messages.
>>
>> Long Winded Version:
>>
>> Antony Miguel, in a private e-mail with me, pointed out that the 
>> inputVariable attribute is optional on invokes. Given that all invoke 
>> MEPs MUST have an outgoing message does it make sense to have the 
>> attribute be optional?
>>
>> The only scenario I can come up with where it makes sense to not have 
>> an inputVariable attribute is if the outgoing message is 'empty'. 
>> This is not a completely insane idea. Some protocols do have 'empty' 
>> messages which have an address header but no body. This could be used 
>> for things like pings.
>>
>> But all BPEL messages have to be sent using a WSDL message structure 
>> and it isn't possible to define an operation that doesn't point at a 
>> message. However it MAY be legal to define a WSDL message with no 
>> parts. There is a contradiction between the text in WSDL 1.1 and the 
>> schema. The text in section 2.3 says "Messages consist of one or more 
>> logical parts.". But the psuedo-schema in 2.3 says:
>>
>> <definitions .... >
>>     <message name="nmtoken"> *
>>         <part name="nmtoken" element="qname"? type="qname"?/> *
>>     </message>
>> </definitions>
>>
>> Furthermore the XML Schema in the appendix says:
>>
>>    <complexType name="messageType">
>>       <complexContent>
>>          <extension base="wsdl:documented">
>>             <sequence>
>>                <element ref="wsdl:part" minOccurs="0"
>>                         maxOccurs="unbounded"/>
>>             </sequence>
>>             <attribute name="name" type="NCName" use="required"/>
>>          </extension>
>>       </complexContent>
>>    </complexType>
>>
>> Assuming the schema triumphs then this means that it is legal to 
>> define a message with no parts. An empty message.
>>
>> But this still leaves the problem that BPEL requires that all 
>> messages be contained in a WSDL container. This alone would require 
>> that invoke MUST always have an inputVariable attribute.
>>
>> But, if issue 12 passes, then it would make sense to make 
>> inputVariable optional to cover the case where the message for an 
>> operation has no parts.
>>
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>>
>>
>