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Subject: RE: [wsbpel] Issue - 77 - Under specified operation definitions


The only well-defined way in WSDL to actually use parts of abstract messages not appearing in abstract operations is through SOAP header binding is it not?  Not mentioning it does not make it go away, much like those legacy services ;-)

 


From: Ugo Corda [mailto:UCorda@SeeBeyond.com]
Sent: Wednesday, November 19, 2003 12:37 PM
To: Satish Thatte; Ron Ten-Hove; ygoland@bea.com
Cc: wsbpel@lists.oasis-open.org
Subject: RE: [wsbpel] Issue - 77 - Under specified operation definitions

 

The requirement to deal with legacy Web services (it just happens to be a hot item with my company ;-).

 

Please keep in mind that my proposed resolution does not even mention SOAP and bindings. It just extends the current coverage of the abstract interface to include abstract messages not appearing in abstract operations (which, whether you like it or not, are still part of the WSDL abstract interface).

 

Ugo

 

 -----Original Message-----
From: Satish Thatte [mailto:satisht@microsoft.com]
Sent: Wednesday, November 19, 2003 12:31 PM
To: Ugo Corda; Ron Ten-Hove; ygoland@bea.com
Cc: wsbpel@lists.oasis-open.org
Subject: RE: [wsbpel] Issue - 77 - Under specified operation definitions

We came back full circle.  

 

I am starting with the assumption that we do not want to deal with SOAP complexities and binding issues in BPEL.  That leaves us with abstract WSDL interfaces.  This is also Yaron’s position.

 

Now given this as the starting position (which I know you disagree with, but suspend disbelief for a moment), what requirements could motivate Issue#77?

 


From: Ugo Corda [mailto:UCorda@SeeBeyond.com]
Sent: Wednesday, November 19, 2003 12:07 PM
To: Satish Thatte; Ron Ten-Hove; ygoland@bea.com
Cc: wsbpel@lists.oasis-open.org
Subject: RE: [wsbpel] Issue - 77 - Under specified operation definitions

 

Satish,

 

Which requirement are you referring to? A BPEL requirement? A WSDL requirement?

 

As far as I know, according to WSDL (and SOAP too) there is no such requirement that a header must be associated with a secondary protocol or used by intermediaries.

 

BPEL of course is free to add this requirement, but if it does so it should clearly specify that it is something above and beyond what is required by the basic specs (and it would still leave us to deal - or not to deal - with legacy Web services that took a different interpretation).

 

Ugo

-----Original Message-----
From: Satish Thatte [mailto:satisht@microsoft.com]
Sent: Wednesday, November 19, 2003 12:00 PM
To: Ugo Corda; Ron Ten-Hove; ygoland@bea.com
Cc: wsbpel@lists.oasis-open.org
Subject: RE: [wsbpel] Issue - 77 - Under specified operation definitions

Ugo,

 

This is just a requirements issue.  You are absolutely correct that abstract message parts might reflect anything.  The question is: where is the requirement for any additional mechanism coming from if not from contingent data being added via secondary protocols or by intermediaries?

 

Satish

 


From: Ugo Corda [mailto:UCorda@SeeBeyond.com]
Sent: Wednesday, November 19, 2003 11:53 AM
To: Satish Thatte; Ron Ten-Hove; ygoland@bea.com
Cc: wsbpel@lists.oasis-open.org
Subject: RE: [wsbpel] Issue - 77 - Under specified operation definitions

 

The connection between "optional headers" and "secondary protocols" is completely arbitrary. There is nothing in the WSDL spec that says that a header that appears in an operation is not related to a "secondary protocol", or vice versa that a header that appears in an abstract message not part of an operation is indeed related to a "secondary protocol".

 

So BPEL already deals with headers that might be related to "secondary protocols" and that just happen to be part of an abstract operation. Are you suggesting we say something in the spec to disallow those headers?

 

Ugo

-----Original Message-----
From: Satish Thatte [mailto:satisht@microsoft.com]
Sent: Wednesday, November 19, 2003 11:43 AM
To: Ugo Corda; Ron Ten-Hove; ygoland@bea.com
Cc: wsbpel@lists.oasis-open.org
Subject: RE: [wsbpel] Issue - 77 - Under specified operation definitions

Agreed.  I was referring more to the intent of Ron’s rinsing proposal.  To repeat his second paragraph

 

I'm a little leary about having processes directly mess around with secondary protocols (i.e. headers). A process could easily become overwhelmed with chewing on and processing headers, signatures, assertions, and the actual business process being implemented could become unreadable. Do we want, at a business level, to be messing around with such low-level protocols? My sense is that BPEL ought to work at a higher level of abstraction, if it is to be used to express business processes rather than a lot of technical protocol processing.

This suggests that the *source* of optional headers (“secondary protocols”) is out of scope for BPEL, which should “work at a higher level of abstraction.”

 

In case it is not obvious, I should add that I am in complete agreement with the way Ron has characterized the issue.

 

Satish

 


From: Ugo Corda [mailto:UCorda@SeeBeyond.com]
Sent: Wednesday, November 19, 2003 11:19 AM
To: Satish Thatte; Ron Ten-Hove; ygoland@bea.com
Cc: wsbpel@lists.oasis-open.org
Subject: RE: [wsbpel] Issue - 77 - Under specified operation definitions

 

Satish,

 

The concept of optional header needs to be better specified in the context of Yaron's message. There are two cases:

 

1 - The optional header is defined in an abstract message (this is the case I used when raising this issue).

 

2 - The optional header is not defined in any part of the abstract interface (this is not the case I exemplified when I filed this issue, and I prefer to keep it out of the discussion of the issue itself).

 

Yaron's discussion about introspection does not apply to case 1. In case 1 BPEL does not need to concern itself with how to get to the abstract message: that is just part of the underlying binding machinery. All BPEL sees is the abstract message. Reaching that abstract message is not any more complicated for BPEL than reaching any other component of the abstract operation.

 

Ugo

 

 -----Original Message-----
From: Satish Thatte [mailto:satisht@microsoft.com]
Sent: Wednesday, November 19, 2003 11:04 AM
To: Ron Ten-Hove; ygoland@bea.com
Cc: wsbpel@lists.oasis-open.org
Subject: RE: [wsbpel] Issue - 77 - Under specified operation definitions

Ron,

 

With your idea of rinsing SOAP off the body of BPEL, your agreement with Yaron also amounts to rejecting Yaron’s proposals for dealing with optional headers.  I assume that is intentionally left unsaid .. ;-)

 

Satish

 


From: Ron Ten-Hove [mailto:Ronald.Ten-Hove@Sun.COM]
Sent: Wednesday, November 19, 2003 9:09 AM
To: ygoland@bea.com
Cc: wsbpel@lists.oasis-open.org
Subject: Re: [wsbpel] Issue - 77 - Under specified operation definitions

 

Yaron,

    I have to agree with you; the only sane course of action here is to demand that any message constructs that BPEL can use must be described in WSDL, otherwise BPEL is blind to them. This doesn't prohibit lower-levels of a "stack" from mucking around with the message further, injecting or processing headers as needs be. We sure don't want to be in business of building exceptions to this rule into the BPEL vocabulary!

    I'm a little leary about having processes directly mess around with secondary protocols (i.e. headers). A process could easily become overwhelmed with chewing on and processing headers, signatures, assertions, and the actual business process being implemented could become unreadable. Do we want, at a business level, to be messing around with such low-level protocols? My sense is that BPEL ought to work at a higher level of abstraction, if it is to be used to express business processes rather than a lot of technical protocol processing.

    Getting back on topic: some confusion arises with the confusion of SOAP with WSDL. I know that SOAP and WSDL could have been better designed to keep this clearer, but the fact is some (many, perhaps?) associate web services only with SOAP, and look at BPEL as, in part, a way to play directly with SOAP messages. This is a misleading way to look at it,  just as it is misleading to regard SOAP as just HTTP. Let's just rinse all that SOAP off our thinking, and stick with nice, clean WSDL. :-)

-Ron

Yaron Goland wrote:

Issue - How do to deal with message content that is not specified in the
WSDL abstract operation definition?
 
        For example, if a BPEL process receives a SOAP message with a SOAP
security header that wasn't specified in the WSDL abstract operation
definition then how does the BPEL process reach into the header and pull out
the name of the sender so that the BPEL process can send a message such as
"I just got a signed message from Joe"?
 
        The inverse example is also possible. The BPEL engine may have been
given a standard WSDL definition that does not specify the use of a callback
header in the WSDL abstract operation definition. If the BPEL process needs
to insert such a header, how does it do it?
 
        The original issue that started this thread
(http://lists.oasis-open.org/archives/wsbpel/200310/msg00197.html) also
provides another example of the problem that uses some fairly naughty but
not apparently illegal WSDL behavior.
 
There would seem to be two fairly straight forward solutions to the issue -
Introspection or re-write the WSDL.
 
Introspection would require us to introduce a new BPEL activity that could
somehow plum a message so that it is possible to 'see' parts of the concrete
message that are not present in the abstract operation definition. Similarly
we would need to be able to edit the concrete message before it goes out in
order to include content that wasn't defined in the WSDL abstract operation
definition. The complexity of introspection makes for what appears to me to
be a solution that is much worse than the problem.
 
The other solution is to require that people re-write their WSDLs. If you
want to receive message content that isn't in the abstract operation
definition you were given then you need to edit the WSDL you feed your BPEL
engine to include that content in its abstract operation definition. The
same logic applies to sending messages with content that wasn't specified in
the original WSDL abstract operation definition. 
 
Re-writing WSDLs may not be pretty but introducing introspection seems
worse.
 
        Yaron
  
 
 
 
 
 
 
 
 
 



 
 
 
 
 
 
 
 
 
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