Assigning the Value of the Service-Ref Element

[<andrew.francis@mail.mcgill.ca>]

Hello:

I would like to soon implement section Nine (variables,
expressions, and assignment) of the BPEL4WS specification.
I am trying to figure out how to implement partnerLinks,
keeping issue 34 and 152 in mind.

I am trying to figure out the machinery for service-ref.
I have a question: how are the values for the service-ref
element and more specifically, the reference-schema
acquired? Since service-element is partner specific
and one binds this partner specific information essentially
at runtime (you pick an actual port/end-point), it seems
to me that service-ref is difficult to use for compile
time checking. For example, how to I figure out if a
variable or variable property's type agree with a
partnerlink's EPR, if I can only really only know this
at runtime? At best I can only do a runtime  type checking
for what the specification calls "undefined behaviour."
It also seems to me that this information is difficult
to acquire a priori. Is my compiler/BPEL tool looking at
a WSDL or a UDDI tModel?

Do I really need all this machinery to invoke say
Amazon's, Google's, or most currently existing web
services?

I am interested to hear how others are approaching this
problem.

Cheers,
Andrew