On 2/28/07, Jiang Liu <[EMAIL PROTECTED]> wrote:
As you said: "As soon as you have a callback EPR, you should be able to invoke it", if i am correct, i think "you" in your sentence means the "external service", am i right? if so, :-), how does it be able to invoke BPEL back since there is no implementation at external server side.
The consumer (external service in this case) needs a service description (WSDL) for the callback. It can be either static (known a priori) or obtained dynamically (from the EPR). In the second case, the customer requires a webservice stack that supports the dynamic scenario. As WS-I suggests (?), WSDL only supports one-way and receive-reply patterns
(not sure about WSDL2), so technically, external service is not "required" to send message back because BPEL's invocation is just a one-way pattern.
If you mean a sequencing of one-way or request-response invocations then falls outside of the scope of WSDL. BPEL itself can be used as an interface description language to describe such composition of simple message exchange patterns. But you don't need BPEL per-se, all you need is an application that knows the composition and it able to participate in it. alex
