Hi Alex For your advise,i think its based on BPEL's perspective, for example, you talked about how BPEL processes quened messages. I have been confused about the "external" service.
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. 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. Thank you so much!! -----Original Message----- From: "Alex Boisvert" <[EMAIL PROTECTED]> To: [email protected] Date: Wed, 28 Feb 2007 17:43:18 -0800 Subject: Re: Re: Asynchronous service invocation question On 2/28/07, Jiang Liu <[EMAIL PROTECTED]> wrote: > > Hi Jim > Really thanks for your quick reply. I did read somewhere that said > WS-Addressing is utilized here, but for WSDL2, is still? > > And the main problem is since the external service does not have to > implement "callback" logic, so even it got BPEL's EPR, how does it know when > is the best time to send reply back? As soon as you have a callback EPR, you should be able to invoke it. Now whether it works in practice is a question of message exchange pattern and transport layer. Ode queues all messages it receives, so if you have a one-way invocation, or a request-response invocation happening over a connection-less protocol (e.g. JMS) then it should work. The message will be queued and processed when the process reaches the corresponding <receive> activity. For the HTTP protocol, you have to stick to one-way invocations to avoid transport-level timeouts. alex ------------------------------ Jiang Liu Student Number: 3075163 CS/Yallara Name: ljiang RMIT, Melbourne
