Trond, I hope you don't mind, but I'm posting this note to the general discussion list. I suspect that others would appreciate it.
There are two possible definitions of the term "asynchronous". In one case, it means one-way messaging (as I descrbed it below). In the other case it means non-blocking request/response messaging. In the first case, you don't use callbacks (because you aren't sending a message back). In the second case, you do use callbacks. In the first case, it doesn't make sense to use RPC style, because RPC style assumes a request/response message exhange pattern. But when it comes right down to it, I suppose it really doesn't matter whether you structure your one-way message as a document or as an RPC. Now, one of the problems you should expect to see is from the fact that the SOAP/WSDL specifications don't define how a SOAP implementation should support asynchronous computing, so each implementation is likely to do it slightly differently (if at all). Lots of implementations say they support asynchronous communications, when in fact what they support is asynchronous transport. In other words, they can transport messages over JMS or some other message queuing system. But they don't really provide any support within the programming API to support either one-way messages or non-blocking request/response messages. As far as I know, MS .NET, BEA, and Systinet WASP are the only implementations that provide an asynchronous API (built-in support for non-blocking request/response messages using callbacks). Anne > -----Original Message----- > From: Trond Hjelmaas [mailto:[EMAIL PROTECTED]] > Sent: Wednesday, November 27, 2002 1:00 AM > To: [EMAIL PROTECTED] > Subject: RE: Document style web services > > > Hi, > > I thought I'd send this to you personally. If you find it rude, please > forgive me. > > I tried your theory with async web services. I define a simple java class > with a method that delays execution for 10 seconds and returns void. > > The WSDL file generated by Oracle jDeveloper 9.0.0.3 had both request > message and response messages. I deleted the response message from the > WSDL expecting my call to the webservice to return immediately. That was > not the case and a reponse came back to me after 10 secs. > > I use style=RPC and not document, maybe that's the thing? > > I currently do some research on async web services, and I just started to > explore style=document. Both Microsoft and Bea are using call back design > patterns to achieve asynch calling of web services (the examples they > use are RPC but they do not state specifically that it's not valid > for style=document), i.e. start a separete thread that requests and waits > for reponse. To me that strongly suggest to me that RPC is not async, > but yet I have not find the proof (been through WSDL and SOAP deifitions) > > Sorry again if you consider this rude. > > Kind regards, Trond > > > > > --- Anne Thomas Manes <[EMAIL PROTECTED]> wrote: > > > Document style web services are not inherently > > > asynchronous. The synchronous > > > nature of a Web service is determined by the message > > > exchange pattern > > > described in the WSDL Operation. If the service is > > > defined as having an > > > input and output message, then it is a > > > request/response service (inherently > > > synchronous). If it is defined as having only an > > > input message, then it is a > > > one-way message (inherently asynchronous). > > > > > > Anne >
