asynchronous subscriptions

[Oleg Krogius <ol...@virginia.edu>]

I have an existing (gsoap based) service, and I'm trying to write an axis2
client for it. However, I'm having some troubles with one asynchronous
'notification' part.

 

In particular, this service that offers a subscription to real time data:

1. client connects to it

2. client issues a one-way call to subscribe to xyz (subscribe)

3. then while on the same keep-alive connection the server issues one-way,
server to client, notification (publish) responses as the respective data
comes in

4. this goes on until the connection breaks or the client issues an
unsubscribe call

 

I'm having some problems with the notification/publish part. The wsdl file
generated by gsoap gives both subscribe and publish as one-way requests from
the client to the server. Obviously that's wrong; therefore I changed the
one way description in the wsdl for publish from an operation with just an
input sub-element, to one with just an output sub-element.

 

Normally with the simple one-way or the request/response I can run the
wsdl2java tool on the gsoap's wsdl, and then simply use the generated code
something like:

RequestObject req = new RequestObject(.....);

ResponseObject res = getServiceStub().request(req);

// or for the one-way's just: getServiceStub().request(req);

 

However, I'm puzzled what do I do with the notification/publish interaction.
The wsdl2java does seem to generate the code to handle the response content
wise, but how do I get at it. In other terms, seems like the logical
approach would be:

 

SubscribeObject req = new SubscribeObject(...);

getServiceStub().subscribe(req);

while (....) {

      //something comparable to gsoap's soap_recv_ns__event(connection, data
struct);

      PublishData data = getServiceStub().receivePublish();

      doSomething(data);

}

 

But the concrete details seem fuzzy at best. If someone can help out with
this, I'd greatly appreciate it. Thanks.