Client/Server project with Java?

[Andy DePue]

We are looking to develop a client/server type application for
deployment across the internet (this, of course, would be accessible
through a web page). We have looked at several different solutions,
and Java appears to be an excellent option.
Our application is currently windows based with a few specialized
dialogs that allow the user to access knowledge in an expert system.
At the heart of our application is an "inference engine" written in
ANSI Standard C that is best thought of as an API. Whenever the
inference engine needs to get some user input (such as the answer to
a question), it sends a "message" (by way of a "callback" function).
The message handler (or callback function) can implement this in any
way.
We really have no desire to rewrite this inference engine, and would
like to keep it "as is". However, at the same time we are needing to
develop expert system applications that can be deployed over the
World Wide Web. At first, we didn't consider Java to be a solution,
since we thought we may have to rewrite our inference engine in Java,
and didn't know a great deal about its architecture. However, we
believe it may be possible to set up our application so that our
inference engine executable runs on the web server, and whenever it
sends a "message", we would re-route that message across the net, to
be picked up by a Java "front end" application. This application
would only contain user interface specific code (written in Java, of
course), which would do its job, and return the results to the server
machine.
Is this possible with Java? If so, how would we go about developing
such an application? What pieces would we need to put this together?
Thank you in advance for any information you can provide.

Andy DePue - The GINESYS Corporation
ADE...@GINESYS.COM

[SMPfeffer]

You definitely can build this. Your Java applet would have to contain
middleware code (delivered with the app, of course) that would allow it to
communicate with an application server running (presumably) on the same
machine as the http daemon, although not necessarily. You probably
could derive this middleware code off the already-supplied java network
package...

The Java program would be the client.

The application server would:
a. invoke the inference engine as needed.
b. have call back code that the inference engine invokes as needed.
c. send data back to the java program (using the middleware between
java client and C(++) application server) as required.

The java client, upon receiving a response message via the middleware
would display it, or do whatever it was supposed to do upon receiving
that data....

The only thing you would use the http (web) server for would be to deliver
java code across the wire, along with addressing information for it to
contact
the application server. You would NOT use the web server for the
subsequent client/server interaction needed.

--Scott

New Yorker by Birth, Floridian by Growth, Georgian by Education,
St. Louisan by Dumb Luck.