VB6 Java interoperability

I have been asked to investigate the possibility of a VB6 app working with a java app.

Scenario: VB6 app processes financial transactions and posts requests to some proprietory software which talks to mainframe. Messages sent both ways.

We are trying to get rid of proprietory software - but some conditions. All new software must be written in Java. Also likely that Java app and VB6 app will be both be on client machine.

Java app will talk to mainframe using TCP/IP

I am looking for any suggestions on how to approach this, and pointers to references on relevent material.

A few questions we are looking at in relation to this follow. Any help greatly appreciated.

Can VB6 generate XML data which a Java app can read? Does SOAP need to be used? Does HTTP need to be used if both apps on same machine

This isn't as hard as you think. It isn't fun, but not impossible.
There are a few ways to do this, and there are more than I am willing to put down here... however, here are a couple.

1.
Take a look at .NET.
Look into its web services solutions.
There are samples out on the net.
VB and Java can interact with each other through Web services.

2.
Take a look at Java Native interface (JNI).
This allows Java to call a method in a DLL.
The DLL can communicate with the VB Applicaiton through remote method calls or its COM interface.

Thanks - that's a good start for me. All of the stuff I have seen uses some form of internet protocol for the web services route. My probelm is that both apps are on the same machine, and there will be no web server installed. Is there another way of sending the xml direct or is it a case of saving it to a file and getting the other app to read the file?

If you can save the xml to a file and have the other app read it, you should have no problem.

The only time you may have a problem is if the xml is not written in time.