Web services. You can validate the data as it comes in and limit what they can get to. And, it won't really matter what language their application is written in nor what platform it runs on.

>Hi,
>
>I have a hypothetical question. Say, some other software vendor wants to integrate their system with you vertical market application. Basically they want to "send" information" from their software to your software on a real-time basis.
>
>What is the best, most effective way of doing it? Web Services? Another approach?
>
>TIA