Which Technology?

[AWhiteC]

My client wants to do something, and I'm not sure about the best Microsoft technology to use.

What does it sound like to you?

I view a Web page in a browser. I see link and I click on it. It opens up a C++ application (already installed on my PC). This accesses a document on the server. (The document is of a client-specific type.) It automatically opens the document at a position given for that document by a record in a database on the server.

Sounds a bit like Acrobat Reader accessing a PDF document, but it isn't.

Is it an OLE server application? An ActiveX control? An IE plugin? Something else?

[CardboardHammer]

Have the server return a file with an extension that you can cleanly associate with your C++ app (or a tiny app whose sole purpose is to fire up the other app with the correct parameters, if you can't recode the primary app). In the file, include the info necessary for the app to request the right document and position.

There might be a bit more fiddling to it than that, but you should be able to avoid any major security issues with such a scheme (and since it's an inhouse type of thing, it doesn't matter if it's not a worldwide suitable solution, etc.)