Creating an ISAPI Extension DLL under Visual C++ 4.0

Creating an Extension DLL is a simple, but multi-step, process. Because Visual C++ 4.0 doesn't have built in ISAPI classes, a fair bit of standard code has to be added to each DLL by hand. It seems like a lot more work than it is, though.

There are 4 steps to getting your script created and running:

  1. Make sure you've got the ISAPI header files. They are available at http://www.genusa.com/isapi/isapihdr.zip
  2. Create a bare DLL using Microsoft Studio's New... Wizard.
  3. Add code to the .DEF and .CPP files created by the wizard. The code supplied here is fairly standard. I have included 2 support functions: one sends back a standard header, the other allows formatted output to the client.
  4. Move the DLL into the 'scripts' directory on the web server. This is usually something like C:\InetSrv\Scripts. You will find your DLL in the ./debug directory under the directory you specified in the DLL creation wizard. If, as in this example, you specified F:/ISAPI/Skeleton, you will find your DLL in F:/ISAPI/Skeleton/debug
  5. Test your DLL, the URL should be something like: http://www.yoursite.com/scripts/yourdll.dll
With any luck, you should have a running ISAPI Extension, the rest is up to you. ;)

This page last updated on September 2, 1996.

© Copyright 1996 by Stephen Genusa. All Rights Reserved.
© Copyright 1996 by Jeff House. All Rights Reserved.