The recommended environment for developing application filters for Forefront TMG is Visual C++ .Net. All the samples provided in the Forefront TMG Software Development Kit (SDK) are ready to be compiled in Visual C++ .Net. Application filters can also be written and compiled in a Visual C++ 6.0 development environment. However, to use Visual C++ 6.0, you must install Visual C++ 6.0 Service Pack 5 and the Platform Software Development Kit (Platform SDK).
The Platform SDK contains newer include files and binary files, including the Microsoft Interface Definition Language (MIDL) Compiler version 5.03.0280, which is needed by Visual C++ 6.0 to correctly compile application filters for Forefront TMG. The Platform SDK can be downloaded by anyone free of charge from the Platform SDK Update Web site. The Platform SDK consists of several components, of which you need to download and install only the core SDK.
After you compile your application filter, you must install it on a Forefront TMG computer before running it. An application filter can include self-registration code, or separate scripts can be created to install it. For more information about installing your application filter on a Forefront TMG computer, see Filter Setup.
Build date: 7/12/2010