The ACF File

The ACF file enables you to customize your client and/or server applications' RPC interface without affecting the network characteristics of the interface. For example, if your client application contains a complex data structure that only has meaning on the local machine, you can specify in the ACF file how the data in that structure can be represented in a machine-independent form for remote procedure calls.

This tutorial demonstrates another use of the ACF file—specifying the type of binding handle that represents the connection between client and server. The [implicit_handle] attribute in the ACF header allows the client application to select a server for its remote procedure call. The ACF defines the handle to be of the type handle_t (a MIDL primitive data type). The MIDL compiler will put the binding handle name that the ACF specified, hello_IfHandle into the header file it generates. Notice that this particular ACF file has an empty body.

//file: hello.acf
    implicit_handle (handle_t hello_IfHandle)
interface hello

The MIDL compiler has an option, /app_config, that lets you include certain ACF attributes, such as implicit_handle, in the IDL file, rather than creating a separate ACF file. Consider using this option if your application doesn't require a lot of special configuration and if strict OSF compatibility is not an issue.