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Overview

In G2, the term foreign function refers to a function written in C or C++ code that a KB can access as if it were a local function. The foreign function interface is platform-independent and efficient, allowing you to isolate G2 from the effects of possible coding errors.

The term foreign image describes an executable file, external to G2, that contains the foreign functions you plan to call from your KB.

A foreign function call is synchronous. G2 does not perform other tasks until the function returns or times out. For asynchronous calls to C functions, see the description of GSI remote procedure calls, described in the G2 Gateway Bridge Developer's Guide.

You can start foreign images two ways:

As an external process, independent of G2 control
By spawning a process from within G2

Several advantages to using external foreign image processes are:

You can run a foreign image on a computer other than the one on which G2 is running.
Using an external foreign image can prevent excessive memory usage on certain platforms during process spawning.
A separately running foreign image is easier to debug.

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