Abstract: A graphical programming language (GPL) that allows GPL user functions to be callable from other software. The present invention employs a client/server model to allow GPL user functions to be called, much like a procedure from one language is called by a second language. The client is a library of ‘C’ procedure calls. The GPL server is the service. This allows a GPL user function to be called by any application that can link in the ‘C’ library. The ‘C’ client can exist on a separate machine from the GPL service or on the same machine in the presence of a multitasking operating system. When calling a GPL user function, the arguments of the ‘C’ call correspond to the input and output terminals of the GPL user function. The data being sent to the GPL user function is the input data. The data being returned from the GPL user function is the result from the execution of the GPL user function.