The InterSystems Callout Gateway (implemented in the Caché $ZF functions) allows you to invoke external programs and system services from Caché. It also provides a way to integrate your custom code into Caché.
This book addresses the following topics:
Introduction introduces concepts important to understanding the rest of this book, summarizes the capabilities of the InterSystems Callout Gateway, and provides links to other resources.
Creating an InterSystems Callout Library describes how to create a Callout shared library with functions that can be invoked from Caché. Code can be written in any language that supports C/C++ calling conventions.