About This Book

See the Table of Contents for a detailed listing of the subjects covered in this document.

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.

• Running Programs or System Commands with $ZF(-100) — describes how to use a $ZF option that provides functionality similar to a command line interface.

• 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.

• Invoking Callout Library Functions — describes how to call functions dynamically from a Callout shared library.

• Statically Linked Callout Functions — describes how to create a customized version of Caché that includes your Callout functions.

• Special Considerations for UNIX® — discusses issues relevant only to UNIX® and related operating systems.

• InterSystems Callout Quick Reference — provides a detailed description of each $ZF function.

For general information, see Using InterSystems Documentation.