In this section, you will learn how you can use a VMD file containing two message definitions and some simple Python scripts to generate auto acknowledgments. The concepts behind each VMD file are nearly identical for ACK or NACK messages, with the only difference being the actual code (AA for positive; AE for negative) that is inserted in the first field of the MSA segment.

iNTERFACEWARE's products, Chameleon and Iguana, are shipped with two VMD files that generate acknowledgment messages:

• autoack.vmd, which generates a positive acknowledgment (AA) message;
• autonack.vmd, which generates a negative acknowledgment (AE) message.

These VMD files are stored in the directory in which Iguana is installed. If you are writing a Chameleon server application using the Stubcode Generation Wizard, and you want to use either or both of these files, save a copy of the files in the directory in which your project is generated.