The Registration Facility on your IBM i provides a multitude of exit points that let you integrate system functions with your own programs and tools by adding exit programs to these exit points. You can develop the exit programs yourself, or for some exit points, third-party products are available. Some of the more common examples of the latter are the products that monitor and control access to the client connections on your IBM i, such as FTP, Telnet, ODBC, and many others. To get an overview of all the exit points available, run the command Work with Registration Information (WRKREGINF).
Today’s APIs by Example focuses on two distinct exit points: Change Command and Retrieve Command Exit Points. The former enables you to register a single exit program for almost any CL command on your system. The latter provides for up to 10 exit programs being registered for each CL command. There are a few commands, mainly CL programming ones, for which exit programs can’t be registered. CL commands to add and remove exit programs to specific exit points and exit point formats are included with the system, as are corresponding Registration Facility APIs. With this article, I’m also adding three CL commands of my own invention to offer a dedicated support of the command exit points mentioned.
The two command exit points, QIBM_QCA_CHG_COMMAND and QIBM_QCA_RTV_COMMAND, were added to the System i Registration Facility with release 4.5.