One of the hard parts of any server-based architecture is knowing when your server has been canceled; this article shows you how to address that.

Written by Joe Pluta

I saw an email message in the midrange.com mailing lists the other day about the old standby for termination, the scope message. Scope messages are cool; using the QMHSNDSM API, you can identify a program to call when the job or call stack entry ends, and I'll address that another time. But I really like the CEERTX API. CEERTX is the ILE version of the concept and allows you to identify a procedure to be called if your call stack entry is terminated.

Store pointers in a job's Local Data Area.

Written by Junlei Li

The Local Data Area (LDA) is a user-domain, permanent space object (with MI object type code/subtype code hex 19CE) that is allocated to each IBM i job by the system when the job becomes active. The 1024-byte storage of an LDA can be accessed through CL commands (DSPDTAARA, RTVDTAARA, CHGDTAARA, and CHGVAR), APIs (QXXRTVDA and QXXCHGDA), or built-in support of high-level languages (the IN and OUT opcodes of RPG, and the ACCEPT and DISPLAY statements of COBOL).

Make compiling easier for service programs with the use of binding directories.

Written by Tom Snyder

With the end of the year comes time to close out my series of articles on service programs. In previous articles, I discussed how to create a service program, followed by discussing the benefits and cautions of using the binding language with your service programs. In this article, I'll discuss how to create binding directories and why you would want to use them.

Retrieve the exact table of MI object types via the undocumented API QLICNV.

Written by Junlei Li

On IBM i, historically there are two flavors when referring to objects. At the MI level, MI objects are categorized by a 2-byte MI object type code (1-byte type code and 1-byte subtype code). At the OS level, external objects (also known as CL objects) are categorized by external symbolic type names—for example, *FILE. An external object may consist of one or more MI objects. Each MI object type also has a corresponding descriptive external object type name; for example, the external object type name of a cursor object (with MI object type hex 0D50) is *MEM (Member). As you might know, the number of MI object types changes from release to release. This makes sense for an object-based system that has been evolving continuously.

Find out how to support multiple signatures and what to be aware of when changing service programs.

Written by Tom Snyder

I initially intended on just doing a three-part series that worked its way toward binding directories, but I feel as though I need to cover more on the binding language before I can move on. So this follow-up article will discuss support for multiple signatures and things that you should be cautious of when using the binding language.

Provide your users with everything they've ever wanted in a subfile program.

Written by Kevin Vandever

Editor's Note: This article is an excerpt from the book Subfiles in Free-Format RPG published by MC Press.

If you've ever looked at Program Development Manager (PDM), you might have marveled at what a cool subfile application it is. PDM is extremely flexible. It allows you to move anyplace in a subfile-like panel, page forward or backward from that position, change a record on any page of the subfile, and process all changed records only when the Enter key is pressed. On their own, each of these features is simple to code in an RPG subfile program. The real fun begins, though, when you combine the features.

Modernizing for a GUI doesn't mean you have to give up the power of RPG.

Written by Thomas M. Stockwell

Fueled by the talent of more than a dozen IBM RPG programmers, and an overall staff of 50, INFOCON is an IBM Business Partner with a vision of efficiency and service for its clients. But modernizing to a fully functional, user-friendly graphical user interface (GUI) has been a challenge.

Discover the essence and usage of the COL associated with a library.

Written by Junlei Li

In the reply post in 2009 to a question called "Best Way to Check if a Library Has At Least 1 Changed Object" in the midrange-l mailing list, CRPence mentioned the term "changed object list" (COL). The following is the original reply post by CRPence. (Sorry, Chuck, I don't know your full name.)