Combine the merits of open-source software configuration management (SCM) tools and i5/OS native utilities.

For decades, in i5/OS (aka OS/400, iSeries, or IBM i), there has been a lack of free, powerful, and easy-to-use software configuration management (SCM) tools for i5/OS programmers working on green-screens. Now, it's the time to change this condition.

The approach I introduce here is a complete SCM solution that covers everything from source code editing to source change management to build automation. It is based on both existing i5/OS utilities, such as the Source Entry Utility (SEU) and the Portable Application Solutions Environment (PASE) make utility, and mature and powerful open-source SCM software, such as Subversion. This combination allows you to receive continual support from both IBM and the open-source community. It is based on the i5/OS Integrated File System (IFS), which is the prerequisite of applying SCM tools such as Subversion and PASE make.

These are the main steps in this solution:

Let's go through these steps one by one.

Storing Source Code in IFS

Storing source code in stream files in the IFS is the starting point of the whole SCM solution discussed here because it is the prerequisite to applying modern SCM tools. Can you imagine the efforts required to modify an existing Subversion client or implement a new one to manage source code stored in source physical file members in the library/database file system? By storing source code in stream files, you can directly apply a Subversion client with little or no need for migration or modification. But here comes the problem: how do you edit source code stored in stream files?

Editing Source Files with STMFSEU

For many green-screen programmers, the Source Entry Utility (SEU) is the preferred tool to edit source in i5/OS native languages such as RPG, CL, or DDS. But unfortunately, SEU does not support stream files and hence cannot be used to edit stream source files directly.

To solve this problem, the open-source project i5/OS Programmer's Toolkit developed the CL command Start SEU on Stream Files (STMFSEU). STMFSEU is a glue layer that connects SEU with stream source files. Enter CL command STMFSEU, set the STMF parameter to the path name of your target stream source file, and specify the OPTION parameter. Then you can edit, view, or print source stream files in your familiar SEU screen. For example, the following CL command starts SEU and allows you to edit (with syntax checking) the CL stream source file /home/pgmr/hello.clp .

Accomplishing Source Change Management by Subversion

Apache Subversion (command name svn) is a revision control system. Developers on different computers use Subversion to maintain current and historical versions of files such as source code, Web pages, and documentation. As an open-source SCM utility, Subversion is so famous for its power, usability, and flexibility that there seems no need to introduce the detailed features of Subversion in this article. If you're new to Subversion, please refer to the official documentation of Subversion, Version Control with Subversion.

To manage changes to source code stored in IFS stream files by Subversion, what we need is a Subversion client that can run on i5/OS. For this solution, I chose SVNKit, a pure-Java toolkit. It implements all Subversion features and provides APIs to work with Subversion working copies and to access and manipulate Subversion repositories. So it can be directly used on i5/OS with no change.

Installing SVNKit on i5/OS is quite straightforward. Here's an example:

Download the latest release package of SVNKit's standalone version without JNA. For example, org.tmatesoft.svn_1.3.3.standalone.nojna.zip.

Upload the .zip file to your IFS directory /usr/local and unzip it using the jar utility in PASE. To start a PASE shell session to complete the following installation steps, call program QSYS/QP2TERM.

The script file jsvn under the extracted directory has all you need to accomplish all Subversion client tasks. It works just like the standard Subversion client command svn. Make a symbolic link pointing to svnkit-1.3.3.6648/jsvn under directory /QOpenSys/usr/bin, which is by default in the PATH environment variable of each PASE shell session:

Add the system-level environment variable JAVA_HOME to your i5/OS machine using the Add Environment Variable (ADDENVVAR) Command. For example:

Note that a newly added system-level environment variable will take effect only after you've signed off your current interactive job and signed on again.

Ready to try it? Start a PASE shell session by calling program QSYS/QP2TERM; then enter the following shell command to list the contents under the target repository URL:

Automating Build Processes via the make Utility

make is a widely used dependency-tracking build utility that automatically builds binary components such as executable programs from source code by reading files called Makefiles. These are make's key features:

• Tracking dependencies of a target recursively
• Building out-of-date targets selectively
• Stopping execution when one of the targets fails to be built 

make has gone through many rewrites, including a number of from-scratch variants that used the same file format and basic algorithmic principles and also provided some of their own non-standard enhancements, e.g., BSD make and GNU make.

The Portable Operating System Interface for UNIX (POSIX) includes standardization of the basic features and operation of the make utility and is implemented with varying degrees of completeness in UNIX-based versions of make. The PASE make utility is a migrated version of AIX make, so it uses the same syntax as AIX make and behaves just like AIX make. Documentation on AIX make also applies to PASE make.

The design of make separates its dependency-driven mechanism from implementation details of this mechanism that can be defined by user: rules to build a specific target or a type of targets. For this reason, make is not limited to a single platform or to only the task of building binary components from source code. It can be used to describe and drive other processes, such as unit tests, integrated tests, and installation. It can also be used to build i5/OS objects from source code if you are willing to provide the necessary i5/OS-specific implementation: the make rules to create or update i5/OS objects.

Here is an example single-suffix rule you can use to build RPG program objects automatically from ILE RPG stream source files with filename extension .rpgle.

For more examples of make rules for building different types of i5/OS objects, please refer to Makefiles of open-source project i5/OS Programmer's Toolkit (e.g., rules.mk). Objects of most sub-projects of the project are built from PASE make.

Choosing a Proper Shell Environment

As you have seen in the above steps, to work with stream source files and directories, to access Subversion source repositories, or to initiate build processes, a proper shell environment is necessary. PASE includes three shells (Korn, Bourne, and C Shell) and over 200 utilities that you can use in your SCM processes, including the above-mentioned make utility. For example:

• File management commands, such as cat, cd, cp, file, head, tail, ln, ls, mkdir, more, mv, pwd, rm, rmdir, and wc
• Comparing and searching commands, such as diff, diff3, cmp, comm, dircmp, grep, and find
• Text-processing commands, such as cut, join, paste, sort, split, uniq, awk, and sed
• Storage commands, such as compress, uncompress, cpio, pack, and tar

Additionally, PASE uses PC character-set encodings rather than EBCDIC encoding, which cannot be handled correctly by many common-platform utilities. Stream files created in the PASE shell environment are in PC character-set encodings—for example, UTF-8 (CCSID 1208) or ISO 8859-1 (CCSID 819).

The above-mentioned reasons are why I chose PASE shells as the shell environment for SCM processes in this solution.

A Great Combination

Now green-screen programmers have an IFS-based SCM solution for i5/OS that's a combination of IBM and open-source utilities. What could be better?

If you want to learn more about using Subversion or PASE make in i5/OS, please let me know!

Junlei Li is a programmer from Tianjin, China, with 10 years of experience in software design and programming. Junlei Li began programming under i5/OS (formerly known as AS/400, iSeries) in late 2005. He is familiar with most programming languages available on i5/OS—from special-purpose languages such as OPM/ILE RPG to CL to general-purpose languages such as C, C++, Java; from strong-typed languages to script languages such as QShell and REXX. One of his favorite programming languages on i5/OS is machine interface (MI) instructions, through which one can discover some of the internal behaviors of i5/OS and some of the highlights of i5/OS in terms of operating system design.

 

Junlei Li's Web site is http://i5toolkit.sourceforge.net/, where his open-source project i5/OS Programmer's Toolkit (https://sourceforge.net/projects/i5toolkit/) is documented.

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