Rexx Today

Since Rexx is standards-based and not owned by any one company, several Windows interpreters are available. You can select the one that best meets your own criteria. The downside to this benefit is that of the hundreds of free Rexx tools and add-ons available, not every one works with every interpreter.

The Windows Resource Kits included the Regina interpreter. Regina has come a long way since its RK days. Regina features very professional, complete documentation, a large global user community, compatibility with the special features of interpreters for other platforms, and a plethora of add-ons and extensions.

Reginald and r4 are two Rexx interpreters that are specifically extended for Windows and run only on Windows. Both come bundled with tons of free tools and easily readable documentation.

BRexx runs on many platforms. It's the Rexx to look into for handhelds running Windows CE and Windows Mobile (and even for DOS emulation). It's a very fast, lightweight system.

Thus far, I've discussed traditional procedural Rexx, usually referred to as classic Rexx. Like many traditional scripting languages, Rexx has been extended for fully object-oriented programming. Object-oriented Rexx supports classes, messaging, single and multiple inheritance, encapsulation, operator-overloading, and polymorphism. In short, all the object-oriented principles and techniques you'd expect.

Object-oriented Rexx is a true superset of classic Rexx. Any classic Rexx program runs unchanged under "OO Rexx." This yields big compatibility benefits. For example, you could download a standard mainframe Rexx script and run it under object-oriented Rexx on Windows without changing anything.

There are two object-oriented Rexx interpreters. Open Object Rexx is an open source project supported by the international Rexx Language Association. It runs under Linux and Unix as well as Windows. The Windows version integrates into Windows facilities including WSH, OLE/ActiveX, ADSI, WMI, and its own GUI runtime called OODialog. roo! is a Windows-only object Rexx from the same company that supports the r4 classic Rexx interpreter.

I should also mention NetRexx, the one Rexx interpreter that does not conform to the Rexx language standards. NetRexx is designed for Java compatibility and runs under the Java Virtual Machine. Its goal is to bring Rexx's ease of use to the Java environment. You can develop applications, applets, servlets, and beans in NetRexx. You can use Java classes in NetRexx scripts and develop classes in NetRexx for use from within Java.

Tools and Resources

One question you should always ask about any scripting language is: how many free tools are available for it? By this measure, Perl is the hands-down winner. Rexx, Tcl/Tk, Python, Ruby, Korn and the others do not approach Perl's 8,000-plus free add-on modules (see the Comprehensive Perl Archive Network for a complete list). But Rexx does offer a free tool to perform about any task you'd want. This list directs you to over 75 web sites that all offer multiple free Rexx tools. Rexx's hundreds of free tools places it somewhere in the middle of the pack among scripting languages.

The same goes for support. Rexx has three or four active forums in English, and others in French, German, Russian, and Japanese. Rexx is not the leader, but it's not the follower either. Its support level easily meets most users' needs. Of course, vendor contracts are always available if your organization is not comfortable dwelling solely in the free/open source world.

Rexx is more diverse than many languages in terms of the platforms it supports and the world-wide distribution of its user community. This is both a strength and a source of balkanization. I find it fascinating interacting with developers from such different backgrounds. My own Rexx information web site, for example, gets visitors from at least ten different countries daily and often more than twenty. For a month-old site, that's diversity! The rexxinfo.org Web site also offers free interpreter- and platform- independent information, including tutorials, downloads for all interpreters and tools, how-to's, and reference materials. You'll also want to check out the Rexx Language Assocation. Any of the Rexx intepreter web sites I've cited above also give you further information.

Does Rexx make sense for you? Like any programming language decision, it all depends on your requirements. Some developers find Rexx useful because they can code straight from memory, without reviewing the manuals even if they don't use it every day. Others like it for systems requiring high reliability or ease of maintenance. Ultimately, it's yet another free tool in your developer's toolbox.

Howard Fosdick, the author of the Rexx Programmer's Reference, is an independent DBA who has scripted in many languages.