The REXX Sourcebook (inf)

About the REXX SourceBook

The REXX Sourcebook is a collection of REXX information gotten from various places on the Internet and turned into a document. Except as noted, I have not contributed any of the factual information contained herein.

Dirk Terrell

Frequently Asked Questions About REXX

By Eric Giguere

Introduction

This document is intended to serve as a useful reference for REXX-related information. It aims for breadth as opposed to depth, and references to other material are given where appropriate. Suggestions and updates should be sent to the author in an attempt to keep this document relevant and up- to-date.

Readers will notice the prevalence of OS/2-related materials in this document. Most of the REXX-related activity at this time is occurring on the OS/2 platform. This document is not intended to be OS/2-specific. The author is quite happy to include information on other platforms if you pass it on to him.

More information on REXX can also be had from the REXX Language Association.

What is REXX

REXX is a programming language designed by Michael Cowlishaw of IBM UK Laboratories. In his own words: "REXX is a procedural language that allows programs and algorithms to be written in a clear and structured way." REXX doesn't look that different from any other procedural language. Here's a simple REXX program:

/* Count some numbers */

say "Counting..."
do i = 1 to 10
say "Number" i
end

What makes REXX different from most other languages is that it is also designed to be used as a macro language by arbitrary application programs. The idea is that application developers don't have to design their own macro languages and interpreters. Instead they use REXX as the macro language and support the REXX programming interface. If a REXX macro comes across an expression or function call that it cannot resolve, it can ask the application to handle it instead. The application only has to support the features that are specific to it, freeing the developer from handling the mundane (and time-consuming) task of writing a language interpreter. And if all applications use REXX as their macro language, the user only has to learn one language instead of a dozen.

REXX and the Internet

Networks connect computers in various ways for the exchange of data. The terminology is a bit confusing to the new user. Here are the definitions this document uses:

Usenet: Not really a network, just the set of machines that exchange network news. Network news is really an extended form of electronic mail that groups messages from individuals into newsgroups that users can read using special newsreaders.

Internet: The worldwide network based on TCP/IP protocols. Besides being able to receive mail and newsgroups, these machines can use programs like ftp and telnet to communicate with other machines in real time. Most Internet machines are Unix-based.

BITNET: The worldwide network that connects many IBM mainframes. BITNET users can also transfer files using methods that are incompatible with those of the Internet.

NewsGroups

The Usenet group comp.lang.rexx exists for discussion of REXX in all its variations. Anything posted to this newsgroup also gets sent to the REXXLIST mailing list (see below) and vice-versa.

Other newsgroups of interest are machine-specific. Recommended groups are comp.os.os2.programmer and comp.sys.amiga.programmer.

FTP Sites of Interest

FTP is a file transmission protocol used on the Internet to transfer files between machines. The transfers are done in real time and usually require that the user have an account on both machines. However, many machines on the Internet support what is known as anonymous FTP, which allows users on other machines access to a limited set of files without requiring an account. Some of the more interesting sites that offer this service are:

rexx.uwaterloo.ca General repository for REXX-related information, including free REXX interpreters for Unix and DOS. An XEDIT clone for Unix and OS/2 may also be found here. Look under /pub/rexx.

flipper.pvv.unit.no The official home of Regina, one of the free Unix interpreters. An archive of the messages in comp.lang.rexx is also maintained here. Check under /pub/rexx.

ftp-os2.cdrom.com, ftp.luth.se General OS/2 archives.

wuarchive.wustl.edu General Amiga archive. Look under /pub/aminet.

Mailing Lists

Mailing lists are similar to newsgroups but use normal electronic mail to deliver the messages. The following mailing lists are mostly BITNET-based but are accessible from the Internet as well:

      List name     BITNET      Internet           Discusses
                     Node        Address
      REXXLIST      UCF1VM    ucf1vm.cc.ucf.edu    REXX in general
       AREXX-L      UCF1VM    ucf1vm.cc.ucf.edu    Amiga REXX
       PC-REXX      UCF1VM    ucf1vm.cc.ucf.edu    Personal REXX
      REXXCOMP      UCF1VM    ucf1vm.cc.ucf.edu    IBM's REXX compiler
      TSO-REXX      UCF1VM    ucf1vm.cc.ucf.edu    TSO REXX
       VM-REXX      UCF1VM    ucf1vm.cc.ucf.edu    VM/SP REXX
       UREXX-L      (none)    liverpool.ac.ak      Unix REXX

To subscribe to any of these lists, send a one-line message to the address LISTSERV@node, where node is the BITNET node or Internet address for the list you wish to join. In the body of your message should be the line

SUBSCRIBE list-name your--full-name

as in

SUBSCRIBE UREXX-L Eric Giguere

You will then be subscribed to the list and messages will start arriving in your mailbox. To send a message to the list, simply mail it to listname@node, as in UREXX- L@liverpool.ac.uk. Note the distinction between the LISTSERV address and the listname address. You can receive help by sending a HELP message to the LISTSERV address. Note that some of these mailing lists may be available on Usenet in the form of newsgroups with names starting with "bit.listserv". Ask your system administrator if you're not sure.

Thanks to Scott Ophof for providing this summary.

Gopher Service

Gopher clients may find REXX-related information at the site gopher.pvv.unit.no (Europe) and index.almaden.ibm.com (N. America).

Free REXX Productos

This sections contains information on some free REXX products.

Interpreters

There are at least three REXX interpreters available for free on the Internet. The first two are Unix based and are well-supported by their authors. The third is an MS-DOS interpreter.

Regina is Anders Christensen's REXX interpreter for various flavours of Unix and VMS. It is fairly complete and Anders even has an API for developers. It also apparently can be ported to OS/2. Anders can be reached at anders@pvv.unit.no. Regina's official home is ftp.pvv.unit.no.

REXX/imc is Ian Collier's REXX interpreter for SunOS, though it has also been ported to other Unix systems. Ian can be reached at imc@prg.ox.ac.uk.

BREXX is Bill Vlachoudis' REXX interpreter for MS-DOS. The interpreter is not complete but is quite small. Bill can be reached at bill@donoussa.physics.auth.gr.

All three interpreters are available for anonymous FTP on rexx.uwaterloo.ca in the /pub/freerexx directory, each interpreter in its own subdirectory. Regina and REXX/imc are in source form, BREXX is only available as binary.

REXX-Aware Text Editors

Also on rexx.uwaterloo.ca in the /pub/editors directory is the text editor THE by Mark Hessling (mark@snark.itc.gu.edu.au). THE is a full-featured XEDIT/KEDIT clone (by XEDIT here we mean the IBM mainframe text editor, not the X Windows editor xedit) with REXX support. THE is available in versions for OS/2 and Unix. THE's official home is on ftp.gu.edu.au in /src/THE.

Comercial REXX Products

This Section contains information on some commercial REXX products.