the REXX Files- by Paul Monaghan

Okay, so here I am again, talking about my REXX exploits. I apologize to all my readers for not being here last month, day jobs can be such a pain, but the dust has settled and I am back in the REXX saddle again. I left you last time, talking about REXX add-ons such as REXXUTIL, and I'm back to continue where I left off. This month we'll talk about Surf'nRexx, a REXX DLL from InnoVal Systems Solutions, Inc. I'll also lead into Visual REXX and VX-REXX, the granddaddy of REXX DLLs.

Surf'nRexx is a great little REXX extension, and really shows what REXX can do if someone sits down and writes a simple DLL. Surf'nRexx is an Internet add-on for REXX that comes with a great set of already written utilities for doing such things as sending e-mail from the command line, etc. But I don't want to turn this into a review of Surf'nRexx (after all there is already one in this issue). I want to talk about Surf'nRexx from the programmer's standpoint.

Surf'nRexx is quite a simple DLL, and if used correctly will let any REXX program be "Interneted". Take myself for instance, as a Network Manager of an Internet Service Provider (my new position) I intend to write a program that monitors the e-mail server on our network by simply sending e-mail to the server every 15-20 minutes--a simple thing to do with Surf'nRexx, but this is not where the program will stop. The program will then get the e-mail that it just sent; if there is a network error during the sending or receiving, the program will send the message again; if it fails again, it will then send a few commands to a modem that will page me. Quite simple and very easy to do with Surf'nRexx.

There are a few things that one must know when implementing any of Surf'nRexx's functions. First, many people probably don't understand the TCP/IP protocol as well as Surf'nRexx wants them to; you don't simply send e-mail with Surf'nRexx by giving it a command "Send Email". Suffice it to say, you need to connect to the correct TCP/IP port for the service you wish to use (TCP/IP has standard ports for most functions, for example, HTTP (WWW) is port 80). You also have to make certain that you are using the correct protocol for the service you want to use; the WWW uses HTTP (HyperText Transfer Protocol). For the most part Surf'nRexx is configured to use the de facto standard ports and protocols for the services it utilizes, but all of these things have to be taken into account when using Surf'nRexx if you are writing your own REXX programs or using nonstandard port addresses.

Once the protocol and the port have been established, you are more or less off and running, and can "Internet enable" your REXX applications in no time. Imagine writing a small text editor in Visual REXX; you could simply add a few lines of code and the Surf'nRexx DLL and e-mail text files directly from the editor, it's that easy!

Speaking of Visual REXX...

Okay, now on to visual REXX. There are several companies out there making visual programming tools for REXX, but I'd have to say that HockWare's VisPro REXX, and Watcom's VX-REXX, are the two big players. Using a visual programming environment is a little daunting at first--after all, you're programming backwards! But these visual tools for REXX are nothing more that a collection of DLL's for describing Windows, dialog boxes and the like.

VisPro REXX, and VX-REXX, like any graphically oriented development tools, are also event driven. By this I mean that you draw a button, such as an "OK" button, and you then assign REXX code to the button. Every time the "OK" button is pressed it executes the code associated to it. A little weird at first, but you soon get the hang of it. In this day and age most people don't take a program seriously unless it's visual, and with REXX visual tools you can create these programs with very little bother.

I hope to be speaking more on VX-REXX and VisPro REXX in upcoming columns. For those that are interested, both HOCK-WARE and WATCOM have Web pages, with downloadable demos of both their visual programming environments. As for Surf'nRexx check out InnoVal's web page for more info, and don't forget to read the full review of Surf'nRexx in this month's issue.

That's it for this month, tune in next time for more REXX, and hopefully we'll dive into VisPro or VX-REXX. See ya in a month!

Paul Monaghan is a Network Manager for ULIX a Montreal ISP. He also maintains a web page on How to make a BBS Telnetable and is a member of Team OS/2.

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