** 1 page (new) regular / 709 words **

Inside GEM

We've enjoyed Mark Wherry's System Extensions features so much we've 
perseuded him to turn them into a mini-series - now if we can just sell 
the film rights, Romancing the GEMstone, anyone?...

In previous issues we've explored programs that add extra functionality to 
your computer. In this mini-series we'll be looking at how both users and 
developrs can make use of these system extensions, so hopefully something 
of interest to everyone - please do write or email me with your questions 
and feedback so we can keep the mini-series focused. In this first episode 
I've taken a closer look at GEMScript - a subject that seems to be 
creating more than a little confusion!

Are you sitting comfortably?

First of all let's try clear up the confusion. Quite a few people seem to 
believe there's a a program called GEMScript which actually does 
something - there isn't.

GEMScript is a protocol, a mere set of rules devised by various German 
programmers including Thomas Much, Manfred Lippert and Holger Weets which 
effectively enables one program to control another.

Although GEMScript does nothing on its own, the fun begins when you have 
several programs on your system that are GEMScript aware, like CAB, Texel, 
jinnee, GEMJing, GEMTrade and so on.

At its most basic level, two GEMScript aware programs could communicate to 
achieve certain tasks, but in order to make the most of the protocol you 
need a GEMScript interpreter. This is a program which can send user 
specified GEMScript commands to other programs - effectively allowing 
specified tasks to be carried out autonomously.

Back in the DOS style Command Line Interface (CLI) era batch files were 
used to automate repetitive tasks and processed using programs like Mupfel 
on the Atari platfrom. These days the graphical user interface (GUI) 
reigns supreme and automating modern GEM applications required a 
different approach.

Think about the tasks you carry out regulary, for example, logging onto 
the internet and visiting a series of websites to check the latest news, 
running a Texel spreadsheet to generate reports and printing out the 
results for future reference and so on. How many mouse clicks do these 
tasks normally take? I've run out of fingers (and toes), but if I use a 
GEMScript interpreter I can count the clicks on one finger!

We need an interpreter!

** SIMPSCRP.GIF here
** RD11.IMG here

Currently two GEMScript interpreters exist: Scripter, a German commercial 
product published by ASH and my own Simple Script which I have released as 
freeware and you can find on the Reader Disk.

Both products have different uses. For example, although both interpreters 
can carry out the simple tasks mentioned above if you want to write a set 
of instructions which fully interacts with the receiving program then 
Scripter is your only choice. Scripter is a full interpreted C-style 
programming language and very powerful.

** SCRIPTER.GIF here

How it works

The GEMScript protocol implements a system where commands can be sent to 
an application that has been established to support them. The application 
then tries to execute a command and returns the result to the sender. To 
use the interpreter you must first of all create a list of instructions (a 
script) using an ASCII editor (Everest, QED, Edith etc) then this can be 
loaded into the interpreter which executes your script. To understand this 
more fully, here's a flowchart:

** FLOWCHAR.GIF here

Conclusion

Hopefully by now you'll be aware of the potential this offers GEM 
programmers and you're interested enough to try out the scripts included 
with Simple Script. Of course you can modify the scripts or write your own 
to perform other tasks if you have suitable GEMScript aware applications.

Next time we'll delve further and look at how programmers can implement 
GEMScript support. There's more information on my web pages, including 
some English GEMScript documentation at:

** BC **
http://www.cix.co.uk/~mark_wherry/
Email: mark_wherry@cix.co.uk
4 Fernpark Close, Topsham Road, Exeter, Devon, EX2 6AW, England
** /BC **

** SCRIPT.GIF
Here's a script you can run in Simple Script which plays a sound sample in 
GEMjing then opens CAB's internal pages