experience with CASE/diagramming tools in Erlang

Ulf Wiger <>
Wed Mar 14 13:18:17 CET 2001

On 14 Mar 2001, Torbjorn Tornkvist wrote:

>Magnus Fröberg wrote a SDL-pr to Erlang compiler
>a number of years ago. There should exist a paper
>describing it somewhere (perhaps www.ericsson.se/cslab ).
>The conclusion was basically: "why bother, it is easier
>to write the code directly in Erlang".
>Cheers /Tobbe

Yes... except developing complex systems is not just about getting 
runnable code.

There are some excellent system architects that don't enjoy having
to read Erlang in order to understand how a system is implemented
(I know one personally, he sits 5 meters away from me, has 
programmed in a large variety of languages -- but not Erlang --
and has done research on distributed systems at MIT; another
sitting 5 meters in the other direction is the chairman of ATM
Forum -- also not an Erlang programmer.) 

In order to discuss architecture with these people, you need some
documentation other than the code. How will you write this 
documentation? They both understand SDL pretty well...
Once written, how does the documentation keep up with the 

Also, I'd like to say that you can implement complex state machines
in Erlang, and automatically extract a graphical model of the FSM
from the code, but it just doesn't work like that (try it.)

Basically, for excellent Erlang programmers, excellently well 
written Erlang code needs very little other documentation. 
But many of our programmers are more average than excellent, and 
much of our code (even much code written by excellent programmers) 
is everything but excellently written.

Then, you need some good tools for describing your models as well
-- something other than MS Word or FrameMaker...

I'm not saying that generating Erlang from SDL/SDT is necessarily 
the answer. I'm just saying that there is a need for something along 
those lines.

Ulf Wiger                                    tfn: +46  8 719 81 95
Senior System Architect                      mob: +46 70 519 81 95
Strategic Product & System Management    ATM Multiservice Networks
Data Backbone & Optical Services Division      Ericsson Telecom AB

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