ARTHUR.RUDOLPH.ART.LAVALLE@OFFICE.WANG.COM (Art LaValle) (04/03/91)
Kathy Saint of Hughes Aircraft would like a high level explanation of ISODE from someone who is familiar with Computer Science. I don't think a Computer Scientists tutorial on ISODE would be High Level, or what she wants! Has Kathy read Marshall Rose's book ? If she's looking for a "run of the mill" Software Developers view of what the "meaning" of what ISODE really is, here's mine: ISODE was funded as a means to provide a "free implementation of the OSI refer- ence model" (particularly the very upper layers). It in itself is not a prod- uct, but does provide a significant amount of developed software which can be productized by any vendor that wishes to. In deploying this "free OSI" e software the original project instigators were presenting vendors everywhere with an "offer they couldn't refuse". And I'm sure a number of vendors every- where took this stuff in and examined it to see just what it would take to productize it under their label. Another way of looking at this is, a number of very vocal customers who have been screaming that they want OSI products for years (and been somewhat frustrated at the slow appearance of them from their favorite vendors) took the bull by the horns and started the ball rolling with the "core development" we know as ISODE. Now they've turned around and said to these vendors "OK Guys here it is we've built the underlying components for you - now all you have to do is add your own flavor of product different- iation - Go to it ! These opinions are mine alone and do not necessarily represent the opinions of my employer.
osmith@acorn.co.uk (Owen Smith) (04/04/91)
In article <b39vym.mjw@wang.com> ARTHUR.RUDOLPH.ART.LAVALLE@OFFICE.WANG.COM (Art LaValle) writes: >Kathy Saint of Hughes Aircraft would like a high level explanation of ISODE >from someone who is familiar with Computer Science. I don't think a Computer >Scientists tutorial on ISODE would be High Level, or what she wants! Has Kathy >read Marshall Rose's book ? If she's looking for a "run of the mill" Software >Developers view of what the "meaning" of what ISODE really is, here's mine: > >ISODE was funded as a means to provide a "free implementation of the OSI refer- >ence model" (particularly the very upper layers). The problem I found wih ISODE version 3 was that it was too poor in quality and functionality to be used in a commercial product. The area I was involved with was ASN.1, trying to use PEPY. PEPY produced enormous code, that repeatedly did the same things. On top of that, the entire X.400 message was dragged into memory in one go, which was a bit of a shame if you were trying to process a message with 32,000 recipients and two 20 mega-byte body parts. The situation is even worse when your process is trying to simultanteously process six different messages. Virtual memory runs out eventually and anyway it is in-efficient compared to the program knowing what it is doing more. So we (Data General) went our own way. We wrote a new ASN.1 compiler which generated memory efficient tables which represented the ASN.1 and what was to be done to it (eg. value passing, pointers to action statement code functions etc.) and then we had the runtime library run over these tables doing the appropriate thing. This resulted in a very considerable (factor of two to three) memory saving over the PEPY generated code, and did not run much slower. We also allowed the programmer to break the message up and process it in bits, leaving the rest of it on disk. This didn't work very well, but it could have been made to work with a bit of a re-design. Please not that I am not trying to belittle the efforts of the people working on ISODE. As something to "get you going" it is very worthwhile, and if ISODE has improved in the areas I have highlighted above since version 3, even better. The views expressed are my own and are not necessarily those of Acorn.