Tag Archives: ESA

Architecture of a Real World Haskell Application part II

OK, did take some time since the last post, but I am really busy now.

Last time we looked at the general structure of the application in terms of threads and model/interface separation. For this post, I want to write a little bit about the protocol handling and parsing and how it evolved. While this is not the most central part of the application, it is the oldest and therefore I think good to show some historical development.

Ok, so the tool began as a command line application which could only receive telecommands and send back correct responses (which on itself is not as simple as it sounds). Also at that point in time I just more or less started learning Haskell while my main language at that time was C++, so of course the first solution was a lot C++ like. So let’s see how it goes.

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Architecture of a Real World Haskell Application

There were numerous posts on reddit, SO and the like which were asking for how to architect real world Haskell applications. Well, this is my go at it for an in-house testing tool which is used extensively. I would not claim myself an advanced Haskeller, some of the code is probably not idiomatic Haskell (and also some parts are really, ah well, horrible), it’s (by it’s nature) very stateful (read: imperative), BUT… it works. It even worked out better than I thought initially…

How it came to this…

I am working in the space domain and I am mostly concerned with mission control systems, especially the ones from the ESA (European Space Agency) named SCOS-2000. What we needed was a tool to be able to test certain new features implemented in the mission control system with a closed-loop test. The standard tools that come with SCOS are quite limited (and buggy) and written quite verbosely in C++. So why not try to create one in Haskell?

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