Asterisk PBX. Well-chosen small set of module types (channel drivers, applications, functions, resources, codecs & formats), allowing to implement literally any behaviour, and converge with any thinkable external technology. Not working in VoIP anymore for quite long time, but the clarity of design of Asterisk has deeply influenced me.
Gstreamer. Pipeline is very powerful model for software, the potential of it is tremendous. Unfortunately I find level of development & maintenance of Gstreamer project itself quite poor - the code is horribly complicated for questionable reasons (it's said to be non-blocking everywhere; I find it bad excuse for being ridden with subtle bugs and for failures to use custom pipelines as blocks for higher-level pipelines).
I find such projects as ffmpeg and linux kernel quite well engineered, but have nothing special to say about them except that they are reasonably well organized and get better day by day.
For user-interface apps with considerations of high user productivity, I find such software as readline, tmux, mutt and bunch of other following wise pattern of extensible and scriptable software: if you want hotkeys, you need a domain-specific language and bindings must be
I am grateful to work with a few of the asterisk developers and they strive hard for quality. A project that long running and feature-rich is not easy to keep up to date, stable and well architected. If you want to see a project with professional commit messages, it is a solid example (the past several years at least).
Just in case anyone were to be led to believe this:
Asterisk's code base is a pile of crap.
It's been getting a bit better over the years, but it still is terrible, tons of conceptual blunder, protocol implementations are only losely inspired by the specification, system APIs are used incorrectly, lots of code doesn't bother with dynamic string lengths, but instead simply truncates strings arbitrarily if they don't fit into some fixed-size buffer, ...
The only reason it kindof works is because bugs that happen often enough do end up being fixed at some point, but that's about it. If you know your C and POSIX APIs and you don't believe me, just go and have a look at the code, I promise you'll find a bug in less than an hour.
Yes I know Asterisk is ridden with bugs and has very nasty spots at its core (e.g. "channel cloning" or whatever it is called). It was my job to debug the code with gdb and valgrind :)
What is still amazing to me is the set of core design concepts which I've listed - channels, applications... I have a case for comparison here, where the project is of comparable complexity but all features are bolted-on ad-hoc without such complexity compartmentalization which Asterisk has.
Gstreamer. Pipeline is very powerful model for software, the potential of it is tremendous. Unfortunately I find level of development & maintenance of Gstreamer project itself quite poor - the code is horribly complicated for questionable reasons (it's said to be non-blocking everywhere; I find it bad excuse for being ridden with subtle bugs and for failures to use custom pipelines as blocks for higher-level pipelines).
I find such projects as ffmpeg and linux kernel quite well engineered, but have nothing special to say about them except that they are reasonably well organized and get better day by day.
For user-interface apps with considerations of high user productivity, I find such software as readline, tmux, mutt and bunch of other following wise pattern of extensible and scriptable software: if you want hotkeys, you need a domain-specific language and bindings must be
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