A few years ago I bought my first Apple PowerMac G4 in order to try and get into producing my own music. At the time I was doing a bit of part time DJing and fancied getting into creating bootlegs and remixes. Sadly, a lack of talent let me down. However, one app I did find easy and intuitive to use was Propellerheads Reason. Reason allowed you to link up soft synths, mixers, drum machines and more into a virtual rack. When you spun it around, it displayed the back of the rack panel, complete with patch cables for joining everything together. You could direct an input such as a drum machine into a modulator such as the subtractor and produce all sorts of weird and wonderful sounds.
As you moved cables around and tweaked knobs on the front of the rack, so the output generated changed in real-time. All very impressive and fun.
The Pipes API is very similar and employs a lot of the same concepts. It has the same patch cable type approach to wiring the modules together, and the debugger shows you the results of your actions pretty much immediately. All in all it is one of the most impressive web based UIs I’ve ever seen.
Looking again at Tim O’Reilly’s post about pipes, I notice that Jamie Pitts makes the same connection to Reason in a comment. On his blog, he also references the similarity to Apple Quartz Composer, which I admit I’d not come across before.