On Linux using ALSA (and something similar is probably possible with JACK):
* It is possible to create virtual MIDI ports. These ports can be accessed by other programs on the system (I haven't checked to see if they need to be running as the same user). Hence, if a DAW can take input from a MIDI device, it can take input from a virtual MIDI device created by my program.
* It is possible, using aconnect, to connect MIDI ports to each other. This isn't necessarily a 1:1 mapping, so I can connect the keyboard to both timidity (a software synth) and another program that records it at the same time. I could also choose to connect the keyboard to my program's input, and my program's output to timidity.

So, I can easily connect devices and programs together without too much trouble. This does really feel a lot like UNIX pipes, which allow connecting the standard output of one program to the standard input of another, and given that UNIX pipes are very useful, this whole MIDI routing should also be similarly useful.

(Also, there's nothing preventing me from making a program to send MIDI messages over the network.)

I got a simple transposition program to work.

Play a note on the keyboard, and out comes a note a whole step lower. With this, I could play a Bb clarinet part on the keyboard and have it sound at the correct pitch.

Of course, I could just play that part on an actual clarinet, but then I wouldn't be able to send the note to another program.

Now I can play with other transformations, like inverting everything or randomizing the key to pitch mapping.

(One thing: My program doesn't do any error checking, so if the keyboard sent some midi event other than a note, it would probably crash; that wouldn't be too hard to fix, however.)

Edit: Why has this topic, which has spawned some interesting (and non-controversial) discussion, been "low rated"?

Aye. I also wrote a little fractal renderer a few weeks ago. Unfortunately you can't do deep zooms because it's stuck with 64-bit floats.

Some folks may not see the pleasure of getting a new piece of computer hardware.

I still remember my first printer.

*sigh*

I was wondering the same thing. I've dinged you a few times but not as much as I've upvoted you. Misery loves company and all that sort of pettiness, I suppose.

I upvoted to balance it out. Maybe people did not get the "joke". I can even imagine people thinking "This forum would be chaos if everyone would create a topic whenever they buy a new 'keyboard' "