On RDMSs Look, I like SQL as much as the next man, but its really not appropraite for storing application state. RDMSs have loads of features that we just dont need for this.
Most applications allready handle saving (some of) thier state to a file, we just need to define a way to instruct them to do it on demand, into a particular directory (socket, fifo, signal+/tmp, whatever). When they want to be restarted they can be given the file as an argument. Simple. One hard thing is how to deal with communication interdependencies, eg. app A talks jack to app B and app B talks alsa sequencer to app A. - Steve
