I want to use as much as the default HTTP protocol here - to minimize the things that I need to explain.

HTTP protocol defines a way to submit multi-value parameters - http://en.wikipedia.org/wiki/Query_string which is how we did the args.
In my view we should use the same protocol for the list of piped commands - the only difference is that unix command are now webcommands ie, urls of webservices that support our "webcommand protocol".