You might be interested in reading about Frontier, Dave Winer's outline/tree-oriented scripting language/object database/web server from the 90s:

http://davewiner.userland.com/historyOfFrontier

More context: http://scripting.com/davenet/

A lot of the infrastructure of the current web sprung out of Dave Winer's experiments with Frontier. From RSS/OPML/podcasts to weblogs to RPC-over-HTTP, Dave and his employees at UserLand (which included Brent Simmons and IIRC Aaron Swartz) were pioneers that contributed a lot to the Internet we currently live in.