Someone asked what we use to produce the documentation for VoltDB. The simple answer is DocBook.
svn as our source repository, XSLTPROC, DITA is modelled after “topic maps” rather than books. This makes DITA better suited for hypertext information, particularly HTML-based online help. If you are looking for an online-only solution, I would recommend DITA over Docbook. However, the topic map model makes DITA less effective for printed or sequential content.