Can somebody recommend any task + workflow management engine?

Does somebody know any good open source (ideally free) task + workflow management engine (library, framework)? Maybe something like activity.org.

Preferably with: organization structure (hierarchy) management, collaboration work, document workflows. Ideally with implementation of BPMN/BPEL.

Based on Ruby (ideally), Java, PHP. Or maybe does somebody know any plugins with this functionality (say for Redmine, Trac)?

Solution

You may have a look on some opensource BPEL alternatives like;