Enhydra Shark http://www.enhydra.org/workflow/shark/index.html
The Enhydra Shark project delivers an Open Source Java workflow server with a difference. It is an extendable and embeddable Java open source workflow engine framework including a standard implementation completely based on WfMC specifications using XPDL (without any proprietary extensions !) as its native workflow process definition format and the WfMC "ToolAgents" API for serverside execution of system activities. Every single component (persistence layer, transaction manager, scripting engines, process repository,...) can be used with its standard implementation or extended/replaced by project specific modules.
Enhydra JaWE http://www.enhydra.org/workflow/jawe/index.html
Enhydra JaWE (Java Workflow Editor) is the first open source graphical Java workflow process editor fully according to WfMC specifications supporting XPDL as its native file format. It can be used to edit / view every XPDL file which conforms to WfMC XPDL specifications , does NOT use any proprietary XPDL extensions and is available in English, German, French and Serbian language already. Advanced features like the consistency validation and guided property editor dialogs for all XPDL objects make it really easy to create valid XPDL files. The representation of workflow participants as "swimlanes" in the editor graphics gives a comprehensive overview of process responsibilities.