Just to point out another workflow engine that hasn't been named yet:
It's explicitly unambitious and it's pure Zope 3. Those may be things
that are either good or bad, depending on your project.
It has been used in the document library for a reasonably complex
multi-version workflow. We also started to use it in the Grokstar blog
app, but that's only a start.
Here's the documentation:
I'm not advocating its use; it depends on your requirements. It isn't in
any way compatible with any standards, it lacks significant power you
may or may not need, but it is simple and fairly clean.
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