PHP and Workflow Engines

Hi, Have you implemented or planned to implement a PHP interface to a workflow engine instead of building the process routing logic into the PHP scripts? The idea is to separate the processing of activities (mainly through the interactions of users an a web form) and the connections between those activities that route an instance of a process from start to end. The benefits I see are mutliple, but the main ones are: - If business logic and routing logic are not separated, then every modelled business process must handle its own life and implement its own supporting structure (db tables, etc.) resulting in a lot of inefficiency and duplication. - Processes modelled would not be flexible to change. - Better fit in the enterprise framework: if handled by a standalone workflow engine, processes can contain some activities executed by user over a PHP web app, while other activities are executed on other applications (ERP, etc). Following are some of the points I am considering to go forward: - Follow standards with as few deviations as possible to ease upgrade and integrations with existing tools: http://www.wfmc.org/, XPDL, etc. - The workflow engine itself would probably not be built on PHP; again, follow standards such as OMG, etc... - Evaluate open-source wf engines: http://wfmopen.sourceforge.net/ seems like an interesting option, but there are quite a few, most of them written in Java. Please let me know if you are interested in continuing this discussion. Pascal