title: Open alternatives to Windows Workflow
body: <p><strong>Pre-warning</strong>: There are some other questions similar to this but don't quite answer the question (these include: <a href="https://stackoverflow.com/questions/19314/alternatives-to-windows-workflow-foundation">Alternatives to Windows Workflow Foundation?</a>, <a href="https://stackoverflow.com/questions/932924/can-anyone-recommend-a-net-open-source-alternative-to-windows-workflow">Can anyone recommend a .Net open source alternative to Windows Workflow?</a>)</p>
  
  <p>We are developing a system that is an event based state machine, currently we are investigating windows workflow, our system needs to be low latency in its response to events from a multitude of sources (xmpp, http, sms, phone call, email etc etc) coming into the system, scalable and resilient and most importantly customisable. For a variety of reasons (and due diligence) I am looking for  open workflow engines that support functions similar to Windows Workflow Foundation (and more - if possible), mainly (but it doesn't matter too much if there are engines that don't support some features):</p>
  
  <ol>
  <li>Persistence of long running tasks, and resumption of tasks on external events</li>
  <li>High performance, low latency</li>
  <li>Ability to develop custom actions</li>
  <li>The ability to specify workflows dynamically</li>
  <li>Tracking and tracing</li>
  </ol>
  
  <p>I am not constrained to platform or language, and I would love some help and tips from you guys so that I can start to investigate the engines more closely and any experiences you had with the engines.</p>
  
  <p>Paul.</p>