One of the simplest participants. Simply passes a workitem to a block of ruby code.

  engine.register_participant :alpha do |workitem|
    workitem.fields['time'] = Time.now
  end

This participant implicitely replies to the engine when the block execution is over.

You can pass the flow_expression (participant expression) as well.

  engine.register_participant :alpha do |workitem, flow_exp|
    workitem.fields['amount'] = flow_exp.lookup_variable('amount')
  end

do_not_thread

By default, this participant (like most other participants) is executed in its own thread (in a Ruby runtime where EventMachine is running, EM.next_tick is used instead of a new thread).

You can change that behaviour (beware block thats monopolises the whole engine !) by doing

  alpha = engine.register_participant :alpha do |workitem|
    workitem.fields['time'] = Time.now
  end

  alpha.do_not_thread = true

(you could also override do_not_thread, the method …)