a.rb

require 'rubygems'
require 'yajl'
require 'ruote'

engine = Ruote::Engine.new(Ruote::Worker.new(Ruote::HashStorage.new))

pdef = Ruote.define do
  sequence do
    alpha
    bravo
    zebulon
  end
end

class ThisParticipant
  include Ruote::LocalParticipant
  def consume (workitem)
    puts "* #{workitem.participant_name}"
    reply_to_engine(workitem)
  end
end
class ThatParticipant
  include Ruote::LocalParticipant
  def consume (workitem)
    puts ". #{workitem.participant_name}"
    # no reply to engine
  end
  def cancel (fei, flavour)
    # ok, let pass
  end
  def do_not_thread; true; end
end

engine.register_participant 'alpha', ThisParticipant
engine.register_participant 'bravo', ThisParticipant
engine.register_participant 'charlie', ThisParticipant
engine.register_participant 'zebulon', ThatParticipant

#engine.context.logger.noisy = true

wfid = engine.launch(pdef)

engine.wait_for(:zebulon)

ps = engine.process(wfid)

sequence = ps.expressions.find { |fexp| fexp.fei.expid == '0_0' }

puts "re_applying..."

engine.re_apply(sequence.fei, :tree => Ruote.to_tree do
  sequence do
    charlie
    bravo
    alpha
  end
end)

engine.wait_for(wfid)