modify_process_dynamically.rb

# in reply to http://groups.google.com/group/openwferu-users/browse_frm/thread/96354a232e2cad8e

# let's assume the engine is accessible via the 'engine' variable and
# that the process instance id (wfid) is '20090119-biropoheku'

process_status = engine.processes_status('20090119-biropoheku')

sequence_expression = process_status.all_expressions.find { |fexp|
  fexp.fei.expid == '0.0'
  # or
  #fexp.class == OpenWFE::SequenceExpression
}

sequence_expression.raw_expression = [
  'sequence', {}, [
    [ 'get_pictures', {}, [] ],
    [ 'concurrence', { 'merge_type' => 'mix' }, [
      [ 'user_alice', {}, [] ],
      [ 'user_bob', {}, [] ]
    ] ],
    [ 'show_pictures', {}, [] ] # <== adding this participant
  ]
]

engine.update_expression(sequence_expression)

# ...