Mario Bravetti Gianluigi Zavattaro Contract Compliance and Choreography Conformance in the Presence of Message Queues. 37-54 2008 WS-FM http://dx.doi.org/10.1007/978-3-642-01364-5_3 conf/wsfm/2008 db/conf/wsfm/wsfm2008.html#BravettiZ08a