@InBook{	  Padovani09,
  author	= {Luca Padovani},
  title		= {{C}ontract-{B}ased {D}iscovery and {A}daptation of {W}eb
		  {S}ervices},
  booktitle	= {Formal Methods for Web Services, 9th International School
		  on Formal Methods for the Design of Computer,
		  Communication, and Software Systems (SFM 2009)},
  year		= {2009},
  volume	= {LNCS 5569},
  pages		= {213-260},
  publisher	= {Springer},
  url		= {http://www.di.unito.it/~padovani/Papers/ContractsTutorial.pdf}
		  ,
  doi		= {10.1007/978-3-642-01918-0\_6},
  abstract	= {A contract describes the observable behavior of a Web
		  service. When looking for Web services providing specific
		  capabilities, the contract can be used as an important
		  search key. This calls for a notion of contract equivalence
		  that goes beyond nominal or structural equivalence. In this
		  paper we define a simple, yet expressive formal language
		  for describing Web service contracts. We provide a natural,
		  set-theoretic semantics of contracts and we use it for
		  defining a family of equivalence relations that can be
		  effectively used for discovering and adapting Web services
		  implementing a specific contract.}
}