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						                              The abstract boundary that a service exposes. It defines the types of messages and the message exchange patterns that are involved in interacting with the service, together with any conditions implied by those messages.
						                            Source(s):
						                            
								                            
                                                                    NIST SP 800-95
										                            
                                                                            Web Services Glossary - W3C Working Group Note 11 February 2004