<XML><RECORDS><RECORD><REFERENCE_TYPE>0</REFERENCE_TYPE><REFNUM>5318</REFNUM><AUTHORS><AUTHOR>Gay,S.J.</AUTHOR><AUTHOR>Hole,M.</AUTHOR></AUTHORS><YEAR>1999</YEAR><TITLE>Types and Subtypes for Client-Server Interactions</TITLE><PLACE_PUBLISHED>Proceedings of the European Symposium on Programming Languages and Systems, Amsterdam. (Swiersta, D., Ed.). Lecture Notes in Computer Science, Volume No. 1576.</PLACE_PUBLISHED><PUBLISHER>Springer</PUBLISHER><PAGES>74-90</PAGES><ISBN>3-540-65699-5</ISBN><LABEL>Gay:1999:5318</LABEL><KEYWORDS><KEYWORD>types</KEYWORD></KEYWORDS<ABSTRACT>We define an extension of the $\pi$-calculus with a static type system which supports high-level specifications of extended patterns of communication, such as client-server protocols. Subtyping allows protocol specifications to be extended in order to describe richer behaviour; an implemented server can then be replaced by a refined implementation, without invalidating type-correctness of the overall system. We use the POP3 protocol as a concrete example of this technique.</ABSTRACT><URL>http://www.dcs.gla.ac.uk/~simon/publications/esop99.pdf</URL></RECORD></RECORDS></XML>