A Concurrent Object Calculus with Types that Express Sequences

              Franz Puntigam and Christof Peter
    Institut für Computersprachen, Technische Universität Wien
           Argentinierstraße 8, A-1040 Vienna, Austria
             E-mail: franz@complang.tuwien.ac.at

Sequencing of messages specified by types of objects is desirable
especially in concurrent systems. Types in popular concurrent object
calculi cannot support sequencing of messages. We present a calculus
that supports sequencing of messages and compare it to the calculus
of Vasconcelos and Honda. Type safety in our calculus does not allow
a certain kind of nondeterminism supported by other calculi.