Current technology trends make it possible to build communication networks that can support high-performance distributed computing. This paper describes issues in the design of a prototype switch for an arbitrary topology point-to-point network with link speeds of up to 1 Gbit/s. The switch deals in fixed-length ATM-style cells, which it can process at a… (More)
An axiomatic method for proving a number of properties of parallel programs is presented. Hoare has given a set of axioms for partial correctness, but they are not strong enough in most cases. This paper defines a more powerful deductive system which is in some sense complete for partial correctness. A crucial axiom provides for the use of auxiliary… (More)
Competitive analysis is concerned with comparing the performance of on-line algorithms with that of an optimal off-line algorithm. For some problems, ran-domized on-line algorithms have yielded better performance ratios than deterministic on-line algorithms, assuming that the input sequences are generated by an adversary that has no knowledge about the… (More)
A liveness property asserts that program execution eventually reaches some desirable state. While termination has been studied extensively, many other liveness properties are important for concurrent programs. A formal proof method, based on temporal logic, for deriving liveness properties is presented. It allows a rigorous formulation of simple informal… (More)
A common operation in multiprocessor programs is acquiring a lock to protect access to shared data. Typically , the requesting thread is blocked if the lock it needs is held by another thread. The cost of blocking one thread and activating another can be a substantial part of program execution time. Alternatively, the thread could spin until the lock is… (More)
To a client of a loosely-coupled distributed system, one of the simplest services is a time service. Usually the client simply requests the time from any subset of the time servers making up the service, and uses the first reply. Issues that need to be considered in other services, such as connection establishment or client authentication, need not be… (More)
A network object is an object whose methods can be invoked over a network. This paper describes the design, implementation, and early experience with a network objects system for Modula-3. The system is novel for its overall simplicity. The paper includes a thorough description of realistic marshaling algorithms for network objects.