Actor monitors for adaptive behaviour

This paper describes a structured approach to encoding monitors in an actor language. Within a configuration of actors, each of which publishes a history, a monitor is an independent actor that triggers an action based on patterns occurring in the actor histories. The paper defines a model of monitors using features of an actor language called ESL including time, static types and higher-order functions. An implementation of monitors is evaluated in the context of a simple case study based on competitive bidding

Actor monitors for adaptive behaviour

This paper describes a structured approach to encoding monitors in an actor language. Within a configuration of actors, each of which publishes a history, a monitor is an independent actor that triggers an action based on patterns occurring in the actor histories. The paper defines a model of monitors using features of an actor language called ESL including time, static types and higher-order functions. An implementation of monitors is evaluated in the context of a simple case study based on competitive bidding

The application of message passing to concurrent programming

The development of concurrency in computer systems will be critically reviewed and an alternative strategy proposed. This is a programming language designed along semantic principles, and it is based upon the treatment of concurrent processes as values within that language's universe of discourse. An asynchronous polymorphic message system is provided to enable co-existent processes to communicate freely. This is presented as a fundamental language construct, and it is completely general purpose, as all values, however complex, can be passed as messages. Various operations are also built into the language so as to permit processes to discover and examine one another. These permit the development of robust systems, where localised failures can be detected, and action can be taken to recover. The orthogonality of the design is discussed and its implementation in terms of an incremental compiler and abstract machine interpreter is outlined in some detail. This thesis hopes to demonstrate that message-oriented communication in a highly parallel system of processes is not only a natural form of expression, but is eminently practical, so long as the entities performing the communication are values in the languag