A Tour of Hybrid --- {A} Language for Programming with Active Objects

Abstract

Object-oriented programming is a powerful paradigmfor organizing software into reusable components.There have been several attempts to adapt and extendthis paradigm to the programming of concurrent anddistributed applications. Hybrid is a language whosedesign attempts to retain multiple inheritance,genericity and strong-typing, and incorporate anotion of active objects. Objects in Hybrid arepotentially active entities that communicate withone another through a message-passing protocolloosely based on remote procedure calls.Non-blocking calls and delay queues are the twobasic mechanisms for interleaving and schedulingactivities. A prototype implementation of a compilerand run-time system for Hybrid have been completed.We shall review aspects of the language design andattempt to evaluate its shortcomings. We concludewith a list of requirements that we pose as achallenge for the design of future concurrentobject-oriented languages.