The problem of providing operating system–level support for the construction of distributed applications using the object-oriented programming approach is addressed. The authors describe the COOL project, which attempts to overcome the fundamental “mismatch between the services and abstractions that [operating] systems provide, and those that [object-oriented] languages offer.” The COOL system extends the CHORUS microkernel with support for distributed virtual memory, a generic runtime environment for distributed concurrent objects, and a language-specific runtime environment that maps the object model of the particular language to the generic runtime model. An important design feature of the COOL system is the up-call mechanism by which the generic runtime environment can access language-specific information about objects.

In addition to an overview of the design of the COOL system, the authors briefly describe the CIDRE system, which is a distributed platform for the creation and management of intelligent documents. The design of the COOL system is shown to suitably support the requirements of the CIDRE application.

Perhaps the most valuable aspect of the paper is the authors’ description of the problems of mapping the abstractions supported by object-oriented languages to the abstractions provided by the operating system. These problems become more difficult in a distributed environment with the conflicting goals of transparency and efficiency. The authors conclude by saying that even the COOL system does not completely resolve these difficulties.