Experience implementing CES, a distributed collaborative editing system, is described. CES was written in Argus, a language that was designed to support the construction of reliable distributed programs, and exhibits a number of requirements typical of distributed applications. The authors' experience illustrates numerous areas in which the support provided by Argus for meeting those requirements was quite helpful, but also identifies several areas in which the support provided by Argus was inadequate. Some of the problems arise because of the distinction in Argus (and in other systems) between locally and remotely accessible data and the mechanisms provided for implementing each. Others arise because of limitations of the mechanisms for building user-defined data types. The authors discuss the problems they encountered, including the implications for other systems. They also suggest solutions to the problems, or in some cases further research directed at finding solutions.>

This paper describes our experience implementing CES, a distributed Collaborative Editing System written in Argus, a language that includes facilities for managing long-lived distributed data. Argus provides atomic actions, which simplify the handling of concurrency and failures, and mechanisms for implementing atomic data types, which ensure serializability and recoverability of actions that use them. This paper focuses on the support for atomicity in Argus, especially the support for building new atomic types. Overall the mechanisms in Argus made it relatively easy to build CES; however, we encountered interesting problems in several areas. For example, much of the processing of an atomic action in Argus is handled automatically by the run-time system; several examples are presented that illustrate areas where more explicit control in the implementations of atomic types would be useful.