A relational model of data for large shared data banks
Communications of the ACM
SOSP '69 Proceedings of the second symposium on Operating systems principles
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This paper describes the Janus data management and analysis system which has been designed at the Cambridge Project. A prototype of Janus is currently running on the Multics time-sharing system at M.I.T. The data model for the design of Janus is very general and should be usable as a model for data handling in general, as well as for Janus in particular. The Janus command language is an English-like language based on procedural functions - such as define, display, and delete - which act on logical objects from the data model, such as datasets, attributes and entities. For example, delete-attribute, define-attribute and define-dataset are all commands. The implementation of Janus is interesting for a number of reasons: it runs on the Multics system which has segmented and paged memory; it is based almost entirely on datasets (tables), which describe each other as well as themselves; and it is organized in a functionally modular way that is often talked about, but less often done.