CODASYL

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CODASYL (often spelt Codasyl) is an acronym for "Conference on Data Systems Languages". This was an IT industry consortium formed in 1959 to guide the development of a standard programming language that could be used on many computers. This effort led to the development of COBOL.

CODASYL's members were individuals from industry and government involved in data processing activity. Its larger goal was to promote more effective data systems analysis, design, and implementation. The organization worked on various languages over the years but never actually standardized one. The standardization process was left to ANSI.

In 1965 CODASYL formed a List Processing Task Force. This group was chartered to develop COBOL language extensions for processing collections of records; the name arose because Charles Bachman's IDS system (which was the main technical input to the project) managed relationships between records using chains of pointers. In 1967 the group renamed itself the Data Base Task Group, and its first report in January 1968 was entitled COBOL extensions to handle data bases. In October 1969 the DBTG published its first language specifications for the network database model which became generally known as the Codasyl Data Model. This specification in fact defined several separate languages: a data description language (DDL) to define the schema of the database, another DDL to create one or more subschemas defining application views of the database; and a data manipulation language (DML) defining verbs for embedding in the COBOL programming language to request and update data in the database. Although the work was focused on COBOL, the idea of a host-language independent database was starting to emerge, prompted by IBM's advocacy of PL/I as a COBOL replacement.

In 1971, largely in response to the need for programming language independence, the work was reorganized: development of the Data Description Language was continued by the Data Description Language Committee, while the COBOL DML was taken over by the COBOL language committee. With hindsight, this split had unfortunate consequences. The two groups never quite managed to synchronize their specifications, leaving vendors to patch up the differences. The inevitable consequence was a lack of interoperability among implementations.

A number of vendors implemented database products conforming (roughly) to the DBTG specifications: the most well-known implementations were Honeywell's Integrated Data Store (IDS/2), Cullinet's Integrated Database Management System IDMS, Univac's DMS-1100, and Digital Equipment Corporation's DBMS32. Cullinet, originally known as Cullinane, obtained the technology from B.F. Goodrich. Cullinet was eventually sold to Computer Associates, which as of 2006 still sells and supports a version of IDMS.

Some of the CODASYL committees continue their work today, but CODASYL itself no longer exists. The records of CODASYL were donated to the Charles Babbage Institute and may be found at their website.

Interest in CODASYL generally faded due to growing interest in relational databases beginning in the early 1980's.

[edit] References

The Codasyl Approach to Data Base Management. T. William Olle. Wiley, 1978. ISBN 0-471-99579-7.
The Codasyl Model. J. S. Knowles and D. M. R. Bell, in Databases - Role and Structure, ed. P. M. Stocker, P. M. D. Gray, and M. P. Atkinson, CUP, 1984. ISBN 0-521-25430-2