Transact ion Mechanisms for Softvcwe Environment Databases

Databases for software environments have a set of requirements that are fundarnentally different from conventional databases. Besides requiring an objectoriented or semantic data model, CASE databases need to support interactive design transactions, trigger facilities, and an application model for integrating software tools. Design transactions are necessary for interactive applications where the duration of a transaction may last days or months. Triggers are useful for incremental da.ta derivation and constraint nialntenance. Composite tools, built by reusing tool components, require a multithreaded transaction facilit,y where changes made by one member tool are immediat,ely visible t80 other members, and the entire complex tool executes as one transaction. This paper describes design transactions, multithreaded transact,ions, t.he int,eract,ion between the transact,ion model and triggers, and the rationale for including these features in an environment database.