First Speci cation of Phoenix , an Active Database Programming

This report aims at introducing the novel active database language Phoenix which is currently under development at the computer science department of the university of Bonn. Phoenix essentially integrates three di erent concepts into one language: imperative programs, declarative database queries, and active rules. Imperative programs and declarative queries make up a database programming language that enables the user to merge procedural and declarative features at arbitrary granularity. Into this DBPL an active rule mechanism is incorporated. Active rules, called trigger-reaction rules in Phoenix, provide the possibility to locally specify adequate reactions which are to be automatically performed when certain situations arise. A situation is characterized by the occurrence of a particular event (e. g. a database update or a procedure call) and by certain conditions on the database state reached at the point in time when the event has taken place. Our major interest in developing Phoenix was to obtain a suitable tool for investigating various applications of active rule processing. A rst prototypical implementation has just been nished, such that we are able to gain practical experience as well.