The aim of this paper is to present an active relational DBMS which is typed and extensible (its domains are extended to Abstract data types). We were inspired by the notion of tasks in the Ada programming language to specify the activity in the system. Users dispose of a contructor to create rule behaviour modela (called) rule type ) for describing the behaviour of objects of this type when activated. Users can therefore create object rules and define relations attributes as rule. Like an Ada task, each rule is a program unit that runs in parallel with other rules or program. Its role is to execute services in response to requests. Synchronisation between the appellant and the rule is achieved using the principles of rendezvous. When an event occurs the system generates a rendezvous request with the concerned rules and services. We use the rendezvous principle to implemment composite events.