The Reaction RuleML Classification of the Event / Action / State Processing and Reasoning Space

— Reaction RuleML is a general, practical, compact and user‐friendly XML‐serialized language for the family of reaction rules. In this white paper we give a review of the history of event / action /state processing and reaction rule ap‐ proaches and systems in different domains, define basic concepts and give a classification of the event, action, state processing and reasoning space as well as a discus‐ sion of relevant / related work 1 Overview on Event / Action Processing Active Databases and ECA Rule Systems Active databases are an important research topic due to the fact that they find many applications in real world systems and many commercial databases systems have been extended to allow the user to express active rules whose execution can update the database and trigger the further execution of active rules leading to a cascading sequence of updates (often modelled in terms of execu‐ tion programs). Several active database systems have been developed, e. These systems mainly treat event detection and processing purely pro‐ cedural and often focus on specific aspects. In this spirit of procedural ECA formalisms are also systems such as AMIT [7], RuleCore [8] or JEDI [9]. Several papers dis‐ cuss formal aspects of active databases on a more gen‐ eral level – see e.g. [10] for an overview. Several event algebras have been developed, e.g. Snoop [11], SAMOS [12], ODE [4]: The object database ODE [4] implements event‐detection mechanism using finite state automata. SAMOS [12] combines active and object‐oriented fea‐ tures in a single framework using colored Petri nets. As‐ sociated with primitive event types are a number of pa‐ rameter‐value pairs by which events of that kind are de‐ tected. SAMOS does not allow simultaneous atomic events. Snoop [11] is an event specification language which defines different restriction policies that can be applied to the operators of the algebra. Complex events are strictly ordered and cannot occur simultaneously. The detection mechanism is based on trees correspond‐ ing to the event expressions, where primitive event oc‐ currences are inserted at the leaves and propagated up‐ wards in the trees as they cause more complex events to occur. There has been a lot of research and development concerning knowledge updates in active rules (execution models) in the area of active databases and several tech‐ niques based on syntactic (e.g. triggering graphs [13] or activation graphs [14]) and semantics analysis (e.g. [15], [16]) of …