J. Eriksson. CEDE: Composite Event Detector in an Active Object-Oriented Database, Master's thesis. Department of Computer Science, University of Skvde, Sweden, 1993.  @ NUS  Home/Search   Document Not in Database   Summary   Related Articles   Check

....automatically by the system, which means that the applications does not have to signal method events explicitly. Composite events in ACOOD can be constructed by combining other primitive or composite events by using one of the following event operators: disjunction, conjunction and sequence [Eri93]. With regard to the conjunction and sequence operator it is possible to restrict the composition to events originating from the same object. This means, for example, that a conjunction will trigger only if all of its components have occurrences originating from the same object. Feature 2.b: An ....

J. Eriksson. CEDE: Composite Event Detector in an Active Object-Oriented Database, Master's thesis. Department of Computer Science, University of Skvde, Sweden, 1993.

....the consumers and producers cannot be located at separate address spaces. In order to overcome the above limitation we are working on extending the approach to a distributed, heterogeneous environment. As a proof of principle prototype, we have taken a composite event detector module, named CEDE [10], and distributed event signaling using CORBA as the distribution layer. Basically, each agent has a CORBA client process to allow it to subscribe to remote events, and a CORBA server process to receive remote event signals. 7 Conclusions In this paper we have considered the domain of result ....

J. Eriksson. CEDE: Composite Event Detector in an Active Object-Oriented Database. Master's thesis, University of Skovde, 1993.

....through object references. DEVICE uses complex events for matching production rules, therefore our rule language can also be used as a high level complex event specification language. Many active OODB systems incorporate complex event detection, e.g. Snoop [11] Samos [20] Ode [23, 24] ACOOD [16], etc. However, these systems are mainly concerned with complex temporal events and therefore their event algebra is richer and more complicated. The complex event scheme of DEVICE involves only logically connected database events, therefore a simpler event algebra and detection technique are ....

....network describe combinations of events that have occurred in the database. Furthermore these tokens describe states of the database that have been reached somehow. Since database states are persistent tokens must persist too, beyond the end of the transaction. Contrary to all previous techniques [8, 11, 16, 20, 24] where event occurrences are preserved at most until the end of the transaction, because they are not required any more, in DEVICE event occurrences must be preserved. This feature is vital for the implementation of DEVICE on other complex event supporting systems. Notice that even the preserved ....

J. Eriksson, CEDE: Composite event detector in an active object-oriented database, MSc Thesis, Dept. of Computer Science, University of Skvde, Sweden (1993).

....composite events constructed with history, negation, and closure. Several di#erent approaches are used for composite event detection including syntax graphs #Deutsch, 1994; Chakravarthy et al. 1993#, Petri nets #Gatziu and Dittrich, 1994#, #nite state automata #Gehani et al. 1992#, and arrays #Eriksson, 1993#. 2.2 Conditions The condition part of a rule is usually a boolean expression, a predicate, or a set of queries, and it is satis#ed if the expression evaluates to true, or all the queries return non empty results, respectively. In addition to the current state of the database, the condition may ....

Eriksson J., CEDE: Composite Event Detector in an Active Object-Oriented Database, Master's Thesis, UniversityofSkovde, Skovde, Sweden, 1993.

....and conjunction, whereas the latter group comprises composite events constructed with history, negation, and closure. Several different approaches are used for composite event detection including syntax graphs [Deu94, CKAK93] Petri nets [GD94] finite state automata [GJS92] and arrays [Eri93] 2.2 Conditions The condition part of a rule is usually a boolean expression, a predicate, or a set of queries, and it is satisfied if the expression evaluates to true, or all the queries return non empty results, respectively. In addition to the current state of the database, the condition ....

J. Eriksson. Cede: Composite event detector in an active object-oriented database. Master 's thesis, Department of Computer Science, University of Sk¨ovde, 1993.

....the basic definitions needed for further discussion of our concepts. The formal and complete description of our meta model can be found in [Zim97] In principal, the data and transaction models of the underlying database system are orthogo 2 Parameter contexts were later used in ACOOD [Eri93] and in an extended version in ADL [Beh95] nal to the functionality of ECA rules and thus will not be considered in our model. Definition 1: An event is an indicator for the occurrence of a situation which may require an (automatic) reaction from the system. It is defined to be an ....

....as well as their realization is postponed to a future paper. 4. 2 Specification of the Event Algebras In this section we will specify the semantics of the event algebras of Snoop, SAMOS and Ode on the basis of our meta model (for the specification of further event algebras, such as ACOOD [Eri93] ADL [Beh95] Chimera [MPC96] NAOS [CC96] see [Zim97] For each of these event algebras we will present a table which contains its specification. Each table is organized as follows. For each operator of an event algebra there is an entry that may stretch over a maximum of three rows. The first ....

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J. Eriksson. CEDE: Composite Event DEtector In A Active Object-Oriented Database. Master Thesis University of Skovde, 1993.

....generator, we need to know both the class and the name of the method to which the event definition is related. Furthermore, event generators can signal an event occurrence either before or after the execution of a method. Initial definition and implementation of composite events are explored in [9]. Event Primitive event Composite event Temporal event Method event Fig. 1 Event hierarchy 4 2.3 Rules Several approaches have been taken to representing rules within object oriented databases. Representation of rules in object oriented databases can be broadly classified into: i) rules ....

J. Eriksson. CEDE: Composite Event DEtector in an Active Object-Oriented Database, Master's thesis, Department of Computer Science, University of Skövde, Sweden, 1993.

....sequence, disjunction, and conjunction, whereas the latter group comprises composite events constructed with history, negation, and closure. Several different approaches are used for composite event detection including syntax graphs [18, 11] Petri nets [22] finite state automata [24] and arrays [20]. An event composition policy identifies which event occurrence of a particular event type will be used in the event composition process. Consider the CHAPTER 2. BACKGROUND 8 composite event defined as the sequence of event types event1 and event2, and the sequence of event occurrences e 11 , e ....

J. Eriksson. Cede: Composite event detector in an active object-oriented database. Master's thesis, Department of Computer Science, University of Sk¨ovde, 1993.

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J. Eriksson. CEDE: Composite Event DEtector in an Active Object-Oriented Database, Master's thesis, Department of Computer Science, University of Skövde, Sweden, 1993.

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