S.Gatzin, A.Geppert and K.R.Dittrich, "Integrating Active Concepts into an Object-Oriented Database System", Proc 3rd International Workshop on database programming languages, Nafplion, 1991.  Home/Search   Document Details and Download   Summary   Related Articles   Check

....Rgles Actives, lvnements primitifs et composites, Dtection d vnements. 1 Introduction In this paper, we are interested in events in active databases. Such databases are becoming popular and many research projects concern this area [12, 23, 17, 23, 29] also many prototypes have been developed [27, 30, 15, 22, 8, 2]. Event models and languages have received a lot of attention [18, 26, 16, 14, 5] Events are either considered as points in time [16, 14] or as happening of interest occurring at specific points in time [18] Events may be primitive (e.g. the update of Bobs salary) or composite, i.e. comprised ....

S. Gatziu, A. Geppert, and K.R. Dittrich. Integrating active concepts into an object- oriented database system. In Proc. of the 3rd Int. Workshop on Database Programming Languages: Bulk Types 4 Persistent Data, pages 399-415, Nafplion - Greece, 1991. Morgan Kaufmann.

....rule concept. References: BBKZ92] BBKZ93] BZBW95] BB95] 2.15 SAMOS SAMOS is a project at the University of Zurich, Switzerland. While aiming at the HiPAC functionality, it has a rich language comparable to ODE (2.13) A prototype is implemented on top of ObjectStore. References: GGD91] GD92] GD93a] GD93b] GD94] GGD95a] Secondary: PDW 93] TGD95] 2.16 Sentinel Sentinel is a project at the University of Florida, Database Systems Research and Development Center, Gainesville, Florida. It developed directly from results obtained in the HiPAC project. Several ....

S. Gatziu, A. Geppert, and K.R. Dittrich. Integrating active concepts into an object-oriented database system. In 3rd Int'l.Workshop on Database Programming Languages, Naflion, August 1991. Annotation: This paper introduces the basic concepts of the SAMOS project. It is a good description of the utilization of object-oriented features for active rules.

....2.13 SAMOS SAMOS is a project at the University of Zurich, Switzerland. While aiming at the HiPAC functionality, it has a rich language comparable to ODE (2.11) A prototype was based on GemStone OODB. GD93a] and [GD94] mention a new prototype implementation on top of ObjectStore. References: GGD91] GD92] GD93a] GD93b] GD94] 3 SPECIAL ISSUES 4 2.14 Sentinel Sentinel is a project at the University of Florida, Database Systems Research and Development Center, Gainesville, Florida. It developed directly from results obtained in the HiPAC project. Several papers discuss prototypes ....

S. Gatziu, A. Geppert, and K.R. Dittrich. Integrating active concepts into an object-oriented database system. In 3rd Int'l.Workshop on Database Programming Languages, Naflion, August 1991. Annotation: This paper introduces the basic concepts of the SAMOS project. It is a good description of the utilization of object-oriented features for active rules.

....of its transition predicate occurs and the ECA rule s precondition evaluates to true. That is to say, an ECA rule consists of events, conditions and actions. The semantics of an ECA rule is that when the event occurs, evaluate the condition; if the condition is true, then execute the action(s) [10]. Characteristics of ECA rules and their collective behaviour in both relational and object oriented database systems have been analysed by various researchers and are now well known [4, 24] ECA rules have been used for database system extensions like supporting integrity constraints, for closed ....

Gatziu E, Geppert A, Dittrich K R (1991). Integrating active concepts into an object-oriented database system. In: 3 rd International Workshop on Database Programming Languages, Naphlion, Greece.

....section 4 describes in detail the production rule compilation scheme, while section 5 briefly sketches incremental rule matching. Finally, section 6 discusses various implementation issues and section 7 concludes the paper. 2. Related Work Several active OODB systems have been developed so far [8, 11, 13, 20]. Traditionally OODB systems incorporate ECA rules only, since event driven rules conform to the message driven nature of OODB programming languages. Potential event is every recognisable message method and rule triggering can be easily implemented as a detour from normal method execution. ....

Gatziu, S, Geppert, A and Dittrich, K R, Integrating active concepts into an object-oriented database system, in: Kanellakis, P and Schmidt, J W, eds., Proc. 3rd Workshop on Database Programming Languages, Morgan-Kaufmann, 1991, 399-415.

....features of E DEVICE; Section 7 discusses the system performance, presenting results for deductive rules; and finally, section 8 concludes this paper with a summary of the main points and a discussion of future work. 2. Related Work There are several active OODB systems that support ECA rules [9, 10, 12, 11, 15]. The ECA rule type is the most easy to implement in OODBs since events conform to the message passing paradigm of OO computation and every recognizable message method can be a potential event. Therefore, they can be executed as a detour from normal method execution. There are a few active OODB ....

S. Gatziu, A. Geppert, and K.R. Dittrich, " Integrating active concepts into an object-oriented database system," Proc. Workshop on Database Programming Languages, Morgan-Kaufmann, Nafplion, Greece, 1991, pp. 399415.

....with various optimizations, and section 8 presents some performance results. Finally, section 9 concludes this paper with a summary of the main points and a discussion of future work. 2. Rule Integration in Active Databases Several active database systems have appeared in the literature so far [10, 12, 14, 21, 22, 28, 29, 38, 44]. All of them incorporate the active rule facility which allows one to provide automatic execution of database operations in response to certain events and or conditions. There is a certain confusion about the term active rules ; some researchers [28, 29] denote by this term the production rules ....

....database operations in response to certain events and or conditions. There is a certain confusion about the term active rules ; some researchers [28, 29] denote by this term the production rules met in expert system technology [17, 18] while others refer to the Event Condition Action (ECA) rules [10, 12, 14, 21] met in many active database systems. To avoid the confusion we will explicitly use the above terms interchangeably with the term data driven for the production rules, i.e. the rules of the form: #FRQGLWLRQ#7 (1#DFWLRQ because these rules describe data states that should be reached in order ....

[Article contains additional citation context not shown here]

S. Gatziu, A. Geppert and K.R. Dittrich, Integrating active concepts into an object-oriented database system, Proc. 3rd Workshop on Database Programming Languages, Nafplion, Greece, Morgan-Kaufmann (1991) 399-415.

....are based on the query language of the underlying database system, and thus support declarative expression of conditions and straightforward facilities for performing updates. Such systems generally have simple event specification languages and execution models. Active object oriented databases [12, 17, 11, 6], which are based on the programming language of the underlying database system, and thus support procedural mechanisms for the expression of conditions and for performing updates. Such systems generally have sophisticated event specification languages and execution models. However, the trend ....

....are based on the query language of the underlying database system, and thus support declarative expression of conditions and straightforward facilities for performing updates. Such systems generally have simple event specification languages and execution models. Active object oriented databases [12, 17, 11, 6], which are based on the programming language of the underlying database system, and thus support procedural mechanisms for the expression of conditions and for performing updates. Such systems generally have sophisticated event specification languages and execution models. However, the trend ....

S. Gatziu, A. Geppert, and K. Dittrich. Integrating active concepts into an objectoriented database system. In P. Kanellakis and J.W. Schmidt, editors, Proc. 3 rd Workshop on Database Programming Languages. Morgan-Kaufmann, 1991.

....that are executed automatically when certain conditions are met. They offer a flexible, unifying mechanism for common database management tasks, like constraint enforcement and view maintenance. As a consequence, a number of proposals for incorporating rules into DBMS s appeared recently [16, 4, 6, 3, 9, 5, 2, 11, 12]. The correct implementation of constraint enforcement and view maintenance based on rules requires that the set is confluent and terminates [15] A rule set terminates if its execution terminates on all database states. A terminating rule set is confluent if for each initial database state db 0 ....

S. Gatziu, A. Geppert, and K.R. Dittrich. Integrating active concepts into an object-oriented database system. In Proceedings of the 3th International Workshop on DBPL, pages 341--357, 1991.

....most important advantage of object orientation is the encapsulation of data and behaviour in one object. Rules are part of the behaviour of objects. They describe what actions triggered in specific situation. Examples of object oriented DBMSs that offer encapsulation of rules in objects are SAMOS [15] and Chimera [10] However, these systems offer a hybrid model. In both systems it is still possible to define rules separate from a class. Thus, we do not have a single place to look for the behaviour of an object. We take encapsulation to its extremes. All behaviour is encapsulated with an ....

....= M(S; I(fc (a)ja 2 Ag) 4. Related Research Active Databases An autonomous objects has active rules. Therefore a database of autonomous objects is an active database. Some active DBMSs have been constructed using the relational model [16, 25] Others are based on an object oriented data model [15, 12]. In most systems there is a separate rulebase, where all rules are stored. In an object oriented system this rulebase can be integrated with the database [13, 14] in such a way that rules can be treated as objects themselves. A object oriented system would offer the possibility of defining a rule ....

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Stella Gatziu, Andreas Geppert, and Klaus R. Dittrich. Integrating active concepts into an object-oriented database system. In Paris Kanellakis and Joachim W. Schmidt, editors, The Third International Workshop on Database Programming Languages: Bulk Types and Persistent Data, pages 399-415, San Mateo,. CA, USA, August 1991. Morgan Kaufmann.

....2.13 SAMOS SAMOS is a project at the University of Zurich, Switzerland. While aiming at the HiPAC functionality, it has a rich language comparable to ODE (2.11) A prototype was based on GemStone OODB. GD93a] and [GD94] mention a new prototype implementation on top of ObjectStore. References: GGD91] GD92] GD93a] GD93b] GD94] Secondary: PDW 93] 2.14 Sentinel Sentinel is a project at the University of Florida, Database Systems Research and Development Center, Gainesville, Florida. It developed directly from results obtained in the HiPAC project. Several papers discuss ....

S. Gatziu, A. Geppert, and K.R. Dittrich. Integrating active concepts into an object-oriented database system. In 3rd Int'l.Workshop on Database Programming Languages, Naflion, August 1991.

....that executes concurrently with the triggering transaction. The same modes are available for C A coupling, which specifies the relationship between condition evaluation and action execution. 2. 2 SAMOS The overall goal of SAMOS (Swiss Active Mechanism Based Object Oriented Database System) [Gatz91, Gatz92, Gatz94] is the combination of active and objectoriented characteristics within one coherent system by means of a layered approach. Since current OODBS differ in their data models and functionalities only characteristic properties provided by almost all OODBS, like inheritance, user definable types and ....

S. Gatziu, A. Geppert, K.R. Dittrich, Integrating Active Concepts into an Object-Oriented Database System, Proc. of the 3rd Int. Workshop on Database Programming Languages, Nafplion, August 1991

.... Ramamritham, 1987) In general, these assumptions are not applicable in the type of complex environments that characterize the next generation of real time systems (Stankovic, 1988b) Considerable research has been made on reactive databases, e.g. Chakravarthy, 1989; Gehani and Jagadish, 1991; Gatziu et al. 1991), and also real time databases, e.g. Singal, 1988) but results on reactive real time databases are limited to discussion in a few research projects, e.g HiPAC (Chakravarthy et al. 1989) and REACH (Buchmann et al. 1992) In the HiPAC report, active databases and time constrained databases are ....

Gatziu, S., Geppert, A., and Dittrich, K. (1991). Integrating active concepts into an objectoriented database system. In Proc. Third Int'l Workshop on Database Programming Languages (DBPL), Nafplion, Greece.

.... When object oriented database systems [ADM 89] were developed, projects on integrating reactive behavior into such systems emerged, the most comprehensive being HiPAC [CBB 89] which was followed by several projects such as Sentinel [Cha89, CM91] from University of Florida, and SAMOS [GGD91, GD92] developed at Universitat Zurich. Other active OODBMSs are Ode [GJ91, GJ92, GJS92a] from AT T, ADAM [Pat89] REACH [BBKZ93] from Technical University of Darmstadt, which also includes real time behavior, and ACOOD [Ber91] and DeeDS [AHEM94, AHE 96] from University of Skovde. All of the ....

Stella Gatziu, Andreas Geppert, and Klaus R. Dittrich. Integrating active concepts into an object-oriented database system. Proceedings on the Third International Workshop on Database Programming Languages (DBPL), Nafplion, Greece, August 1991.

....1991] Stonebraker et al. 1990] Stonebraker and Kemnitz 1991] Delcambre and Etheredge 1988] Widom et al. 1991] Widom and Finkelstein 1990] Beeri and Milo 1991] Cohen 1989] Diaz et al. 1991] Kotz et al. 1988] Schreier et al. 1991] Simon et al. 1992] Buchmann 1990] E. Anwar 1993] S. Gatziu 1991] In this chapter, we will illustrate the features of active database systems using Ariel [Hanson 1992] HiPAC [Chakravarthy et al. 1989, Dayal et al. 1988, McCarthy and Dayal 1989] POSTGRES [Stonebraker et al. 1990, Stonebraker and Kemnitz 1991] and Starburst [Widom et al. 1991, Widom and ....

....describing run time rule processing in HiPAC, it is necessary to introduce the concept of coupling modes. Coupling modes originated in the HiPAC project but subsequently have been discussed in the context of other active database systems, e.g. Gehani and Jagadish 1991, Schreier et al. 1991, S. Gatziu 1991, E. Anwar 1993, Buchmann 1990] Coupling modes determine how rule events, conditions, and actions relate to database transactions. Whereas in Ariel, POSTGRES, Starburst, and many other active database systems, rule conditions are evaluated and actions are executed in the same transaction as the ....

S. Gatziu, A. Geppert, K. D. (1991). Integrating active concepts into an objectoriented database systems. In Proceedings of the Third International Workshop on Database Programming Languages.

....be required to express the same functionality as a single production rule. Thus systems which support only ECA rules may provide cumbersome solutions to certain tasks which have been felt to be important applications of active functionality. While many proposals have been made for active OODBs [13, 22, 17, 12, 29], none of these support production rules. There thus seems to be a need for work on the integration of production rule facilities with OODBs. This paper addresses two issues of relevance to this task the way in which such functionality can be implemented, and the performance which can be ....

S. Gatziu, A. Geppert, and K. Dittrich. Integrating active concepts into an object-oriented database system. In P. Kanellakis and J.W. Schmidt, editors, Proc. 3 rd Workshop on Database Programming Languages. Morgan-Kaufmann, 1991.

....extended model based methodology with notable flexibility in reuse. This paper shows its applicability to this area with a formal respecification of the Starburst active rule system. The specifica2 tion is structurally comparable with active rule system implementations in which rules are objects [7, 8, 11], with three important distinctions: 1. functionality inherited from the underlying system in the implementations is made overt here; 2. the Object Z specification is much more concise and readable than the implementations; 3. Object Z is amenable to formal reasoning, allowing for verification of ....

....environments for Petri nets (such as LOOPN from the University of Tasmania) There are some tools for analysis of nets, but they can only decide a limited range of questions about temporal phenomena. Petri nets have been employed in event specification formalisms for active databases; see [11]. 3.2.8 Process algebras These include CCS [29] CSP [18] and simpler calculi like path expressions and flow languages. These systems have not been used for large scale specifications, and are only modular in a limited sense (some form of compositionality holds for some of them) These systems ....

Stella Gatziu, Andreas Geppert, and Klaus Dittrich. Integrating active concepts into an objectoriented database system. In P. Kanellakis and J.W. Schmidt, editors, Proc. 3 rd Workshop on Database Programming Languages. MorganKaufmann, 1991.

.... Corporation of America (and later Xerox) which pioneered many of the features and techniques found in active databases today [DBM88] Other important object oriented systems include Ode, which uses finitestate automata to detect events [AG89] SAMOS, which uses Petri net based event detection [GGD91]; and Sentinel, which features a subscription scheme for linking events to rules [AMC93] A number of well developed active relational databases also exist, such as Postgres [SK91] Ariel [Han92] and Starburst [WF90] Many specific proposals have been made for using active databases in various ....

S. Gatziu, A. Geppert, K.R. Dittrich, "Integrating active concepts into an object-oriented database system," in 3rd International Workshop on Database Programming Languages, Naphlion, Greece (1991).

....GemStone. Concerning the underlying concepts of active object oriented database systems it is commonly accepted that the pioneering work of HiPAC [Daya88] in terms of its knowledge model and execution model has influenced a whole fleet of active object oriented database system proposals, e.g. [Anwa93, Chak90, Diaz91, Gatz91, Geha91, Kotz93, Mede91]. TriGS also builds on this work. Like in most systems the knowledge model of TriGS comprises Event Condition Action (ECA) rules. Unlike most systems, however, TriGS does not exploit coupling modes to describe the execution model of the rule scheduler. Instead, the event specification mechanism is ....

....continues evaluating the next condition. Finally, the Action Executor has to execute all actions still waiting for execution within the AEP dictionary according to the specified priorities and according to the specified transaction semantics. 5. Comparison and Outlook Almost all active systems [Daya88, Diaz91, Gatz91, Geha91, Mede91, Kotz93] use coupling modes to define CEPs and AEPs, which implies that the condition has to be evaluated either immediately after the signaled event ( immediate coupling) or at the end of the triggering transaction ( deferred coupling) or in a separate transaction ( separate coupling) The same ....

S. Gatziu, A. Geppert, K.R. Dittrich, Integrating Active Concepts into an Object-Oriented Database System, Proc. of the 3rd Int. Workshop on Database Programming Languages, Nafplion,

.... very powerful rule language for an object oriented data model, a flexible execution semantics, and several main memory experimental prototypes [20] Recently there has been an explosion of projects in object oriented active database systems many of these projects are still preliminary; see e.g. [3,4,6,7,10,11, 24,25,26,27,33,35]. Several previous papers have described language, implementation, or application development issues related to the Starburst Rule System. An initial proposal for the Starburst rule language appears in [49] 48] describes how the extensibility features of the Starburst prototype are used in ....

S. Gatziu, A. Geppert, and K.R. Dittrich. Integrating active concepts into an object-oriented database system. In Proceedings of the Third International Workshop on Database Programming Languages, Nafplion, Greece, August 1991.

.... combination of the above dimensions, has recently been proposed and inves 1 An expert database sysetm that uses deductive reasoning (backward chaining) is often referred to as a Deductive Database System [17] tigated, as exemplified by such prototypes systems as HiPac [13] ADAM [15] SAMOS [19], Ode [20, 22] Chimera [4] and Sentinel [8] A system taking such an approach allows a wide range of internal functions and external applications to be supported in a more general and extensible manner. Some of these systems are implemented by developing a totally new database kernel from ....

....22] Chimera [4] and Sentinel [8] A system taking such an approach allows a wide range of internal functions and external applications to be supported in a more general and extensible manner. Some of these systems are implemented by developing a totally new database kernel from scratch (e.g. [14, 15, 19, 22]) and others by building a special rule management module inside an existing OODBMS (e.g. 4, 8] However, this built in approach is system specific, rather than general purpose, as the specially implemented database kernel and or rule management module can not be (easily) used by different ....

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S. Gatziu, A. Geppert, and K.R. Dittrich. "Integrating active concepts into an object-oriented database system." In Proceedings of the 3rd Int'l Workshop on Database Programming Languages, pages 399--415, 1992.

....point(E) 2DAYS) monitors the occurrence of E during two days in August after its first occurrence. 3 Integrating active Components into an OO Environment The combination of active and object oriented characteristics within one, coherent system is another major goal of SAMOS [GGD 91] Using ooDBS characteristics like user defined types, methods, inheritance or encapsulation increases the flexibility of an active mechanism twofold: first in that method and value events are supported and second in that rules are subject to encapsulation and inheritance and are represented as ....

S. Gatziu, A. Geppert, K.R. Dittrich. Integrating Active Concepts into an Object-Oriented Database System. Proc. of the 3. Intl. Workshop on Database Programming Languages, August 91.

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S.Gatzin, A.Geppert and K.R.Dittrich, "Integrating Active Concepts into an Object-Oriented Database System", Proc 3rd International Workshop on database programming languages, Nafplion, 1991.

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GGD91 S. Gatziu, A. Geppert, K.R. Dittrich: "Integrating Active Concepts into an Object-Oriented Database System", Proc. 3rd. Int. Workshop on Database Programming Languages (DBPL), Nafplion, 1991.

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S. Gatziu, A. Geppert, and K.R. Dittrich, "Integrating Active Concepts into an Object-Oriented Database System", Proc. of the Third International Workshop on Database Programming Languages, August 1991.

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