Gatziu, S., et al.: SAMOS: An active object-oriented database system. IEEE Data Engineering, Special issue on active databases. (1992) 15(1-4): 23-26  Home/Search   Document Details and Download   Summary   Related Articles   Check

....interested in all people entering a room after a broken window was signaled, but only the first one. 3 Methods for Composite Event Filtering Several proposals have been made for the filtering of composite events. We distinguish approaches using automata (e.g. Ode [7] petri nets (e.g. Samos [6], Eve [9] or trees (e.g. Ready [11] GEM [16] Here, we do not consider the specific conditions of distributed event filtering. Example 1. Let us consider a composite event profile for the sequence of two events within a time span T : E T = E 1 ; E 2 ) T . The steps for the detection of the ....

....the composite event is detected. This extension is shown in the second row in Figure 1. Petri Nets Petri nets are used in several event based systems to support the detection of complex events that are composed of parameterized primitive events, for example in the active database system SAMOS [6], and the monitoring system HiFi [2] In a Petri Net created for a profile regarding a composite event, the input places refer to primitive events, and the output places model the composite event. Each new profile describing a composite event causes the creation of the appropriate Petri Net. The ....

S. Gatziu and K. R. Dittrich. SAMOS: An Active Object-Oriented Database System. IEEE Quarterly Bulletin on Data Engineering, Special Issue on Active Databases, 15(1-4):23--26, December 1992.

....the case where the pattern is a variable x : T . In this case, we dene E : T # x F : T iff T = T and E satises F 8. Related work Most work into event languages and composite event detection has been in the context of active databases and ECA (Event Condition Action) rules [7] 11][10] [5] ECA Rules are of the form on event, if condition then action . An ECA Rule, like a subscription in a publish subscribe network, is user dened, but, unlike publish subscribe networks, most active databases are centralised systems with centralised event detection capability. Event languages ....

S. Gatziu and K. Dittrich. SAMOS: An Active ObjectOriented Database System. IEEE Quarterly Bulletin on Data Engineering, Special Issue on Active Databases, 15(14) :23--26, December 1992.

....simple algorithms, clustering, and tree based algorithms. Several hybrid algorithms have also been introduced; these algorithms support certain types of operators, such as equality or inequalityoperators, set containment, or range tests (see [6] Other approaches support SQL oriented queries [7, 10], XMLquery languages [2, 4, 5] or IR like keyword queries [15] Our work is inspired by tree based indexing strategies for keyword based search, such as the ranked tree method [14] Closely related to our work is the Elvin system [13] which includes a quenching mechanism that discards unneeded ....

S. Gatziu and K. Dittrich. SAMOS: An Active ObjectOriented Database System. IEEE Quarterly Bulletin on Data Engineering, 15(1-4):23--26, 1992.

....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 papers ....

.... [HJ91] MT95] Smi92] SKdM92] Wid93] WF90] Object Oriented Extensions of object oriented data models are desribed in: References: AMC93] BBKZ92] BBKZ93] BOGM92] BL92] CHS92] CM93] CM95] DPG91] DJPAQ94] DM89] EGB93] Etz93c] FRS93b] GGD95a] HK87] HK89] GD92] GD93a] GD93b] IK93] KD93] KLS92] LW93] MPC96] NI93] RS92] SC93] SVK93] TJ95] 3.5 Deductive Approaches Rule processing in deductive databases has a formal semantics. It is often restricted to first order logic and therefore is not well suited for active rule processing ....

Stella Gatziu and K.R. Dittrich. SAMOS: An active object-oriented database system. IEEE Quarterly Bulletin on Data Engineering, 15(1-4):23--26, December 1992. Annotation: This paper gives a short but very good overview on the project 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 on the ....

.... in: References: GHJ93] HJ91] Smi92] Beh94] SKdM92] Wid93] WF90] Object Oriented Extensions of object oriented datamodels are desribed in: References: AMC93] BBKZ92] BBKZ93] BOGM92] BL92] CHS92] CM93] DPG91] DJPAQ94] DM89] EGB93] HK87] HK89] Etz93] GD92] GD93a] GD93b] IK93] KD93] KLS92] LW93] NI93] RS92] SC93] SVK93] 3.4 Deductive Approaches Rule processing in deductive databases has a formal semantics. It is often restricted to first order logic and therefore is not well suited for active rule processing which requires a ....

Stella Gatziu and K.R. Dittrich. SAMOS: An active object-oriented database system. IEEE Quarterly Bulletin on Data Engineering, 15(1-4):23--26, December 1992. Annotation: This paper gives a short but very good overview on the project SAMOS.

....[3] 14] which extends the O database programming language with facilities for expressing rules in the form of constraints and triggers. Among other projects we would like to mention Adam [15] NAOS [16] SAMOS IEEE TRANSACTIONS ON KNOWLEDGE AND DATA ENGINEERING, VOL. XX, NO. Y, MONTH 1999 3 [17] and TriGS [4] In Table I we compare these systems along a number of dimensions. Among the considered systems, NAOS and TriGS are extensions of commercial object oriented database systems with active capabilities. All the proposals support ECA rules. However, in some systems, such as Ode, ....

....in NAOS the elimination of events due to net effect composition results in the de triggering of rules, this is not true for Chimera. IEEE TRANSACTIONS ON KNOWLEDGE AND DATA ENGINEERING, VOL. XX, NO. Y, MONTH 1999 4 HiPAC Ode Adam NAOS TriGS SAMOS Chimera Reference [10] 3] 14] 15] 16] 4] [17] [18] o o data model OODAPLEX new new O 2 GemStone new new messages messages messages messages messages messages messages primitive db ops db ops db ops db ops db ops events temporal temporal user def temporal migrations external user def event composition YES YES NO YES NO YES YES (1) ....

S. Gatziu and K. Dittrich, "SAMOS: an Active Object-Oriented Database System," IEEE Data Engineering Bulletin, Special Issue on Active Databases, vol. 15, no. 4, pp. 23--26, December 1992.

.... which is an efficient event monitoring techniqure, and event contexts; Gehani and Jagadish, 1992b, Gehani and Jagadish, 1992a, Jagadish et al. 1992, Gehani et al. 1993] covering the active database ODE which are based on finite state maching for event detection rather than event graphs; [Gatziu and Dittrich, 1992, Gatziu and Dittrich, 1993, Gatziu et al. 1994] covering the active database SAMOS. Real time databases: Articles: Ramamritham, 1993a, Ramamritham, 1993b] which give a good overview of the problems in real time databases; Graham, 1992, Kao and Garcia Molina, 1992] additional ....

Gatziu, S. and Dittrich, K. R. (1992). SAMOS: An active object-oriented database system. IEEE Data Engineering, Special issue on active databases, 15(1-4):23--26.

.... discuss the stream based operator graph approach as used in Sentinel ( CKAK94] Kri94] Reach [BBKZ92] Adl [Beh95] Smile [Jae95] and others ( PW93] WC94] Variations of the graph approach are: finite automata in Ode ( GJS92b] GJS92a] and modified colored Petri nets in Samos ( Gat95] GD92] GD94] Operator Graphs. An operator graph is represented by a set of nodes and edges. An edge indicates a stream of totally ordered entries. Entries are appended at the end of the stream and received from the head. A node is either a leaf, a root, or an operator node. A detection graph forms ....

....produces the composition of A:14 and B:17, bearing the time stamp 17. ticks LEAF (A) LEAF (B) BEFORE 1 A:14 2 B:17 3 (A:14; B:17; 17) Table 1. Example table for BEFORE(A,B) Composite event detection in ADBMS so far is sequential and centralized ( Beh95] BBKZ92] CKAK94] Gat95] GD92] GJS92b] Jae95] Kri94] PW93] WC94] For composite events the detection process advances step by step with each constituent event. The composite event detector accepts events in a totally ordered stream. For the sequential synchronized execution of the operator graph, we assume that new ....

S. Gatziu and K.R. Dittrich. SAMOS: An Active Object-Oriented Database System. IEEE Quarterly Bulletin on Data Engineering, 15(1-4), December 1992.

....can be cast as an event; discussing implementation issues; and comparing our approach with other systems. The paper is structured as follows. In Section 2 we describe PFL, including its support for transactions and ECA rules, we compare the expressiveness of event specification with that of SAMOS [9, 10], and we describe how event detection can be optimised. In Section 3 we specify the semantics of transaction execution. Abort handling complicates these semantics so we postpone this issue to Section 4. The invocation of any function can be designated as an event as we show in Section 5. In ....

....in our approach no implicit event 8 consumption occurs; instead, all primitive events that have occurred since the last commit are accessible via the history relations. 2.6. Expressiveness of event specification In this section we compare the expressiveness of events in PFL with those of SAMOS [9], which we take as representative of ECA systems with a rich set of event specification constructs. Primitive events in SAMOS are recorded with four event parameters: the transaction id, the object triggering the event, the time of the event occurrence and the originating user. The last two of ....

Gatziu, S. and Dittrich, K.R. "SAMOS: an Active Object-Oriented Database System", IEEE Bulletin of the TC on Data Engineering: Special Issue on Active Databases, 15:(1-4), 1992.

....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 prototypes on the ....

.... in: References: GHJ93] HJ91] Smi92] Beh94] SKdM92] Wid93] WF90] Object Oriented Extensions of object oriented datamodels are desribed in: References: AMC93] BBKZ92] BBKZ93] BOGM92] BL92] CHS92] CM93] DPG91] DJPAQ94] DM89] EGB93] HK87] HK89] Etz93] GD92] GD93a] GD93b] IK93] KD93] KLS92] LW93] NI93] RS92] SC93] SVK93] 3.4 Deductive Approaches Rule processing in deductive databases has a formal semantics. It is often restricted to first order logic and therefore is not well suited for active rule processing which requires a ....

Stella Gatziu and K.R. Dittrich. SAMOS: An active object-oriented database system. IEEE Quarterly Bulletin on Data Engineering, 15(1-4):23--26, December 1992.

....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, K.R. Dittrich, SAMOS: an Active Object-Oriented Database System, Bulletin of the IEEE Technical Commitee on Data Enginieering, Vol. 15, No. 1-4, December 1992

.... 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 and Klaus R. Dittrich. SAMOS: An active object-oriented database system. IEEE Data Engineering, Special issue on active databases, 15(1-4):27-- 30, December 1992.

....et des donn ees d eriv ees, des autorisations, des alerteurs, des bases de connaissance, des applications de workflow . Les bases de donn ees actives ont donn e lieu a de nombreuses recherches durant les derni eres ann ees [WC96] Elles ont abouti a l impl ementation de plusieurs prototypes [WC96, CC94, SKdM92, KRSWV94, AMC93, GJ91, GD92] tant dans le cadre des bases de donn ees relationnelles que dans celui des bases de donn ees objet. Actuellement, cette technologie a atteint un stade de maturit e tel que plusieurs syst emes de bases de donn ees relationnelles commercialis es offrent des m ecanismes d ex ecution de r egles ....

....exemples des choix s emantiques adopt es par les diff erents syst emes actifs et support es par notre mod ele. Les syst emes consid er es sont : NAOS [CC94] TriGS [KRSWV94] Sentinel [AMC93] A RDL [SKdM92] Starbust [WCL91] Ode [GJ91, GJS92] Chimera, Ariel, WC96] Exact [DPG91] et Samos [GD92]. 3 L architecture 3.1 Fonctionnalit es Notre syst eme fonctionne au dessus de la base de donn ees objet passive O2. Ses principales caract eristiques sont les suivantes : ffl ex ecution des r egles de fa con s equentielle en mode synchrone, ffl compilation des r egles et des transactions (pas ....

S. Gatziu, K.R. Dittrich. SAMOS: An Active Object-Oriented Database System. IEEE Data Engineering Bulletin, Special Issue on Active Databases, 15(4):23--26, December 1992.

....called decomposable PTL, that is amenable to more efficient evaluation. We present an evaluation algorithm for decomposable PTL. We also describe the implementation of the system on top of the Sybase DBMS. 1 Introduction The most popular model of rules in active database systems is the ECA model [42, 7, 29, 6, 15, 19]. It defines a rule to consist of three parts, event, condition, and action. The semantics is that whenever the event happens, the condition (which is usually a database query) is evaluated, and if satisfied then the action is taken. One drawback of ECA is that the condition is static and cannot ....

S. Gatziu and K. Dittrich, SAMOS: an Active Object-Oriented Database System, Data Engineering Bulletin, Dec. 92.

....can distinguish triggers and assertions as proposed for System R [EC75, Esw76] to enforce integrity constraints and declarative rules to express relationships between data items. Active rule systems for object oriented DBMSs have also been developed. Two representatives of this class are SAMOS [GD93] and HiPAC [DBM88] SAMOS supports its own object oriented data model whereas HiPAC is a prototype rule system for the object oriented data model PROBE. Conventional DBMSs only manipulate data as a reaction to a request from an application. In this sense these systems can be regarded as ....

S. Gatziu and K.R. Dittrich. SAMOS: An Active Object-Oriented Database System. IEEE Quarterly Bulletin on Data Engineering, January 1993.

....temporal aggregates. We present an efficient incremental algorithm for detecting conditions specified in this language. The given algorithm, for a subclass of the logic, was implemented on top of Sybase. 0 1 Introduction The most popular model of rules in active database systems is the ECA model [41, 6, 28, 5, 14, 18]. It defines a rule to consist of three parts, event, condition, and action. The semantics is that whenever the event happens, the condition (which is usually a database query) is evaluated, and if satisfied then the action is taken. The event may be composite and temporal, such as, transaction A ....

S. Gatziu and K. Dittrich, SAMOS: an Active Object-Oriented Database System, Data Engineering Bulletin, Dec. 92.

....The next requirement is storage of transition tables. The best any proposed systems seem to support is event parameters, which are the values of the data that caused the event. For instance, when a stock price changes, the new and or old value might be included as event parameters. In SAMOS [GD92], the user has to choose which value is used, although both can be supported with additional rules and use of versioning. Even given both values, there are still two shortcomings. First, only data involved in the event is stored and not data computed in the condition check: this is equivalent to ....

S. Gatziu and K.R. Dittrich. SAMOS:an active object-oriented database system. IEEE Data Engineering Bulletin, 15(4):23--6, 1992.

....Events represent real world situations (e.g. a machine breakdown) that form the basis for subsequent rule execution. TriGS supports message events, that is any message sent to an object may be associated with a message event, and time events (e.g. every day or at 9 p.m. as proposed in SAMOS [Gatz92]. The condition part of a rule is specified by a condition event selector, which defines when to evaluate the condition, and a Boolean expression (e.g. is the machine available ) possibly based on the result of a database query (e.g. select all orders that are scheduled on the damaged machine) ....

S. Gatziu, K.R. Dittrich, SAMOS: an Active Object-Oriented Database System, IEEE Bulletin of the Technical Commitee on Data Enginieering, Vol. 15, No. 1-4, December 1992

....is Ode [25, 27, 26] which extends the O database programming language with facilities for expressing rules in the form of constraints and triggers. A prototype implementation of Ode has recently been completed [31] Among other projects we would like to mention Adam [21] NAOS [19] SAMOS [24] and TriGS [29] In Table 1 we compare these systems along a number of dimensions. Among the considered systems, NAOS and TriGS are extension of commercial object oriented database systems with active capabilities. All the proposals support ECA rules; however, in some systems, such as Ode, ....

....The considered systems differ not only with respect to the supported rule language, but also for the rule execution semantics. First of all, active database rule execution can be either instance oriented or set4 HiPAC Ode Adam NAOS TriGS SAMOS Chimera Reference [20] 25, 26] 21] 19] 29] [24] [14] o o data model OODAPLEX new new O 2 GemStone new new messages messages messages messages messages messages messages primitive db ops db ops db ops db ops db ops events temporal temporal user def temporal migrations external user def event composition YES YES NO NO NO YES YES (1) parametric ....

S. Gatziu and K. Dittrich. SAMOS: an Active Object-Oriented Database System. IEEE Data Engineering Bulletin, Special Issue on Active Databases, 15(4):23--26, December 1992.

....themselves to object specific synchronization we called objects with this capability autonomous objects but continue to treat objects as islands, and thus do not touch on the problems mentioned in Section 1. Active objects in active object oriented database systems (OODBS) as, e.g. in [7, 9, 10, 11], are able to detect events and to execute also asynchronously some predefined code as a reaction. But they are not able to limit method invocations. One can interpret the raising and detection of an event as a communication between raising object and detecting objects. Following this ....

S. Gatziu and K. R. Dittrich. Samos: An active object-oriented database system. IEEE Quarterly Bulletin on Data Engineering, Jan. 1993.

....a local rule manager detects local events and notifies the corresponding global rule managers in case of event occurrences. Please notice, if a component database system does not support any active mechanisms, an additional active layer on top this system is required (see the SAMOS approach [GGD94] As depicted in Figure 2 this layer can be seamlessly integrated into the mediator layer. 4.5 Examples for Active Global Integrity Maintenance In this section, we exemplarily show how global integrity maintenance in an active federated database environment can work. Especially, we present an ....

S. Gatziu, A. Geppert, and K. R. Dittrich. SAMOS: an Active Object-Oriented Database System. Technical Report 94.16, University of Zurich, 1994.

....next cycle of the recognise act loop. As in main memory production systems, a single rule is considered for firing each time round the recognise act loop, which leads to some rules being triggered but never fired. 3. 4 SAMOS SAMOS is an acive rule system based upon an object oriented data model [14, 13], which supports the dimensions as described in Table 5. At time of writing, not all of SAMOS has been implemented. Noteworthy features of SAMOS include an event language in which composite events can be constructed using the operations disjunction, conjunction, sequence and negation (which occur ....

....E has occurred n times during a given time interval. As well as supporting Clock events, composite events can be specified to have taken place within a given time interval. Clock events can be described in terms of absolute, periodic and relative points in time. Events can also be parameterised [13]. A rule can be defined either as a property of a class or as an independent entity. The former, known as class internal rules, can be associated with the encapsulated structure of a class. Rules defined independently of classes are Table 5 Dimensions in SAMOS Event Type ae fPrimitive, ....

S. Gatziu and K.R. Dittrich. Samos: an active object-oriented database system. IEEE Quartely Bulletin on Data Engineering, January 1993.

....NEW UPDATED and OLD UPDATED contain new and old values of updated rows, respectively. In [72] the set oriented semantics of Starburst rules is presented. In a set oriented rule the action part is executed for all tuples for which the condition is true. Other systems based on ECA rules are [11][38]. In Ariel [41] production rules were defined on top of POSTGRES. In Ariel CA rules were allowed which use only the condition to specify logical events which trigger rules. In Ode [39] constraints and triggers were introduced into an Object Oriented database. The basic events that can be ....

....However, the events that are intercepted in AMOS include all operations of high level objects. This makes it possible to extend rules to trigger on any change in the system, including schema updates. This is further discussed in section 3.2. Systems that can trigger on external events include [11][38]. 2.4 Active Database Classifications Considerable research has been carried out in the area of active databases. There exist several good introductory papers to active database architectures [19] 42] Two important evaluation aspects for comparing different architectures are the expressiveness ....

Gatziu S., Dittrich K. R: SAMOS: an Active Object-Oriented Database System, IEEE Data Engineering bulletin, Vol. 15, No. 1-4, Dec. 1992, pp. 23-26

....with the general architecture, mechanisms for expressing and detecting events, conditions and actions, their representation within the DBMS, the embedding of triggers in transactions and their applications. Widely known approaches for the general architecture of active DBMS include SAMOS ( GD92] GD93] with a very powerful event specification language and refined facilities for the detection of composite events using Petri nets ( GD94] the event specification language Snoop ( CM93] with very powerful mechanisms for the expression of complex events and REACH ( BBKZ92] with the ....

S. Gatziu and K.R. Dittrich. Samos: an active object--oriented database system. IEEE Bulletin of the TC on Data Engineering, 15(1--4):23--26, December 1992.

....that automatically collect and combine constituent events of the event composition. In this paper, we discuss the operator graph approach as used in SENTI NEL [5,15] REACH [2] ADL [1] SMILE [13] and others [18,25] Finite automata in ODE [11,12] and modified colored Petri nets in SAMOS [8,9,10] are variations of the detection technique based on operator graphs. All approaches are sequential. Event detection is centralized. During runtime, the Active DBS receives atomic events and collects those in a timely ordered history. For example, a history of event instances of atomic types A, B, ....

S. Gatziu and K. R. Dittrich. SAMOS: An Active Object-Oriented Database System. Data Eng. Bull., 15(1-4), December 1992.

....instead, previous findings of others and ourselves are put into context and are viewed from the perspective of working towards a 2 general infrastructure for time in databases. Most details are drawn from SAMOS, an active objectoriented DBMS currently researched and prototyped in our group ( GaDi 93] However, though some of our means for event specification seem to be pretty novel, similar time requirements might be gained from other aDBS (e.g. some of those represented in [Chak 93] as well. 2 An overview of time issues in active database systems In the sequel, we present an enumeration ....

Gatziu, S; Dittrich, K.R.: SAMOS -- an active object-oriented database system. In:

....model supported by the database system (some aspects are presented in [7] Rule management incorporates tasks for the internal representation of rules and events, for the event detection and the selection of all rules that have to be executed. A short general description of SAMOS can be found in [8]. In this paper, we focus on rule specification and rule management. In particular, we introduce powerful yet rather simple constructs for the specification of events based on an event algebra. Furthermore, we integrate time specification facilities into event definitions. We show that even ....

Gatziu S, Dittrich K.R. SAMOS: an Active Object-Oriented Database System. IEEE Bulletin of the TC on Data Engineering, 15(1-4), Special Issue on Active Databases, December 92

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Gatziu, S., et al.: SAMOS: An active object-oriented database system. IEEE Data Engineering, Special issue on active databases. (1992) 15(1-4): 23-26

No context found.

S Gatziu and KR Dittrich. Samos: an active object-oriented database system. IEEE Data Engineering, pages 23--26, 1992.

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