H.V. Jagadish anf I.S. Mumick and O. Shmueli. Events with attributes in an active database. Technical report, AT&T, 1992.  Home/Search   Document Details and Download   Summary   Related Articles   Check

....The automaton for the expression has to have 3600 states. They rather propose to specify time as an attribute. For example, two IBM stock sales by the same customer within one hour of each other is specified as follows: relative(sell(IBM, Y, A1, T1) sell(IBM, Y, A2, T2) T2 T1) 3600) aIMS92] None of the other two languages deal with explicit time. ffl In ODE arbitrary (boolean and relational) predicates can be specified on event CHAPTER 3. ACTIVE AND TEMPORAL DATABASES 55 attributes, but aggregate operations are not supported. ffl The support for predicates or operations on event ....

H.V. Jagadish anf I.S. Mumick and O. Shmueli. Events with attributes in an active database. Technical report, AT&T, 1992.

.... the REACH project, which is another active real time database project; Chakravarthy and Mishra, 1994, Chakravarthy et al. 1993, Chakravarthy et al. covering the Snoop event detector based on event graphs 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 ....

.... another active real time database project; Chakravarthy and Mishra, 1994, Chakravarthy et al. 1993, Chakravarthy et al. covering the Snoop event detector based on event graphs 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. ....

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Jagadish, H. V., Mumick, I. S., and Schmueli, O. (1992). Events with attributes in an active database. AT&T Technical Memorandum 11356-921214-18TM.

....to specify patterns of events (event expressions) that trigger specific actions. Compose only allows regular expressions as patterns to ensure constant additional storage requirements. However, the need for more complex patterns, in particular dealing with time and sequences, soon became evident [JMS92]. Space optimization is very important to bound the space utilized for detecting such complex patterns. Such patterns can be expressed using logic programs, and our techniques (in particular the monotonicity based techniques described in Section 6) are then directly applicable. Our techniques can ....

H. V. Jagadish, I. S. Mumick, and O. Shmueli. Events with attributes in an active database. Technical report, AT&T Bell Laboratories, 1992.

....events through the use of a closed algebra. A composite event occurs at a time instant, as specified by the closed algebra in terms of the time instants of component basic events. 2 Several algebras for composite events have been proposed, e.g. Snoop [CM93] SAMOS [DG93] Chom92] and ODE [GJS92b, GJS92a, JMS92, GJMS93]. We permit simple conditions, such as X 10 on attribute X of an event, or a boolean predicate on attributes of events, to be included in the algebra for composite events. Note that the boolean predicates in a composite event do not refer to items stored in the database, and can be evaluated ....

....simple forms of temporal queries, and can provide simple temporal features. Active rules using such event algebras must therefore be considered to be temporal rules . The composite algebras can be used in non temporal databases, provided mechanisms to recognize these event patterns are provided [CM93, DG93, Chom92, GJS92a, JMS92]. While we will not discuss any particular algebra in this paper, we will illustrate their relationship to temporal databases through a representative syntax. EXAMPLE 4.1 Consider an inventory database in a store. There is an inventory(item, amount) relation storing the amount of each item in ....

H.V. Jagadish, I.S. Mumick, and O. Shmueli. Events with attributes in an active database. Technical Report 921214-18-TM, AT&T Bell Laboratories, December 1992.

....or false. Evaluation of the mask takes us beyond finite automata. We implement parameters using generic automata. These automata are used to instantiate ordinary automata for each combination of new parameter values. We are currently investigating techniques for optimizing such finite automata [MJS] In a distributed database, there may not be a well defined unique system history. In [JS92] we discuss how to coordinate the different views of the history seen at different sites. As mentioned earlier, the motivation behind our work was the design of trigger facilities for the Ode object ....

I. S. Mumick, H. V. Jagadish, and O. Shmueli. Events with attributes in an active database. Technical report.

....a language to express temporal events that we believe will be efficiently computable. A computation using finite automata for temporal events without attributes was presented in [GJS92b] and computations using extended automata for a large class of temporal events with attributes is discussed in [JMS92, JMS93] 2 Temporal Event Expressions Events without Attributes An event is a happening of interest. Events, including composite events, happen instantaneously at specific points in time. Basic events, such as before insert or after delete occur at points in time just before an insertion ....

....the entire history of the database states. We propose a declarative temporal language that we believe has this property. A subset of this language has been implemented at AT T Bell Laboratories. Algorithms for implementation a large subclass of the language (except for negation) are discussed in [JMS92, JMS93] The implementation uses extended automata with a relational store on each state. Alert [SPAM91] Snoop [CM91] Ch92] GM91] and [Ric92] provide some form of temporal querying. In Alert , there is no representation for sequencing of events, except what may be visible as the net ....

H. V. Jagadish, Inderpal Singh Mumick, and Oded Shmueli. Events with attributes in an active database. Technical Report 921214-18-TM, AT&T Bell Laboratories, December 1992.

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