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Event Condition Action
Event condition action (ECA) is a short-cut for referring to the structure of active rules in event driven architecture and active database systems. Such a rule traditionally consisted of three parts: *The ''event'' part specifies the signal that triggers the invocation of the rule *The ''condition'' part is a logical test that, if satisfied or evaluates to true, causes the action to be carried out *The ''action'' part consists of updates or invocations on the local data This structure was used by the early research in active databases which started to use the term ECA. Current state of the art ECA rule engines use many variations on rule structure. Also other features not considered by the early research is introduced, such as strategies for event selection into the event part. In a memory-based rule engine, the condition could be some tests on local data and actions could be updates to object attributes. In a database system, the condition could simply be a query to the database, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Event Driven Architecture
Event-driven architecture (EDA) is a software architecture paradigm promoting the production, detection, consumption of, and reaction to events. Overview An ''event'' can be defined as "a significant change in state". For example, when a consumer purchases a car, the car's state changes from "for sale" to "sold". A car dealer's system architecture may treat this state change as an event whose occurrence can be made known to other applications within the architecture. From a formal perspective, what is produced, published, propagated, detected or consumed is a (typically asynchronous) message called the event notification, and not the event itself, which is the state change that triggered the message emission. Events do not travel, they just occur. However, the term ''event'' is often used metonymically to denote the notification message itself, which may lead to some confusion. This is due to Event-driven architectures often being designed atop message-driven architectures, where suc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Active Database
An active database is a database that includes an event-driven architecture (often in the form of ECA rules) which can respond to conditions both inside and outside the database. Possible uses include security monitoring, alerting, statistics gathering and authorization. Most modern relational databases include active database features in the form of database trigger A database trigger is procedural code that is automatically executed in response to certain events on a particular table or view in a database. The trigger is mostly used for maintaining the integrity of the information on the database. For example ...s. References Types of databases Department of Computer Science, University of Manchester {{Database-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rule Engine
A business rules engine is a software system that executes one or more business rules in a runtime production environment. The rules might come from legal regulation ("An employee can be fired for any reason or no reason but not for an illegal reason"), company policy ("All customers that spend more than $100 at one time will receive a 10% discount"), or other sources. A business rule system enables these company policies and other operational decisions to be defined, tested, executed and maintained separately from application code. Rule engines typically support rules, facts, priority (score), mutual exclusion, preconditions, and other functions. Rule engine software is commonly provided as a component of a business rule management system which, among other functions, provides the ability to: register, define, classify, and manage all the rules, verify consistency of rules definitions (”Gold-level customers are eligible for free shipping when order quantity > 10” and “maxi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rete Algorithm
The Rete algorithm ( , , rarely , ) is a pattern matching algorithm for implementing rule-based systems. The algorithm was developed to efficiently apply many rules or patterns to many objects, or facts, in a knowledge base. It is used to determine which of the system's rules should fire based on its data store, its facts. The Rete algorithm was designed by Charles L. Forgy of Carnegie Mellon University, first published in a working paper in 1974, and later elaborated in his 1979 Ph.D. thesis and a 1982 paper. Overview A naive implementation of an expert system might check each rule against known facts in a knowledge base, firing that rule if necessary, then moving on to the next rule (and looping back to the first rule when finished). For even moderate sized rules and facts knowledge-bases, this naive approach performs far too slowly. The Rete algorithm provides the basis for a more efficient implementation. A Rete-based expert system builds a network of nodes, where each ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ConceptBase
ConceptBase (a.k.a. ConceptBase.cc) is a deductive and object-oriented database management system developed at University of Aachen and University of Skövde. It is mainly used for conceptual modeling and metamodeling in the domain of software engineering and related domains. ConceptBase.cc is free and open-source software. ConceptBase combines the following features: * Object-oriented concepts such as classes and inheritance * Deductive rules evaluated by a Datalog engine * Active rules conforming to the event condition action (ECA) paradigm * Recursive function definitions * Metamodeling with arbitrarily many abstraction levels (metaclasses, meta metaclasses) ConceptBase implementO-Telos which is a variant of the knowledge representation Telos. See also * MetaCASE tool A metaCASE tool is a type of application software that provides the possibility to create one or more modeling methods, languages or notations for use within the process of software development. Often the resu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Databases
In computing, a database is an organized collection of data stored and accessed electronically. Small databases can be stored on a file system, while large databases are hosted on computer clusters or cloud storage. The design of databases spans formal techniques and practical considerations, including data modeling, efficient data representation and storage, query languages, security and privacy of sensitive data, and distributed computing issues, including supporting concurrent access and fault tolerance. A database management system (DBMS) is the software that interacts with end users, applications, and the database itself to capture and analyze the data. The DBMS software additionally encompasses the core facilities provided to administer the database. The sum total of the database, the DBMS and the associated applications can be referred to as a database system. Often the term "database" is also used loosely to refer to any of the DBMS, the database system or an applicat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
