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Event (UML)
An event in the Unified Modeling Language (UML) is "something that may occur at a specific instant in time". Events can, but do not necessarily, cause state transitions from one state to another in state machine A finite-state machine (FSM) or finite-state automaton (FSA, plural: ''automata''), finite automaton, or simply a state machine, is a mathematical model of computation. It is an abstract machine that can be in exactly one of a finite number o ...s represented by state machine diagrams. Consider "the case of two Transitions originating from the same State, triggered by the same event, but with different guards. If that event occurs and both guard conditions are true, then at most one of those Transitions can fire in a given run-to-completion step." References Unified Modeling Language Data modeling {{uml-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Object Management Group
The Object Management Group (OMG®) is a computer industry Standards Development Organization (SDO), or Voluntary Consensus Standards Body (VCSB). OMG develops enterprise integration and modeling standards for a range of technologies. Business activities The goal of the OMG was a common portable and interoperable object model with methods and data that work using all types of development environments on all types of platforms. The group provides only specifications, not implementations. But before a specification can be accepted as a standard by the group, the members of the submitter team must guarantee that they will bring a conforming product to market within a year. This is an attempt to prevent unimplemented (and unimplementable) standards. Other private companies or open source groups are encouraged to produce conforming products and OMG is attempting to develop mechanisms to enforce true interoperability. OMG hosts four technical meetings per year for its members an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Unified Modeling Language
The Unified Modeling Language (UML) is a general-purpose visual modeling language that is intended to provide a standard way to visualize the design of a system. UML provides a standard notation for many types of diagrams which can be roughly divided into three main groups: behavior diagrams, interaction diagrams, and structure diagrams. The creation of UML was originally motivated by the desire to standardize the disparate notational systems and approaches to software design. It was developed at Rational Software in 1994–1995, with further development led by them through 1996. In 1997, UML was adopted as a standard by the Object Management Group (OMG) and has been managed by this organization ever since. In 2005, UML was also published by the International Organization for Standardization (ISO) and the International Electrotechnical Commission (IEC) as the ISO/IEC 19501 standard. Since then the standard has been periodically revised to cover the latest revision of UML. In ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
State (computer Science)
In information technology and computer science, a system is described as stateful if it is designed to remember preceding events or user interactions; the remembered information is called the state of the system. The set of states a system can occupy is known as its state space. In a discrete system, the state space is countable and often finite. The system's internal behaviour or interaction with its environment consists of separately occurring individual actions or events, such as accepting input or producing output, that may or may not cause the system to change its state. Examples of such systems are digital logic circuits and components, automata and formal language, computer programs, and computers. The output of a digital circuit or deterministic computer program at any time is completely determined by its current inputs and its state. Digital logic circuit state Digital logic circuits can be divided into two types: combinational logic, whose output signals a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
State Machine
A finite-state machine (FSM) or finite-state automaton (FSA, plural: ''automata''), finite automaton, or simply a state machine, is a mathematical model of computation. It is an abstract machine that can be in exactly one of a finite number of ''states'' at any given time. The FSM can change from one state to another in response to some inputs; the change from one state to another is called a ''transition''. An FSM is defined by a list of its states, its initial state, and the inputs that trigger each transition. Finite-state machines are of two types— deterministic finite-state machines and non-deterministic finite-state machines. For any non-deterministic finite-state machine, an equivalent deterministic one can be constructed. The behavior of state machines can be observed in many devices in modern society that perform a predetermined sequence of actions depending on a sequence of events with which they are presented. Simple examples are: vending machines, which dispens ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
State Diagram
A state diagram is used in computer science and related fields to describe the behavior of systems. State diagrams require that the system is composed of a finite number of states. Sometimes, this is indeed the case, while at other times this is a reasonable abstraction. Many forms of state diagrams exist, which differ slightly and have different semantics. Overview State diagrams provide an abstract description of a system's behavior. This behavior is analyzed and represented by a series of events that can occur in one or more possible states. Hereby "each diagram usually represents objects of a single class and track the different states of its objects through the system". State diagrams can be used to graphically represent finite-state machines (also called finite automata). This was introduced by Claude Shannon and Warren Weaver in their 1949 book ''The Mathematical Theory of Communication''. Another source is Taylor Booth in his 1967 book ''Sequential Machines and Aut ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Guard (computer Science)
In computer programming, a guard is a Boolean expression that must evaluate to true if the execution of the program is to continue in the branch in question. Regardless of which programming language is used, a guard clause, guard code, or guard statement is a check of integrity preconditions used to avoid errors during execution. The term guard clause is a Software design pattern attributed to Kent Beck who codified many often unnamed coding practices into named software design patterns, the practice of using this technique dates back to at least the early 1960's. The guard clause most commonly is added at the beginning of a procedure and is said to "guard" the rest of the procedure by handling edgecases upfront. Uses A typical example is checking that a reference about to be processed is not null, which avoids null-pointer failures. Other uses include using a Boolean field for idempotence (so subsequent calls are nops), as in the dispose pattern. public String foo(String us ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
