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Event (computing)
In computing, an event is a detectable occurrence or change in the system's state, such as user input, hardware interrupts, system notifications, or changes in data or conditions, that the system is designed to monitor. Events trigger responses or actions and are fundamental to event-driven systems. These events can be handled synchronously, where the execution Thread (computing), thread is blocked until the event handler completes its processing, or asynchronously, where the event is processed independently, often through an event loop. Even when synchronous handling appears to block execution, the underlying mechanism in many systems is still asynchronous, managed by the event loop. Events can be implemented through various mechanisms such as Callback (computer programming), callbacks, message objects, signals, or interrupts, and events themselves are distinct from the implementation mechanisms used. Event propagation models, such as Event bubbling, bubbling, capturing, and pub/s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Computing
Computing is any goal-oriented activity requiring, benefiting from, or creating computer, computing machinery. It includes the study and experimentation of algorithmic processes, and the development of both computer hardware, hardware and software. Computing has scientific, engineering, mathematical, technological, and social aspects. Major computing disciplines include computer engineering, computer science, cybersecurity, data science, information systems, information technology, and software engineering. The term ''computing'' is also synonymous with counting and calculation, calculating. In earlier times, it was used in reference to the action performed by Mechanical computer, mechanical computing machines, and before that, to Computer (occupation), human computers. History The history of computing is longer than the history of computing hardware and includes the history of methods intended for pen and paper (or for chalk and slate) with or without the aid of tables. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Interrupt
In digital computers, an interrupt (sometimes referred to as a trap) is a request for the processor to ''interrupt'' currently executing code (when permitted), so that the event can be processed in a timely manner. If the request is accepted, the processor will suspend its current activities, save its state, and execute a function called an '' interrupt handler'' (or an ''interrupt service routine'', ISR) to deal with the event. This interruption is often temporary, allowing the software to resume normal activities after the interrupt handler finishes, although the interrupt could instead indicate a fatal error. Interrupts are commonly used by hardware devices to indicate electronic or physical state changes that require time-sensitive attention. Interrupts are also commonly used to implement computer multitasking and system calls, especially in real-time computing. Systems that use interrupts in these ways are said to be interrupt-driven. History Hardware interrupts wer ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Computer Programming
Computer programming or coding is the composition of sequences of instructions, called computer program, programs, that computers can follow to perform tasks. It involves designing and implementing algorithms, step-by-step specifications of procedures, by writing source code, code in one or more programming languages. Programmers typically use high-level programming languages that are more easily intelligible to humans than machine code, which is directly executed by the central processing unit. Proficient programming usually requires expertise in several different subjects, including knowledge of the Domain (software engineering), application domain, details of programming languages and generic code library (computing), libraries, specialized algorithms, and Logic#Formal logic, formal logic. Auxiliary tasks accompanying and related to programming include Requirements analysis, analyzing requirements, Software testing, testing, debugging (investigating and fixing problems), imple ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Java Package
A Java package organizes Java classes into namespaces, providing a unique namespace for each type it contains. Classes in the same package can access each other's package-private and protected members. In general, a package can contain the following kinds of types: classes, interfaces, enumerations, records and annotation An annotation is extra information associated with a particular point in a document or other piece of information. It can be a note that includes a comment or explanation. Annotations are sometimes presented Marginalia, in the margin of book page ... types. A package allows a developer to group classes (and interfaces) together. These classes will all be related in some way – they might all have to do with a specific application or perform a specific set of tasks. Programmers also typically use packages to organize classes belonging to the same category or providing similar functionality. Using packages In a Java source file, the package that this file' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Javadoc
Javadoc (also capitalized as JavaDoc or javadoc) is an API documentation generator for the Java programming language. Based on information in Java source code, Javadoc generates documentation formatted as HTML and other formats via extensions. Javadoc was created by Sun Microsystems and is owned by Oracle today. The content and formatting of a resulting document are controlled via special markup in source code comments. As this markup is de facto standard and ubiquitous for documenting Java code, many IDEs extract and display the Javadoc information while viewing the source code; often via hover over an associated symbol. Some IDEs, like IntelliJ IDEA, NetBeans and Eclipse, support generating Javadoc template comment blocks. The @tag syntax of Javadoc markup has been re-used by other documentation generators, including Doxygen, JSDocEDocand HeaderDoc. Javadoc supports extension via doclets and taglets, which allow for generating different output formats and for sta ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Virtual Synchrony
Reliable multicast is any computer networking protocol that provides a '' reliable'' sequence of packets to multiple recipients simultaneously, making it suitable for applications such as multi-receiver file transfer. Overview Multicast is a network addressing method for the delivery of information to a group of destinations simultaneously using the most efficient strategy to deliver the messages over each link of the network only once, creating copies only when the links to the multiple destinations split (typically network switches and routers). However, like the User Datagram Protocol, multicast does not guarantee the delivery of a message stream. Messages may be dropped, delivered multiple times, or delivered out of order. A reliable multicast protocol adds the ability for receivers to detect lost and/or out-of-order messages and take corrective action (similar in principle to TCP), resulting in a gap-free, in-order message stream. Reliability The exact meaning of ''r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Signal Programming
SIGNAL is a programming language based on synchronized dataflow (flows + synchronization): a process is a set of equations on elementary flows describing both data and control. The SIGNAL formal model provides the capability to describe systems with several clocks (polychronous systems) as relational specifications. Relations are useful as partial specifications and as specifications of non-deterministic devices (for instance a non-deterministic bus) or external processes (for instance an unsafe car driver). Using SIGNAL allows one to specify an application, to design an architecture, to refine detailed components down to RTOS or hardware description. The SIGNAL model supports a design methodology which goes from specification to implementation, from abstraction to concretization, from synchrony to asynchrony. SIGNAL has been mainly developed in INRIA Espresso team since the 1980s, at the same time as similar programming languages, Esterel and Lustre. A brief his ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Proactor Pattern
Proactor is a software design pattern for event handling In computing, an event is a detectable occurrence or change in the system's state, such as user input, hardware interrupts, system notifications, or changes in data or conditions, that the system is designed to monitor. Events trigger responses or ... in which long running activities are running in an asynchronous part. A ''completion handler'' is called after the asynchronous part has terminated. The proactor pattern can be considered to be an asynchronous variant of the synchronous reactor pattern.Pattern-Oriented Software Architecture, Volume 2, Schmidt et al., Jon Wiley & Sons, Ltd, 2000 Interaction Operation specific actors: * The ''Proactive Initiator'' starts the asynchronous operation via the Asynchronous Operation Processor and defines the Completion Handler * ''Completion Handler'' is a call at the end of the operation from the Asynchronous Operation Processor * ''Asynchronous Operation'' Standardized acto ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reactor Pattern
The reactor software design pattern is an event handling strategy that can respond to many potential service requests concurrently. The pattern's key component is an event loop, running in a ''single'' thread or process, which demultiplexes incoming requests and dispatches them to the correct request handler. By relying on event-based mechanisms rather than blocking I/O or multi-threading, a reactor can handle many concurrent I/O bound requests with minimal delay. A reactor also allows for easily modifying or expanding specific request handler routines, though the pattern does have some drawbacks and limitations. With its balance of simplicity and scalability, the reactor has become a central architectural element in several server applications and software frameworks for networking. Derivations such as the multireactor and proactor also exist for special cases where even greater throughput, performance, or request complexity are necessary. Overview Practical considerati ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Observer Pattern
In software design and software engineering, the observer pattern is a software design pattern in which an object, called the ''subject'' (also known as ''event source'' or ''event stream''), maintains a list of its dependents, called observers (also known as ''event sinks''), and automatically notifies them of any state (computer science), state changes, typically by calling one of their method (computer science), methods. The subject knows its observers through a standardized interface and manages the subscription list directly. This pattern creates a one-to-many dependency where multiple observers can listen to a single subject, but the coupling is typically synchronous and direct—the subject calls observer methods when changes occur, though asynchronous implementations using event queues are possible. Unlike the publish-subscribe pattern, there is no intermediary broker; the subject and observers have direct references to each other. It is commonly used to implement event ha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Interrupt Handler
In computer systems programming, an interrupt handler, also known as an interrupt service routine (ISR), is a special block of code associated with a specific interrupt condition. Interrupt handlers are initiated by hardware interrupts, software interrupt instructions, or software exception handling, exceptions, and are used for implementing device drivers or transitions between protected modes of operation, such as system calls. The traditional form of interrupt handler is the hardware interrupt handler. Hardware interrupts arise from electrical conditions or low-level protocols implemented in digital logic, are usually dispatched via a hard-coded table of interrupt vectors, asynchronously to the normal execution stream (as interrupt masking levels permit), often using a separate stack, and automatically entering into a different execution context (privilege level) for the duration of the interrupt handler's execution. In general, hardware interrupts and their handlers are used ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thread (computing)
In computer science, a thread of execution is the smallest sequence of programmed instructions that can be managed independently by a scheduler, which is typically a part of the operating system. In many cases, a thread is a component of a process. The multiple threads of a given process may be executed concurrently (via multithreading capabilities), sharing resources such as memory, while different processes do not share these resources. In particular, the threads of a process share its executable code and the values of its dynamically allocated variables and non- thread-local global variables at any given time. The implementation of threads and processes differs between operating systems. History Threads made an early appearance under the name of "tasks" in IBM's batch processing operating system, OS/360, in 1967. It provided users with three available configurations of the OS/360 control system, of which Multiprogramming with a Variable Number of Tasks (MVT) ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
