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Event Driven Programming
In computer programming, event-driven programming is a programming paradigm in which the flow of the program is determined by external events. UI events from mice, keyboards, touchpads and touchscreens, and external sensor inputs are common cases. Events may also be programmatically generated, such as from messages from other programs, notifications from other threads, or other network events. Event-driven programming is the dominant paradigm used in graphical user interfaces applications and network servers. In an event-driven application, there is generally an event loop that listens for events and then triggers a callback function when one of those events is detected. Event-driven programs can be written in any programming language, although the task is easier in languages that provide high-level abstractions. Although they do not exactly fit the event-driven model, interrupt handling and exception handling have many similarities. It is important to differentiate bet ... [...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] |
Abstraction (computer Science)
In software engineering and computer science, abstraction is the process of generalizing concrete details, such as attributes, away from the study of objects and systems to focus attention on details of greater importance. Abstraction is a fundamental concept in computer science and software engineering, especially within the object-oriented programming paradigm. Examples of this include: * the usage of abstract data types to separate usage from working representations of data within programs; * the concept of functions or subroutines which represent a specific way of implementing control flow; * the process of reorganizing common behavior from groups of non-abstract classes into abstract classes using inheritance and sub-classes, as seen in object-oriented programming languages. Rationale Computing mostly operates independently of the concrete world. The hardware implements a model of computation that is interchangeable with others. The software is structured in archit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Event Dispatching Thread
The event dispatching thread (EDT) is a background thread used in Java to process events from the Abstract Window Toolkit (AWT) graphical user interface event queue. It is an example of the generic concept of event-driven programming, that is popular in many other contexts than Java, for example, web browsers, or web servers. The events are primarily update events that cause user interface components to redraw themselves, or input events from input devices such as the mouse or keyboard. The AWT uses a single-threaded painting model in which all screen updates must be performed from a single thread. The event dispatching thread is the only valid thread to update the visual state of visible user interface components. Updating visible components from other threads is the source of many common bugs in Java programs that use Swing. The event dispatching thread is called the primordial worker in Adobe Flash and the UI thread in SWT, .NET Framework and Android. Message loop for se ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Message Loop In Microsoft Windows
The message loop is an obligatory section of code in every program that uses a graphical user interface under Microsoft Windows. Windows programs that have a GUI are event-driven. Windows maintains an individual message queue for each thread that has created a window. Usually only the first thread creates windows. Windows places messages into that queue whenever mouse activity occurs on that thread's window, whenever keyboard activity occurs while that window has focus, and at other times. A process can also add messages to its own queue. To accept user input, and for other reasons, each thread with a window must continuously retrieve messages from its queue, and act on them. A programmer makes the process do that by writing a loop that calls GetMessage (which blocks for a message and retrieves it), and then calls DispatchMessage (which dispatches the message), and repeats indefinitely. This is the message loop. There usually is a message loop in the main program, which runs o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Integrated Development Environment
An integrated development environment (IDE) is a Application software, software application that provides comprehensive facilities for software development. An IDE normally consists of at least a source-code editor, build automation tools, and a debugger. Some IDEs, such as IntelliJ IDEA, Eclipse (software), Eclipse and Lazarus (software), Lazarus contain the necessary compiler, interpreter (computing), interpreter or both; others, such as SharpDevelop and NetBeans, do not. The boundary between an IDE and other parts of the broader software development environment is not well-defined; sometimes a version control system or various tools to simplify the construction of a graphical user interface (GUI) are integrated. Many modern IDEs also have a class browser, an object browser, and a class diagram, class hierarchy diagram for use in object-oriented programming, object-oriented software development. Overview Integrated development environments are designed to maximize progra ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Database
In computing, a database is an organized collection of data or a type of data store based on the use of a database management system (DBMS), the software that interacts with end users, applications, and the database itself to capture and analyze the data. The DBMS 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 application associated with the database. Before digital storage and retrieval of data have become widespread, index cards were used for data storage in a wide range of applications and environments: in the home to record and store recipes, shopping lists, contact information and other organizational data; in business to record presentation notes, project research and notes, and contact information; in schools as flash c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Flag (computing)
In computer programming, flag can refer to one or more bits that are used to store a binary numeral system, binary value or a Boolean variable for signaling special Source code, code conditions, such as file empty or full queue statuses. Flags may be found as members of a defined data structure, such as a Row (database), database record, and the meaning of the value contained in a flag will generally be defined in relation to the data structure it is part of. In many cases, the binary value of a flag will be understood to represent one of several possible states or statuses. In other cases, the binary values may represent one or more attributes in a bit field, often related to abilities or permissions, such as "can be written to" or "can be deleted". However, there are many other possible meanings that can be assigned to flag values. One common use of flags is to mark or designate data structures for future processing. Within microprocessors and other logic devices, flags are ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
IBM RPG
RPG is a high-level programming language for business applications, introduced in 1959 for the IBM 1401. It is most well known as the primary programming language of IBM's midrange computer product line, including the IBM i operating system. RPG has traditionally featured a number of distinctive concepts, such as the program cycle, and the column-oriented syntax. The most recent version is RPG IV, which includes a number of modernization features, including free-form syntax. Platforms The RPG programming language originally was created by IBM for their 1401 systems. IBM later produced implementations for the 7070/72/74 and System/360; RPG II became the primary programming language for their midrange computer product line, (the System/3, System/32, System/34, System/38, System/36 and AS/400). There have also been implementations for DEC VAX, Sperry Univac BC/7, Univac system 80, Siemens BS2000, Burroughs B700, B1700, Hewlett Packard HP 3000, the ICL 2900 series, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Main Loop
In computer science, the event loop (also known as message dispatcher, message loop, message pump, or run loop) is a programming construct or software design pattern, design pattern that waits for and dispatches event-driven programming, events or Message Passing Interface, messages in a computer program, program. The event loop works by making a request to some internal or external "event provider" (that generally blocking (computing), blocks the request until an event has arrived), then calls the relevant event handler ("dispatches the event"). It is also commonly implemented in servers such as Web server, web servers. The event loop may be used in conjunction with a reactor pattern, reactor, if the event provider follows the #File interface, file interface, which can be selected or 'polled' (the Unix system call, not actual polling (computer science), polling). The event loop almost always operates asynchronously with the message originator. When the event loop forms the centra ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Amazon Simple Queue Service
Amazon Simple Queue Service (Amazon SQS) is a distributed message queuing service introduced by Amazon.com as a beta in late 2004, and generally available in mid 2006. API Amazon provides SDKs in several programming languages, including: * C++ * Go *Java *JavaScript * Kotlin *.NET * PHP * Python *Ruby * Rust * Swift A Java Message Service (JMS) 1.1 client for Amazon SQS was released in December 2014. Operation Amazon SQS FIFO and Azure Service Bus sessions are queue-based messaging systems that provide ordering guarantees within a message group or session attempt but do not necessarily guarantee ordered delivery in cases of retries or failures. In SQS FIFO, messages in the same message group are processed in order, with subsequent messages held until the preceding message is successfully processed or moved to the dead-letter queue (DLQ). Once a message is placed in the DLQ, it is no longer retried, creating a gap in the sequence. However, the remaining messages continue ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Amazon Simple Notification Service
Amazon Simple Notification Service (Amazon SNS) is a notification service provided as part of Amazon Web Services since 2010. It provides a service for sending messages. Amazon SNS acts as a single message bus that can message to a variety of devices and platforms. A single code interface can address all of these equally, or message formats can be tailored to the particular needs of each platform. Amazon SNS can also deliver messages by SMS to 200+ countries. Description Amazon SNS uses the publish/subscribe model for delivery of messages. Recipients subscribe to one or more 'topics' within Amazon SNS. This may be hidden from the user as an internal part of a mobile app A mobile application or app is a computer program or software application designed to run on a mobile device such as a smartphone, phone, tablet computer, tablet, or smartwatch, watch. Mobile applications often stand in contrast to desktop appli .... Receipt of a message may also be hidden from the user: ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Message Queue
In computer science, message queues and mailboxes are software-engineering components typically used for inter-process communication (IPC), or for inter- thread communication within the same process. They use a queue for messaging – the passing of control or of content. Group communication systems provide similar kinds of functionality. The message queue paradigm is a sibling of the publisher/subscriber pattern, and is typically one part of a larger message-oriented middleware system. Most messaging systems support both the publisher/subscriber and message queue models in their API, e.g. Java Message Service (JMS). Competing Consumers pattern enables multiple concurrent consumers to process messages on the same message queue. Remit and ownership Message queues implement an asynchronous communication pattern between two or more processes/threads whereby the sending and receiving party do not need to interact with the message queue at the same time. Messages placed ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
