ilide.info-event-driven-complete-pr_2038c0d3570030ce3ea1533883938682.pdf

ilide.info-event-driven-complete-pr_2038c0d3570030ce3ea1533883938682.pdf

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  EVENT DRIVEN PROGRAMMING NURATHIRAH BINTI MIMOL D20111048162 NURUL SYUHADA BINTI MAZLINA D20111048161 NOR SUHAIBAH BT ABDUL WAHAD@WAHAB D20111048212 NORSHAFILAH BINTI RAMLI D20111048176 NOR HAFIZA BINTI UTHMAN D20112052115
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  Event driven programming •is a programming paradigm in which the flow of the program is determined by events such as user actions (mouse clicks, key presses), sensor outputs, or messages from other programs/threads.
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  • Event-driven programmingis the dominant paradigm used in graphical user interfaces (GUI) and other applications (e.g. Javascript web applications) that are centered around performing certain actions in response to user input.
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  Purpose
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  Purpose With the developmentof a program with a graphical user interface (GUI) normally you want something to happen when the user performs certain actions, for example:  Clicking on an area of the interface using the mouse  Pressing a labelled button  Entering text into a text field
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  • In eachof these cases, a program 'event' occurs, and the program can be designed to incorporate specific actions that would occur when different events occur. This type of program is referred to as an event- driven program.
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  • In event-drivenprograms, the program is said to run in a 'main loop', referred to as an event loop. • When some user input occurs, then the program responds appropriately. The program will be in one state prior to the event occurring, and will usually be in a different state after the program has responded to the event.
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  Characteristics of eventdriven programming • Can be written in any programming languages • Event-driven approach contrasts with batch processing. Because event-driven programming is an approach rather than a type of language, event-driven apps can be created in any programming language. • Event-driven processing can improve responsiveness, throughput and flexibility. • Events are generally referenced, indexed, or named based on an object (noun) and the type of action that triggered the event. For example, "icon3_click" or "icon3 - onClick". Thus, they usually have at least two "keys" (in an informal sense).
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  • The taskis easier in languages that provide high-level abstractions. • Windows-based applications or programs are being regard as event-driven. For example, when the end user chooses menu items, clicks the mouse and move objects on the screen. • With the advent of the World Wide Web (WWW), event-driven programming has gained in popularity as a way to add interaction to web pages.
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  Example : Event handler Refer to application responds to the events which executing particular code for each type of event. Input  Come from event sources. Source of an event  Modeled as an object  Example: button click’s object is a button. Type of the event  Example : ActionEvent, WindowEvent, MouseEvent  ActionEvent: passed to application which contain info about the action.
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  Differences with otherprogramming
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  Advantages  It allowsfor more interactive programs  It allows sensors and other hardware to easily interact with software  It can be implemented using hardware interrupts, which will reduce the power used by the computer  Flexibility  Very user friendly and highly interactive systems  The lack of concurrent data access
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  Disadvantages Event-Driven Programming •Event Driven Programming is often more complex and cumbersome than batch programming • The flow of the program is usually less logical and obvious • Classes are often not reusable or hard implement in other applications • Generally only useful in GUI programming • Is often not portable to other operating system, such as in the case .NET framework under windows that uses event driven programming