Service from a database. Time driven Time

Service orientatedService-orientatedtechniques are used so that different applications are able to reusecomponents. Different types of software applications can benefit from theseservices, for example so they can request data from a database. Time drivenTime driven programmingis a type of computer programming that is frequently used in real-timecomputing, where code execution is managed by the computer clock. Thisprogramming concept is mainly used for safety-critical programs, because theperformance of the program is highly deterministic.

Event handlersEvent handlers are made in code form and they determine whatis to happen if a user is to (for example) make an action with the mouse byclicking a specific button. One the button is clicked by the mouse the event handlesthe action by carrying it out and actually making the event happen.Trigger functionsWhen using event driven programming, trigger functions areused to select which type of event handler should be run according to the eventoccurring.EventsAn event is the result of an action. There are loads ofevents that trigger the event handlers to run. For example:·        A mouse clicks events include left click, doubleleft click, right click and hover·        Keyboard events include key press, key down andkey up·        HTML object events happens when a user clicks onan object that may be connected to a linked web page·        Form events have to do with the load event whenthe form shows up for the first time and the activate event used when a formregains focus. Form events also triggers event handlers intended for objects onthe form for instance, defining the accept button code for when the user usesthe enter key on a form.

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·        A user interface event happens with anythingthat the user does with a GUI operating system or to the form of a runningprogram.Event loopsEvent loops are needed so that they can continuously testthe user interface to detect whether anything has happened, for instanceclicking on a button or typing into a text box. If events are detected, theevent is then passed to the trigger functions which would then call the bestevent handler that is suitable to run any code in the program that’s designedand written for the event. FormsForms are a major feature and are used to hold all thecontrols the programmer used to create programs.

Forms can also be a type ofcontrol that has a collection of events that may be used by the programmer.Using these forms can be a strong way to control a program mostly when aprogram loads and ends. One example of a form event is Load, which occurs when a form is first used. The load event isuseful for code in order to set variables, to be able to set default values andother matters that is needed to be done just once.

Another example of a formevent is activated which occurswhenever the form has received focus (is brought up). An activated event isused as an advantage for updating a form whenever a user returns to it fromanother form. FlexibilityFlexibility is an advantage for a programmer as they havecontrol over codes and how they can start them. Each object has choices ofevents that the program can respond to. The events allow you to have goodcontrol over what the program will respond to when the user does something. Forexample when using a text box, there is usually a choice of events that isgiven so that fine programming has good control over anything typed into it.Suitability for graphical interfacesEvent driven programs are suitable for graphical userinterfaces when paired as they work well with each other.

A GUI allows theusers to have a good variety of graphical choices and menus that are used withthe mouse or keyboard or any other input device, with no set sequence that theuser has to follow. Controls used will react to events with code that issuitable for each event and for how the program is likely to be used.Simplicity of programmingEvent driven programming language is able to makeprogramming seem straightforward compared to traditional flow driven languages,because the programming language is very visual.Ease of developmentProgram development can be easy with an event drivenlanguage as the programmer would only need to work on one event of one controlat a time.

Flow driven languages must be complete before they can run and betested, whereas an event driven language will run with as little as only thecode for a single event completed.DisadvantagesSome event driven languages have long and complicatedcommands that programmers would have to use, and as a downside, sometimesprogrammers would need to type them all up. Testing would be essential in orderto make sure the program works as normal. Also event driven languages can bequite slow due to the fact that processing power gets soaked up by event loops,and more processing power is taken up by the trigger functions.


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