unit 14 M1

Explain how an operating system can be viewed as an event driven application

There are many ways that an operating system could be referred to as an event driven application.

The first thing that there is on an operating system that is event driven is the fact that the start button at the bottom of the desktop is activated through a click event.  When you click on the button, it comes up with a list of other functions that can be done.  The action was when you clicked on the button and the event that occurred because of it was the list of buttons opening up.

Another good example of how the operating software can viewed as event driven is the fact that there are drag and drop characteristics on the desktop, and other places on a computer for that matter.  For example the most common place to see the Recycle Bin on a computer desktop is the bottom right hand corner but when you first set the computer up, it is towards the left with all the other icons such as Internet Explorer and My Documents.  Another time drag and drop occurs on a computer desktop is when you want to place one thing inside another.  For example, when you want to put a typed word document into a folder with other similar documents.  The action in these would be the icon being clicked on and dragged and the reaction would be the object being in a different place to where it was.

The third example of how I think that the computers operating system can be referred to as an event driven application is the fact that when the user presses a key on the keyboard, it is registered as a KeyDown command which is linked with other data that is linked with the press, such as which key the user has pressed.  An example of this would be when you have created a new folder and you want to input a new name to it.  The event here would have been when you were typing and the reaction being the fact that the letters appeared in the box.

Another reason an operating system could be referred to as an operating system is the fact that you can save a file and it will be written to a disk.  For example when you are on word and you have just finished typing a document, you would obviously save it because if you didn't then you would have to start from the previous save point and if it was a brand new document and you Had just been constantly typing and not saving, you would completely lose your document.  The events in this instance would be you clicking on save and the consequence would be the document being saved to the hard drive or USB stick.

The next example to support the reference of a computer operating system being a type of event driven application is hen you are searching through the icons on the menus.  An example of this would be when you are on the start button and there is all the mini icons to direct you to other parts of the screen.  When you hover over the icons, it highlights it with a blue glow on Microsoft's Windows 7.  The event in this example is you hovering the mouse over the icon, and the reaction is the blue glow behind it.

Another example would be when you input a USB stick and it comes up with the multiple options of what files to open and what software to open them with.  For example, if you have videos on your pen drive, it will ask if you want to open them up in Windows media player or a similar software.  The event in this instance is when you put the pen drive in and the consequence is the operating system deciding to use that particular software.

There isn't many more examples to do.  This example to show that a computer operating system is an event driven language is to do with switching users.  When you click on the start button in the bottom corner, it has a little extra bit in the bottom right hand corner of that which gives you extra options including switch user, lock and log off.  The action in each bit of this would be when you decide which of the individual buttons to click and the reaction would be exactly as the button says.

The final thing that I am going to use to prove that an operating system is a type of event driven application or program is the fact that when you click on the shut down, the operating system gets shut and stops the power supply getting through the power supply unit and getting to the other key components that are required to run the computer.  The event in this instance is the user clicking the Shut Down button and the reaction from the operating system is the computer going off.