Data exchange 2.2

Data exchange 2.2

1. Bi-directional transmission

   • Bi-directional transmission has several meanings within data communication, but it is essentially about transmitting in both directions. Most recently the term has been applied to fi bre optics. Using the current technology, light passes in one direction only, so you have to add extra fi bres to the bundle to carry a signal in the opposite direction.

2. Client-side processing

   • Client-side processing is the use of a scripting language to create code on web pages which provides interactivity. The important point is that the interaction takes place within the web page and the code is downloaded to the user’s computer when the web page is opened by the user’s browser. A good example of a client-side interaction is a roll over (often called a mouseover), where some code is triggered when you move the mouse over a particular part of the web page. This might be something simple like the display of an advertisement, or it could be a demand for some data entry (e.g. filling in your details on a social networking site)
   • Benefits
     • • Speed: The interaction may be faster once the code has been downloaded with the page. • S ecurity: It is more secure (than server-side processing) as all the action takes place in the downloaded page and nothing comes from the browser, which could cause corruption or security problems.
   • Disadvantages of client-side processing include:
     • it is a browser specific:: Not all scripts work the same way on all browsers, so you may have to cr eate dierent versions depending on the browsers used. • Computer speed: It can be aected by the speed of your own computer. As all of the activity is taking place on a downloaded web page, the speed of the download and the speed of pr ocessing will depend on your computer system. If the processing is complex or resource hungry, it may run slowly or cause other programs to run slowly on your system.

3. Server-side processing

   • Server-side processing involves the use of scripts which reside and are run on another computer on the internet (the web server). Information is submitted to a server which processes it to provide results in the form of a web page. A good example of server-side processing is the submission of a search through a search engine. The search engine matches the word or phrase against an index of website content on the web server using scripts.
   • Benefits
     • Efficiency: complex code may run more efficiently, as it does not have to be downloaded on to the users computerBrowser independent: The code is browser independent so therefore can be run on any web browser. • Speed: Performance is aected only by the speed of the web server. As all of the processing is done on the web server, the speed of your own computer is only significant for the downloading of web pages. all of the other processing takes place on a highly resourced and speedy server.
   • Disadvantages of server-side processing include:
     • • Security: The exchange of data over the network may present security risks. • Overloading: A server needs to be able to cope with large volumes of users.