AJAX

What is AJAX?
AJAX = Asynchronous JavaScript and XML.

AJAX is a technique for creating fast and dynamic web pages.

AJAX allows web pages to be updated asynchronously by exchanging small amounts of data with the server behind the scenes. This means that it is possible to update parts of a web page, without reloading the whole page.

Classic web pages, (which do not use AJAX) must reload the entire page if the content should change.

Examples of applications using AJAX: Google Maps, Gmail, Youtube, and Facebook tabs.


The XMLHttpRequest Object
All modern browsers support the XMLHttpRequest object (IE5 and IE6 use an ActiveXObject).

The XMLHttpRequest object is used to exchange data with a server behind the scenes. This means that it is possible to update parts of a web page, without reloading the whole page.


The onreadystatechange event
When a request to a server is sent, we want to perform some actions based on the response.

The onreadystatechange event is triggered every time the readyState changes.

The readyState property holds the status of the XMLHttpRequest.

Three important properties of the XMLHttpRequest object:

Property Description
onreadystatechange Stores a function (or the name of a function) to be called automatically each time                                                                the readyState property changes

readyState Holds the status of the XMLHttpRequest. Changes from 0 to 4:
0: request not initialized
1: server connection established
2: request received
3: processing request
4: request finished and response is ready

status 200: "OK"
404: Page not found

Difference between Server side scripting and Client side scripting

We would define a script as a set of instructions. For Web pages they are instructions either to the Web server(server-side scripting) or to the Web Browser (client-side scripting). Let’s have a look how they differ from each other :

>> Server side scripting is used to create dynamic pages based a number of conditions when the users browser makes a request to the server.

Client side scripting is used when the users browser already has all the code and the page is altered on the basis of the users input.

>> The Web Server executes the server side scripting that produces the page to be sent to the browser.

The Web Browser executes the client side scripting that resides at the user’s computer.

>> Server executes server-side scripts to send out a page but it does not execute client-side scripts.

The browser receives the page sent by the server and executes the client-side scripts.

>> Server side scripting is used to connect to the databases that reside on the web server.

Client side scripting cannot be used to connect to the databases on the web server.

>> Server side scripting can access the file system residing at the web server.

Client side scripting can’t access the file system that resides at the web server.

>> The  settings that belong to Web server can be accessed using Server side scripting.

The files and settings that are local at the user’s computer can be accessed using Client side scripting.

>> Examples of Server side scripting languages : PHP, JSP,  ASP, ASP.Net, Ruby, Perl n many more.

Examples of Client side scripting languages : Javascript, VB script, etc.

70-480 Programming in HTML5 with JavaScript and CSS3

It is quite good to appear for the professional certification Exams. On April 20 th I have cleared my first certification in ‘Programming in HTML5 with JavaScript and CSS3’

Here I have shared some quick steps for those who like to appear for these exams.

How to register?

1. You need to register first for the exam from a Prometric center, like http://register.prometric.com/

2. Follow the registration steps and choose your convinient date/time available there. If you have promo code or any voucher code, you can enter while registering for the exam so the exam fees will be 0!

3. Once registered, you will receive  an email from the prometric site with details entered while registering.

How to prepare?

Generally preparation depends upon the exam selected.

You can read dumps! dumps are something like previous exam papers of the MS exams appeared. Users post latest dumps online. One of the site to refer dumps is http://examcollection.com. It gives a list of the dumps posted by date. Its a really good practice to follow these dumps to at least score passing marks for MS exams. Passing score is 700 out of 1000. Time duration is 2 hours and number of questions is 39.

How to get Certificate?

After completion of the exam, if you are passed, you will be given marksheet/report from the prometric center and you will recieve the mail from MS.
Approx in 7 working days, you will recieve the mail and it will have your MC ID and access code which you need to enter on the MCP site – mcp.microsoft.com

You will get digital copy (PDF format) of your certificate as well transcript etc from there.


All the best!!