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AJAX and REST.

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Presentation on theme: "AJAX and REST."— Presentation transcript:

1 AJAX and REST

2 What is AJAX? It’s an acronym for Asynchronous JavaScript and XML
Although requests need not be asynchronous It’s not really a single technology but several HTML / CSS / DOM / XML It’s used to dynamically update Web pages or at least parts of them

3 What is AJAX? It uses the HTTPRequest and HTTPResponse objects to
Make a server request from client JavaScript And process the server-side response

4 AJAX (model) From W3Schools.com

5 AJAX Frameworks Most vendors have their own AJAX abstraction layers
ASP has a script manager and an AJAX toolkit It’s a layer on top of AJAX There are several for PHP Phery, CJAX, Quicknet There are frameworks for Python, Perl, Ruby and others

6 RestFull APIs These are generally available API that accept and execute AJAX requests Yahoo has YQL SQL-like queries are built into the URL (GET request) I’ll show this in class

7 RestFull APIS Google has a number of APIs These use JSON typically
JSON is an alternative to moving the responses around as XML

8 AJAX (The Mechanics) The XMLHttpRequest object is used to create a request The request gets configured with the open method The request gets sent with the send method The responseText and responseXML properties store the returned information Use the onreadystatechange event for async requests

9 AJAX XMLHttpRequest The following creates the request
var req = new XMLHttpRequest(); The open method define the type of request The first argument contains the method to use (GET or POST) The second argument contains the URL The third argument contains true (asynchronous) or false (synchronous) The send method sends the request to the server

10 AJAX XMLHttpRequest (Example)
Create open and send a synchronous request

11 AJAX Response (Synchronous)
When the request completes, we get at the response through the following properties of the XMLHttpRequest object responseText – gets the response data as a string responseXML gets the response data as XML, which we can then parse using the DOM This is the same DOM we talked about

12 AJAX Response (Synchronous)

13 AJAX Response (Asynchronous)
The onreadystatechanged event fires as the request progresses Initialize Loading Loaded Interactive Completed Status and status contain the result status information 404 – not found / 200 success

14 AJAX Response (Asynchronous)

15 AJAX (jQuery) As usual, jQuery makes the process simple

16 A Few Words about XML It’s the extensible markup language
Data is frequently stored and transported as XML It looks like XHTML 5 Tags, attributes and elements Nesting concepts are the same However the tag and attribute names can be any valid name .NET knows about them

17 A Few Words about XML Sample XML document

18 REST Acronym for Representational State Transfer
REST (restful Web services) is a way of exchanging HTTP requests and responses between client and server It’s an alternative to Web Services and SOAP It’s an alternative to Remote Procedure Calls (RPC)

19 REST For read requests we
Send all data to the server via a URL and GET request URLs are a logical location, rather than a physical resource Data is typically returned as XML It’s not a standard but a way of doing things An architecture of style YQL is restful

20 A Few Words about YQL Yahoo Query Language
Implemented as a Web service, they maintain a number of tables Finance Geography and many more

21 AJAX (References) http://w3schools.com/ajax/default.asp

22 HTML 5


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