Ajax Rich Internet Applications ICW Lecture 21 Errol

Ajax / Rich Internet Applications ICW Lecture 21 Errol Thompson

Proposed learning • Clarify the divide between client and server in web programming • Expand understanding of client programming options – Asynchronous interaction options – Rich internet applications • Thinking outside the box

The client / server divide • What is the nature of • A desktop application • A browser based application • A server-based application • Is it possible to treat them as the same thing? • If not, why not? • If so, why and how?

Assumed knowledge – Protocols • Transport protocol • TCP/IP and sockets • Application protocols • smtp, https, ftp • What did you have to implement with your browser? • What do you expect the server to be doing?

Assumed knowledge – Static content • What does it mean to have static content? • What does the server have to do? • What does the browser have to do • What is the problem with static pages?

A scenario Jack want an application that will allow him to enter information about cyclists who enter his road race events. He wants it to be a web application as he wants to integrate the list with a system for commissaires to manage the race and for reporting race progress and results. • Will this work with static pages? – Why or why not?

Dynamic content – Server based • • • Where is the servlet or JSP code run? What does it do? What protocols are involved? What happens in the browser? Where is Javascript code run? • What does Javascript do? • What are its limitations?

Removing page reload - AJAX • On what technologies and protocols is AJAX coding based? • In what respect is it asynchronous? • What type of requests can be made? • How are responses to requests handled? • What are the states that nee to be considered? • Why check the status codes in a response? • What do you need to do to have changes reflected on the web page? • What is the impact of browser caching and how can it be resolved?

Transferring data • How is parameter data passed to the server? • ‘GET’ parameters • ‘POST’ data • How is data returned from the server? • Is there any limitations on the data transferred? • Why or why not?

Formatting data for transfer • What data formats can be used? • Anything that you can handle • Write your own logic • XML • Work with a document object model (DOM) • JSON (Java. Script Object Notation) • Uses “normal” Java. Script

JSON Rider data {“rider”: [ { “number”, 231, “name”, “Fred Dagg”, “club”, “Uof. B Cycling Club”, “sponsor”, “” } ] };

Accessing JSON data var rider= eval(‘(‘ + request. response. Text + ‘)’ ); var name = rider[0]. name; var number = rider[0]. number; . . .

Issues with AJAX • How vulnerable is AJAX code to attack? • How easy is it to maintain the DOM model? • Is it possible to use other protocols with AJAX type coding? • How compatible are browsers?

Application in the browser – Rich Internet Applications (RIA) • Can we code for the browser in the same way that we can browse for the desktop? • Flex/Flash, Java. FX, Silverlight • What are the issues? • Browser support • Install of virtual machine (VM)

Cloud computing • Applications accessible through the browser • Configurable to individual customer needs • Removes need for company to manage their own application servers

Breaking the boundaries • The future of the browser • Collaboration over the web • Portability between desktop and mobile device • Remove the boundaries between browser and desktop

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