AJAX in Action : AJAX in Action A look at AJAX Frameworks, compared
Brandon Kelly
BusinessRx
AJAX in Action : AJAX in Action Thanks for coming today!
Please feel free to ask questions any time throughout today’s presentation.
In the next hour, we will:
Spend 10-15 minutes discussing AJAX, it’s history, present and future state
Spend 20-25 minutes reviewing code in a real-world AJAX application.
Spend 10-15 minutes in an interactive Q&A session.
AJAX inside Web 2.0 : AJAX inside Web 2.0 There’s a lot of confusion on what “Web 2.0” really is all about.
Web 2.0 is really based on one simple concept:
Customers have choices when using services on the web.
Because customers have choices, the quality and responsiveness of software on the web is part of delivering great service.
AJAX is one delivery mechanism for creating great software for the web.
HTTP as a stateless protocol : HTTP as a stateless protocol HTTP is the communications protocol for establishing a connection with a Web server and transmitting HTML pages to the client browser or any other files required by an HTTP client application.
HTTP is a stateless request/response system. The connection is maintained between client and server only for the immediate request after which the connection is subsequently closed.
Where the problem lies : Where the problem lies The problem with the stateless nature of the web becomes apparent when developing “applications” for the medium: Each time a page is requested, it doesn’t know about how the page was last viewed.
With older web technologies (ASP, PHP), software developers had to invent their own state mechanisms.
Web 1.0 – Software in 2002 : Web 1.0 – Software in 2002 ASP.Net 1.0 and 1.1 introduced server-side controls – scriptable objects that could “remember” their state between page posts (called “postbacks”).
By 2002, Software Developers could write web applications leveraging their own controls, 3rd party controls, or controls provided by Microsoft without worrying about state mechanisms.
Each time one of these controls needed to update a page, the entire page would be refreshed inside the user’s web browser.
Where AJAX comes in : Where AJAX comes in AJAX alleviates the need to refresh the entire contents of a page (which can be heavy in some usage scenarios) by initiating a request from the client, and updating just the portions of a web page that change between requests.
Various AJAX Frameworks do the above-mentioned job better than others. Only now are standard for this implementation emerging (JSON, OpenAjax Alliance, etc.)
How is this accomplished? : How is this accomplished? At the heart of most AJAX Frameworks lies the following:
Cross-browser XmlHttp implementation
JSON serializer/parser
An output caching engine (that can compare diff’s of output streams between page renders)
A server side packaging/un-packaging mechanism for handling requests.
What does this mean for you? : What does this mean for you? Modern AJAX frameworks are able to handle all of the client-side scripting.
Most require little developer knowledge of Javascript or XML.
The short story is:
Modern AJAX Frameworks provide a complete programming model that allows developer to AJAX-ify existing server-side code with ltitle to no additional knowledge.
A History of AJAX Technology : A History of AJAX Technology Remote ScriptingIn 1996, Microsoft released Remote Scripting, an ASP-scriptable Java component capable of intiating server-side calls from client-side script. The technology was limited as it was:
Difficult to implement
Slow
Could only initiate one synchronous request at a time
A History of AJAX Technology : A History of AJAX Technology Server-side XMLHttp (ActiveX Object)
In 1999, Microsoft released an ActiveX Object with their MSXML library called XMLHttp.
XMLHttp allowed developers to initiate HTTP calls from client-side script through ActiveX. It had a limited audience because only Internet Explorer supported hosting ActiveX objects in the browser.
In the early 2000’s, Mozilla came on-board and implemented an almost identical version of XmlHttp in their browser.
A History of AJAX Technology : A History of AJAX Technology XMLHttp is the cornerstone of modern AJAX Frameworks.
Some browsers use a “hidden IFRAME” trick to initiate synchronous requests from client-side code.
XMLHttp in Internet Explorer allows for 2 simultaneous HTTP requests. Modern AJAX Frameworks can correctly pool requests to alleviate this limitation.
AJAX Frameworks : AJAX Frameworks Microsoft AJAX for ASP.Net 1.0 was released a few months back.
Microsoft charges nothing for this framework
Framework itself provides AJAX ability, UpdatePanel which can contain any normal ASP.Net server-side control and AJAX-ify it.
AJAX Control toolkit extends this concept further with pre-built “extenders” allowing the developer to add AJAX-type behaviors to existing controls.
AJAX Frameworks : AJAX Frameworks Telerik radControls Q4 2006
Telerik releases updates for it’s AJAX products quarterly and inter-quarterly through Service Packs
radControls contains over 18 AJAX-enabled UI controls including:
WYSIWYG HTML editor
Charting system
Toolbar / Window management
Menu system
PanelBars
AJAX Frameworks : AJAX Frameworks Infragistics NetAdvantage 2007
Like telerik, Infragistics releases UI components quarterly to it’s customers.
Components are a little bulkier, meaning they require more extensive download to client browsers.
Infragistics controls have great designer support, which lowers the barrier-to-entry for newcomers to ASP.Net or AJAX
HelpDesk Application : HelpDesk Application We’ve created a starter kit Help Desk application that features some AJAX technology at work.
It’s time to look at some code!
Learn More! : Learn More! Come speak with me after the Q&A if you’d like.
Find this sample on the web at:
http://helpdesk.businessrx.com
Find out more about AJAX Frameworks:
http://ajax.asp.net
http://www.telerik.com
http://www.infragistics.com