Ajax PageMethods using JSON (JavaScript Object Notation)

Page Methods

Page methods allow ASP.NET AJAX pages to directly execute a page’s static methods, using JSON (JavaScript Object Notation). JSON is basically a minimalistic version of SOAP, which is perfectly suited for light weight communication between client and server. For more information about how to implement page methods and JSON, take a look at Microsoft’s Exposing Web Services to Client Script in ASP.NET AJAX.

Instead of posting back and then receiving HTML markup to completely replace our UpdatePanel’s contents, we can use a web method to request only the information that we’re interested in:

[WebMethod] public static string GetCurrentDate() { return DateTime.Now.ToLongDateString(); }

Using JSON, the entire HTTP round trip is 24 bytes, as compared to 872 bytes for the UpdatePanel. That’s roughly a 4,000% improvement, which will only continue to increase with the complexity of the page.

Not only has this reduced our network footprint dramatically, but it eliminates the necessity for the server to instantiate the UpdatePanel’s controls and take them through their life cycles to render the HTML sent back to the browser.