ASP.NET ViewState is a great mechanism that simplifies the life of ASP.NET developers. But, as everybody knows, the .NET Framework saves the ViewState data as a hidden field on your ASPX page. If your page has only a few controls, this is not a problem. But, if your page has some Panels and/or some DataGrids, with the technique demonstrated on this article, you could reduce dramatically the load time of the page.

We will start our analysis thinking where the Framework needs to work with the data saved on the ViewState hidden field. The answer is: only on the server side. The system doesnt need to work with the ViewState data on the client side, so, if we start to save this data on the server instead of carrying all this from the server to the client and from the client to the server again, we will save a lot of time while loading our documents. You probably wont note the difference while loading the page on the same computer that the application is installed, but, test it using a dial-up connection and you will see what happens. You cold also see the the size of the source code generated with and without this technique.

This example consist of a class that inherits the System.Web.UI.Page, and overrides the methods SavePageStateToPersistenceMedium and LoadPageStateFromPersistenceMedium. These methods are responsible for saving and loading the ViewState used by the controls on a page. What we do is intercept the call to these methods and, using some simple custom config keys on the Web.Config, set how this class should work. It can save the ViewState on the server using two destinations: Session and Cache, and, has the ability to work as the original class, saving the ViewState data to the ASPX page.

If you already have a project and want to start using this technique, all that you need to do is add a reference to the class that accompanies this example and inherit your "code-behind files" from it instead of the System.Web.UI.Page, and add the Config information to your Web.Config.

To develop this technique, I read a lot of articles over the internet, but, one really "opened my mind" of how this implementation could be done and the benefits of it. See more information on the Points of Interest Section.

I included a demo project that you could download and use to test the implementation. Note that the demo project saves the ViewState to the session, which I think is the best place to store it.http://www.codeproject.com/aspnet/ServerViewState.asp