ViewState in Session

This is how to persist the viewState to the database (not the session). 

If you want to put the viewstate in the session you will need to make a sessions table or run the .net utility to do it for you. Here is a good article on that http://articles.techrepublic.com.com/5100-10878_11-5766717.html

You will need to create a database table. I think there is a utility that will do it for you but I would roll my own.

Create Table ViewState (

 Id int IDENTITY(1,1) NOT NULL,

 Value Text NOT NULL,

 Expires NOT NULL

)

The id is an identity so you know you have a unique number acrossed all of your servers in the garden
The id is an int instead of a guid because the size of the guids will shread you pages with the huge numbers of inserts and deletes
The Expires is added so expired viewstates can be purged.

Next you will need to create a base page that all of your pages inherit.

Then add the method that saves the viewstate to the basepage:

protected override void SavePageStateToPersistenceMedium(Object viewState)
{
        DateTime expires = DateTime.Now.AddMinutes(Session.Timeout);
        string key = [ save a serialized version of view state and the expires date to database here and return the id ]
        ClientScript.RegisterHiddenField("_VIEWSTATE_KEY", key);
}

Then add the method that retreives it:

protected override object LoadPageStateFromPersistenceMedium()
{
        int? key = (int?)Request.Form["_VIEWSTATE_KEY"];
        if (key != null) return [ load the viewstate out of database based on the key and deserialized it and then delete it]
        return null;
}