I'm a newbie to Asp.Net 2.0 so it's probably me doing something wrong but I'm trying to modify this excellent Asp.Net chat room (http://steveorr.net/articles/WebChat.aspx). I've delved into the coding and I've tried to insert my own variable into the coding that can hold data inbetween server calls. I've named it MyVariable in the extract below...

  Private _LastMsgID As Long = 0

  Private MyVariable As Long

Within the class theres a RaiseCallBackEvent function gets called when someone is chatting, into which I've inserted:

try using a viewstate variable or a application variable and see if you have the same results. I alway do something like this...

  Private Property MyVariable() As Long
    Get
      Return ViewState("MyVariable")
    End Get
    Set(ByVal value As Long)
      ViewState("MyVariable") = value
    End Set
  End Property

^^^^ Exactly -- that will solve it completely. The reason why your code isn't working is that the page class, including all of the controls, are atomic to a single request. In order for values to persist, you need to use some sort of persistance mechanism. ViewState is what the .NET server controls use to maintain state.

When working with viewstate, you need to pay attention to when the 'Save Viewstate' and 'Load Viewstate' events fire. If you see some strange persistance problems pop up, it's probably because values are being set after viewstate is saved, or before viewstate is loaded. Here is a link to a good diagram:

http://www.eggheadcafe.com/articles/o_aspNet_Page_LifeCycle.jpg

Thanks guys - that was very useful. I was initially a bit thrown by the problem because I hadn't spotted the following line in the code:

Cheers