[asp.net] What is the difference between SessionState and ViewState?

What is the difference between SessionState and ViewState in ASP.NET?

Usage: If you're going to store information that you want to access on different web pages, you can use SessionState

If you want to store information that you want to access from the same page, then you can use Viewstate

Storage The Viewstate is stored within the page itself (in encrypted text), while the Sessionstate is stored in the server.

The SessionState will clear in the following conditions

1. Cleared by programmer
2. Cleared by user
3. Timeout

Session state is saved on the server, ViewState is saved in the page.

Session state is usually cleared after a period of inactivity from the user (no request happened containing the session id in the request cookies).

The view state is posted on subsequent post back in a hidden field.

Session is used mainly for storing user specific data [ session specific data ]. In the case of session you can use the value for the whole session until the session expires or the user abandons the session. Viewstate is the type of data that has scope only in the page in which it is used. You canot have viewstate values accesible to other pages unless you transfer those values to the desired page. Also in the case of viewstate all the server side control datas are transferred to the server as key value pair in __Viewstate and transferred back and rendered to the appropriate control in client when postback occurs.

SessionState

• Can be persisted in memory, which makes it a fast solution. Which means state cannot be shared in the Web Farm/Web Garden.
• Can be persisted in a Database, useful for Web Farms / Web Gardens.
• Is Cleared when the session dies - usually after 20min of inactivity.

ViewState

• Is sent back and forth between the server and client, taking up bandwidth.
• Has no expiration date.
• Is useful in a Web Farm / Web Garden