Introduction
In web applications, HTTP is stateless, meaning it does not store information between requests.
To remember user actions, login details, shopping cart data, etc., ASP.NET uses state management techniques.
There are two types:
| Type | Example |
|---|---|
| Client-Side State Management | ViewState, Cookies, Hidden Fields, QueryString |
| Server-Side State Management | Session, Cache, Application State |
In this article, we will explain ViewState, Session, Cookies, Cache with real-time examples and code.
1. ViewState
What It Is
ViewState stores values in the page (client side) and retains them during postbacks.
Use Case
Remember control values after button click
1. Forms
2.Dropdowns, Textboxes
Limitations
Increase page size (slower page load)
Works only in Web Forms (not MVC/Core)
Example
ASPX Page
<asp:TextBox ID="txtName" runat="server"></asp:TextBox>
<asp:Button ID="btnSave" runat="server" Text="Save" OnClick="btnSave_Click"/>
<asp:Label ID="lblResult" runat="server"/>
Code Behind
protected void btnSave_Click(object sender, EventArgs e)
{
ViewState["UserName"] = txtName.Text;
lblResult.Text = "Saved: " + ViewState["UserName"];
}
2. Session
What It Is
Session stores data per user on the server until the browser is closed or timeout (default 20 min).
Real-Time Use Case
Shopping cart
User login info
Banking portal session security
Limitations
Uses server memory
Too many sessions affect performance
Example
Store in Session
Session["UserId"] = 101;
Retrieve
int userId = Convert.ToInt32(Session["UserId"]);
Remove
Session.Remove("UserId");
3. Cookies
What It Is
Cookies store data in the browser.
Use Case
Remember Me login
Store user preferences (language, theme)
Example
Create Cookie
HttpCookie ck = new HttpCookie("UserName");
ck.Value = "Sandhiya";
ck.Expires = DateTime.Now.AddDays(7);
Response.Cookies.Add(ck);
Read Cookie
string name = Request.Cookies["UserName"].Value;
Delete Cookie
Response.Cookies["UserName"].Expires = DateTime.Now.AddDays(-1);
Limitations
Max 4KB size
Stored on client → less secure
4. Cache
What It Is
Cache stores frequently used data on the server for fast access.
Use Case
Load product catalog once, reuse many times
Caching stock market data
Caching configuration and lookup tables
Example
Insert into Cache
Cache["StockPrice"] = 102.55;
Retrieve
var price = Cache["StockPrice"];
Remove
Cache.Remove("StockPrice");
Benefit
Improves performance
Reduces database calls
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