State Management in asp.net

State management means to preserve state of a control, web page, object/data, and user in the application explicitly because all ASP.NET web applications are stateless, i.e., by default, for each page posted to the server, the state of controls is lost. Nowadays all web apps demand a high level of state management from control to application level.

State management 2 types :

1. Client side state management
2. Server side state management

Client side

1. Hidden Field
2. View State
3. Cookies
4. Control State
5. Query Strings
   
   

Server side

1. Session
2. Application

1.Hidden Field

Hidden field is a control provided by ASP.NET which is used to store small amounts of data on the client. It store one value for the variable and it is a preferable way when a variable's value is changed frequently. Hidden field control is not rendered to the client (browser) and it is invisible on the browser. A hidden field travels with every request like a standard control’s value.

Design :

<asp:HiddenField ID="HiddenField1" runat="server"  />

Code Behind :

protected void Page_Load(object sender, EventArgs e)
{
   if (HiddenField1.Value != null)
   {
    int val= Convert.ToInt32(HiddenField1.Value) + 1;
    HiddenField1.Value = val.ToString();
    Label1.Text = val.ToString();
   }
}
protected void Button1_Click(object sender, EventArgs e)
{
  //this is No Action Button Click
}

2.View State 

View state is another client side state management mechanism provided by ASP.NET to store user's data, i.e., sometimes the user needs to preserve data temporarily after a post back, then the view state is the preferred way for doing it. It stores data in the generated HTML using hidden field not on the server.

Code Behind :


protected void Page_Load(object sender, EventArgs e)
{
    if (IsPostBack)
    {
        if (ViewState["count"] != null)
        {
            int ViewstateVal = Convert.ToInt32(ViewState["count"]) + 1;
            Label1.Text = ViewstateVal.ToString();
            ViewState["count"]=ViewstateVal.ToString();
        }
        else
        {
            ViewState["count"] = "1";
        }
    }
}
protected void Button1_Click(object sender, EventArgs e)
{
       Label1.Text=ViewState["count"].ToString();
}

3. Cookie

Cookie is a small text file which is created by the client's browser and also stored on the client hard disk by the browser. It does not use server memory. Generally a cookie is used to identify users.

Types of Cookies

1. Persistence Cookie: Cookies which you can set an expiry date time are called persistence cookies. Persistence cookies are permanently stored till the time you set.

Response.Cookies["nameWithPCookies"].Value = "This is A Persistance Cookie";
Response.Cookies["nameWithPCookies"].Expires = DateTime.Now.AddSeconds(10); 

And the second one is:  


HttpCookie aCookieValPer = new HttpCookie("Persistance");
aCookieValPer.Value = "This is A Persistance Cookie";
aCookieValPer.Expires = DateTime.Now.AddSeconds(10);
Response.Cookies.Add(aCookieValPer);

2. Non-Persistence Cookie: Non persistence cookies are not permanently stored on the user client hard disk folder. It maintains user information as long as the user accesses the same browser. When user closes the browser the cookie will be discarded. Non Persistence cookies are useful for public computers.

Let us see how to create a non persistence cookies. There are two ways, the first one is:

Response.Cookies["nameWithNPCookies"].Value = "This is A Non persistence Cookie";

And the second way is:


HttpCookie aCookieValNonPer = new HttpCookie("NonPersistance");
aCookieValNonPer.Value = "This is A Non Persistance Cookie;
Response.Cookies.Add(aCookieValNonPer);how to create cookie : 

How to read a cookie:


if (Request.Cookies["NonPersistance"] != null)
Label2.Text = Request.Cookies["NonPersistance"].Value;

4. Control State

Control State is another client side state management technique. Whenever we develop a custom control and want to preserve some information, we can use view state but suppose view state is disabled explicitly by the user, the control will not work as expected. For expected results for the control we have to use Control State property. Control state is separate from view state.

How to use control state property: Control state implementation is simple. First override the OnInit() method of the control and add a call for the Page.RegisterRequiresControlState() method with the instance of the control to register. Then override LoadControlState and SaveControlState in order to save the required state information.

Server side

1. Session   

Session management is a very strong technique to maintain state. Generally session is used to store user's information and/or uniquely identify a user (or say browser). The server maintains the state of user information by using a session ID. When users makes a request without a session ID, ASP.NET creates a session ID and sends it with every request and response to the same user.

How to get and set value in Session:

Session["Count"] = Convert.ToInt32(Session["Count"]) + 1;//Set Value to The Session
Label2.Text = Session["Count"].ToString();

2. Application

Application state is a server side state management technique. The date stored in application state is common for all users of that particular ASP.NET application and can be accessed anywhere in the application. It is also called application level state management. Data stored in the application should be of small size.  

How to get and set a value in the application object:

Application["Count"] = Convert.ToInt32(Application["Count"]) + 1; //Set Value to The Application Object
Label1.Text = Application["Count"].ToString();