State management

State management is very important and useful in ASP.NET. It is also asked in many interviews to fresher and experienced developers.

State management is a preserve state control and object in an application because ASP.NET web applications are stateless. A new instance of the Web page class is created each time the page is posted to the server. If a user enters information into a web application, that information would be lost in the round trip from the browser (MSDN).

In a single line, State management maintains and stores the information of any user till the end of the user session.

Types of state management 

There are two types of state management techniques: client side and server side.

Client side

1. Hidden Field

2. View State

3. Cookies

4. Control State

5. Query Strings

Server side

1. Session

2. Application

Server side

 Session

Session is a very important technique to maintain state. Normally session is used to store information and identity. The server stores information using Sessionid.

Set User Session

protected void btnSubmit_Click(object sender, EventArgs e)

        {

            Session["UserName"] = txtName.Text;

            Response.Redirect("Home.aspx");

        }

Session Event

Session event can be seen in project Global.asax file.

Two types of Session Events

Session_Start

The Session_start event is raised every time a new user requests without a session ID.

void Session_Start(object sender, EventArgs e)

        {

            Session["master"] = "~/Master.master";

        }

Session_End

The Session_End event is raised when session is ended by a user or a time out using Session end method.

void Session_End(object sender, EventArgs e)

        {

            Response.Write("Session_End");

        }

The session is stored in the following for ways in ASP.NET.

•InProcMode

It is a default session mode and a value store in web server memory (IIS). In this the session value stored with server start and it ends when the server is restarted.

•State Server Mode

In this mode session data is stored in separate server.

•             SQL Server Mode

In this session is stored in the database. It is a secure mode.

•             Custom Mode

Generally under session data is stored in InProc, Sql Server, State server, etc. If you store session data with other new techniques then provide ASP.NET.

Application

Application State is a server side management state. It is also called application level state management. In this mainly store user activity in server memory and application event shown in Global.asax file.

There are three types of applications in ASP.NET.

Application_Start

  void Application_Start(object sender, EventArgs e)

        {

            Application["AppstartMessage"] = "Welcome to my blog";

        }

This event begins with domain start.

Application_Error

In this section manage unhandled exception error.

void Application_Error(object sender, EventArgs e)

        {

            // Write an unhandled error code exception 

        }

Application_ End

This ends with domain or restarts IIS.

   void Application_End(object sender, EventArgs e)

        {

            Application["AppEndMessage"] = "Application Closed";

        }

Cache

Cache is stored on server side. It implements Page Caching and data caching. Cache is use to set expiration polices

Response.Cache.SetExpiresTime(DateTime.Now.AddDays(1));

Client Side

Now here I am explaining client side state management one by one:

Also state management has the following four important parts available on the client side,

Cookie

Cookie is a small and an important part of ASP.NET. In this store user information, session and application. It can be created constant and temporary and they work with browser request. Cookies are store on client side. The server can read cookies and abstract data.

Two types of cookies are available,

Persistence

This type of cookie works with Date and time.

  Response.Cookies["CookieName"].Value = "Test Cookies"; 

//set expire time  

Response.Cookies["CookieName"].Expires = DateTime.Today.AddHours(1); 

Non-Persistence

This is a temporary cookie. It is created with access application and discards the close application.

Response.Cookies["CookieName"].Value = "Test Cookies"; 

Hidden Field

Hidden fields are used to store value to client side. Hidden field is not displayed on the browser, but it works on a request.

if (HiddenField1.Value != null) 

{ 

   int val = Convert.ToInt32(HiddenField1.Value) + 1;

        HiddenField1.Value = val.ToString(); 

   Label1.Text = val.ToString(); 

}

Viewstate

Viewstate is a very useful client side property. It is used for page level state management. Viewstate stores any type of data and used for sending and receiving information,

Viewstate is easy to apply and does not need access to any server resources. In a Viewstate, do not store big data, only store small values. Viewstate enables and disables on page level control. It also supports Encryption and Decryption and data/value is stored in hashed format. So we are not storing important data such as password, account information, etc. When more data is stored in this, then the page becomes heavy.

Query String

Query string stores the value in URL.

Response.Redirect("ShowStringValue.aspx?Username=" + txtUsername.Text);