state management in asp client side

7/29/2019 State Management in ASP Client Side .

1/27

State Management In Asp.Net

Client Side


2/27

Introduction

State Management is the process by which we

maintain session related information and

additional information about the controls and

its state.

The necessity of state management arises

when multiple users request for the same or

different Web Pages of a Web Site.


3/27

Types Of State Management

There are two types of state management:

1. Server Side

Data is stored in memory on the server. Itincludes application state, session state andprofiles.

2. Client Side

Data is stored on the client in various ways. Itincludes cookies, viewstate, query strings andhidden fields.


4/27

Types to be covered:

1. Cookies

2. Query Strings.

3. Hidden Field.

4. ViewState 5. Applications

6. Sessions

7. Profiles


5/27

Cookies

A cookie is a small text file sent by web serverand saved by web browser on client machine.

Cookies are also known by many names, HTTP

Cookie, Web Cookie, Browser Cookie, SessionCookie, etc.

Common use of cookies is to remember users

between visits. In each cookie you can not save more than 4k

of information.


6/27

clients can open cookies and see the contentof a cookie so they are not secure. Cookies are

usually used to save user preferenceinformation.

Size of cookies is limited to 4096 bytes.

Total 20 cookies can be used on a singlewebsite; if you exceed this browser will deleteolder cookies.

End user can stop accepting cookies by

browsers, so it is recommended to check theusers state and prompt the user to enable

cookies.


7/27

Types OF Cookies

There are 2 different types of cookies:

1. PERSISTANT COOKIES:

A persistent cookie is one stored as a file on your

computer, and it remains there when you closeInternet Explorer.

2. TEMPORARY(SESSION) COOKIES:

A temporary or session cookie is stored only for

your current browsing session, and is deletedfrom your computer when you close yourbrowser.


8/27

Example 1:

Creating Cookies(Using HttpCookie Class):

Take a new website and make design page as

shown in the next slide.

Do coding on login button click as shown

below:


9/27


10/27

Coding on login button click:

protected void Button1_Click(object sender,

EventArgs e){

HttpCookie mycookie = newHttpCookie("cookie1");

mycookie["Name"] = TextBox1.Text;mycookie["password"] = TextBox2.Text;

Response.Cookies.Add(mycookie);

mycookie.Expires = DateTime.Now.AddDays(1);

Response.Redirect("home.aspx");

}


11/27

Make another page as home.aspx and do codingon page load as shown:

protected void Page_Load(object sender,

EventArgs e) {

HttpCookie reqcookie =Request.Cookies["cookie1"];

if (reqcookie != null)

{

Label1.Text = reqcookie["Name"];

Label2.Text = reqcookie["Password"]; }

}


12/27

Example:

Create Cookies( Using Response)

Take a textbox and a button.

On button click, do coking as:

protected void Button1_Click(object sender,EventArgs e)

{

Response.Cookies["StudentCookies"].Value =TextBox1.Text;

Response.Cookies["StudentCookies"].Expires

= DateTime.Now.AddDays(1); Response.Redirect("home.aspx");

}


13/27

On home page, on page load, do coding as:

TextBox1.Text =

Request.Cookies["StudentCookies"].Value;


14/27

Using Multi Valued Cookies

You can also store multiple name-value pairs

in a single cookie.

The name-value pairs are referred to as

subkeys.

A cookie with subkeys also helps you limit the

size of cookie files.


15/27

Example 3:

Take a button and do coding as follows:

protected void Button1_Click(object sender, EventArgs e)

{ Response.Cookies["StudentCookies"]["RollNumber"] = "12";

Response.Cookies["StudentCookies"]["FirstName"] ="Abhimanyu";

Response.Cookies["StudentCookies"]["MiddleName"] =

"Kumar"; Response.Cookies["StudentCookies"]["LastName"] = "Vatsa";

Response.Cookies["StudentCookies"]["TotalMarks"] = "499";

Response.Cookies["StudentCookies"].Expires =DateTime.Now.AddDays(1);

Response.Redirect("home2.aspx"); }


16/27

Take another page as home2.aspx and do coding on page load as:

protected void Page_Load(object sender, EventArgs e)

{

string roll; roll = Request.Cookies["StudentCookies"]["RollNumber"];

roll = roll + " " +Request.Cookies["StudentCookies"]["FirstName"];

roll = roll + " " +

Request.Cookies["StudentCookies"]["MiddleName"]; roll = roll + " " +

Request.Cookies["StudentCookies"]["LastName"];

roll = roll + " " +Request.Cookies["StudentCookies"]["TotalMarks"];

Label1.Text = roll; }


17/27

Query Strings In Asp.Net

A query string is information that is appendedto the end of a page URL.

Example:

http://www.contoso.com/listwidgets.aspx?category=basic&price=100

In the URL path above, the query string starts

with a question mark (?) and includes twoattribute/value pairs, one called "category"and the other called "price."


18/27

Query strings provide a simple but limited way

to maintain state information.

some browsers and client devices impose a2083-character limit on the length of the URL.


19/27

Example:

protected void Button1_Click(object sender,

EventArgs e) {

int recordid = 10;

Response.Redirect("Default2.aspx?recordid=" +recordid.ToString());

}

Get the value in the same or another page. string id= Request.QueryString["recordid"];


20/27

Hidden Feilds

A HiddenField control stores a single variable in itsValue property and must be explicitly added to thepage.

The information in a HiddenField control is not dis

it can be read and set in client script. played when thebrowser renders the page.

Example:
http://msdn.microsoft.com/en-us/library/system.web.ui.webcontrols.hiddenfield(v=vs.90).aspxhttp://msdn.microsoft.com/en-us/library/system.web.ui.webcontrols.hiddenfield.value(v=vs.90).aspxhttp://msdn.microsoft.com/en-us/library/system.web.ui.webcontrols.hiddenfield.aspxhttp://msdn.microsoft.com/en-us/library/system.web.ui.webcontrols.hiddenfield.aspxhttp://msdn.microsoft.com/en-us/library/system.web.ui.webcontrols.hiddenfield.value(v=vs.90).aspxhttp://msdn.microsoft.com/en-us/library/system.web.ui.webcontrols.hiddenfield(v=vs.90).aspx


21/27

ViewState Controls

The ViewState property provides a dictionary

object for retaining values between multiple

requests for the same page.

When the page is processed, the current state ofthe page and controls is hashed into a string and

saved in the page as a hidden field, or multiple

hidden fields if the amount of data stored in theViewState property exceeds the specified value in

the MaxPageStateFieldLength property.
http://msdn.microsoft.com/en-us/library/system.web.ui.control.viewstate(v=vs.90).aspxhttp://msdn.microsoft.com/en-us/library/system.web.ui.control.viewstate(v=vs.90).aspxhttp://msdn.microsoft.com/en-us/library/system.web.ui.page.maxpagestatefieldlength(v=vs.90).aspxhttp://msdn.microsoft.com/en-us/library/system.web.ui.page.maxpagestatefieldlength(v=vs.90).aspxhttp://msdn.microsoft.com/en-us/library/system.web.ui.control.viewstate(v=vs.90).aspxhttp://msdn.microsoft.com/en-us/library/system.web.ui.control.viewstate(v=vs.90).aspx


22/27

Make a login application in which user is given 3 chances tologin:

Code:

int counter = 3; SqlConnection con = new SqlConnection();

protected void Page_Load(object sender, EventArgs e)

{

con.ConnectionString =ConfigurationManager.ConnectionStrings["cn"].ConnectionString;

if (con.State == ConnectionState.Closed)

{

con.Open();

}


23/27

if (!Page.IsPostBack)

{

Label2.Text = counter.ToString();

ViewState["count"] = counter; }

protected void Button1_Click(object sender, EventArgs e)

{

SqlCommand cmd = new SqlCommand();

cmd.CommandText = "select password from Table1where name=@sname";

cmd.Connection = con;

cmd.Parameters.Add("@sname",SqlDbType.VarChar,50).Value = TextBox1.Text;


24/27

SqlDataReader dr1 = cmd.ExecuteReader();

if (dr1.HasRows)

{

dr1.Read();

if (TextBox2.Text == dr1["password"].ToString())

{

Label1.Text = "you are successfully login";

}

else

{ int i = (int)ViewState["count"];

i = i - 1;

ViewState["count"] = i;


25/27

if (i > 0)

{

Label1.Text = "retry ...you have " + i +

"chances left now";

}

else

{ Response.Redirect("user.aspx");

}

}

}

dr1.Close();

cmd.Dispose();

//dr.Close();


26/27

Comparison

1. ViewState can be applied to all data types

of asp.net

QueryStrings are limited to string data type.

Cookies are limited to string types.

2. ViewState values are stored in hidden fields.

Querystring in browsers url. Cookies in clients computer.


27/27

3. ViewState lifetime is permanent.

Querystrings are lost when the user enters a

new url or closes the browser.

Cookies lifetime are set by programmers.

4. Scope of viewstate is limited to current

page.

Scope of querystrings are is limited to the

target page.

Scope of the cookies are limited to the entire

application.

state management in asp client side

Documents