State management

State Management
MUHAMMAD AMIR – A M I R 4IT@ GMAI L.COM

Why we need?
Stateless HTTP Protocol:
 No information about the request
 Request created/destroyed with each post backversion.

State Management

Client Side!

Client Side – View State
 Mechanism that allows state values to be preserved across page postbacks
 EnableViewState property will be set to true

Advantages
 No server resources are required
 Simple implementation
 Enhanced security features

Disadvantages
 Performance considerations
 Device limitations
 Potential security risks

 Sample:

//To Save Information in View State
ViewState.Add ("NickName", "Dolly");
//Retrieving View state
String strNickName = ViewState ["NickName"];

 Code Example:
public int SomeInteger {
get {
object o = ViewState["SomeInteger"];
if (o != null) return (int)o;
return 0;
//a default
}
set { ViewState["SomeInteger"] = value; }
}

Code Sample

 Controls that use the view state

Client Side – Control State
 Essential for control to function properly
 It is Private viewstate for the control only
 Work even when ViewState turned off

Client Side – Control State

Code Sample

public class ControlStateWebControl : Control
{
private string _strStateToSave;
protected override void OnInit(EventArgs e)
{
Page.RegisterRequiresControlState(this);
base.OnInit(e);
}
protected override object SaveControlState() { return _strStateToSave; }
protected override void LoadControlState(object state)
{
if (state != null)
{
_strStateToSave = state.ToString();
}
}
}

Client Side – Hidden Fields
 Not rendered in browser
 Use to store small frequently changed data

Client Side – Hidden Fields

Code Sample

protected void Page_Load(object sender, EventArgs e)
{
if(!IsPostBack)|
Label1.Text = string.Format("Clicked {0} times", HiddenField1.Value);
}
protected void Button1_Click(object sender, EventArgs e)
{
HiddenField1.Value = (Convert.ToInt32(HiddenField1.Value) + 1).ToString();

}

Label1.Text = string.Format("Clicked {0} times", HiddenField1.Value);

Client Side – Cookies
 Stored at client side in text file or in memory of the client browser session
 Always sent with the request to the web server
 Read from user machine to identify user

Client Side – Cookies

Code Sample

//Storing value in cookie
HttpCookie cookie = new HttpCookie("NickName");
cookie.Value = "David";
Request.Cookies.Add(cookie);
//Retrieving value in cookie
if (Request.Cookies.Count > 0 && Request.Cookies["NickName"] != null)
lblNickName.Text = "Welcome" + Request.Cookies["NickName"].ToString();
else
lblNickName.Text = "Welcome Guest";

Client Side – Query String
 Used to pass information across pages
 Information passed along with URL in clear text

Client Side – Query String
public partial class _Default : Page
{
{
string v = Request.QueryString["param"];
if (v != null)
{
Response.Write("param is ");
Response.Write(v);
}
string x = Request.QueryString["id"];
if (x != null)
{
Response.Write(" id detected");
}
}
}

Code Sample

Client Side – Summary
State management

Recommended usage

View state

Use when you need to store small amounts of information for a page that will post back to itself. Using the ViewState
property provides functionality with basic security.

Control state

Hidden fields

Cookies

Use when you need to store small amounts of state information for a control between round trips to the server.
Use when you need to store small amounts of information for a page that will post back to itself or to another page,
and when security is not an issue.

Note
You can use a hidden field only on pages that are submitted to the server.
Use when you need to store small amounts of information on the client and security is not an issue.
Use when you are transferring small amounts of information from one page to another and security is not an issue.

Query string

Note
You can use query strings only if you are requesting the same page, or another page via a link.

State Management

Server Side!

Server Side – Application State
 Used to share information among users
 Stored in the memory of the windows process
 Great place to store data that changes infrequently

{
int count = 0;
if (Application["HitCounterForOrderPage"] != null)
count = (int)Application["HitCounterForOrderPage"];
count++;
Application["HitCounterForOrderPage"] = count;
lblcounter.Text = "Page Visited: " + count.ToString() + "Times";
}

//Application.Lock(); and Application.UnLock();

Code Sample

//Stroing information in application state
lock (this)
{
Application["NickName"] = "Nipun";
}
//Retrieving value from application state
lock (this)
{
string str = Application["NickName"].ToString();
}

Code Sample

Server Side – Session State
 Place to store values that will persist across page requests
 Values stored in Session are stored on the server
 Values remain in memory until they are explicitly removed or until the Session expires

Sample:
//Storing informaton in session state
Session["NickName"] = "ABC";
//Retrieving information from session state
string str = Session["NickName"];
Code Example:

object sessionObject = Session["someObject"];
if (sessionObject != null)
{
myLabel.Text = sessionObject.ToString();
}

Code Sample


Code Sample

In Process mode:
 Default mode
 Session values are stored in the web server's memory (in IIS & for each IIS Server)
 Values will be lost on server restart

<configuration>
<sessionstate mode="InProc" />
</configuration>


Code Sample

In State Server mode:
 Store data out of AppPool
 Needs to serialize objects
 Values will not be lost on server restart
See more details

<configuration>
<sessionstate mode="stateserver"
stateConnectionString="tcpip=127.0.0.1:42424" />
</configuration>


Code Sample

In SQL Server mode:
 Highly secure and reliable

 Overhead from serialization and deserialization
 Should be used when reliability is more important than performance
 Setup mode in sql server by running InstallSqlState.sql
Possible Path for .Net 4.0 [C:WindowsMicrosoft.NETFramework64v4.0.30319]
<configuration>
<sessionstate mode="sqlserver"
sqlConnectionString="Data Source=(local);User ID=sa;Password=pwd" />
</configuration>

Server Side – Profile Properties
 Allows you to store user-specific data
 Unlike session state, the profile data is not lost when a user's session expires
 Uses an ASP.NET profile, which is stored in a persistent format and associated with an
individual user
 Each user has its own profile

Server Side – Profile
Sample:
<profile>
<properties>
<add item="item name" />
</properties>
</profile>
Code Example:
<authentication mode="Windows" />
<profile>
<properties>
<add name="FirstName"/>
<add name="LastName"/>
<add name="Age"/>
<add name="City"/>
</properties>
</profile>

Code Sample


Code Sample

State management

Recommended usage

Application state

Use when you are storing infrequently changed, global information that is used by many users, and security is not an
issue. Do not store large quantities of information in application state.

Session state

Use when you are storing short-lived information that is specific to an individual session and security is an issue. Do
not store large quantities of information in session state. Be aware that a session-state object will be created and
maintained for the lifetime of every session in your application. In applications hosting many users, this can occupy
significant server resources and affect scalability.

Profile properties

Use when you are storing user-specific information that needs to be persisted after the user session is expired and
needs to be retrieved again on subsequent visits to your application.

Database support

Use when you are storing large amounts of information, managing transactions, or the information must survive
application and session restarts. Data mining is a concern, and security is an issue.

Links
 http://msdn.microsoft.com/en-us/library/75x4ha6s.ASPX
 http://www.c-sharpcorner.com/uploadfile/nipuntomar/state-management-in-Asp-Net/
 http://www.c-sharpcorner.com/uploadfile/37db1d/hour-1-understanding-5-Asp-Net-statemanagement-techniques-in-5-hours/

with examples:
 http://www.codeproject.com/Articles/492397/State-Management-in-ASP-NET-Introduction
 http://msdn.microsoft.com/en-us/library/ff647327.aspx

State management

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