Module 14: Managing State

1. Module 14:Managing State

2. Overview • State Management • Application and Session Variables • Cookies and Cookieless Sessions

3. Lesson: State Management • What is State Management? • Types of State Management • Server-Side State Management • Client-Side State Management • The Global.asax File

4. What is State Management? Without State Management With State Management Login.aspx Login.aspx Please enter your logon information: Please enter your logon information: First Name First Name John John Last Name Last Name Chen Chen Web Server Submit Submit Web Server Greetings.aspx Greetings.aspx Hello Hello John Chen I forget who you are!!

5. Types of State Management

6. Server-Side State Management • Application state is a global storage mechanism accessible from all pages in the Web application • Session state is limited to the current browser session • Values are preserved through the use of application and session variables • Scalability • ASP.NET session is identified by the SessionID string Web Server Client Computer Application and Session variables SessionID

7. Client-Side State Management • Uses cookies to maintain state • Persistent cookies • Temporary/ Non-persistent cookies • Less reliable than server-side state management options • User can delete cookies • Less secure than server-side state management options • Limited amount of information • Client-side restrictions on file sizes Web Server Client Computer Cookies

8. The Global.asax File • Only one Global.asax file per Web application • Stored in the virtual root of the Web application • Used to handle application and session events • The Global.asax file is optional

9. The Global.asax File (continued) Client Request Response ASP.NET Web Server IIS ASP.NET HTTP Runtime Application_BeginRequest Application_AuthenticateRequest Application_AuthorizeRequest Application_EndRequest Application_ResolveRequestCache Application_UpdateRequestCache Application_AquireRequestState Application_ReleaseRequestState Application_PreRequestHandlerExecute Application_PostRequestHandlerExecute Page execution

10. Lesson: Application and Session Variables • Initializing Application and Session Variables • Using Application and Session Variables • Demonstration: Using Session Variables • Application and Session Variable Duration • Scalable Storage of Application and Session Variables • Saving Application and Session Variables in a Database

11. Initializing Application and Session Variables • Variables are initialized in Global.asax • The Application object shares information among all users of a Web application • The Session object stores information for a particular user session Sub Application_Start(s As Object,e As EventArgs) Application("NumberofVisitors") = 0 End Sub protected void Application_Start(Object sender,EventArgs e) { Application["NumberofVisitors"] = 0; }

12. Using Application and Session Variables • Set session and application variables • Read session and application variables Session("BackColor") = "blue" Application.Lock() Application("NumberOfVisitors") += 1 Application.UnLock() Session["BackColor"] = "blue"; Application.Lock(); Application["NumberOfVisitors"] = (int)Application["NumberOfVisitors"] + 1; Application.UnLock(); strBgColor = Session("BackColor") lblNbVisitor.Text = Application("NumberOfVisitors") strBgColor = (string)Session["BackColor"]; lblNbVisitor.Text = Application["NumberOfVisitors"].ToString();

13. Demonstration: Using Session Variables • Initialize a session variable (a number) in global.asax • Access the session variable from one page • Access the session variable from another page and modify it • Re-access the session variable from the first page

14. Application and Session Variable Duration • Session variables have a set duration after last access • Default is 20 minutes • Session duration can be changed in Web.config: • Application variables persist until the Application_End event is fired <configuration> <system.web> <sessionState timeout="10" /> </system.web> </configuration>

15. Scalable Storage of Application and Session Variables • By default, the session state is managed in process • Disadvantage of in process storage: • Not Scalable • ASP.NET provides out of process storage of session state • State can be stored in a SQL Server database or a state server • Advantages of out of process storage: • Scalable State server Web farm Session and Application variables -Or- SQL Client Session and Application variables

16. Saving Application and Session Variables in a Database 1 • Configure the session state in Web.config • Mode is set to sqlserver or stateserver • Then, configure the SQL server • OSQL creates several stored procedures and temporary databases for storing the variables <sessionState mode="SQLServer" sqlConnectionString="data source=SQLServerName; Integrated security=true" /> 2 c:\> OSQL –S SQLServerName –E <InstallSqlState.sql

17. Lesson: Cookies and Cookieless Sessions • Using Cookies to Store Session Data • Instructor-Led Practice: Using Variables and Cookies • Retrieving Information from a Cookie • Using Cookieless Sessions • Setting Up Cookieless Sessions

18. Using Cookies to Store Session Data • Creating a cookie: • Cookie contains information about the domain name HttpCookie objCookie = new HttpCookie("myCookie"); DateTime now = DateTime.Now; objCookie.Values.Add("Time", now.ToString()); objCookie.Values.Add("ForeColor", "White"); objCookie.Values.Add("BackColor", "Blue"); Response.Cookies.Add(objCookie); HttpCookie objCookie = new HttpCookie("myCookie"); DateTime now = DateTime.Now; objCookie.Values.Add("Time", now.ToString()); objCookie.Values.Add("ForeColor", "White"); objCookie.Values.Add("BackColor", "Blue"); objCookie.Expires = now.AddHours(1); Response.Cookies.Add(objCookie); To create a persistent cookie, specify the expiration time Set-Cookie: Username=John+Chen; path=/; domain=microsoft.com; Expires=Tuesday, 01-Feb-05 00.00.01 GMT

19. Instructor-Led Practice: Using Variables and Cookies • Students will: • See how the application and session variables, and persistent cookies, are used to store user information • Time: 15 Minutes

20. Retrieving Information from a Cookie • Read the cookie • Retrieve values from the cookie Dim objCookie As HttpCookie = Request.Cookies("myCookie") HttpCookie objCookie = Request.Cookies["myCookie"]; lblTime.Text = objCookie.Values("Time") lblTime.ForeColor = System.Drawing.Color.FromName _ (objCookie.Values("ForeColor")) lblTime.BackColor = System.Drawing.Color.FromName _ (objCookie.Values("BackColor")) lblTime.Text = objCookie.Values["Time"]; lblTime.ForeColor = System.Drawing.Color.FromName (objCookie.Values["ForeColor"]); lblTime.BackColor = System.Drawing.Color.FromName (objCookie.Values["BackColor"]);

21. Using Cookieless Sessions • Each active session is identified and tracked using session IDs • Session IDs are communicated across client-server requests using an HTTP cookie or included in the URL • Cookieless sessions • Session ID information is encoded into URLs • Cannot use absolute URLs • Most browsers limit the URL size to 255 characters, which limits use of cookieless Session IDs http://server/(h44a1e55c0breu552yrecobl)/page.aspx

22. Setting Up Cookieless Sessions • Session state is configured in the <SessionState> section of Web.config • Set cookieless = true <sessionState cookieless="true" />

23. Review • State Management • Application and Session Variables • Cookies and Cookieless Sessions

24. Lab 15: Storing Application and Session Data Logon Page Login.aspx BenefitsHome PageDefault.aspx CohoWinery Page HeaderHeader.ascx ASPState Menu ComponentClass1.vb or Class1.cs Registration Register.aspx Web.config tempdb Life InsuranceLife.aspx RetirementRetirement.aspx MedicalMedical.aspx DentalDental.aspx XML Web ServicedentalService1.asmx ProspectusProspectus.aspx DoctorsDoctors.aspx User Controlnamedate.ascx Lab Web Application XML Files Doctors Dentists