chap16 - Chapter 16 Assembling a Three-Tier Web Form...

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Object-Oriented Application Development Using VB .NET 1 Chapter 16 Assembling a Three-Tier Web Form Application
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Object-Oriented Application Development Using VB .NET 2 Objectives In this chapter, you will: Understand the concept of state for Web applications Create an ASP.NET user control Use data binding technology Develop a Web application for Bradshaw Marina Learn about XML and Web services
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Object-Oriented Application Development Using VB .NET 3 Understanding the Concept of State for Web Applications Hypertext Transmission Protocol (HTTP) Used by the Internet A stateless protocol Does not know whether the request is a single request or part of a sequence of requests from the same user
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Object-Oriented Application Development Using VB .NET 4 Maintaining State Options available in HTTP for maintaining state: Application state Uses the Application object for information that needs to be available to all users on the site Session state Uses the Session object Information persists only for the duration of the session of a particular client
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Object-Oriented Application Development Using VB .NET 5 Maintaining State Options available in HTTP for maintaining state (continued): Cookies Save small amounts of information, less than 4 K, in a file on the client's computer Information persists for an assigned length of time Database Saves large amounts of information Information persists beyond the session
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Object-Oriented Application Development Using VB .NET 6 Understanding Application State and the Application Object Application object Can be used to save global information that can be shared among all users of a Web application Only one is available for each Web application Application variables in ASP.NET Stored centrally Can be accessed through the Application property of the ASP.NET Page class Global.asax file Contains the initial application state variable
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Object-Oriented Application Development Using VB .NET 7 Understanding Application State and the Application Object Application variable values are available to all users of the Web site Conflicts can occur if multiple users try to change the same variable’s value at the same time Solution Before changing the value of an application variable Invoke the application’s Lock method After the change has been made Invoke the application’s Unlock method
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Object-Oriented Application Development Using VB .NET 8 Understanding Session State and the Session Object Session object Provides a way to keep information about a user throughout multiple requests to a Web application A session Begins when the user enters the Web site Ends when the user leaves the Web application or a timeout occurs Default timeout is typically 20 minutes
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Object-Oriented Application Development Using VB .NET 9 Understanding Session State and the Session Object Session data is used in: Shopping cart or basket Web applications Web pages which offer personalization
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This note was uploaded on 04/07/2008 for the course CSC 208 taught by Professor Walker during the Spring '06 term at Monroe CC.

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chap16 - Chapter 16 Assembling a Three-Tier Web Form...

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