Creating an Integrated Web Application

1
Chapter 11

• Creating an Integrated Web Application

2
Objectives

• In this chapter, you will
• Become familiar with an integrated Web
  application that contains multiple Web forms
• Understand how to transfer processing from one
  Web form to another
• Learn how to share data values across multiple
  Web forms

3
Objectives

• In this chapter, you will
• Learn how to insert records simultaneously in
  master and detail tables
• Learn how to add template columns to a DataGrid
  control
• Implement security using forms-based
  authentication
• Deploy a completed Web application on a
  production Web server

4
The Clearwater Traders Integrated Web Application

• The Start Page of the Clearwater Traders Web
  application is the Clearwater.htm static Web page
• This Web application supports two primary
  database-driven processes
• Allowing customers to place new orders
• Allowing customers to view their existing orders

5
The Clearwater Traders Integrated Web Application

• Figure 11-1 shows the Clearwater Traders Web
  application

6
The Clearwater Traders New Customer Order Process

• When the user clicks the Catalog hyperlink on the
  Clearwater.htm static Web page, the Catalog.aspx
  Web form appears
• The Catalog.aspx Web form allows the user to view
  merchandise items, determine whether items are in
  stock, and select items to order

7
The Clearwater Traders New Customer Order Process
8
The Clearwater Traders New Customer Order Process

• When the user clicks the View Cart Place Order
  button on the Catalog.aspx Web form, the
  ShoppingCart.aspx Web form appears 
• Figure 11-3 shows the ShoppingCart.aspx Web form

9
The Clearwater Traders New Customer Order Process

• When the user clicks the Place your order now
  button, the Login.aspx Web form appears
• Figure 11-4 shows the Login.aspx Web form

10
The Clearwater Traders New Customer Order Process

• The ConfirmOrder.aspx Web form summarizes the
  order items and displays the total order cost
• Figure 11-6 shows the ConfirmOrder.aspx Web form

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The Clearwater Traders New Customer Order Process

• On the ConfirmOrder.aspx Web form, the user can
  click Continue Shopping to redisplay the
  Catalog.aspx Web form, or Confirm your order to
  display the ProcessOrder.aspx Web form
• Figure 11-7 shows the ProcessOrder.aspx Web form

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The Clearwater Traders View Order Process

• After the user successfully logs on, the
  ViewOrders.aspx Web page appears, which
  summarizes the details of the customers orders
• Figure 11-8 shows the ViewOrders.aspx Web form

13
Running the Integrated Web Application

• Before creating the Clearwater Traders Web
  application, you will first install a completed
  version of the application on your Web server and
  then run the application to become familiar with
  its operation
• Then create a new customer order and place an
  order
• After that, place an order as a new customer
  rather than as a returning customer

14
Creating and Configuring the Clearwater Traders
Tutorial

• To make it easier to create the Clearwater
  Traders Web application, you can base your
  application on partially completed Web form files
  that are on the Data Disk
• These files contain Web form elements and use
  Web/database programming concepts that you
  learned to create in earlier chapters

15
Creating and Configuring the Clearwater Traders
Tutorial

• First, start Visual Studio .NET and create a new
  Web application project named Clearwater
• Then add to the project the Web forms on which
  the integrated application will be based
• Then update data connections and generate
  required data sets in the Web forms

16
Displaying Different Web Forms Within an
Integrated Web Application

• When the user clicks View Cart Place Order on
  the Catalog.aspx Web form, a program command
  executes that displays the ShoppingCart.aspx Web
  form
• ASP.NET supports two different methods that
  transfer application processing from a source Web
  page or form to a target page or form
• Response.Redirect method
• Server.Transfer method

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The Response.Redirect Method

• In ASP.NET, the HttpResponse class stores
  information about an ASP.NET operation
• The Redirect method instructs the client browser
  to display a different Web page
• The general syntax to call the Response.Redirect
  method isResponse.Redirect("target_URL")

18
The Response.Redirect Method

• Figure 11-10 shows the Response.Redirect method
  processing steps

19
The Server.Transfer Method

• In ASP.NET, the Server object is a system object
  that provides access to methods and properties
  that relate to the Web server
• The Server.Transfer method transfers processing
  directly from the current Web form to a target
  Web form
• The general syntax for calling the
  Server.Transfer method isServer.Transfer("target
  _Web_form_URL")

20
The Server.Transfer Method

• Figure 11-11 shows the Server.Transfer method
  processing steps

21
Sharing Data Values Across Multiple Web Forms

• Web applications that contain multiple Web forms
  usually need to share data values among the
  different forms
• There are three approaches for sharing data
  values among different forms
• Server-side cookies
• Session variables
• Application variables

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Server-Side Cookies

• Cookie a data item about a Web server session
  that the client computer stores
• Server-side cookies cookies that server-side
  programs create on the client workstation
• In a Web form, the Response.Cookies method is
  called to create a server-side cookie
• A cookie contains data values as variable
  name/value pairs

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Server-Side Cookies

• The following general command creates a new
  cookie name/value pairResponse.Cookies("variable
  _name").Value variable_value
• The Request.Cookies method is used in a Web form
  event handler to retrieve the value of a cookie
  variable
• This method has the following general
  syntaxobject Request.Cookies("variable_name").
  Value

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Session Variables

• Session variable a value that contains specific
  information about a browser session
• When the browser first requests a Web form
  (.aspx) page from the Web server, a cookie named
  SessionID is created on the browser
• SessionID cookie stores the browser/Web server
  session ID, which is a value that uniquely
  identifies the session

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Session Variables

• Web servers structure session variables as
  name/value pairs
• The following command is used to create a new
  session variableSession("variable_name")
  variable_value
• To retrieve session variable values, the session
  variable value is assigned to an object
• The following command is used to assign the value
  of a session variable to an objectobject
  Session("variable_name")

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Application Variables

• Application variable stores a value on the Web
  server that is associated with a specific Web
  application and is accessible to all application
  users
• The following syntax is used to create a session
  variableApplication("variable_name")
  variable_value

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Application Variables

• The following syntax is used to reference a
  session variableobject Application("variable_n
  ame")
• The following syntax is used to remove a session
  variableApplication.Remove("variable_name")

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Inserting Master-Detail Records Simultaneously

• In a database master-detail relationship, a
  master record in one database table has many
  related detail records in another table
• Often when Web developers insert records in a
  master table, they must simultaneously insert
  related records in a detail table
• Inserting master-detail records simultaneously
  becomes tricky when the DBMS automatically
  generates a surrogate key value

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Retrieving and Storing Oracle9i Sequence Values

• To use an Oracle9i sequence to generate surrogate
  key values automatically, the NEXTVAL sequence
  pseudocolumn is used within the SQL INSERT
  command to retrieve the next sequence value
• This command has the following syntaxINSERT
  INTO tablename (column1_name, column2_name)VALUES
  (sequence_name.NEXTVAL, column2_value)

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Retrieving and Storing Oracle9i Sequence Values

• Another way to retrieve the next value in an
  Oracle9i sequence is to use a SELECT query that
  has the following syntaxSELECT
  sequence_name.NEXTVAL FROM DUAL
• To save the next sequence value in a local
  variable, Web developers create a SQLCommand
  object in which the CommandText property value is
  the SQL query that retrieves the next sequence
  value
• Then, the SQLCommand object is executed using the
  ExecuteScalar method

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Retrieving and Storing Access AutoNumber Values

• To insert master-detail records in a Web
  application project simultaneously using an
  Access database, the master record is inserted as
  usual
• Then the last AutoNumber value inserted by the
  application is retrieved and assigned to a local
  variable using the SQL query SELECT _at__at_IDENTITY

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Retrieving and Storing Access AutoNumber Values

• To store the next AutoNumber value in a local
  variable, the following general syntax is
  usedSQLCommand.CommandText SELECT
  _at__at_IDENTITYDim variable_name As Integer
  CInt(SQLCommand.ExecuteScalar())

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Simultaneously Inserting the Master and Detail
Records

• When the user clicks Confirm your order on the
  ConfirmOrder.aspx Web form, the buttons event
  handler transfers processing to the
  ProcessOrder.aspx Web form
• The ProcessOrder.aspx Web form contains commands
  to insert the new order and order line records
  into the database
• The customer ID (C_ID) field is a foreign key in
  the ORDERS table

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Simultaneously Inserting the Master and Detail
Records

• To insert the new order record in the ORDERS
  table, the system must determine the C_ID value
  for the current customer
• The system determines the customers ID value
  using a query that has a search condition based
  on the values that the user enters in the User
  Name and Password TextBox controls on the
  Login.aspx Web form

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Creating Template Columns in a DataGrid Control

• A DataGrid template column is used to display
  calculated values or alternate values from those
  that the database stores
• When a template column is created, HTML tags are
  used to specify the data that appears in the
  column
• A template column allows you to display almost
  any values on a DataGrid control flexibly 
• A new template column in a DataGrid is created
  with the Property Builder visual configuration
  tool

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Creating a New Template Column

• To create a new template column, you may open the
  Property Builder visual configuration tool,
  select the Columns page, then add and configure
  the template column
• You can specify the template columns position
  and other properties within the DataGrid

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Defining the Web Server Control Template

• Web server control templates are created to
  specify how DataList controls display data
• A Web server control template can contain
  different templates to specify different regions
  within the column 
• Data columns are referenced using the
  DataBinder.Eval method, which has the following
  general syntaxlt DataBinder.Eval(Container.Dat
  aItem, "column_name") gt

38
Implementing Form Security

• ASP.NET supports forms authentication, which is a
  process that allows the system to authenticate
  user identities once
• When implementing forms authentication in a Web
  application project, all Web forms that require
  user authentication are placed in a secure folder
• A secure folder is a folder that contains forms
  that only authenticated users can view

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Implementing Form Security

• An anonymous user is a user who has not yet been
  authenticated
• When an anonymous user connects to the Web
  application, the user cannot access the Web forms
  in the secure folder until he or she is
  authenticated
• The user authenticates his or her identify using
  a login form

40
Configuring Forms Authentication in a Web
Application Project

• To configure a Web application project to use
  forms authentication, the projects Web.config
  file is modified
• First, forms authentication in the project is
  enabled by modifying the mode attribute of the
  ltauthenticationgt element as followsltauthenticati
  on mode"Forms"gt

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Configuring Forms Authentication in a Web
Application Project

• To specify the name of the login form, a ltformsgt
  element is created within the ltauthenticationgt
  element, and its loginUrl attribute is specified
  as the URL and filename of the login form
• The ltformsgt element uses the following
  syntaxltforms loginUrl"login_form_url" /gt

42
Modifying Form Commands to Implement Forms
Authentication

• When Web developers implement forms
  authentication in a Web application project, they
  need to modify how the form commands transfer
  processing to other forms
• To enable forms authentication, the commands that
  transfer processing from the login form to the
  secure forms need to be modified if the login
  form authenticates multiple secure forms

43
Deploying a Completed Web Application to a
Production Web Server

• In deploying a Web application, Web developers
  move the required program files to the production
  Web site
• Then, they configure the production Web site so
  it can accept browser requests and return the
  required application files
• Web programs are developed on a personal Web
  server
• Then, after testing and debugging, the programs
  are deployed on a production Web server

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Configuring the Production Web Server

• To run ASP.NET Web application projects, the
  production Web server must have ASP.NET and the
  .NET common language runtime installed
• To configure the Web server, the production
  project folder is created, which is the folder on
  the Web server that contains the production
  application files
• Then, a new Web application that is associated
  with the new production project folder is created

45
Moving the Production Application Files to the
Web Server

• When deploying a Web application project to a
  production Web server, the projects compiled
  (binary) files must be placed on the Web server
• Then, the production application files need to be
  moved to the production project folder

46
Summary

• To transfer processing to a different Web page in
  a Web application project, the Response.Redirect
  method or the Server.Transfer method can be used
• Server-side cookies and session variables can be
  used to share data values among different Web
  forms in a project
• Application variables are used to store values
  that all application users access, and that
  require small amounts of storage space and quick
  access times

47
Summary

• To insert a master record and detail records
  simultaneously when the master records primary
  key is a surrogate key, the surrogate key value
  is stored as a local variable, and then the local
  variable value is used to insert the detail
  records
• Forms authentication allows the system to
  authenticate a users identity once, and then
  allows the user to access his or her secure
  information for the duration of the browser
  session