.NET Fundamentals ASP.NET - Web Forms December 8, 2003

.NET FundamentalsASP.NET - Web Forms

December 8, 2003

Agenda – December 8, 2003

Homework QuestionsQuick Note on Namespaces

ASP.NET Web Applications Simple WebTime Class Exercise

Web Form GuestBook Class ExerciseHomework Assignment for December 11, 2000

Topics• Quick Note on Namespaces• ASP.NET Technology• ASP.NET Web Applications in Visual Studio• Visual Studio .NET Software Requirements• Internet Information Services (IIS)• Web-Based Application Development• ASP.NET Web Applications in Visual Studio• Things To Look For When Creating a .NET Web Form Project• WebTime Class Exercise• Web Forms Events• Web Controls• Web Form Database Applications• GuestBook Database Class Exercise• Local versus Web Project• Deploying Web Applications• Tic Tac Toe Homework Problem

Namespaces

• Arbitrary grouping• Can be more than one file• Contains at least one class file• Identified with a using statement in C#• Simplifies class declarations• Much freedom in naming (see below)

using System.Microsoft.Chips.GuestBookDB;

ASP.NET Technology

ASP.NET Technology • Web Forms pages are built with ASP.NET technology.• ASP.NET is a unified Web platform that provides all the

services necessary for you to build enterprise-class applications.

• ASP.NET, in turn, is built on the .NET Framework, so the entire framework is available to any ASP.NET application.

• Your applications can be authored in any language compatible with the common language runtime, including Microsoft Visual Basic, Visual C#, and JScript .NET.

ASP.NET Page Framework and the Web Forms Page

• The ASP.NET page framework is a programming framework that runs on a Web server to dynamically produce and manage Web Forms pages.

• In Visual Studio, Web Forms provides a forms designer, editor, controls, and debugging, which together allow you to rapidly build server-based, programmable user interfaces for browsers and Web client devices.

• Web Forms pages run on any browser or client device. However, you can design your Web Forms page to target a specific browser, such as Microsoft® Internet Explorer 5, and take advantage of the features of a specific browser or client device.


• The ASP.NET page framework creates an abstraction of the traditional client-server Web interaction so that you can program your application using traditional methods and tools that support rapid application development (RAD) and object-oriented programming (OOP).

• Within Web Forms pages you can work with HTML elements using properties, methods, and events.

• The ASP.NET page framework removes the implementation details of the separation of client and server inherent in Web-based applications by presenting a unified model for responding to client events in code that runs at the server.


• The framework also automatically maintains the state of a page and the controls on that page during the page processing life cycle.

• The ASP.NET page framework and Web Forms pages also support server controls that encapsulate common UI functionality in easy-to-use, reusable controls.

• ASP.NET supports mobile controls for Web-enabled devices such as cellular phones, handheld computers, and personal digital assistants (PDAs).

XML Web Services• ASP.NET supports XML Web services.• An XML Web service is a component containing business

functionality exposed through Internet protocols.• An XML Web service enables applications to exchange

information between Web-based applications using standards like HTTP and XML messaging to move data across firewalls.

• XML Web services are not tied to a particular component technology or object-calling convention. As a result, programs written in any language, using any component model, and running on any operating system can access XML Web services.

State Management Facilities• ASP.NET provides intrinsic state management

functionality that allows you to save and manage application-specific, session-specific, and developer-defined information. This information can be independent of any controls on the page. It can be shared between pages, such as customer information or the contents of a shopping cart.

• ASP.NET offers distributed state facilities. You can create multiple instances of the same application on one computer or on several computers.

Application Events

• ASP.NET allows you to include application-level event-handling code in the optional global.asax file. You can use application events to manage application-wide information and perform orderly application startup and cleanup tasks.

Compilation• All ASP.NET code, including server scripts, is

compiled, which allows for strong typing, performance optimizations, and early binding, among other benefits. Once the code has been compiled, the runtime further compiles ASP.NET to native code, providing improved performance.

Note: Web Forms pages, XML Web services, and components are compiled into dynamic-link library (.dll) files. Once compiled, these files do not need to be registered on the Web server on which they run.

Configuration

• ASP.NET configuration settings are stored in XML-based files. Since these XML files are ASCII text files, you can read and modify them, so it is simple to make configuration changes to your Web applications. Each of your applications can have its own configuration file and you can extend the configuration scheme to suit your requirements.

Deployment

• Visual Studio provides a simplified mechanism for deploying applications to local or remote servers. You can install files by simply copying them to your specified application directories, or by using a more specialized and configurable deployment project.

Security• When an ASP.NET application runs, it executes

in the context of a special local user on the Web server, called ASPNET, with limited permissions. This enhances the security of your Web application code by restricting its access to Windows resources and processes.

• ASP.NET also provides various authorization and authentication schemes for Web applications. You can easily remove, add to, or replace these schemes depending upon the needs of your application.

ASP.NET Web Applications in Visual Studio

ASP.NET Web Applications in Visual Studio

• Visual Studio .NET allows you to create applications that leverage the power of the World Wide Web.

• This includes everything from:– a traditional Web site that serves HTML pages, – to fully featured business applications that run on an

intranet or the Internet, – to sophisticated business-to-business applications

providing Web-based components that can exchange data using XML.

Visual Studio ASP.NET Web Applications

• ASP.NET is part of the .NET Framework, so that it provides access to all of the framework features.

• Create ASP.NET Web applications using any .NET programming language (Visual Basic, C#, Managed Extensions for C++, and many others) and .NET debugging facilities.

• Access data using ADO.NET.• Access operating system services using .NET

Framework classes, and so on.

Visual Studio ASP.NET Web Applications

• ASP.NET Web applications run on a Web server configured with Microsoft Internet Information Services (IIS). However, you do not need to work directly with IIS. You can program IIS facilities using ASP.NET classes, and Visual Studio handles file management tasks such as creating IIS applications when needed and providing ways for you to deploy your Web applications to IIS.

Where Does Visual Studio Fit In?• As with any .NET application, if you have the .NET

Framework, you can create ASP.NET applications using text editors, a command-line compiler, and other simple tools. You can copy your files manually to IIS to deploy the application.

• Alternatively, you can use Visual Studio. When you use Visual Studio to create Web applications, you are creating essentially the same application that you could create by hand. That is, Visual Studio does not create a different kind of Web application; the end result is still an ASP.NET Web application.

Where Does Visual Studio Fit In?• The advantage of using Visual Studio is that it provides

tools that make application development much faster, easier, and more reliable. These tools include:

Visual designers for Web pages with drag-and-drop controls and code (HTML) views with syntax checking.

Code-aware editors that include statement completion, syntax checking, and other IntelliSense features.

Integrated compilation and debugging. Project management facilities for creating and managing

application files, including deployment to local or remote servers.

Visual Studio .NET Software Requirements


• Certain project types and features in Visual Studio require that specific software components, which may be listed as optional in setup, must be installed before you can use that feature or project. Some of these components must be installed on the development computer, while others can be installed on a remote computer.

Identifying Software Requirement Issues

The following table lists the components that must be installed on the various operating systems to

perform the tasks specified. These components are not installed with Visual Studio .NET Prerequisites.


Do you want to Windows 2000 Windows XPWindows Server

2003 or later

Windows Server 2003 or later

Windows NT41

Windows 98Windows Me

Windows XP HomeDevelop ASP Web applications and XML Web services

Internet Information Services (IIS)


Not supported

Compile code related to Microsoft Windows Message Queuing (MSMQ)

Message Queuing Services

Message Queuing Services

Not supported


Do you want to Windows 2000 Windows XPWindows Server 2003 or later

Windows Server 2003 or laterWindows NT41

Windows 98Windows MeWindows XP Home

Debug code on remote computers

Visual Studio Remote Debugger



Use source code control to version stored procedures

Visual Studio 6.0 Stored Procedure VersioningVisual SourceSafeMicrosoft SQL Server

Visual Studio 6.0 Stored Procedure VersioningVisual SourceSafeMicrosoft SQL Server

Not supported



• Internet Information Services (IIS) 6.0 is a powerful Web server, available in all versions of Microsoft Windows Server 2003, which provides a highly reliable, manageable, scalable, and secure Web application infrastructure.

• IIS 6.0 enables organizations of all sizes to quickly and easily deploy Web sites and provides a high-performance platform for applications built using Microsoft ASP.NET and the Microsoft .NET Framework.

Web-Based Application Development

Web-Based Application Development

• Creates Web content for Web browser clients – HyperText Markup Language (HTML)– Client-side scripting– Images and binary data

• Web Forms (Web Form pages)– File extension .aspx– aspx (Web Form files) contain written code, event

handlers, utility methods and other supporting code– .aspx.cs – C#.NET code behind page

Simple HTTP Transaction

• HyperText Transfer Protocol (HTTP)– Defines methods and headers which allows clients and

servers exchange information in uniform way • Uniform Resource Locator (URL)

– IP address indicating the location of a resource– All HTML documents have a corresponding URL

• Domain Name Server (DNS)– A computer that maintains a database of hostnames and

their corresponding IP addresses

System Architecture • Multi-tier Applications

– Web-based applications (n-tier applications)• Tiers are logical groupings of functionality

• Application Client or User Tier (top level tier)– User Browser Interface to the Application

• Information Tier (data tier or bottom tier)– Maintains data pertaining to the applications– Usually stores data in a relational database management

systems (RDBMS)• Middle Tier

– Acts as an intermediary between data in the information tier and the application's clients

Creating and Running a Simple Web-Form Example

• Visual Component – Clickable buttons and other GUI components

which users interact • Nonvisual Component

– Hidden inputs that store any data that document author specifies such as e-mail address

.NET Frameworks Requires• Internet Information Services (IIS)• FrontPage Server Extensions (FPSE)• See Visual Studio .NET Software Requirements

help text• Not available on:

– Windows NT4– Windows 98– Windows Me– Windows XP Home

Things To Look For When Creating a .NET Web Form Project

Things To Look For When Creating a .NET Web Form Project

• The project location is split:– Project Files C:\inetput\wwwroot\ project name– Solution Files C:\Documents and Settings\...\My

Documents\Visual Studio Projects\ project name• Browser Reference:

– http://localhost/ project name– C:\inetpub\wwwroot\ project name

Project Files• Many Project Files and File Types located in:

C:\Inetpub\wwwroot\Week7\WebTime\…– Global.asax, Global.asax.cs, Global.asax.resx– Web.Config– WebForm1.aspx Windows Form Equivalent– WebForm1.aspx.cs Code Behind File– WebForm1.aspx.resx

or for Visual Basic.NET– WebTime.aspx, WebTime.aspx.vb,

WebForm1.aspx.resx

Web Forms Pages and Projects in Visual Studio

• To work with a Web Forms page in Visual Studio, you use the Web Forms Designer.

• The designer includes a WYSIWYG view, called Design view, for laying out the elements of the page.

• Alternatively, you can switch the designer to HTML view, which gives you direct access to the ASP.NET syntax of the elements on the page.

• Finally, the designer includes a code editor with Intellisense that you can use to create the page initialization and event handler code for your page.

Project Files Created With Web Forms• When you create a Web project, Visual Studio

constructs a Web application directory structure on the target Web server, and a project structure on your local computer.

Note You need to have appropriate privileges on the Web server computer to create and manage Web application files. The correct way to get those privileges is to be a member of the VS Developers group that is automatically created on the Web server.

Project Files Created With Web Forms

File Created DescriptionWebForm1.aspx and WebForm1.aspx.vb files (or WebForm1.aspx.cs for Visual C# Web applications)

These two files make up a single Web Forms page. The .aspx file contains the visual elements of the Web Forms page, for example HTML elements and Web Forms controls. The WebForm1.aspx.vb class file is a hidden, dependent file of WebForm1.aspx. It contains the code-behind class for the Web Forms page, containing event-handler code and the like.

AssemblyInfo.vb (for Visual Basic projects) or AssemblyInfo.cs (for C# projects)

A project information file (AssemblyInfo.vb or AssemblyInfo.cs file) that contains metadata about the assemblies in a project, such as name, version, and culture information. For details on data contained in the assembly file, see Assembly Manifest.

Web.config An XML-based file that contains configuration data on each unique URL resource used in the project. For more information see Application Configuration Files.

Project Files Created With Web Forms

File Created DescriptionGlobal.asax and Global.vb or Global.cs files

An optional file for handling application-level events. This file resides in the root directory of an ASP.NET application. The Global.vb class file is a hidden, dependent file of Global.asax. It contains the code for handling application events such as the Application_OnError event. At run time, this file is parsed and compiled. For more information on Global.asax file usage, see Global.asax File.

Styles.css A cascading style sheet file to be used within the project. For more information see Introduction to Cascading Style Sheets.

Solution Files• Found in a Separate Directory

C:\Documents and Settings\...\My Documents\Visual Studio Projects\ project name

• Visual Studio.Solution (.sln file type)WebTime.sln

• Solution User Options (.suo file type)WebTime.suo

Visual Studio .NET uses two file types (.sln and .suo) to store settings specific to solutions. These files, known collectively as solution files, provide Solution Explorer with the information it needs to display a graphical interface for managing your files.

They allow you to concentrate on your projects and final goals rather than on the environment itself each time you return to your development tasks.

Extension Name Description

.sln Visual Studio.SolutionOrganizes projects, project items and solution items into the solution by providing the environment with references to their locations on disk.

.suo Solution User OptionsRecords all of the options that you might associate with your solution so that each time you open it, it includes customizations that you have made.

Solution Files (.sln and .suo)

WebTime Class Exercise

WebTime Class Exercise

private void Button1_Click(object sender, System.EventArgs e){

Label2.Text = DateTime.Now.ToString();}

• Create a new ASP.NET Web Application (using C#)

• Add a label for the Title “WebTime”

• Add a label for the time (i.e. DateTime.Now.ToString)

• Set the font size on the above to XX-Large

• Add a Button to refresh the time

• and a little code…

Web Form Events

Web Form Events

• Event – an object that encapsulates the idea that something has happened.

• Events are generated or raised (i.e. when a button is clicked)

• Event Handler – method that responds to the event. Event handles are written is C# in the code-behind page.

• Event handlers are delegates

Event Handles

• Return a void• Two parameters:

1. Object raising the event2. Event arguments – object of type EventArgs

that can expose properties specific to that event type.

Types of Events• Local events – mouseover, button clicks, text

changes• Server handled events, requiring a "round trip".

– Postback events cause the form to be posted back to the server immediately, including type events, such as Button Click event.

– Non-postback events are cached by the control until the next postback event occurs. You can override this non-postback behavior by setting a controls AutoPostBack property to true.

Events and Delegates• An event is a message sent by an object to signal

the occurrence of an action.• The action could be caused by user interaction,

such as a mouse click, or it could be triggered by some other program logic.

• The object that raises (triggers) the event is called the event sender.

• The object that captures the event and responds to it is called the event receiver.

Events and Delegates• In event communication, the event sender class

does not know which object or method will receive (handle) the events it raises.

• What is needed is an intermediary (or pointer-like mechanism) between the source and the receiver.

• The .NET Framework defines a special type (Delegate) that provides the functionality of a function pointer.

Events and Delegates• A delegate is a class that can hold a reference to a

method.• Unlike other classes, a delegate class has a

signature, and it can hold references only to methods that match its signature.

• A delegate is thus equivalent to a type-safe function pointer or a callback.

• While delegates have other uses, the discussion here focuses on the event handling functionality of delegates. The following example shows an event delegate declaration.

Event Delegate Declaration.

• button1_Click - the delegate for the button event. • EventArgs - the class that holds event data for the

alarm event. Actually System.EventArgs.

private delegate void button1_Click(object sender, EventArgs e)

• The syntax is similar to that of a method declaration; however, the delegate keyword informs the compiler that button1_Click is a delegate type.

• By convention, event delegates in the .NET Framework have two parameters, the source that raised the event and the data for the event.

Delegate• Note A delegate declaration is sufficient to define a

delegate class.• The declaration supplies the signature of the delegate, and

the common language runtime provides the implementation.

• An instance of the delegate can bind to any method that matches its signature.

Web Controls

Web vs Windows ControlsWindows Controls Web Controls

Label LabelTextBox TextBoxButton Button

RadioButton RadioButtonGroupBox GroupBoxComboBox DropDownListDataGrid DataGrid

Web Controls

AdRotator Control

• Randomly selects an image to display and then generates a hyperlink to the Web page associated with that image

20.5 AdRotator

Web Form Database Applications

Database Insert Command

Map a list of values to a list of the fields to be updated.

INSERT INTO TableName(list of columns) VALUES(corresponding list of data values)


INSERT INTO Messages(EmailAddress, FirstName, LastName, Message, MessageDate) VALUES (‘[email protected]’,‘John’,‘Smith’,‘Hi to me…’, ‘10/21/2003 12:34:16 PM’);


INSERT INTO Messages(EmailAddress, FirstName, LastName, Message, MessageDate) " & _

"VALUES ('" & _ TextBox3.Text & "', '" & TextBox1.Text & "', '"

& _ TextBox2.Text & "', '" & TextBox4.Text & "', '"

& mTime.Now.Today & " " & mTime.Now.ToLongTimeString & "')"

Differences from Windows Forms

• Populating a Data Grid– Windows Form

dg.SetDataBinding(ds, "Books"); dg.Show();

– Web Formdg.DataSource = objDS;

dg.DataBind();

Debugging Web Form Applications

• No MessageBox for error messages…• Use Response.Write to display messages• Use a label or TextBox to display

messages• Enable Tracing

GuestBook Database Class Exercise

Tracing

ASP.NET Tracing• ASP.NET introduces new functionality that allows you to

view diagnostic information about a single request for an ASP.NET page simply by enabling it for your page or application.

• Tracing allows you to write debug statements directly in your code without having to remove them from your application when it is deployed to production servers. You can write variables or structures in a page, assert whether a condition is met, or simply trace through the execution path of your page or application.

ASP.NET Tracing• In order for these messages and other tracing information

to be gathered and displayed, you must enable tracing for the page or application. When you enable tracing, two things occur: – ASP.NET appends a series of diagnostic information

tables immediately following the page's output. The information is also sent to a trace viewer application (if you have enabled tracing for the application).

– ASP.NET displays your custom diagnostic messages in the Trace Information table of the appended performance data.

ASP.NET Tracing• Diagnostic information and tracing messages that you

specify are appended to the output of the page that is sent to the requesting browser. Optionally, you can view this information from a separate trace viewer (Trace.axd) that displays trace information for every page in a given application. This information can help you to clarify errors or undesired results as ASP.NET processes a page request.

• Trace statements are processed and displayed only when tracing is enabled. You can control whether tracing is displayed to a page, to the trace viewer, or both.

Tracing

Tracing

Local versus Web Project

Local versus Web Project

• Factors to consider when deciding between a local or Web project model.– Installation strategy– Impact of workload

Installation strategy

• Quick-deploying application on a server with minimal client configuration, the Web project model is best. You can install and run this project on the server without installing support files on each client, and make upgrades only on the server

• Projects that have little server involvement or for stand-alone applications, a local project model is the better choice. In this scenario, upgrades can be completed on each individual client computer.

Impact of workload

• Web projects offer a server-based strategy where the majority of operations are conducted on the server. The client computer uses a Web browser to send information to and display information from the server-side application.

• If server resources are limited, then use a local project model where the work is done on the client computer without consuming precious server time.

The following table gives a side-by-side comparison of Web projects and local projects in both the design

and working environments:

Consideration Web project Local project

File storage during development

Files are stored at a specified URL on a computer with

Internet Information Services (IIS) installed. The project also

keeps a temporary cache of files on client computers for

working offline.

Project files are stored on the local computer.

Build model when developing

Application code is compiled as a DLL and run on the server.

Results are seen on the client computer.

Code is compiled and run on the client computer.

Deployment method

The project is deployed to a Web server.

Project files are installed on the client computer with required support

files.

Consideration Web project Local project

Workload

Client computers run the application remotely with a Web browser.

Processing is done primarily on the server.

The application is run locally on the client

computer.

UpgradingApplication changes are made at the server level without installation of support files on client computers.

The application upgrades are installed on client

computers.

Moving project files

The Copy Project command is used to move files to the specified URL.

Project files are physically copied from one location to another.

Deploying Web Applications

Deploying Web Applications• Microsoft® ASP.NET applications can take advantage of many

different technologies, such as private and shared assemblies, interoperation with COM and COM+, event logs, message queues, and so on.

• An ASP.NET application is defined as all the Web pages (.aspx and HTML), handlers, modules, executable code, and other (such as images and configuration) that can be invoked from a virtual directory and its subdirectories on a Web server.

• An ASP.NET application includes the project DLL (if the code-behind features of .aspx are used) and typically other assemblies that are used to provide functionality for the application. These assemblies are located in the bin folder underneath the virtual directory of the application.

Deploying ASP.NET Application

• The Microsoft® .NET Framework makes deployment of Web applications much easier than before.

• Configuration settings can be stored in a configuration file (Web.config), which is a text file based on Extensible Markup Language (XML)—these settings can be modified after the Web application is deployed without requiring the Web solution to be recompiled.

Deploying ASP.NET Application • ASP.NET allows changes to be made to assemblies

without requiring that the Web server be stopped and restarted.

• When a newer version of a Web.config, .aspx, .asmx, or other ASP.NET file is copied to an existing Web application, ASP.NET detects that the file has been updated. It then loads a new version of the Web application to handle all new requests, while allowing the original instance of the Web application to finish responding to any current requests. After all requests are satisfied for the original application, it is automatically removed. This feature eliminates downtime while updating Web applications.

Deploying ASP.NET Application • There are a number of different ways for deploying all of

these elements from your development or test environment to the production Web server(s).

• For simple Web applications, it is often appropriate to copy the files to the target computer, using XCOPY, Microsoft Windows® Explorer, FTP, or the Microsoft Visual Studio® .NET development system Copy Project command on the Project menu.

• For more complex solutions, such as those that include shared assemblies or those that rely on specific Microsoft Internet Information Services (IIS) settings to be in place, using Windows Installer technology might be a better choice.

Tic Tac ToeHomework Assignment

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