Module 3: Working with Components

Overview

An Introduction to Key .NET Framework Development Technologies

Creating a Simple .NET Framework Component

Creating a Simple Console Client

Creating an ASP.NET Client

An Introduction to Key .NET Framework Development Technologies

Windows Forms

Web Forms

XML Web Services

Creating a Simple .NET Framework Component

Using Namespaces and Declaring the Class

Creating the Class Implementation

Implementing Structured Exception Handling

Creating a Property

Compiling the Component

Using Namespaces and Declaring the Class

Create a New Namespace

Declare the Class

using System;

namespace CompCS {...}

using System;

namespace CompCS {...}

public class StringComponent {...}public class StringComponent {...}

Creating the Class Implementation

Declare a Private Field of Type Array of String Elements

Create a Public Default Constructor

Assign the stringSet Field to an Array of Strings

stringSet = new string[] {"C# String 0","C# String 1",

... };

stringSet = new string[] {"C# String 0","C# String 1",

... };

private string[] stringSet;private string[] stringSet;

public StringComponent() {...}public StringComponent() {...}

Implementing Structured Exception Handling

Implement the GetString Method

Create and Throw a New Object of Type IndexOutOfRangeException

Exceptions May Be Caught by the Caller in try, catch, finally block

Structured Exception Handling Replaces HRESULT-Based Error Handling in COM

public string GetString(int index) {...}public string GetString(int index) {...}

if((index < 0) || (index >= stringSet.Length)) {throw new IndexOutOfRangeException();

}return stringSet[index];

if((index < 0) || (index >= stringSet.Length)) {throw new IndexOutOfRangeException();

}return stringSet[index];

Creating a Property

Create a Read-Only Count Property to Get the Number of String Elements in the stringSet Array

public int Count { get { return stringSet.Length; }}

public int Count { get { return stringSet.Length; }}

Compiling the Component

Use the /target:library Switch to Create a DLL

Otherwise, an executable with a .dll file extension is created instead of a DLL library

csc /out:CompCS.dll /target:library CompCS.cscsc /out:CompCS.dll /target:library CompCS.cs

Lab 3.1: Creating a .NET Framework Component

Creating a Simple Console Client

Using the Libraries

Instantiating the Component

Calling the Component

Building the Client

Using the Libraries

Reference Types Without Having to Fully Qualify the Type Name

If Multiple Namespaces Contain the Same Type Name, Create a Namespace Alias to Remove Ambiguity

using CompCS;

using CompVB;

using CompCS;

using CompVB;

using CSStringComp = CompCS.StringComponent;

using VBStringComp = CompVB.StringComponent;

using CSStringComp = CompCS.StringComponent;

using VBStringComp = CompVB.StringComponent;

Instantiating the Component

Declare a Local Variable of Type StringComponent

Create a New Instance of the StringComponent Class

CompCS.StringComponent myCSStringComp = new CompCS.StringComponent();

CompCS.StringComponent myCSStringComp = new CompCS.StringComponent();

Calling the Component

Iterate over All the Members of StringComponent and Output the Strings to the Console

for (int index = 0; index < myCSStringComp.Count; index++) {

Console.WriteLine (myCSStringComp.GetString(index));

}

for (int index = 0; index < myCSStringComp.Count; index++) {

Console.WriteLine (myCSStringComp.GetString(index));

}

Building the Client

Use the /reference Switch to Reference the Assemblies That Contain the StringComponent Class

csc /reference:CompCS.dll,CompVB.dll /out:ClientCS.exe ClientCS.cs

csc /reference:CompCS.dll,CompVB.dll /out:ClientCS.exe ClientCS.cs

Lab 3.2: Creating a Simple Console-Based Client

Demonstration: Creating a Windows Forms Client

Creating an ASP.NET Client

Writing the HTML for the ASP.NET Application

Coding the Page_Load Event Handler

Generating the HTML Response

Multimedia: ASP.NET Execution Model

Writing the HTML for the ASP.NET Application

Specify Page-Specific Attributes Within a Page Directive

Import the Namespace and the Physical Assembly

Specify Code Declaration Blocks

<%@ Page Language="C#" Description="ASP.NET Client" %><%@ Page Language="C#" Description="ASP.NET Client" %>

<%@ Import Namespace="CompCS"%><%@ Import Namespace="CompVB"%>

<%@ Import Namespace="CompCS"%><%@ Import Namespace="CompVB"%>

<script language="C#" runat=server>... //client code

</script>

<script language="C#" runat=server>... //client code

</script>

Coding the Page_Load Event Handler

void Page_Load(Object sender, EventArgs EvArgs){ StringBuilder Out = new StringBuilder(""); int Count = 0; // Iterate over component's strings and concatenate Out.Append("Strings from C# Component<br>"); CompCS.StringComponent myCSStringComp = new CompCS.StringComponent(); for(int index = 0; index < myCSStringComp.Count; index++) { Out.Append(myCSStringComp.GetString(index)); Out.Append("<br>"); } Message.InnerHtml = Out.ToString();}

void Page_Load(Object sender, EventArgs EvArgs){ StringBuilder Out = new StringBuilder(""); int Count = 0; // Iterate over component's strings and concatenate Out.Append("Strings from C# Component<br>"); CompCS.StringComponent myCSStringComp = new CompCS.StringComponent(); for(int index = 0; index < myCSStringComp.Count; index++) { Out.Append(myCSStringComp.GetString(index)); Out.Append("<br>"); } Message.InnerHtml = Out.ToString();}

Generating the HTML Response

<body> <span id="Message" runat=server/></body>

<body> <span id="Message" runat=server/></body>

Specify the Body of the HTML Response

Demonstration: Testing the ASP.NET Client

Lab 3.3: Calling a Component Through an ASP.NET Page

Review

An Introduction to Key .NET Framework Development Technologies

Creating a Simple .NET Framework Component

Creating a Simple Console Client

Creating an ASP.NET Client