1. Chapter 9 S. NandaGopalan, BIT
.NET Assemblies
Chapter 9 S. NandaGopalan, BIT

2. Chapter 9 S. NandaGopalan, BIT
Objectives
Overview of .NET Assemblies
Building Single File Assembly
Cross Language Inheritance
Building Multifile Assembly
Private Assembly
Shared Assembly (GAC)
Building Shared Assemblies
Strong Names (sn)
Chapter 9 S. NandaGopalan, BIT

3. Overview of .NET Assemblies
An Assembly is nothing but a versioned, self describing binary (*.dll or *.exe)
Contains classes, interfaces, structures. Also some optional resources like images, string tables, etc.)
Assemblies help in code reuse
The format of .Net binaries are completely new
Chapter 9 S. NandaGopalan, BIT

4. Elements of .NET Binaries
Windows file header
CLR header
CIL code
Metadata
Assembly Manifest
Chapter 9 S. NandaGopalan, BIT

5. Single File Assembly Format
Foo.dll
Manifest
Metadata
CIL Code
Resources
Chapter 9 S. NandaGopalan, BIT

6. Format of Multifile Assembly
Bar.netmodule
Foo.dll
Metadata
Manifest
Metadata
CIL Code
CIL Code
Qazz.netmodule
Metadata
CIL Code
CLogo.bmp
Chapter 9 S. NandaGopalan, BIT

7. Building Single File Assembly
Step 1: Open the new Project Window. Select Visual C# Projects -> Class Library. Name this project as BankLibrary
Chapter 9 S. NandaGopalan, BIT

8. Chapter 9 S. NandaGopalan, BIT
BankLibrary…
Step 2: Type the code for BankLibrary with the following details:
Account – Class
Deposit() – to deposit the amount
Withdraw() – to withdraw the amount
Balance – property
balance – member data
Refer to 'BankLibrary' Folder for the code
Chapter 9 S. NandaGopalan, BIT

9. Chapter 9 S. NandaGopalan, BIT
Subclass : SBAccount
Step 3: Select Project -> Add Class..
and name the class as SBAccount.
Step 4: Select Project -> Add Reference -> System.Windows.Forms.dll.
Press Select button.
Step 4: Add the following line in the program:
using System.Windows.Forms;
Chapter 9 S. NandaGopalan, BIT

10. Chapter 9 S. NandaGopalan, BIT
C# Client Application
How to make use of our BankLibrary type for any client?
We shall show first for a C# client.
Follow the steps as:
Step 1: Open a C# Console Application. Name it as BankClient
Step 2: Press Project->Add Reference.
Press Browse button and click on the appropriate BankLibrary.dll file of BankLibrary project.
Step 3: Add the following line in the code:
using BankLibrary;
Step 4: Type the code as given in the file BankClient.cs.
Chapter 9 S. NandaGopalan, BIT

11. Chapter 9 S. NandaGopalan, BIT
Code and Output
static void Main(string[] args) {
SBAccount sb = new SBAccount();
sb.Deposit(1000);
sb.showBalance(); }
Chapter 9 S. NandaGopalan, BIT

12. Chapter 9 S. NandaGopalan, BIT
VB .NET Client
Add a new VB .NET Project called VBClient (windows application)
Chapter 9 S. NandaGopalan, BIT

13. Chapter 9 S. NandaGopalan, BIT
VB .NET Client
Step 2: Add the following line:
Imports BankLibrary
Step 3: Create a Button and name it as Balance
Step 4: Type the code for this button (double click)
Chapter 9 S. NandaGopalan, BIT

14. Chapter 9 S. NandaGopalan, BIT
Code
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
Dim sb As New SBAccount
sb.Deposit(400)
sb.showBalance()
sb.Withdraw(100)
End Sub
Chapter 9 S. NandaGopalan, BIT

15. Cross Language Inheritance
Can we create a subclass of Account in VB .NET? ……… Yes! But how?
Step 1: In the same project of VBClient, add a class called CAAccount
Press Project->Add Class and select class icon with name of the class as CAAccount
Step 2: Add the following lines in the code:
Public Class CAAccount
Inherits BankLibrary.Account
Public Overloads Sub showBalance()
MessageBox.Show("It is a Current Account")
End Sub
End Class
Step 3: Create a new Button on the same form called 'Current Account'. Double this button to add the following code
Dim ca As New CAAccount
ca.showBalance()
Chapter 9 S. NandaGopalan, BIT

16. Chapter 9 S. NandaGopalan, BIT
Multifile Assembly
Left as an Exercise………..
Chapter 9 S. NandaGopalan, BIT

17. Chapter 9 S. NandaGopalan, BIT
Shared Assemblies
Shared assemblies can be used by several clients on a single machine
For example, System.Windows.Forms.dll is deployed as a shared assembly. This is why any application can set a reference to this dll.
private assemblies must be kept in the same directory as that of the application and this need not be true for shared assemblies
All shared assembly files are kept in C:\WINDOWS\assembly
These assemblies can use machine-wide applications: Global Assembly Cache (GAC)
Chapter 9 S. NandaGopalan, BIT

18. Chapter 9 S. NandaGopalan, BIT
Steps to add in GAC
Step 1: An Assembly should be assigned with a strong name (sn)
Strong Name is used to uniquely identify the publisher of a given .NET binary
Strong Name
string name of the assembly
version number
public key
culture identity
Chapter 9 S. NandaGopalan, BIT

19. Building Shared Assembly
Step 2: Now create a new C# ClassLibrary named as SharedAssembly
Step 3: Type the code as shown in SharedAssembly folder and compile
Step 4: Create the strong key
Chapter 9 S. NandaGopalan, BIT

20. Class Library for Std Class
using System;
using System.Windows.Forms;
public class Std {
private int USN;
public Std()
MessageBox.Show("using Version "); }
public void Dummy()
MessageBox.Show("Calling Dummy method");
public int usn
get { return USN; }
set { USN = value; }
Chapter 9 S. NandaGopalan, BIT

21. Building Shared Assembly…
Step 5: We must inform this snk to C# compiler where the *.snk file is located to record the public key in the assembly manifest
Step 6: Open the AssemblyInfo.cs and modify the file as shown below:
update this line
[assembly: AssemblyKeyFile("")]
Specify the directory path of *.snk file
[assembly: and Settings\SNG\myKey.snk>")]
Step 7: Change the following line
[assembly: AssemblyVersion("1.0.*")] to
[assembly: AssemblyVersion(" ")]
Chapter 9 S. NandaGopalan, BIT

22. Building Shared Assembly…
Step 8: Type the following code after opening a new C# Console Application project named as 'TestSharedAssembly'
using SharedAssembly;
class TestSharedAssembly {
static void Main(string[] args)
Std s = new Std();
s.Dummy(); }
Chapter 9 S. NandaGopalan, BIT

23. Chapter 9 S. NandaGopalan, BIT
Versioning the dll
Step 1: Update your class by adding new functionality or modify the existing class
Step -2: Relocate your old dll file with version
Step 3: Change the AssemblyInfo.cs file to reflect the new version:
Step 4: Compile your *.cs file. Now you will see two binaries with the same name in GAC (however, they are different versions) – try this………!
Chapter 9 S. NandaGopalan, BIT

24. Chapter 9 S. NandaGopalan, BIT
End of Chapter 9
Chapter 9 S. NandaGopalan, BIT