.NET Framework
&
C#

.NET Framework
 Problem
background
 Solution
 Common

Language Runtime (CLR)
MS Intermediate Language
 MSIL
Structure
 MSIL and Java bytecode

Introduction to C# language
 C#
Structure
 C# Features
Problems Background









Good code is hard to write
All system features in any language
COM problems
Platform Interoperability
Automatic memory management
Object-Oriented features in and between all PLs
Safety & Security
Better Access to OS functions
Interoperate with COM (both as client & server)
Solution (Common Language Runtime)
Managed Code in Common Language Runtime
Managed Code
Common Language Runtime
Requests for existing feature
Win 32 OS
New CLR-Only Feature
Solution (Microsoft Intermediate Language)
Different Languages are Compiled into MSIL
Source code :
Any languages
Development
tools
Just-In-Time
MS Intermediate
Language
compiler
Platform specific
code
.Net platform features
Automatic memory management
 Explicit Versioning
 OO features in any languages
 Accessing system functionality throw a
hierarchical namespace
 Code security
 Interoperability with COM

Costs:
OS got harder to write
 More memory and CPU time

CLR structure
Compare with traditional ways
C#
VB
C++
J-script
other
Compiler
Intermediate Language
C++
Compiler
Executable
Existing OS
JIT
econoJIT
Executables
.NET CLR
Machine hardware
PreJIT
A simple example
TimeComponent.vb
Imports Microsoft.VisualBasic
' Declare the namespace that clients will use to access
' the classes in this component
Namespace TimeComponentNS
Public Class TimeComponent
Public Function GetTime(ByVal ShowSeconds As Boolean) As String
If (ShowSeconds = True) Then
Return Now.ToLongTimeString
Else
Return Now.ToShortTimeString
End If
End Function
End Class
End Namespace
Timeclient.cs
using System ;
using TimeComponentNS ;
class MainApp
{
public static void Main()
{
// Declare and create a new component of the class
// provided by the VB server we wrote
TimeComponent tc = new TimeComponent ( ) ;
// Call the server's GetTime method. Write its
// resulting string to a console window.
Console.Write (tc.GetTime (true)) ;
}
}
Assembly
A logical collection of one or more exe and dll file
containing an application’s code and resources
It contains
1-Codes in MSIL
2-Manifest
A metadata description of the code and resources
Metadata

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
What classes and method it contains
What external objects it requires
What version of code it represents
Manifest example (TimeComponent.dll)
.assembly extern mscorlib
{
.publickeytoken = (B7 7A 5C 56 19 34 E0 89 )
.ver 1:0:2411:0
}
.assembly extern Microsoft.VisualBasic
{
.publickeytoken = (B0 3F 5F 7F 11 D5 0A 3A )
.ver 7:0:0:0
}
.assembly TimeComponent
{
.hash algorithm 0x00008004
.ver 0:0:0:0
}
.module TimeComponent.dll
// MVID: {144ACC38-E825-45C4-83A6-C2A9E5A901DD}
.imagebase 0x00400000
.subsystem 0x00000002
.file alignment 512
.corflags 0x00000001
// Image base: 0x032a0000
// .z\V.4..
// .?_....:
Private or Public
 Private
In client directory
 Public (shared)
In Global Assembly Cache (GAC)
\\winnt\assembly
Namespaces
A logical division within which a name
need to be unique
 The best way to handle a large list of
system objects and functions
 System namespace (implemented in
several separated DLLs
 We can import a namespace
 Your code can have its own namespace

Versioning
DLL Hell
Replacing a DLL used by an existing client, with
a newer version (or vice versa)
 .NET
provides a standard way to specify
version
 Each client assembly uses its own
specified versions of related assemblies
Object oriented programming
Whether to smarten up non-object
oriented languages or dump down OO
languages
 .NET provides all languages with
inheritance and constructors features
 Virtual Object Model


All .NET classes inherit from the base
class System.Object
 Equals
 GetHashCode
 GetType
 ToString
Cross-language inheritance
Because of the standardized IL architecture
you can inherit form a class in another
language
For example:
System.Object
.NET memory management
 .NET
CLR provides all languages with
automatic memory management.
 Garbage collector automatically removes
unreferenced objects
 You can force a garbage collection
manually
Interoperability with COM objects
.NET Supports interoperation with COM object
as client or server via a runtime callable
wrapper or a COM Callable Wrapper
Using COM objects from .NET objects
Using .NET objects from COM objects
Transaction in .NET
Transaction ensure the integrity of
databases during complex operations
 Native .NET objects can also participate in
transactions with a simple attribute

Structured exception handling
.NET provides structured exception
handling as a fundamental feature
available in and between all languages
 The exception handler can tell exactly
where the exception originated by using a
stack trace

Code access security

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Most software comes from web
A user doesn’t know whether a Web code is safe
or not
.NET allows an administrator to specify
privileges that each managed code has.
You can specify these privileges in three level
by modifying XML-based files


Enterprise
Machine
 User
\\winnt\microsoft.net\framework\[c.v.]\config\