.NET Framework & C#

1. .NET Framework&C#

2. .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

3. 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)

4. Solution (Common Language Runtime) Managed Code in Common Language Runtime Managed Code Common Language Runtime Requests for existing feature New CLR-Only Feature Win 32 OS

5. Solution (Microsoft Intermediate Language)Different Languages are Compiled into MSIL Just-In-Time compiler Development tools Source code : Any languages MS Intermediate Language Platform specific code

6. .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

7. Costs: • OS got harder to write • More memory and CPU time

8. CLR structure

9. Compare with traditional ways C# VB C++ J-script other Compiler Intermediate Language C++ Compiler JIT econoJIT PreJIT Executable Executables .NET CLR Existing OS Machine hardware

10. A simple example

11. 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

12. // Import the namespaces that this program uses, thereby allowing // us to use the short names of the functions inside them. using System ; using TimeComponentNS ; class MainApp { // The static method "Main" is an application's entry point 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)) ; } } 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)) ; } }

13. 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

14. Metadata • What classes and method it contains • What external objects it requires • What version of code it represents

15. Manifest example (TimeComponent.dll) .assembly extern mscorlib { .publickeytoken = (B7 7A 5C 56 19 34 E0 89 ) // .z\V.4.. .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

16. Private or Public • Private In client directory • Public (shared) In Global Assembly Cache (GAC) \\winnt\assembly

17. 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

18. 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

19. 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

20. All .NET classes inherit from the base class System.Object • Equals • GetHashCode • GetType • ToString

21. Cross-language inheritance Because of the standardized IL architecture you can inherit form a class in another language For example: System.Object

22. .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

23. Interoperability with COM objects • .NET Supports interoperation with COM object as client or server via a runtime callable wrapper or a COM Callable Wrapper

24. Using COM objects from .NET objects

25. Using .NET objects from COM objects

26. Transaction in .NET • Transaction ensure the integrity of databases during complex operations • Native .NET objects can also participate in transactions with a simple attribute

27. 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

28. Code access security • 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\