Using.NET Platform Note: Most of the material of these slides have been taken & extended from Nakov’s excellent overview for.NET framework, MSDN and wikipedia By Muhammad Ali

Components of.NET  Main components Common Language Runtime (CLR) Base Class Library Common Type System Common Language Specification

Common Language Runtime  Foundation of the.NET Framework  An agent that manages code at execution time, providing core services such as ○ Memory management ○ Thread management ○ JIT ○ Code Access Security & Role Base Security  Managed code Code that targets the runtime Represented by Intermediate Language (IL)  Unmanaged code Code that does not target the runtime On the fly Installation Time

Intermediate Language  MSIL … or CIL  CLR compiles IL using JIT Compiler Each function is compiled (to native code) just before execution!  Recompilations of assemblies ~ Possible!

Base Class Library  Helps in accomplishing a range of common programming tasks, including String management Data collection Database connectivity File access

Base Class Library System Threading Text ServiceProcess Security Resources Reflection Net IO Globalization Diagnostics Configuration Collections Runtime Serialization Remoting InteropServices

Common Type System  Full Range of Types that CLR Understands  Defines how types are declared, used, managed in the runtime

Common Language Specification SSubset of CTS AAll Languages in.NET are expected to support CTS AAny Benefits? Cross Language Integration!

Difference between Base Class Library &.NET Framework Library

Relationship between CLR & Framework Library

Code Compilation and Execution Compilation Before installation or the first time each method is called Execution JIT Compiler NativeCode MSIL Code Metadata Source Code Language Compiler Also called Assembly (.EXE or.DLL file) Also called Assembly (.EXE or.DLL file)

Assemblies  Types Library Assembly (DLL) Application Assembly (EXE)  Smallest deployable unit in the CLR  Have unique version number  No version conflicts (known as DLL hell)  Contains IL code to be executed

Assemblies  Security boundary Permissions are granted at the assembly level  Type boundary All types include the assembly name they are a part of  Self-describing manifest Metadata that describes the types in the assembly

Metadata in Assemblies Type Descriptions Classes Base classes Implemented interfaces Data members Methods NameVersionCulture Assembly Description Other assemblies Security Permissions Exported Types

Assemblies  More than One Assemblies… May Conflict!  Assemblies conflict resolution Using metadata ○ Local ○ Shared (Global Assembly Cache or GAC)  Different applications may use different versions of an assembly Easier software updates Easier software removal

References  MSDN Library  Nakov’s Excellent Presentation  WikiPedia