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Building Blocks of .NET
Objectives
 Details of CLR
 Overview of .NET Assemblies
 Single-file and Multifile Assemblies
 Role and Benefits of CIL
 Role of .NET type Metadata
 Role of Assembly Manifest
 CTS Types
Common Language Runtime
 Runtime Environment in which programs are written in C# and .NET languages are executed
Services
 Loading and Execution of Programs
 Supports Cross-Language Interoperability
 Type Safety
 Compiling IL with executable code
 Metadata
 Memory Management ( Automatic Garbage collection)
 Security
 Interoperability with other systems
 Managing Exceptions and errors
 Debugging and Profiling
Components of CLR
CLR Activities while executing a Program
How CLR Works?
Any Program compiled to IL can be run in any .NET environment using CLR leading to portability
Output after compiling C# program – metadata
Describe data used by program and enables code to interact with other code
Exist along with MSIL in same file
Common Type System
Built into CLR
Multiple Language Support
Supports different types and operations found in most Programming Languages and henceforth no Type Casting
Base Class Libraries
 Library in .NET to implement applications quickly
 Instantiate and invoke the methods in it or inherit from derived classes
 Vast Namespace
 Eg. System
Tasks of Framework Base Classes
What C# brings ?
 C# - Cleaned up version of Java which is cleaned up version of C++
 No pointers
 Automatic memory management
 Formal Syntactical constructs for enumerations, structures, class properties
 Operator Overloading
 Ability to build generic types and members like C ++ templates
 Support Interface based programming technique
 Support Aspect Oriented programming via. Attributes ( Assign characters to types and members)
What C# brings Life in Multilanguage World
Need for more than one compiler when all .NET language compiles to Managed Code
 Programmers opt different languages for different purpose and would like to have a combination of all good features together
Overview of .NET Assemblies
 .NET Binaries ( *.dll / *.exe)
 When *.dll or *.exe created by .NET compiler resulting module bundled into assembly (IL & Metadata)
 Metadata describe every “type” in binary
 Assemblies themselves described by metadata called manifest (version of assembly)
Role of Assembly Manifest
 Metadata describing assembly – manifest
 Documents external assemblies required by current assembly to function correctly
 Assembly version number
 Copyright Information
 Module Name
Single-File and Multifile Assemblies
 Assembly with a single *.dll or *.exe module
 Required CIL, Metadata and associated manifest bundled into a single well defined package
 Multifile Assemblies have many .NET binaries, each called as module
 One Module act as primary module(with assembly manifest, CIL & metadata and rest have
module level manifest,CIL & metadata )
 Adv : Easy Deployment
Role of CIL
 Pseudo code
 Portable Assembly Language
 Not Specific to CPU
 Not Executable
 Different from Java’s bytecode
 Instruction Set into which all .NET programs are compiled
 Contains Instructions for Loading, Storing, Initializing and Calling Methods
 Platform-Agonostic
Compiling CIL to Platform Specific Instructions
 .NET Environment leverages a JIT compiler for each CPU targeting the runtime (optimized for underlying platform
 Eg.for High end Server JIT functions as a high-memory environment and for a pocket held device as a low-memory environment
 Same code can be JIT-compiled and executed on machines with different architectures
 Caches results in main memory which can be reused during later recall ( No recompilation)
Role of .NET Type Metadata
 .NET Assembly has Metadata along with CIL
 Describes every type in binary such as class, Structure, Enumeration, Delegate, et.al
 Also their methods such as properties, methods, events, et.al
 Due to self-describing nature, no need of .NET binaries getting registered to system registry
 Backbone for many .NET technologies like XML Web services, Object Serialization
CTS Types
Summary
 Details of CLR
 Overview of .NET Assemblies
 Single-file and Multifile Assemblies
 Role and Benefits of CIL
 Role of .NET type Metadata
 Role of Assembly Manifest
 CTS Types