.NET basics

.NET history

.NET key features

• Object-oriented programming
• Support for multiple languages
• Easy component-based development (assembly concept - metadata, version and code in the same place, no head files required)
• Simplified application deployment (just xcopy)
• Rich base class library support
• Unified runtime infrastructure
• Exception handling

.NET Languages

CLR - common language runtime

CLR is a runtime environment that manages the execution of code and provides services that improves development, deployment and run time.

Services provided by CLR

• managed code
• cross-language operability
• JIT compiler
• common type system (CTS)
• code and memory management
• reflection
• garbage collection
• debugging, profiling and diagnostics

CLR architecture

Buzzwords

• .NET - is the most general name of technology that MS provides (includes tools, infrastructure, code framework etc)
• CLR - runtime which runs code and does a lot of additional services (heart of .NET)
• CLI - public specification of .NET (using this specification project MONO was created)
• CTS - subset of types which must be supported of all languages to support interoperability
• CLS - is a set of rules on which all .NET languages should be based to make sure no types are exposed that some languages cannot deal with.

Types sets

CTS - Common Type System

JIT compilation

• Explicit vs Implicit compilation
• MSIL - MS Intermediate language (low level instructions code)
• MSIL ≠ Machine code (every time, MSIL runs, it’s recompiled again to machine code)
• JIT compiler ≠ Bytecode interpreter (JIT compiles code at runtime and re-use compiled code at next invocations)
• JIT uses such techniques as adaptive optimization and dynamic recompilation which may significantly increase productivity in comparison with static compilation

Compilation Flow

Managed code

“Managed code is a term coined by Microsoft to identify computer program source code that requires and will execute only under the management of a Common Language Runtime virtual machine, typically the .NET Framework, or Mono.” © Wikipedia

Managed code

• machine independent.
• is code that runs on CLR and is fully managed by CLR (including cleaning up memory, reflecting metadata etc)
• provided with metadata which describe types and allows different tools inspect types.

.NET Assemblies

• Assembly - is a chunk of MSIL code that can be run in .NET runtime
• Assembly - is a logical unit, not physical (can include multiple classes, resources and can be executable)

Assembly contains

• manifest (metadata about the assembly itself - name, version, culture, public key and digital signature)
• type metadata (Completely describes all types defined in an assembly + attributes)
• managed code
• resources

.NET Assemblies - GAC

GAC - Global Assembly Cache: - a solution to keep DLLs globally accessible without worrying about conflicts
- stores assemblies shared across few applications - located at C:\Windows\Assembly - to add an assembly to GAC, use gacutil

CLI (ECMA 335)

CLI - Common Language Infrastructure - is an open specification developed by Microsoft and standardized by ISO and ECMA that describes the executable code and runtime environment.

CLI describes

• Common Type System (CTS)
• Metadata Definition and Symantics
• Common Intermeadiate Language (CIL)
• Common Language Specification (CLS)

CLI existing implementations

• .NET / .NET compact / .NET micro framework
• Mono dev platform
• Portable .NET (dotGnu project)
• .NET Core

About:C#

• is a object oriented language derived from C++ and Java.
• a mainstream language in .NET family and whole .NET framework was written in this language
• Author - Anders Hejlsberg (1960, Copenhagen) - Turbo Pascal, Delphi, C#
• standard - ECMA 334 / ISO 23270

C# key features

• Strong-typed - all types are strongly controlled by runtime
• Modern - supports, automatic garbage collection, modern approach to debugging, rich model for error handling, decimal data type for financial application and robust security model.
• Type-Safe - does not permit unsafe casts, enforces overflow checking, use of any uninitialized variables produces an error
• Compatible - enforces the .NET CLS and allows interoperation with other .NET language
• Flexible - delegate classses instead of pointers
• Inter-Operability - supports COM objects and native API

Source Code Editors

• Visual Studio 20xx (commercial/free) - supports the latest version of C#
• SharpDevelop (free) - still alive :)
• MonoDevelop (free) - supports C# 4

Exotic:

• LinqPad (commercial/free) - for test purposes
• Notepad++ (free) - your are always welcome to use plain text editors for programming

Visual Studio

• Ultimate - full possible functionality
• Premium - for development. testing and prototyping
• Profesional - might be used for development
• Express (outdated) - limited version of Professional
• Community - free for even commercial use - the same functionality as Profesional

Visual Studio - code organization

Visual Studio provides two containers to help you efficiently manage the items that are required by your development effort - solutions and projects

• Solution - contain items that you need in order to create your application. Solution contains projects, solution folders, solution files and metadata.
• Project - are used in a solution to logically manage, build, and debug the items that make up your application.

Filetypes: .cs, .vb, .csproj, .sln, *.suo etc