.NET Overview

1. .NET Overview

2. Objectives • Introduce .NET • overview • languages • libraries • development and execution model • Examine simple C# program

3. .NET Overview • .NET is a sweeping marketing term for a family of products • development tools and languages • platform • application management servers • value-added services development platform servers services Languages Compilers Visual Studio .NET Common Language Runtime Framework Libraries SQL Server BizTalk SharePoint ... My Services Alerts Passport ...

4. Overview of .NET • Consistent development modelThe .NET Framework proves an object-oriented and consistent development model for different types of applications, such as Windows Forms applications, Web applications, and Web services. • Robust execution environmentThe .NET Framework provides an execution environment that maximizes security, robustness, and performance of applications while minimizing deployment and versioning conflicts. • Support for standardsThe .NET Framework is built around industry standards such as Extensible Markup Language (XML), Simple Object Access Protocol (SOAP), Common Language Infrastructure (CLI), and C#.

5. Evolution of the platform • .NET is the next evolutionary step for the Microsoft platform • new languages largely replace classic C++ and Visual Basic • new runtime model reduces need for COM style integration • XML web services used in place of DCOM • Windows Forms replace MFC • ASP.NET improves on ASP • etc.

6. Software development • .NET software development and execution has many actors • languages • libraries • compilers • intermediate language • execution engine

7. Languages • Many .NET programming languages available • C# • VB.NET • C++ • etc. • Language choice typically based on many factors • programmer background • problem domain • language features • corporate mandate

8. Language power • All languages can access .NET infrastructure class Hello { static void Main() { System.Console.WriteLine("hello"); } } C# Class Goodbye Shared Sub Main() System.Console.WriteLine("goodbye") End Sub End Class VB.NET

9. Language interoperability • All .NET languages can interoperate class Hello { static void Main() { System.Console.WriteLine(Greeting.Message()); } } C# calling VB.NET Class Greeting Shared Function Message() As String Return "hello" End Function End Class

10. Language variability • Not all .NET languages have exactly the same capabilities • differ in small but important ways C# class Hello { static void Main() { int i; uint u; } } signed integer unsigned integer VB.NET Class Greeting Shared Sub Main() Dim i as Integer End Sub End Class signed integer only

11. Common Language Specification • Common Language Specification (CLS) defines type subset • required to be supported by all .NET languages • limiting code to CLS maximizes language interoperability • code limited to CLS called CLS compliant public class Calculator { public uint Add(uint a, uint b) { return a + b; } } not CLS compliant to use uint in public interface of public class

12. Linux via Mono • FreeBSD via Rotor .NET is cross-platform • .NET apps run on any supported platform .EXE .DLL .DLL ? Win64 Win32 (XP,2K,98) WinCE

13. CLR = Common Language Runtime • FCL = Framework Class Library How is this possible? • .NET applications are not stand-alone apps • require presence of .NET Framework = CLR + FCL .DLL .EXE .DLL Process CLR (MSCOREE.dll) other FCL components JIT Compiler Core FCL (MSCOR LIB.dll) obj code Underlying OS and HW

14. Library • Extensive set of standard libraries available • for wide range of application types • called .NET Framework class library .NET Framework class library Input/Output Collections Networking Reflection Web development Debugging XML processing Threading Windows Forms GUI Database access

15. Framework Class Library (FCL)

16. Writing Windows Programs • Application Programming Interfaces (API) • Win16 - Windows 3.1 [Segmented Memory] • Win32 - Windows 95/98/NT/2000/XP [Flat Memory] • Differences between 9X & NT families • Unsupported functions [Security, etc.] • Unicode vs ASCII • All windows programs use the API, but not all equal • API is C-centric, some things are difficult in VB • Programs are monolithic, can't be part VB, part C • MS .NET is "unified API" on top of Win32

17. Compilation • Compilers produce Intermediate Language (IL) • IL is not executable • similar to assembly language • processor independent C# code VB.NET code <other> code C# compiler VB.NET compiler <other> compiler IL IL IL

18. IL • C# compiler translates C# source code into IL C# source Calc c = new Calc(); int sum = c.Add(2, 4); C# compiler IL .locals init ([0] class Calc c, [1] int32 sum) newobj instance void Calc::.ctor() stloc.0 // c = ptr to new object ldloc.0 ldc.i4.2 // pass second arg ldc.i4.4 // pass first arg callvirt instance int32 Calc::Add(int32,int32) stloc.1 // sum = retval

19. Execution engine • Common Language Runtime (CLR) is the execution engine • loads IL • compiles IL • executes resulting machine code CLR Runtime compiler Execute IL machine code

20. JIT runtime compile • IL is compiled into machine code at runtime by the CLR • compiles methods as needed • called just in time (JIT) compile • JIT compilation model: • first time method is called the IL is compiled and optimized • compiled machine code is cached in transient memory • cached copy used for subsequent calls Cache machine code for F() IL code F() G() H() Execute JIT runtime compiler

21. IL? • IL is the assembly language of the .NET platform • IL = "Intermediate Language" • JIT compiler converts IL to asm lang of underlying HW '** simply adds 2 integers together and returns the result… Public Function Add(ByVal x As Integer, ByVal y As Integer) As Integer Add = x + y End Function

22. NGEN install time compile • Can compile IL into machine code when app installed • use native image generator ngen.exe • can speed startup time since code pre-compiled • but cannot do as many optimizations • original IL must still be available for type information CLR native image cache Execute ngen IL machine code

23. Execution command • CLR automatically invoked when .NET application executed C:\> MyApp hello execute

24. Implications of .NET architecture • Your clients will need .NET Framework • available via Redistributable .NET Framework (20MB) • 2 versions, v1.0 (2002) and v1.1 (2003) • runs on 98, NT (6a), 2000, XP, 2003 • Design trade-off… • managed execution (memory mgmt, security, …) • portability • slower execution (10%?) • JIT compiler has potential to close performance gap

25. C# program • C# program basics • source file has .cs extension • namespace used to group related types • class defines new type • Main is application entry point • WriteLine writes output • { and } delimit code block MyApp.cs namespace MyNamespace { class MyApp { static void Main() { System.Console.WriteLine("hello"); } } }

26. Building console executable • Can use C# compiler to build console executable • use /t[arget]:exe • use /out:<name> to specify output file name • Default values can simplify use • default target type is console executable • default name adds .exe to base name of file containing Main explicit options C:\> csc/target:exe/out:MyApp.exe MyApp.cs implicit options C:\> csc MyApp.cs

27. Building Windows executable • Can use C# compiler to build windows executable • use /t[arget]:winexe build Windows application C:\> csc/target:winexe MyWinApp.cs

28. Building library • Can use C# compiler to build library • use /t[arget]:library • Controlling output file name: • can use /out:<name> to specify output file name • default: adds .dll to base name of first input file create library C:\> csc/target:library/out:MyLib.dll MyLib.cs

29. Summary • .NET requires multiple steps to develop and run software • code in one of the many .NET languages • compile into IL • install the CLR • execute • CLR JIT compiles IL at runtime • always executes compiled code • never interpreted • Can target CLS compliance • to maximize language interoperability