Overview of .NET Framework

1. Overview of .NET Framework Sanjay Vyas

2. Whats New In Base Class Library

3. Managed Extensibility Framework • Create reusable components • Don’t we already have reusable components? • No need to create infrastructure from scratch • MEF is dynamically composed • What’s so dynamic about it • Current plugin model tied to specific apps • Same component cannot be used across apps • Discoverable at runtime • Tagging for rich queries and filtering

4. MEF Architecture

5. MEF • Catalog • Discovers and maintain extensions • CompositionContainer • Coordinate creations and satisfy dependencies • ComposablePart • Offer one or more exports • May depend on imports for extension it uses

6. Demo Managed Extensibiity Framework

7. New Language Features C# 4.0 VB.NET 10 Statement Lambdas Multiline Lambdas Auto implemented Properties Collection Initializer Generic Variance Extension Property • Named Parameters • Optional Parameters • Dynamic Scoping • Generic Variance • Extension Property

8. Optional and Named Parameter • Some methods have excessive parameters • Too many overloads of methods • Most aren’t used in everyday scenario • Developers still have to supply default values • Heavy use of Type.Missing • Comma counting is a pain • Difficult to remember parameter by position

9. Overload Of Overloads class Book { // Multiple constructors Book() : this(“”, “”, “”, ) { } Book(stringisbn) : this(isbn, “”, “”, 0) { } Book(stringisbn, string title) : this(isbn, title, “”, 0) { } Book(stringisbn, string title, string author) : this(isbn, title, author, 0) { } // Master Constructor which gets called by others Book(stringisbn, string title, string author, int pages) { // Do the actual work here } }

10. Optional Parameters class Book { // Use optional parameters Book(stringisbn=“”, string title=“”, string author=“”, int pages=0) { // Do the actual work here } } : : : Book book = new Book(“1-43254-333-1”); Book book = new Book(“1-43254-333-1”, “How not to code”); Book book = new Book(“1-43254-333-1”, “How not to code”, “Copy Paster”); Book book = new Book(“1-43254-333-1”, 240); // Cannot skip parameters

11. Named Parameter class Book { // Use optional parameters Book(stringisbn=“”, string title=“”, string author=“”, int pages=0) { // Do the actual work here } } : : : Book book = new Book(isbn:“1-43254-333-1”); Book book = new Book(isbn:“1-43254-333-1”, title:“How not to code”); Book book = new Book(isbn:“1-43254-333-1”, title:“How not to code”, author:“Copy Paster”); Book book = new Book(isbn:“1-43254-333-1”, pages:240);

12. Dynamic scoping • C# is static type languages • Types are explicitly defined • Methods are bound at runtime • Dynamic dispatch exists • Reflection API • Method.Invoke() is tedious • COM Automation is based on IDispatch • May not have .TLB • Lookup can be purely runtime • Certain Application Types require Dynamism • E.g. SOAP/REST proxies

13. Dynamic in .NET 4.0 • CLR is mostly static type • Compile time type checking (e.g. IUnknown) • DLR added dynamism to .NET • Run time type checking (e.g. IDispatch) • DLR is now part of .NET 4.0 API • Full support of IronRuby, IronPython • Dynamic dispatch now built into .NET/C#

14. Dynamic Dispatch • Introduction of type – dynamic • Compiler merely packages information • Compiler defers binding to runtime • Built-in support for COM Calls • Uses IDispatch interface • PIA not required • Runtime binding for framework objects • Build your own – IDynamicObject • IronPython, IronRuby use this • E.g. RestProxy

15. Dynamic Data Type • Isnt Object type dynamic already? • .NET already has var, why add dynamic? • Object – Static type, base class • var – is ALSO static type, compiler inferred • dynamic – Evaluation deferred

16. Dynamic implementation dynamic d = GetFlyingObject(“Superman”); d.Fly(); // Up, up and away dynamic d = GetFlyingObject(“AirPlane”); d.Fly(); // Take off dynamic d = GetFlyingObject(“Cat”); d.Fly(); // OOPS… but at runtime

17. Demo Dynamic Dispatch

18. Variance • Covariance • Similar to base reference to derived class • Covariance is applied to arrays, delegates.. • Contravariance • Similar to derived instance passed to base

19. Changes to Variance • Variance can now be applied to Interfaces • Variant types supports interfaces and delegates • Variance applies to reference conversion only • Value types are not supported • Covariance • Requires the use of “out” keyword • Contravariant • Requires the use of “in” keyword • It could be automatically inferred but that could lead to code-breaking when interface definition changes

20. Demo Variance

21. Code Contracts • Foundation • Design by contract • Based on MSR’s SPEC# • What does it bring? • Improved testability • Static verification • API Documentation • How does it help? • Guarantee obligations on entry (parameter validations) • Guarantee property at exit (return value range) • Maintain property during execution (object invariance)

22. Code Contracts • New namespace in .NET • System.Diagnostics.Contracts • Parameter validation • Contract.Requires() • Return value guarantee • Contract.Ensures() • Object state guarantee • Contract.Invariant()

23. Code Contracts • Compile generates the IL code • Contracts are conditionally compiled • Define CONTRACTS_FULL to enable

24. Demo Code Contracts

25. Parallelism in .NET 4.0 • Don’t we have multithreading and ThreadPool? • Requires too much work • Requires understanding of nitty-gritties • Bifurcated thinking for single CPU vs. multi • What does parallelism bring in? • Make multicore programming simple • Automatcially handle single vs. multicore • Focus on “what” rather than “how”

26. Visual Studio 2010Tools / Programming Models / Runtimes Integrated Tooling Programming Models Programming Models PLINQ Parallel Debugger Toolwindows Task Parallel Library Parallel Pattern Library Agents Library Data Structures Concurrency Runtime Concurrency Runtime Data Structures Task Scheduler Profiler Concurrency Analysis ThreadPool Task Scheduler Resource Manager Resource Manager Operating System Threads Key: Managed Library Native Library Tools

27. Parallels in .NET • Task Parallel Library (TPL) • Task and Data Parallelism • LINQ to Parallel (PLINQ) • Use LINQ to implement parallelism on queries • Coordinated Data Structures • High performance collection classes which are lock free and thread safe • Parallel Diagnostic Tools • Parallels Debugger and VSTS Profiler concurrency view

28. User Mode Scheduler CLR Thread Pool Global Queue Worker Thread 1 Worker Thread p … Program Thread

29. User Mode Scheduler For Tasks CLR Thread Pool: Work-Stealing Local Queue Local Queue Global Queue … Worker Thread 1 Worker Thread p … Task 6 Task 3 Task 4 Task 1 Program Thread Task 5 Task 2

30. Task Parallel Library • Write code which automatically uses multicore • Expose potential parallelism in sequential code • No language extension (aka Syntactic sugar) yet • Parallelism types • The Task Class – Task Parallelism • The Parallel Class – Data Parallelism • Task Management • TaskManager class • Use default or create your own

31. Demo Task Parallel Library

32. Resources Software Application Developers Infrastructure Professionals http://technet.microsoft.com/ http://msdn.microsoft.com/ technetindia msdnindia @technetindia @msdnindia

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