Visual Studio 2010 and.NET Framework 4 Training Workshop

Presentation Outline (hidden slide): Technical Level: 300 Intended Audience: Developers & Architects Objectives (what do you want the audience to take away): Understand why and where MEF would be used Understand how MEF is used Presentation Outline: What is extensibility? Where does MEF fit? MEF Basics (Import/Export/Container/Catalogs) MEF Intermediate Topics Lifetime Scoping

A Lap Around Managed Extensibility Framework Name Title Organization

Objectives Understand why and where MEF would be used Understand how MEF is used

A MEF-ified Application

Managed Extensibility Framework? The Managed Extensibility Framework (MEF) is a new library in the.NET Framework that enables greater reuse of applications and components. Using MEF,.NET applications can make the shift from being statically compiled to dynamically composed

What is “Extensibility”? In software engineering, extensibility is a systemic measure of the ability to extend a system and the level of effort required to implement the extension.

Open/Closed Principle Software entities should be open for extension, but closed for modification.

KnownUnknown VS.

MEF ABCs

Application built of parts…

Using MEF is as simple as Import and Export

Part, enter stage left… Part A public class SimpleMortgageCalculator : IMortgageCalculator { public ILogger Logger { get; set; } public float Calculate() { Logger.Log("Calculating Mortgage"); return...; }

Imports are Contracts a part needs… Part A public class SimpleMortgageCalculator : IMortgageCalculator { [Import(typeof(ILogger))] public ILogger Logger { get; set; } public float Calculate() { Logger.Log("Calculating Mortgage"); return...; } Import

Exports are Contracts a part offers… Part A [Export(typeof(IMortgageCalculator))] public class SimpleMortgageCalculator : IMortgageCalculator { [Import(typeof(ILogger))] public ILogger Logger { get; set; } public float Calculate() { Logger.Log("Calculating Mortgage"); return...; } Export

Container is the Match Maker Container

Catalogs provide Parts Container Catalog

Catalogs provide Parts Container Catalog TypeCatalog AssemblyCatalog DirectoryCatalog AggregatingCatalog

Hello, MEF!

Parts can be lazy… Part B Export Export [Import(typeof(ILogger))] public ILogger Export Logger { get; set; }

Lifetime Container Part A Part B [CompositionOptions(CreationPolicy=CreationPolicy.NonShared)] [CompositionOptions(CreationPolicy=CreationPolicy.Shared)] Shared Non-Shared On Export [Import(RequiredCreationPolicy=CreationPolicy.NonShared)] [Import(RequiredCreationPolicy=CreationPolicy.Shared)] On Import

Export Defaults Custom Logger Default Logger Export Order Manager Import [Import(typeof(ILogger)] public MortgageCalculator (ILogger logger) { }

Scoping Child Container Parent Container Catalog

ImperativeDeclarative What How The importance of declarative

The importance of discovery Think of a Phonebook…