Applying Design Patterns in C#

Duration:	3 days
Type:	intermediate

Description

This course is designed for developers who want to extend their architectural skills using design patterns and related techniques. It is heavily interactive with delegates spending the majority of their time creating pattern based solutions to real world problems.

Each pattern is introduced in terms of its abstract structure (via UML diagrams), its benefits and drawbacks, sample implementations in C# and practical examples of how it can be used to simplify software development.

The course makes extensive use of the .NET framework libraries as examples of pattern based architecture. In addition it covers C# specific variations on, and alternatives to, the standard 'Gang of 4' patterns.

Prerequisites

Delegates should be experienced C# developers familiar with UML Sequence and Class diagrams.

List of Modules

Introduction to Patterns

What is a design pattern?

The evolution of design patterns

Misconceptions about design patterns

The dangers of becoming 'pattern happy'

Distinguishing between patterns, idioms and refactorings

Using refactorings to introduce patterns incrementally

Using patterns to create an object oriented architecture

Revision of Core OO and SOLID

Abstration, encapsulation, inheritance and polymorphism

The importance of the SOLID principles in OO development

The Single Responsibility and Open / Closed principles

The Liskov Substitution and Interface Segregation principles

The Dependency Inversion principle and Inversion of Control

MVC and MVP

Why classes take on different roles in a layered architecture

How MVC emerged in Smalltalk and has been unversally applied

ASP .NET MVC as an example of an MVC based .NET framework

The evolution of the Model View Presenter (MVP) pattern

Distinguishing between the MVC and MVP patterns

Examples of MVP in ASP .NET and WPF

The Little Language Pattern

When creating your own language is appropriate

SQL, Regular Expresions and XPath as small languages

LINQ as an example of the Little Language Pattern

Little Langauge and Domain Specific Languages (DSL)

The role of Little Language in Software Factories

Proxy

Adding services to objects by intercepting messages

How proxies are using in Windows Communication Foundation (WCF)

Using the .NET interception framework to add proxying to your code

Creating proxy classes using context bound objects

Creating proxy classes using Reflection.Emit

NMock as a practical example of dynamic proxies

Factory

Advantages of separating clients from object creation

Comparing the Factory Method and Abstract Factory Patterns

Extending the Factory Pattern into Dependency Injection

Open Source Dependency Injection containers available for .NET

The Managed Extensibility Framework (MSF) in Visual Studio 2010

Composite

Modelling nested whole-part relationships in OO

Examples of Composite in XML and GUI libraries

Singleton

Why ensure a class only has a single instance?

General problems implementing Singleton objects

Language specific problems with Singletons (Java and C++)

Scala as an example of linguistic support for Singletons

Options for creating Singleton classes in C# and VB .NET

Strategy

Creating class hierarchies to represent algorithms

Separating a class from a changing or complex algorithm

How Strategy is used in the .NET Collections Libraries

Command

Similarities between Srategy and Command

Using Command objects to simplfy event dispatching

Incrementally refactoring code to introduce Command

Template

Using polymorphism to customize algorithms

Similarities between Template and Factory Method

How Template is used when writing ASP .NET Controls

Decorator and Adapter

Using composition to layer extra functionality

How Decorator is used in the .NET I/O libraries

Distinguishing between Adapter and Decorator

Using adapter to communicate with COM components

Iterator

Accessing an aggregate object without knowing its representation

How Iterator is used in the STL, the Java and .NET collections

Adding iterator support to your own collections

Observer

Informing interested objects of state changes

Benefits and dangers in implementing Observer

The Observer Pattern, delegates and events in C#

Visitor

Simplifying class design by modelling operations as visitors

Adding support for Visitor to existing collections of objects

Using Visitor to add reporting and logging behaviour

Using Visitor in the design of a mock objects generator

State

Benefits of the State Pattern over subclassing

Modelling objects with complex internal state transitions

Different approaches to implementing state transitions

Automatically generating state machines

Basic Threading Patterns

Implementing the Active Object Pattern in Java, C# and C++

The Thread Pool Pattern and how it is used in .NET

Introducing the IOU (Asynchronous Completion Token) Pattern

How the IOU Pattern is used in .NET (the Async Pattern)

Parallel Programming Patterns

Overview of the new threading features in .NET 4 (VS2010)

Parallel loops and running LINQ queries in parallel (PLINQ)

Using the Fork / Join and MapReduce Patterns effectively