Getting Started with Dependency Injection using...

Getting Started with

Dependency Injection using

Spring.NET

Joe Walton

Orlando .NET Code Camp

March 31, 2012

Agenda

Software Design Checklist

Building a better house

What is…

Case Study

And it does that too?

Software Design Checklist

Testable (reliability)

– Test Driven Development (TDD)

– Continuous Integration (CI)

– MSTest, NUnit, Selenium

Reusable (share)

– No more redundant code!

Maintainable (capacity to change)

– Change without pain!

Separable (layered)

– Decomposing into functional layers

A very RAD example…

The email feature is great, but can

it send a text message too?

Straw Scorecard

Testable (reliability)

Reusable (share)

Maintainable (capacity to change)

Separable (layered)

Let’s build a better house…

What are we doing now?

Dependency Injection Principle (DIP)

– Introduce abstractions (code to interface)

Improved Separation and Reusability

– Separation of Concerns (SoC)

Decomposing system into layered architecture

DI is a form of SoC – configuration is separated

– Single Responsibility Principle (SRP)

Dependency Injection (DI) Pattern

– Dependencies injected at creation

– Constructor, setter and method style injection

Show us the code!

Stick Scorecard

Testable (reliability)

Reusable (share)

Maintainable (capacity to change)

Separable (layered)

We can do better…

Inversion of Control (IoC)

Client delegates control to IoC container

– Removes client knowledge of how to create objects

– Inverted relationship

Looks and smells like Factory Design Patterns

– Framework for the plumbing

Pick your flavor

– Unity, Castle Windsor, Ninject, Spring.NET,

StructureMap

More code please!

Brick Scorecard

Testable (reliability)

Reusable (share)

Maintainable (capacity to change)

Separable (layered)

.NET Configuration File

...

<configSections>

<sectionGroup name="spring">

<section name="context"

type="Spring.Context.Support.ContextHandler, Spring.Core" />

<section name="objects"

type="Spring.Context.Support.DefaultSectionHandler, Spring.Core" />

</sectionGroup>

</configSections>

...

<spring>

<context>

<resource uri="config://spring/objects" />

<resource uri="file://Config/services-context.xml" />

<resource uri=“assembly://MyAssembly/MyProject/common-context.xml" />

</context>

<objects xmlns="http://www.springframework.net">

...

</objects>

</spring>

...

Optional

Optional

External Configuration

Metadata

Configuration Metadata

...

<object id=“MyService”

name=“MyServiceName”

type=“CodeCamp.Services.MyService, CodeCamp.Services”

factory-method=“CreateInstance”

factory-object=“ServiceFactory”

parent=“InheritedObject”

init-method=“Initialize”

destroy-method=“Cleanup”

singleton=“true or false”>

<constructor-arg name=“Enabled” value=“true” />

<constructor-arg type=“string” value=“true” />

<constructor-arg index=“0” value=“true” />

<property name=“MyProperty1” ref=“MyObject” />

<property name=“MyProperty2” expression=“MyExpression” />

<property name=“MyList1”>

<list>

<value>A</value>

<value>B</value>

</list>

</property>

</object>

...

Lifecycle

Scope

Constructor

injection

Setter

injection

Instantiation

Inheritance

Client

using Spring.Context;

using Spring.Context.Support;

Context Registry:

...

IApplicationContext context = ContextRegistry.GetContext();

IService service = (IService)context.GetObject(“MyObject");

Resource Registry:

...

IApplicationContext context = new XmlApplicationContext(“file://common.xml”, “assembly://MyAssembly/MyService/services.xml”);

IService service = (IService)context.GetObject(“MyObject");

It really does work!

Batch Job Framework

– 75 assorted C/C++ console apps

Generate various files

Email, Copy/Move, FTP, Load Data, etc.

– 150 shell scripts

Call apps and pass parameters

– Scheduled and On-demand

BMC Control-M

Advantages

Reduces coupling

Change is not pain!

Increases code reuse

Improves code maintainability

Simplifies testing

Orchestrate the collaboration of objects

What is Spring.NET?

Enterprise application framework

You are here!

Spring.Web.MVC Example

Spring.NET

http://www.springframework.net/

“Led and sustained by SpringSource, a division of VMware, Spring.NET is an open source application framework that makes building enterprise .NET applications easier.”

Projects – Code-based Configuration

– Visual Studio Add-in

– Social - establish connections with Software-as-a-Service (SaaS) Providers including Facebook and Twitter to invoke APIs.

Thank you!

http://joemwalton.com