1

Introduction to Swiz

It’s easy. Seriously. No, I mean it. It is.

Nicholas Tunney

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Session Goals

• What problems are we trying to solve?• How do I set up Swiz?• How do I put Swiz to work for me?• Where else can I learn about Swiz?

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WHAT PROBLEMS ARE WE TRYING TO SOLVE?

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Inversion of Control

• Decentralize application control• Provide for actions on setup and teardown• Separate the WHAT from the WHEN

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Inversion of Control

DANGER!

Cour

tesy

of J

oam

Tal

l (Fl

ickr

)

6

Dependency Injection

• Objects are dependent on other objects• Objects need those objects to be created

(instantiated) to perform a task• Objects that handle their own object creation

are said to be ‘tightly coupled’• A simple change to the program results in

major code changes, just not flexible• Problem is best illustrated with an example

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Dependency Injection

public class Boat {private var engine:Engine = new Merc230();

public function boat () {}

cruise (int RPM):String {engine.go(RPM);return engine.thrillFactor;

}}

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Dependency Injection

public class Boat {private var _engine:Engine;

public function boat () {}

set Engine (engine:Engine):void {_engine = engine;}

cruise (int RPM):String {_engine.go(RPM);return _engine.thrillFactor;}

}

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Dependency Injection

myBoat:IBoat = new Boat();myEngine:IEngine = new Merc230();myBoat.setEngine(myEngine);myBoat.go(3000) // ‘w00t!’myNewEngine:IEngine = new Merc57();myBoat.go(3000) // ‘YEEEHHHHHAAAA!!!’

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Dependency Injection

• Can see how powerful dependency injection can be

• Can do that in various places across files (still lots of code to change, or via configuration using a framework like Swiz (one file to change)

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Singletons

• Create once, use everywhere• Low overhead, single instantiation

• Swiz is used to create these objects, and handle keeping state across the application

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Creation of Transient Objects

• Swiz permits Prototyping objects• Acts like an object factory• Ask Swiz for an object, it injects dependencies

and hands you a single instance of that object• Not persistent

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Event Handling

• We react to events in the application and perform tasks (WHAT versus WHEN)

• Event handling in Flex can be a nightmare challenge• Events need to be dispatched from non-display objects to

varied display objects• Events need to be dispatched from display objects to non-

display objects like controllers or their presentation models• I want to fire an event ANYWHERE in my Flex application,

and mediate it ANYWHERE in my Flex application

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Interaction with External Services

• Every Flex app I have written (except 1) has interacted with external services, it’s the way of the web anymore

• Each external service call has a set signature and workflow

• Writing this workflow for every call is tedious, or moreover redundant

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HOW DO I SET UP SWIZ?

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Grab the SWC

• http://www.swizframework.org• Place correct swc in /lib directory

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SwizConfig

• Brutally simple, just like the framework• Can simply copy/paste• A few knobs to turn

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SwizConfig

<swiz:config> <swiz:SwizConfig setUpEventType="{ Event.ADDED_TO_STAGE }" setUpEventPhase="{ EventPhase.CAPTURING_PHASE }" setUpEventPriority="50" tearDownEventType="{ Event.REMOVED_FROM_STAGE }" tearDownEventPhase="{ EventPhase.CAPTURING_PHASE }" tearDownEventPriority="50" eventPackages="com.foo.event.*, org.bar.event.*" viewPackages="com.foo.view.*, org.bar.view.*" defaultFaultHandler="handleUnhandledFaults" defaultDispatcher="global" /> </swiz:config>

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SwizConfig

<swiz:config> <swiz:SwizConfig eventPackages="com.foo.event.*, org.bar.event.*" viewPackages="com.foo.view.*, org.bar.view.*” /> </swiz:config>

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Logging Target

• I do not write perfect code, I need to log – a lot• Built in logging for Swiz to console• Can override and customize by extending the

AbstractSwizLoggingTarget class

<swiz:loggingTargets> <swiz:SwizTraceTarget id="myTraceTarget" /> </swiz:loggingTargets>

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Stuff We Didn’t Do

• Verbose configuration• Force the usage of J2EE patterns• Have to define any special directory structure• Tightly couple Swiz to our code (except with

ServiceHelper and command chain) – no extending framework classes, etc)

• Take more than 5 minutes to review the Quickstart ;)

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HOW DO I PUT SWIZ TO WORK FOR ME?

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Review of Problems We Are Solving

• Inversion of Control• Dependency Injection• Singletons• Creation of Transient Objects (Factory)• Event Handling• Interaction with External Services

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Inversion of Control

• Permits us to define and declare dependencies:– Controllers – for server interaction– Model– Delegates– Services

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Dependency Injection

• IoC container is defined by BeanProviders– Define non-view classes– Once defined, they can all be injected into your UI,

presentation model, controllers, etc• Can define in main application file, best

practice to define and include <- but Swiz doesn’t try to force you to do this ;) - Use the <swiz:Bean /> tag

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Dependency Injection

• Beans.mxml – or whatever you call it<swiz:BeanProvider xmlns:swiz=" xmlns:service="org.swizframework.quickswiz.service.*" xmlns:controller="org.swizframework.quickswiz.controller.*"> <service:UserService id="userService"/> <controller:UserController id="userController"/> <!-- We'll use the Swiz ServiceHelper to help simulate a server-side call. --> <swiz:ServiceHelper id="serviceHelper" /> </swiz:BeanProvider>

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Dependency Injection

• So how do we inject these objects? METADATA!(Note that Swiz can inject into public properties only)

– Inject by type (preferred)[Inject]variableName:Type

– Inject by name[Inject (“myService”)]variableName:RemoteObject;

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Dependency Injection

Can also inject a bean property[Inject (“ApplicationConfig.mode”)]currMode:String;

Or provide a destination[Inject ( source=“ApplicationConfig.mode”,

destination=“presentationModel.mode” ) ]

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Dependency Injection

Setter Injection is also possible

[Inject]public function setModel (model:UserModel):void {

…}

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Singletons

• All objects created in the beans.mxml as described are officially singletons

• This statement is not true for prototype objects

BEAN LIFECYCLE

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Bean LifeCycle

• [PostConstruct]• [PreDestroy]

Type Step

Flex Removed event

Flex Removed from stage event

Swiz [PreDestroy] processed

Swiz [Inject] tear down

Swiz [EventHandler] tear down

Swiz [Dispatcher] tear down

Swiz Default custom metadata tear down

Swiz [ViewRemoved] processed

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Creation of Transient Objects

• New object created for each request• Much like an object factory• Can send in properties via configuration as

well<swiz:Prototype id=”User" type="{ User }" constructorArguments="{ someOtherBean }" />

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Event Handling

• Event mediation – decouples the WHAT from the WHEN– Code the WHAT– Wire the WHEN

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Event Handling

• Two things we care about– Dispatching events– Mediating events

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Event Handling

• Dispatching Events– From a UIComponent• dispatchEvent()

– important! The event must bubble!– Swiz listens in the root container

– From other objects• Inject a dispatcher

– [Dispatcher]– Variable should have a type of IEventDispatcher– Swiz handles the dependency injection

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Event Handling

• Mediating Events– Sooooooo easy!– This was my aha moment for using a Flex

framework

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Event Handling

• Simple Event Mediation– We can do this since we defined event packages– Otherwise, specify fully qualified classname

[EventHandler( event=“EventClass.EVENT_CONSTANT” )] public function myEventHandler (event:Event): void { … }

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Event Handling

Swiz inspects the handler and reacts accordingly(note there is no event property in this method)

[EventHandler( event=“EventClass.EVENT_CONSTANT” )] public function myEventHandler (): void { … }

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Event Handling

Grab properties from the event(note that we can now explicitly call this method outside of an event)

[EventHandler( event=“MyEvent.EVENT”, properties=“user” )] public function myEventHandler (user:User): void { … }

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Event Handling

Mediate multiple events with the same handler

[EventHandler( event=“MyEvent.EVENT”] [EventHandler( event=“MyEvent.OTHER_EVENT”] public function myEventHandler (): void { … }

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Interaction with External Services

• Swiz provides beans for Async and other services– Async: ServiceHelper– Non Async: URLRequestHelper

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Interaction with External Services

• ServiceHelper– Define the bean– Inject the bean– Call the service– Handle the results

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Interaction with External Services

Define the ServiceHelper bean<swiz:ServiceHelper id="serviceHelper" />

Inject the bean[Inject]

public var sh:ServiceHelper;

Call the servicesh.executeServiceCall(ro.method(), resultHandler, faultHandler);

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Demo

Demonstrates everything we have talked about today, plus supports the Cat Internet meme.

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Bonus: Client Persistence

SharedObject - Provides methods for storing items

<swiz:BeanProvider xmlns:swiz=" xmlns:storage="org.swizframework.storage.*”> <storage:SharedObjectBean id="soBean" /></swiz:BeanProvider>

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Bonus: Client Persistence

Using the SharedObject bean

[Inject]public var so:ISharedObjectBean; [Bindable]public function get appIndex():int{ // the second parameter is the initial value return so.getInt("appIndex", 0);} public function set appIndex(index:int):void{ so.setInt("appIndex", index);}

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WHERE ELSE CAN I LEARN ABOUT SWIZ?

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Continued Learning

• http://swizframework.org– Starting point for everything– Wiki – everything in this preso is on the wiki

• Quickstart• Configuration• FAQ• Everything else

– @swizframework– Google Group –

groups.google.com/group/swiz-framework

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Thanks!@ntunney

blog.nictunney.comnic.tunney@nictunney.com

bind53@gmail.com