Designing Java EE Applications in the Age of CDI

Designing Java EE Applications in the Age of CDI

Michael Nascimento SantosMichel Graciano

JavaOne 2012

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Michael Nascimento Santos

• +13 years of Java experience, from Java ME to Java EE, and over 19 years of practical programming experience

• JSR-310 (Date and Time API) co-leader and expert at JSRs 207, 250, 270 (Java SE 6), 296 (Swing Application Framework), 303 (Bean Validation), 349 (Bean Validation 1.1)

• genesis (http://java.net/projects/genesis) and ThinNB (http://java.net/projects/thinnb) founder

• JavaOne Rock Star Speaker and speaker at JustJava, Abaporu, FISL, COMDEX, BrasilOne and Conexão Java

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Michel Graciano

• +9 years of experience with the Java platform• Former NetBeans translation project

coordenator and contributor• Active open source member of NetBeans and

other projects• Committer of genesis

(http://java.net/projects/genesis)• Speaker at JustJava, The Developer's

Conference and JavaOne

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Agenda

• CDI crash-course• CDI unique features• Putting it all together

Demos

• Q&A

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Terminology

• JSR 299 - CDIContexts and Dependency Injection for the Java

EE platform

• WeldJSR-299 Reference Implementation

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“CDI is more than a framework. It's a whole, rich programming model. The theme of CDI is loose-

coupling with strong typing.” Weld specification

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@InjectGreeting greeting;@InjectGreeting greeting;

CDI crash-course

• Beans can be injected using @Inject• Injected beans can be filtered and/or

disambiguated using @Qualifier

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@Informal@InjectGreeting greeting;

@Informal@InjectGreeting greeting;

CDI crash-course

• Beans can be injected using @Inject• Injected beans can be filtered and/or

disambiguated using @Qualifier

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@Qualifier@Retention(RUNTIME)@Target({METHOD, FIELD, PARAMETER, TYPE})public @interface Informal {}

@Qualifier@Retention(RUNTIME)@Target({METHOD, FIELD, PARAMETER, TYPE})public @interface Informal {}

CDI crash-course

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CDI crash-course

• Beans can be named using @Named

@Named(“pageModel”)public class PageModel { public getName() { ... }}

@Named(“pageModel”)public class PageModel { public getName() { ... }}

<h:body> #{pageModel.name}</h:body>

<h:body> #{pageModel.name}</h:body>

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public class Shop { @Produces PaymentProcessor getPaymentProcessor() { ... }

@Produces List<Product> getProducts() { ... }}

public class Shop { @Produces PaymentProcessor getPaymentProcessor() { ... }

@Produces List<Product> getProducts() { ... }}

CDI crash-course

• Beans with special initialization can be constructed using producers

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public class Shop { @Produces @ApplicationScoped @Catalog @Named("catalog") List<Product> getProducts() { ... }}

public class Shop { @Produces @ApplicationScoped @Catalog @Named("catalog") List<Product> getProducts() { ... }}

CDI crash-course

• Beans with special initialization can be constructed using producers

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CDI crash-course

• Activation and some configuration is done by beans.xml file

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But what's the point of CDI anyway?

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Unique features

• Clean scope combination• Event system• AOP without interfaces• Access to injection point• Portable extensions

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Clean scope combination

• Scopes determine the bean instances lifecycle and can be safely combined as needed

@ApplicationScopedpublic class System implements Serializable { @Inject User user; ...}

@ApplicationScopedpublic class System implements Serializable { @Inject User user; ...}

@SessionScopedpublic class User implements Serializable { ... }

@SessionScopedpublic class User implements Serializable { ... }

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Custom scopes

• SeamRenderScoped

• MyFaces CODI@ConversationScoped@WindowScoped@ViewAccessScoped

• Apache DeltaSpike@TransactionScoped

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public void afterDocumentUpdate(@Observes @Updated Document document) { ... }

public void afterDocumentUpdate(@Observes @Updated Document document) { ... }

public void onAnyDocumentEvent(@Observes Document document) { ... }public void onAnyDocumentEvent(@Observes Document document) { ... }

Event system

• Loose-decoupled event producers from consumers by the event notifications model

• Events can be filtered using qualifiers

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@Inject @Any Event<Document> event;

...

public void someMethod() { event.fire(document);}

@Inject @Any Event<Document> event;

...

public void someMethod() { event.fire(document);}

Event system

• Loose-decoupled event producers from consumers by the event notifications model

• Events can be filtered using qualifiers

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@Inject @Updated Event<Document> event;

...

public void someMethod() { event.fire(document);}

@Inject @Updated Event<Document> event;

...

public void someMethod() { event.fire(document);}

Event system

• Loose-decoupled event producers from consumers by the event notifications model

• Events can be filtered using qualifiers

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Event system

• Conditional observersIF_EXISTSALWAYS

public void afterDocumentUpdate(@Observes(receive=IF_EXISTS)@Updated Document document) { ... }

public void afterDocumentUpdate(@Observes(receive=IF_EXISTS)@Updated Document document) { ... }

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Event system

• Transactional observersIN_PROGRESS,BEFORE_COMPLETION,AFTER_COMPLETION,AFTER_FAILURE,AFTER_SUCCESS

public void afterDocumentUpdate(@Observes(during=AFTER_SUCCESS)@Updated Document document) { ... }

public void afterDocumentUpdate(@Observes(during=AFTER_SUCCESS)@Updated Document document) { ... }

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AOP without interfaces

• Interceptors decouple technical concerns from business logicOrthogonal to the application and type system

• Decorators allow business concerns to be compartmentalized using the interceptor conceptAttached to a Java type, aware of business

semantics

• ConfigurableEnabled and ordered at beans.xml file, allowing

different behaviours for different environments

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@Inherited@InterceptorBinding@Target({TYPE, METHOD})@Retention(RUNTIME)public @interface Secure {}

@Inherited@InterceptorBinding@Target({TYPE, METHOD})@Retention(RUNTIME)public @interface Secure {}

Interceptors

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@Secure@Interceptorpublic class SecurityInterceptor { @AroundInvoke public Object manageSecurity(InvocationContext ctx) throws Exception { // manage security... return ctx.proceed(); }}

@Secure@Interceptorpublic class SecurityInterceptor { @AroundInvoke public Object manageSecurity(InvocationContext ctx) throws Exception { // manage security... return ctx.proceed(); }}

Interceptors

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@Securepublic class System { ...}

@Securepublic class System { ...}

public class ShoppingCart { @Secure public void placeOrder() { ... }}

public class ShoppingCart { @Secure public void placeOrder() { ... }}

Interceptors

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Decorators

@Decoratorclass TimestampLogger implements Logger { @Inject @Delegate @Any Logger logger;

@Override void log(String message) { logger.log( timestamp() + ": " + message ); } ...}

@Decoratorclass TimestampLogger implements Logger { @Inject @Delegate @Any Logger logger;

@Override void log(String message) { logger.log( timestamp() + ": " + message ); } ...}

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Access to injection point

• Allowed at @Dependent scoped beans to obtain information about the injection point to which they belong

• Empowers producers with the ability to react according to the injection point

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Access to injection point

@ProducesLogger createLogger(InjectionPoint ip) { return Logger.getLogger( ip.getMember().getDeclaringClass(). getName());}

@ProducesLogger createLogger(InjectionPoint ip) { return Logger.getLogger( ip.getMember().getDeclaringClass(). getName());}

public class SomeClass { @Inject Logger logger; ...}

public class SomeClass { @Inject Logger logger; ...}

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Portable extensions

<T> void processAnnotatedType(@Observes final ProcessAnnotatedType<T> pat) { final AnnotatedTypeBuilder builder = new AnnotatedTypeBuilder(). readFromType(pat.getAnnotatedType(), true).addToClass(NamedLiteral.INSTANCE);

pat.setAnnotatedType(builder.create());}

<T> void processAnnotatedType(@Observes final ProcessAnnotatedType<T> pat) { final AnnotatedTypeBuilder builder = new AnnotatedTypeBuilder(). readFromType(pat.getAnnotatedType(), true).addToClass(NamedLiteral.INSTANCE);

pat.setAnnotatedType(builder.create());}

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Portable extensions

<X> void processInjectionTarget(@Observes ProcessInjectionTarget<X> pit) { for (InjectionPoint ip : pit.getInjectionTarget(). getInjectionPoints()) { ... }}

<X> void processInjectionTarget(@Observes ProcessInjectionTarget<X> pit) { for (InjectionPoint ip : pit.getInjectionTarget(). getInjectionPoints()) { ... }}

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Putting it all together

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Named queries are not safe

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Named queries are not safe

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Typesafe @TypedQuery

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Typesafe @TypedQuery

-------------------------------------------------------------COMPILATION ERROR : -------------------------------------------------------------and returns false.model/CustomerModel.java:[47,25] error: Named query 'Customer.findByNme' not defined yet.model/CustomerModel.java:[43,25] error: Named query 'Customer.findAl' not defined yet.2 errors -------------------------------------------------------------

-------------------------------------------------------------COMPILATION ERROR : -------------------------------------------------------------and returns false.model/CustomerModel.java:[47,25] error: Named query 'Customer.findByNme' not defined yet.model/CustomerModel.java:[43,25] error: Named query 'Customer.findAl' not defined yet.2 errors -------------------------------------------------------------

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Demo

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Features used

• CDIDependency injectionProducer methodsAccess to the injection point

• Annotation processors

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Auto-generated MBeans

• Portable extensions and event system allow deployed components to be easily detected

• Provide good entry point for enabling management for CDI components

• Metadata can be used to generate JMX MBeans on the fly

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Auto-generated MBeans

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Demo

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Features used

• CDIDependency injectionProducer fieldsPortable extensionsCallback eventsInterceptors

• JMXMXBeanDynamicMBean

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Conclusion

• CDI is more than a simple dependency injection framework

• Unique features like access to injection point information, events and portable extensions enable creative typesafe solutions to be explored

• It is a new era, the age of CDI, so keep this in mind when designing your JavaEE applications

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Q&A

Michael N. Santos | @mr__mhttp://blog.michaelnascimento.com.br/

michael.nascimento@tecsinapse.com.br

Michel Graciano | @mgracianohttp://www.summa.com.br/

michel.graciano@summa.com.br

https://github.com/mgraciano/javaone-2012/

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Thank you

Michael N. Santos | @mr__mhttp://blog.michaelnascimento.com.br/

michael.nascimento@tecsinapse.com.br

Michel Graciano | @mgracianohttp://www.summa.com.br/

michel.graciano@summa.com.br

https://github.com/mgraciano/javaone-2012/