JavaOne 2011: Migrating Spring Applications to Java EE 6

Bert ErtmanFellow at Luminis in the Netherla ndsJUG Leader for NLJUG and a Java Champion @bertertmanPaul BakkerSenior developer at Luminis Tech nologies @pbakker

Who is this talk for?You are using old schoolSpring and wonder how tomove forwardJava EE seems to be hot again,should you jump on thistrain?You love the J2EE Design andDevelopment book; but is itstill actual?

Why listen to us? d endless ..workedWe’ve ha extensively with Ja va EE vs. J2EE, Spring and Spring modern Java EE dis cussions.....not employed by ..and we’re no an application Rod Johnson server vendor groupies either

some disclaimers:Not looking for another holy warNo shootoutNo silver bullets

Why migrate? Spring is proprietary technologyUpgrading fromold school Spring requires a lot of work anyway Why not take it to the standard?

This m ight have been competitive in the past...

But now we want THIS!

Let’s geta couple of misunderstandings out of the way ﬁrst...

Isn’t Java EE too fat?Startup times with application deployed JBoss AS 7 ~2 seconds Glassfish V3 ~4 seconds Tomcat 6 + Spring ~4 secondsJava EE 6 WAR file < 100kb

Isn’t Java EE too fat?Startup times with application deployed JBoss AS 7 ~2 seconds Glassfish V3 ~4 seconds Our favorite quote: Tomcat 6 + Spring ~4 secondsJava EE 6 WAR file < 100kb in the Java EE spec “Nowhere does it say that Java EE servers should be heavy weight and slow...”

Isn’t Java EE supposed to be evil?Based on 2004 rhetoricsEver heard of the fable of the tortoise andthe hare?

But I need dependency injection?Java EE 6 introduced CDI More powerful, contextual DI model Makes the platform extensible in a standard way

But I must have AOP! Really?You love getting your code all Or are you justasymmetric and using AOP light unreadable? a.k.a. Spring AOP a.k.a. (Java EE) Interceptors?

Can I still do unit testing?It took a while to get there, but yes Java EE supports testing as well

do I need heavy tooling?

NO!do I need heavy tooling?

Ca pabilities comparison Spring JavaEECapability Dependency CDI Spring Container Injection EJB Transactions AOP / annotations JSF Web framework Spring Web MVC Interceptors AOP AspectJ (limited to Spring beans) JMS JMS / CDI Messaging JPA Data Access JDBC templates / other ORM / JPA RESTful Web JAX-RS Spring Web MVC (3.0) Services Arquillian * Integration testing Spring Test framework tion * Not part of the Java EE specifica

Apparently,it can all be done usingplain vanilla light weight Java EE

rm -Rf spring*

Sure it would befun, but not very realistic

We need a recipe that moves us forward step by step

Old school Spring applots of complex XML, no annotationsold / outdated ORM solution JDBC Templates, Kodo, Toplink, etc.deprecated extension based Web MVC(SimpleFormController, etc.)

Migration path1. Upgrade Spring version2.Replace old frameworks (ORM, web framework) within Spring3.Run Spring and Java EE container side by side4.Replace Spring entirely5.Remove Spring container

Upgrade Spring versionUpgrade Spring runtime (replace JAR files)No code / configuration changes

replace old frameworks within Springpresentaton layer Web MVC @AutoWiredbusiness Spring beans layer Tasks @AutoWired @AutoWiredData / Integration Spring JDBC layer Kodo JMS beans Templates

replace old frameworks within Springpresentaton layer Web MVC @AutoWiredbusiness Spring beans layer Tasks @AutoWired @AutoWiredData / Integration Spring JDBC layer JPA JMS beans Templates

replace old frameworks within Springpresentaton layer JSF @AutoWiredbusiness Spring beans layer Tasks @AutoWired @AutoWiredData / Integration Spring JDBC layer JPA JMS beans Templates

replace old frameworks within Springpresentaton layer JSF Don’t touch Spring @AutoWired speciﬁc APIs yetbusiness Spring beans layer Tasks @AutoWired @AutoWiredData / Integration Spring JDBC layer JPA JMS beans Templates

W hat about Spring APIs wedon’t want to change yet? Jdbc Templates REST Templates Task Scheduling etc.

Using Spring and Java EE side-by-sideDisclaimer 1: this is just to give an idea, thisis not a production ready framework! Disclaimer 2: this is a migration path. Not the way you should build your next application...

Spring applicationServlet Container myapp.war Spring container TX manager ORM Spring beans AOP Spring beans

Java EE applicationJava EE 6 application server CDI / EJB container myapp.war TX manager Interceptors Security JPA CDI beans Session beans

MixedJava EE 6 application server CDI / EJB container myapp.war CDI beans Session beans TX manager Interceptors Security JPA Spring TX manager Spring ORM AOP beans Spring beans

run Spring within Java EE containerpresentaton layer JSF @AutoWiredbusiness f Spring beans d stuf layer Ad here... Tasks @AutoWiredData / Integration Spring JDBC layer JPA JMS beans Templates

add Java EE code keep old Spring codepresentaton layer JSF @AutoWired @Injectbusiness layer Spring beans EJB CDI Tasks @AutoWired @InjectData / Integration Spring JDBC layer JPA JMS beans Templates

Dependency InjectionSpring already supportsJSR-330Use @Inject anywhere you use@AutoWiredCDI could be almost a drop-inreplacement for Spring DI but opens up much more powerful options

Encapsulate Spring with CDI Write a CDI extension that bootstraps the Spring container looks up Spring Beans in the Spring container and publish in CDI context

The Spring DAO

JSF / CDI bean Here we don’t want to know about Spring

CDI extension examplehttps://github.com/paulbakker/migrating-spring-to-javaee

presentaton layer entirely replace Spring JSF @AutoWired @Injectbusiness Spring beans EJB CDI layer Tasks @AutoWired @InjectData / Integration Spring JDBC layer JPA JMS beans Templates

presentaton layer entirely replace Spring JSF @Inject @Injectbusiness EJB CDI EJB Timers layer @Inject @InjectData / Integration Spring JDBC layer JPA MDB Templates

The TX layerMigrate Spring TX and DAOs to EJBThe TX manager is in the app serverAn EJB is transactional by defaultEJB has JPA integration

Come on, are you telling me EJBs are cool now? You bet! Just like EJBs are just Spring beans, container but without managed the container POJOs configuration

The Spring DAO

The Java EE alternative btw - this is an EJB! :)

Dealing with lazy loadingMany Spring apps use the Open-EntityManager-In-View patternEJB has the Extended PersistenceContext

LazyInitializationException

Fixing lazy loading

Detached entitiesSpring DAOs are stateless (all singletons)Load > edit > save needs a mergeWith an Extended PU we don’t

Migration path

Template addict?Hooked to JDBC Templates!? Hmm, let’s start the old discussion whether or not to use ORM... Phase 1: denial Phase 2: migrate ;-)

Using JD BC Templates1. Can b e injected with simple Producer method2.It is n ot relying on Spring container3.some extra dependencies though

Template producer example

Removing DependenciesOur classpath just has tocontain APIs, no frameworkclassesFrom ~40 dependencies to just:

What about testing?Spring is pretty good at this Java EE was not

How to test this?

CDI alternatives

What about JPA code?

Ar quillianCreate micro deployments using an API Run tests in real containers

Arquillian example

Wrap up

Is it all worth it?blissful ignorance or painful reality ?!

Is there life after Spring? We believe that there is always room for innovation Ideally through Open Source When it flies, bring it back to the spec!

Other sessions of interestArquillian: TheExtendable Enterprise Test Introducing Contexts andPlatform (24121) Dependency Injection 1.1Beginning Java EE 6 (22480)(23421) Java EE 6: The Cool PartsCDI Today and Tomorrow (21641)(19941) Java EE and Spring/MVCEnterprise JavaBeans Shoot-out (24161)Technology 3.2 (23180) Rethinking Best PracticesHacking Java EE: CDI with Java EE 6 (21622)Extension Writing n00b tol33t (23805)

contact us:Bert Ertmanbert.ertman@lum inis.euPaul Bakkerpaul.bakker@lum inis.eu

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JavaOne 2011: Migrating Spring Applications to Java EE 6

by ertmanb on Oct 09, 2011

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