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How to cuddle your EJBs

Carlo de WolfEJB 3 Product LeadJBoss by Red Hat

October 2010

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Agenda

● Quest for The Holy Grail● EAP● Why use EJB?

– Simple– Predictable– Re-usable– Testable

● Road-map

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Quest for The Holy Grail

● Looking for software components that are:– Simple– Predictable– Re-usable– Testable

● Also– Performant

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Enterprise Application Platform

● A fork of AS 5● Plus functional patches● Plus performance patches● Plus support● Some bits available through Plugin 1.0.19

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Why use EJB(tm)?

● Allow rapid development of reusable business components

● Using an easy infrastructure which does:– Memory management– Remote invocation– Thread management

● Thus having a predictable QoS

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What is an EJB(tm)?

● It's not a POJO!● It consists of a class + interceptor classes

+ interfaces● Construction is different● Invocation is different● It's an assembly with one or more views

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Quest for The Holy Grail

● Looking for software components that are:– Simple– Predictable– Re-usable– Testable

● Also– Performant

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Simplicity

● Create an EJB with a remote business view

● Create an EJB archive● Deploy it

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Creating an EJB

● Learn how to code EJBs with Andrew's book: Enterprise JavaBeans 3.1

– ISBN: 978-0-596-15802-6– Develop your first EJBs with a

hands-on walkthrough of EJB 3.1 concepts

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Creating an EJB archive

● Use Ant to create an archive<jar jarfile=”${build.lib}/myfirstejb.jar”> <fileset dir=”${build.class}”/></jar>

● Or use Maven

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Deploying an archive

● Copy into deploy$ cp myfirstejb.jar $JBOSS_HOME/server/default/deploy/

● Use the MainDeployerMbeanServerConnection conn = iniCtx.lookup(“jmx/invoker/RMIAdaptor”);conn.invoke(“jboss.system:service=MainDeployer”, “deploy”, new URL(“file:myfirstejb.jar”));

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Quest for The Holy Grail

● Looking for software components that are:– Simple– Predictable– Re-usable– Testable

● Also– Performant

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Dynamic Code Changing

● EJBTHREE-1096: Make SLSB and SFSB hot deployable for RAD.

● Allow changing functionality / invariants● Allow changes in the EJB structure● Compiling (Deploying) vs Interpreted

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Bean State

● Bean State is governed by invariants@Statefulpublic class ConsentWizard{ private Date birthdate;

public void setBirthday(Date date) { if(age(date) < 18) throw new IllegalStateException("Minors not allowed"); this.birthdate = date; }}

● Changing an invariant leaves artifacts● Bean State has become non-deterministic

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Application State

● Application state is determined by the assembly of all components

@Statefulpublic class ConsentWizard implements RemoteWizard{}

public class SomeServletThingy{ @EJB RemoteWizard wizard;}

● Changing component structure may leave application undeployable

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Deploying is like Compiling

● It checks whether the application is deployable

● It sets up a clean slate to begin tests from

● So, Dynamic Code Changing is a fluffy white rabbit. Looks cute, but will kill you in the end.

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Quest for The Holy Grail

● Looking for software components that are:– Simple– Predictable– Re-usable– Testable

● Also– Performant

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Separation of Concerns

● By making aspects configurable and manageable

● Security● Transaction Management● Remoting● Interceptors (now separated!)● Persistence (separated into JPA)

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Spec EJB 3.1 Async

● A re-usable component separates concerns

● Brings an application developer requirement to the bean developer

● Ergo doesn't make for re-usable components

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JBoss EJB 3.1 Async

● A callers functional concern● If the caller resides in the same VM, let the

EJB manage it

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Quest for The Holy Grail

● Looking for software components that are:– Simple– Predictable– Re-usable– Testable

● Also– Performant

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Test it using a remote view

● Create an archive, deploy it, then call itpublic class RemoteTestCase{ @Test public void test() throws NamingException { MyFirstView bean = (MyFirstView) iniCtx.lookup("MyFirstBean/remote"); String result = bean.doSomething(); assertEquals("done", result); }}

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Assembled Directory

● Use VFS 2 AssembledDirectory jar = AssembledContextFactory.getInstance().create("test.jar"); jar.addClass(GreetingsBean.class); jar.addClass(Greetings.class);● The venerable JBoss Embeddable

Bootstrap.getInstance().deploy(jar);

● JBoss Reloaded Embedded prototype VFSDeployment deployment = VFSDeploymentFactory.getInstance().createVFSDeployment(root); mainDeployer.deploy(root);

● EJB 3.1 Embeddable prototype EJBContainer container = EJBContainer.createEJBContainer(); on(container).deploy(deployment(jar));

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ShrinkWrap

● Easily build an archive JavaArchive jar = ShrinkWrap.create(JavaArchive.class, "test.jar") .addClasses(GreetingsBean.class, Greetings.class); File tempFile = File.createTempFile("test", ".jar"); jar.as(ZipExporter.class).exportZip(tempFile, true); URL url = tempFile.toURI().toURL();

● Deploy the archiveMbeanServerConnection conn = iniCtx.lookup("jmx/invoker/RMIAdaptor");conn.invoke("jboss.system:service=MainDeployer", "deploy", url);

● See it in action$ git clone git://github.com/jbossejb3/jboss-ejb3-timerservice.git$ cd jboss-ejb3-timerservice$ mvn install

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EJB 3.1 Embeddable

● By spec only does local session beans● You want more services, so ultimately a

full Application Server● Two solutions:

– Paravirtualized, not standalone– JBoss Embedded

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Arquillian

● Or we could go to the server@RunWith(Arquillian.class)

public class GreetingManagerTest { @Deployment public static JavaArchive createDeployment() { return ShrinkWrap.create(JavaArchive.class, "test.jar") .addClasses(GreetingsBean.class, Greetings.class); }

@EJB private Greetings alien; @Test public void shouldGreetUser() throws Exception { String name = "Earthlings"; assertEquals("Hello, " + name, alien.greet(name)); } }

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Arquillian #2

● Access to local views● Debug my EJBs and unit test

– Breakpoints– Step through– Happens on the VM running the Server

● JBoss AS becomes an 'OS' resource– No worry about Server lifecycle / startup time

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ShrinkWrap + Arquillian

● The Aliens love any container

● Complete separation of concerns

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Road-map

● EAP 6 will do EJB 3.1● AS 6 CR1 time-box closes Nov 16th● AS 7 M1 is coming up● Bug reports / requests can end up in a

milestone, get on the band-wagon.

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EJB 4

● More separation of concerns● Concrete aspects of Managed Beans?● CDI Extension?

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How to cuddle your EJBs?

● Don't try to bring the EJBs to you.● Go to the EJBs.● Use ShrinkWrap & Arquillian for your

travels!

Q & A

http://jboss.org/ejb3http://jboss.org/shrinkwraphttp://jboss.org/arquillian