Enterprise Java JNDI Enterprise Naming Conext (ENC) and Injection
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EnterpriseJava
JNDI Enterprise Naming Conext
(ENC)and
Injection
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EnterpriseJava
Goals
• Configure applications using the JNDI Enterprise Naming Context (ENC)
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EnterpriseJavaObjectives
• JNDI ENC Overview• JNDI ENC Lookup• XML Population• Annotation Population• Dependency Injection
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EnterpriseJavaJNDI ENC Overview
• Component's individual address space• Holds references to values and objects in the
environment• Theoretical equivalent to Unix soft links
– ln -s <some physical file path> $HOME/<my logical path>• Object's registered
– EJB interfaces (local and remote)– JMS connection factories– JMS destinations– data sources– any JCA resource– primitive values
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EnterpriseJavaJNDI ENC and Injection
• Objects are placed in the component's JNDI ENC by the container
• Components may look these values up– using raw JNDI calls– using SessionContext convenience method– allows any nested component to also get the environment
• Components may have values injected into properties/fields.
– fewer lines of code dedicated to lookups– inversion of control
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EnterpriseJavaReading JNDI ENC
• JNDIInitialContext jndi = new InitialContext();object = jndi.lookup(“java:comp/env/encname);
• SessionContextSessionContext ctx;...object = ctx.lookup(“encname”);
• Note: “java:comp/env” does not work with JBoss 4.0.xGA EJB3
– use “java:comp.ejb3/env” or SessionContext in the short term
– works with 4.2.xGA
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EnterpriseJavaExample: Deployed JNDI Tree
• Local JNDI Namespace+- ejavaDS (class: org.jboss.resource.adapter.jdbc.WrapperDataSource)
• Global JNDI Namespace– default names +- jndiDemoEAR (class: org.jnp.interfaces.NamingContext)
| +- Hospital (class: org.jnp.interfaces.NamingContext)
| | +- local (... ejava.examples.jndidemo.ejb.HospitalLocal ...)
| | +- remote (... ejava.examples.jndidemo.ejb.HospitalRemote ...)
– custom-configured JNDI names (jboss.xml) +- ejava (class: org.jnp.interfaces.NamingContext)
| +- examples (class: org.jnp.interfaces.NamingContext)
| | +- jndidemo (class: org.jnp.interfaces.NamingContext)
| | | +- AidScheduler (class: org.jnp.interfaces.NamingContext)
| | | | +- local (... ejava.examples.jndidemo.ejb.AidSchedulerLocal
| | | | +- remote (... ejava.examples.jndidemo.ejb.AidSchedulerRemote
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EnterpriseJavaXML Population: Example POJO Style
//@Local declared by ejb-jar.xml entrypublic interface HospitalLocal extends Scheduler {}
//@Remote declared by ejb-jar.xml entrypublic interface HospitalRemote extends Scheduler {}
//@Stateless(name=”Hospital”) declared by ejb-jar.xml entrypublic class HospitalEJB extends SchedulerBase implements HospitalLocal, HospitalRemote { public String getName() { return "HospitalEJB"; }
@Resource public void setSessionContext(SessionContext ctx) { this.ctx =
ctx; }}
//@Local declared by ejb-jar.xml entrypublic interface AidSchedulerLocal extends Scheduler {}
//@Remote declared by ejb-jar.xml entrypublic interface AidSchedulerRemote extends Scheduler {}
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EnterpriseJavaXML Population: Example POJO Style
//@Stateless(name=”AidScheduler”) declared by ejb-jar.xml entrypublic class AidSchedulerEJB extends SchedulerBase implements AidSchedulerLocal, AidSchedulerRemote { private EntityManager em; private DataSource ds; private String message; private HospitalLocal hospital; @Resource //in super - protected SessionContext ctx; public void setSessionContext(SessionContext ctx) {
this.ctx = ctx; } public void init() { log.info("************* AidScheduler Created ************"); log.debug("ctx=" + ctx); log.debug("ejb/hospital=" + ctx.lookup("ejb/hospital")); log.debug("message=" + message); log.debug("em=" + em); log.debug("ds=" + ds); log.debug("hospital=" + hospital); } public String getName() { return "AidScheduler"; } }
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EnterpriseJavaXML Population: Example Output
[AidSchedulerEJB] ******************* AidScheduler Created ******************
DEBUG [AidSchedulerEJB] ctx=org.jboss.ejb3.BaseSessionContext@5f6ac6
DEBUG [AidSchedulerEJB] ejb/hospital=Hospital
DEBUG [AidSchedulerEJB] message=Hello Helping World
DEBUG [AidSchedulerEJB] em=org.jboss.ejb3.entity.TransactionScopedEntityManager@16fa2a5
DEBUG [AidSchedulerEJB] ds=org.jboss.resource.adapter.jdbc.WrapperDataSource@ede19e
DEBUG [AidSchedulerEJB] hospital=Hospital
DEBUG [JNDIHelper] listing java:comp/env
...
listing java:comp/env
+jdbc :org.jnp.interfaces.NamingContext
----myds :javax.naming.LinkRef
+ejb :org.jnp.interfaces.NamingContext
----hospital :javax.naming.LinkRef
+persistence :org.jnp.interfaces.NamingContext
----jndidemo :org.jboss.ejb3.entity.TransactionScopedEntityManager
+vals :org.jnp.interfaces.NamingContext
----message :java.lang.String
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EnterpriseJavaXML Population: META-INF/ejb-jar.xml
<?xml version="1.0"?>
<ejb-jar
xmlns="http://java.sun.com/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/ejb-jar_3_0.xsd"
version="3.0">
<enterprise-beans>
...
<session>
<ejb-name>Hospital</ejb-name>
<remote>ejava.examples.jndidemo.ejb.HospitalRemote</remote>
<local>ejava.examples.jndidemo.ejb.HospitalLocal</local>
<ejb-class>ejava.examples.jndidemo.ejb.HospitalEJB</ejb-class>
</session>
</enterprise-beans>
</ejb-jar>
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EnterpriseJavaXML Population: META-INF/ejb-jar.xml
<enterprise-beans>
<session>
<ejb-name>AidScheduler</ejb-name>
<remote>ejava.examples.jndidemo.ejb.AidSchedulerRemote</remote>
<local>ejava.examples.jndidemo.ejb.AidSchedulerLocal</local>
<ejb-class>ejava.examples.jndidemo.ejb.AidSchedulerEJB</ejb-class>
<!-- REMAINDER OF EXAMPLE GOES HERE -->
<post-construct>
<lifecycle-callback-method>
init
</lifecycle-callback-method>
</post-construct>
</session>
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EnterpriseJavaXML Population: env-entry
<env-entry> <env-entry-name>vals/message</env-entry-name> <env-entry-type>java.lang.String</env-entry-type> <env-entry-value>Hello Helping World</env-entry-value> <injection-target> <injection-target-class> ejava.examples.jndischeduler.ejb.AidSchedulerEJB </injection-target-class> <injection-target-name>message</injection-target-name> </injection-target> </env-entry>
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EnterpriseJavaXML Population: ejb-local-ref
<ejb-local-ref> <ejb-ref-name>ejb/hospital</ejb-ref-name> <ejb-ref-type>Session</ejb-ref-type> <local>ejava.examples.jndischeduler.ejb.HospitalLocal</local> <ejb-link>Hospital</ejb-link> <injection-target> <injection-target-class> ejava.examples.jndischeduler.ejb.AidSchedulerEJB </injection-target-class> <injection-target-name>hospital</injection-target-name> </injection-target> </ejb-local-ref>
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EnterpriseJavaXML Population: DataSource
<resource-ref> <res-ref-name>jdbc/myds</res-ref-name> <res-type>javax.sql.DataSource</res-type> <res-auth>Container</res-auth> <injection-target> <injection-target-class> ejava.examples.jndidemo.ejb.AidSchedulerEJB </injection-target-class> <injection-target-name>ds</injection-target-name> </injection-target> </resource-ref>
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EnterpriseJavaXML Population: EntityManager
<persistence-context-ref> <persistence-context-ref-name> persistence/jndischeduler </persistence-context-ref-name> <persistence-unit-name>jndischeduler</persistence-unit-name> <persistence-context-type>Transaction</persistence-context-type> <injection-target> <injection-target-class> ejava.examples.jndischeduler.ejb.AidSchedulerEJB </injection-target-class> <injection-target-name>em</injection-target-name> </injection-target> </persistence-context-ref>
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EnterpriseJavaXML JNDI mapping META-INF/jboss.xml
<?xml version="1.0" encoding="UTF-8"?><jboss xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
http://www.jboss.org/j2ee/schema/jboss_5_0.xsd" version="3.0"> <enterprise-beans> <session> <ejb-name>AidScheduler</ejb-name> <jndi-name>
ejava/examples/jndidemo/AidScheduler/remote</jndi-name>
<local-jndi-name>ejava/examples/jndidemo/AidScheduler/local
</local-jndi-name> <resource-ref> <res-ref-name>jdbc/myds</res-ref-name> <jndi-name>java:/ejavaDS</jndi-name> </resource-ref> </session> </enterprise-beans></jboss>
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EnterpriseJavaExample: Deployed JNDI Tree
• Local JNDI Namespace+- ejavaDS (class: org.jboss.resource.adapter.jdbc.WrapperDataSource)
• Global JNDI Namespace– default names +- jndiDemoEAR (class: org.jnp.interfaces.NamingContext)
| +- CookEJB (class: org.jnp.interfaces.NamingContext)
| | +- local (.. ejava.examples.jndidemo.ejb.CookLocal ...)
| +- BakeScheduler (class: org.jnp.interfaces.NamingContext)
| | +- remote (class: java.lang.Object)
| | +- remoteStatefulProxyFactory (... org.jboss.ejb3.ProxyFactory)
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EnterpriseJavaAnnotation Population: Example Entities
@Localpublic interface CookLocal extends Scheduler {}
@Statelesspublic class CookEJB extends SchedulerBase implements CookLocal { public String getName() { return "CookEJB"; }
@Resource protected void setSessionContext(SessionContext ctx) { super.ctx = ctx; }}
@Remotepublic interface BakeSchedulerRemote extends Scheduler {}
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EnterpriseJavaAnnotation Population: Example Java Class
@Stateful(name="BakeScheduler")@EJBs({ @EJB(name="ejb/cook", beanInterface=CookLocal.class, beanName="CookEJB")})@PersistenceContext(unitName="jndischeduler", name="persistence/jndischeduler", type=PersistenceContextType.EXTENDED)public class BakeSchedulerEJB extends SchedulerBase implements BakeSchedulerRemote {
@Resource(name=”persistence/jndischeduler”) private EntityManager em; @Resource(mappedName=”java:/ejavaDS”) private DataSource ds; @Resource protected void setSessionContext(SessionContext ctx) { super.ctx = ctx; }
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EnterpriseJavaAnnotation Population: Example Java Class
@Resource(name=”ejb/cook”) protected CookLocal cook; @Resource(name="vals/message") String message;
@PostConstruct public void init() {
log.info("********* BakeScheduler Created ********");
log.debug("ctx=" + ctx);
log.debug("ejb/cook=" + ctx.lookup("ejb/cook"));
log.debug("em=" + em);
log.debug("ds=" + ds);
log.debug("persistence/jndischeduler=" +
ctx.lookup("persistence/jndischeduler"));
log.debug("message=" + message);
log.debug("cook=" + cook);
}
}
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EnterpriseJavaAnnotation Population: Example Output
BakeSchedulerEJB] ******************* BakeScheduler Created ******************
[BakeSchedulerEJB] ctx=org.jboss.ejb3.BaseSessionContext@a1a602
[BakeSchedulerEJB] ejb/cook=CookEJB
[BakeSchedulerEJB] em=org.jboss.ejb3.entity.ExtendedEntityManager@16b3939
[BakeSchedulerEJB] ds=org.jboss.resource.adapter.jdbc.WrapperDataSource@155bd22
[BakeSchedulerEJB] persistence/jndidemo=org.jboss.ejb3.entity.ExtendedEntityManager@16b3939
[BakeSchedulerEJB] message=null
[BakeSchedulerEJB] cook=null
[BakeSchedulerEJB] cook2=CookEJB
[JNDIHelper]
listing java:comp/env
+env :org.jnp.interfaces.NamingContext
+ejb :org.jnp.interfaces.NamingContext
---cook :javax.naming.LinkRef
+ejava.examples.jndidemo.ejb.BakeSchedulerEJB :org.jnp.interfaces.NamingContext
---ds :javax.naming.LinkRef
+persistence :org.jnp.interfaces.NamingContext
---jndidemo :org.jboss.ejb3.entity.ExtendedEntityManager
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EnterpriseJavaDependency Injection
• fields– simple, less verbose
• property setter– easier to plug into unit tests– no need for getter– inheritance supported
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EnterpriseJavaSummary
• Populate– XML– Annotations
• Lookup– JNDI– SessionContext
• Property Assignment– Lookup– Dependency Injection
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EnterpriseJava
References
• “Enterprise JavaBeans 3.0, 5th Edition”; Burke & Monsen-Haefel; ISBN 0-596-00978-X; O'Reilly
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