J2EE EJB OpenEJB

1.Generally speaking the only way to get a Container-Managed Resource is via dependency injection or lookup from within a Container-Managed Component.

 

2. Singleton

a.Singletons have an '@Startup' annotation which can be applied to the bean class. When used, the Container will instantiate the Singleton instance eagerly when the application start up, otherwise the Container will instantiate the Singleton instance lazily when the bean is first accessed.

@DependsOn({"SingletonB", "SingletonC"})

@Singleton

@Startup

public class SingletonA {

...

}

b.Note that @DependsOn is only required(and should only be used) if a Singleton uses another Singleton in its @PostConstruct method or @PreDestory method. Simply having a reference to another Singleton and using it in other business methods does not require an @DependsOn declaration.

 

3. Containers

a.CMP_ENTITY

1.openejb.xml

<Container id="Foo" type="CMP_ENTITY">

</Container>

2.properties file

Foo=new://Container?type=CMP_ENTITY

3.property

CmpEngineFactory - org.apache.openejb.core.cmp.jpa.JpaCmpEngineFactory

 

b.BMP_ENTITY

1.openejb.xml

<Container id="Foo" type="BMP_ENTITY">

</Container>

2.properties file

Foo=new://Container?type=BMP_ENTITY

3.property

PoolSize - 10

c.STATELESS

1.openejb.xml

<Container id="Foo" type="STATELESS">

</Container>

2.properties file

Foo=new://Container?type=STATELESS

3.property

Timeout - 0 millisecond

PoolSize - 10

StrictPooling - true

d.STATEFUL

1.openejb.xml

<Container id="Foo" type="STATELESS">

</Container>

2.properties file

Foo=new://Container?type=STATEFUL

3.property

Passivator - org.apache.openejb.core.stateful.RAFPassivater

  - org.apache.openejb.core.stateful.Simplepassivater(default)

TimeOut - 20 minutes

PoolSize - 1000

BulkPassivate - 100

e.MESSAGE

1.openejb.xml

<Container id="Foo" type="MESSAGE">

</Container>

2.properties file

Foo=new://Container?type=MESSAGE

3.property

ResourceAdapter - The resource adapter delivers messages to the container. Default value is Default JMS Resource Adapter

MessageListenerInterface - Specifies the message listener interface handled by this container. Default value is javax.jms.MessageListener.

ActivationSepcClass - Specifies the activation spec class. Default value is org.apache.activemq.ra.ActionMQActivationSpec.

instanceLimit - Specifies the maximum number of bean instances that are allowed to exists for each MDB deployment. Default value is 10.

f.Resource

1.javax.sql.DataSource

<Resource id="Foo" type="javax.sql.DataSource">

</Resource>

Foo=new://Resource?type=javax.sql.DataSource

properties:JtaManaged, JdbcDriver, JdbcUrl, UserName, Password, ConnectionProperties, DefaultAutoCommit, DefaultReadOnly, DefaulTransactionIsolation, InitialSize, MaxActive, maxIdle, MinIdle, MaxWait, ValidationQuery, TestOnBorrow, TestOnReturn, TestWhileIdle, TimeBetweenEvictionRunsMillis, NumTestsPerEvictionRun, MinEvictableIdleTimeMillis, PoolPreparedStatements, MaxOpenPreparedStatements, AccessToUnderlyingConnectionAllowed

 

2.ActiveMQResourceAdapter

<Resource id="Foo" type="ActiveMQResourceAdapter">

</Resource>

Foo=new://Resource?type=ActiveMQResourceAdapter

properties:

BrokerXmlConfig - broker:(tcp://localhost:61616)?useJmx=false

ServerUrl - vm://localhost?async=true

DataSource - Default value is Default Unmanaged JDBC Database

 

3.javax.jms.ConnectionFactory

<Resource id="Foo" type="javax.jms.ConnectionFactory">

</Resource>

Foo = new://Resource?type=javax.jms.ConnectionFactory

properties:

ResourceAdapter

TransactionSupport

PoolMaxSize

PoolMinSize

ConnectionMaxWaitMilliseconds

ConnectionMaxIdleMinutes

 

4.javax.jms.Queue

<Resource id="Foo" type="javax.jms.Queue">

</Resource>

Foo = new://Resource?type=javax.jms.Queue

properties:

destination - Specifies the name of the queue

 

5.javax.jms.Topic

<Resource id="Foo" type="javax.jms.Topic">

</Resource>

Foo = new://Resource?type=javax.jms.Topic

properties:

destination - Specifies the name of the topic

 

6.org.omg.CORBA.ORB

<Resource id="Foo" type="org.omg.CORBA.ORB">

</Resource>

Foo = new://Resource?type=org.omg.CORBA.ORB

 

7.javax.mail.Session

<Resource id="Foo" type="javax.mail.Session">

</Resource>

Foo = new://Resource?type=javax.mail.Session

 

4. Configuring Datasource

@Resource(name = "myDerbyDatasource", type = javax.sql.DataSource.class)

<Resource id="myDerbyDatasource" type="javax.sql.DataSource">

. . . .

<Resource>

 

5. JNDI names for configured DataSources

<Resource id="Default JDBC Database" type="DataSource">

. . . . .

</Resource>

The global jndi name would be java:openejb/Resource/Default JDBC Database

 

6. Obtaining a DataSource

DataSource references in your EJB should get automatically mapped to the Resource you declare. The shortest and easiest rule is that 'if your reference name matches a Resource in you openejb.xml, that's the one you get'. Essentially, the rules for mapping are as follows:

1. Name Attribute Match - @Resource with a name attribute matching the resource name gets that resource injected

2. Injected Name Match - variable name matching the resource name gets that resource injected

3. No Match - nothing matches a resource name, so the first resource available gets injected

e.g.:

Resource:

<Resource id="myDerbyDatabase"  type="DataSource">

. . . . .

</Resource>

a. BY matching variable name to resource name:

@Stateless

public class FooBean {

@Resource DataSource myDerbyDatabase;

}

b. BY matching name

@Stateless

public class FooBean {

@Resource(name="myDerbyDatabase")

DataSource dataSource;

}

c. BY JNDI lookup

@Resource(name="myDerbyDatabase", type=javax.sql.DataSource.class)

@Stateless

public class FooBean {

 

public void setSessionContext(SessionContext sessionContext) {

DataSource dataSource = (DataSource) sessionContext.lookup("myDerbyDatabase");

}

 

public void someOtherMethod() throws Exception {

InitialContext initialContext = new InitialContext();

DataSource dataSource = (DataSource) initialContext.lookup("java:comp/env/myDerbyDatabase");

}

}

 

<resource-ref>

   <res-ref-name>myDerbyDatabase</res-ref-name>

   <res-type>javax.sql.DataSource</res-type>

</resource-ref>

 

<resource-ref>

<res-ref-name>jdbc/myDerbyDatabase</res-ref-name>

<res-type>javax.sql.DataSource</res-type>

</resource-ref>

 

<resource-ref>

<res-ref-name>someOtherName</res-ref-name>

<res-type>javax.sql.DataSource</res-type>

<mapped-name>myDerbyDatabase</mapped-name>

</resource-ref>

 

7. Working with OpenJPA

    a.jndi.properties

        java.naming.factory.initial=org.apache.openejb.client.LocalInitialContextFactory

        java.naming.provider.url=ejbd://localhost:4201

        oracleDatabase=new://Resource?type=DataSource

        oracleDatabase.JdbcDriver=oracle.jdbc.driver.OracleDriver

        oracleDatabase.JdbcUrl=jdbc:oracle:thin:@10.199.130.142:1521:apj

        oracleDatabase.UserName=trs

        oracleDatabase.Password=trs

    b.persistence.xml

        <?xml version="1.0" encoding="UTF-8"?>

        <persistence xmlns="http://java.sun.com/xml/ns/persistence" version="1.0">

            <persistence-unit name="oracle">

                <jta-data-source>oracleDatabase</jta-data-source>

                <properties>

                    <property name="openjpa.jdbc.SynchronizeMappings" value="buildSchema(ForeignKeys=true)" /> <!-- auto_ddl=true -->

                    <property name="openjpa.Log" value="SQL=TRACE" /> <!-- print SQL -->

                    <property name="openjpa.ConnectionFactoryProperties" value="PrettyPrint=true, PrettyPrintLineLength=80" /> <!-- pretty print SQL -->

                </properties>

            </persistence-unit>

        </persistence>

    c.ejb-jar.xml

        <?xml version="1.0" encoding="UTF-8"?>

        <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">

            <display-name>ejb3</display-name>

        </ejb-jar>

    d.PersistenceContext injection

        @PersistenceContext(unitName = "oracle")

        protected EntityManager entityManager;

    e.EJBTest.java

        import java.io.IOException;

        import java.util.Properties;

        import javax.naming.InitialContext;

        import javax.naming.NamingException;

        import org.junit.Before;

        public abstract class EJBTest {

            private InitialContext ctx;

            public EJBTest() {

            }

            @Before

            public void initialise() {

                final Properties props = new Properties();

                try {

                    props.load(Thread.currentThread().getContextClassLoader()

                            .getResourceAsStream("ejb-test-configure.properties"));

                    this.ctx = new InitialContext(props);

                    this.init();

                } catch (NamingException e) {

                    e.printStackTrace();

                } catch (IOException e) {

                    e.printStackTrace();

                }

            }

            protected <T> T getEJBBean(final Class<T> clz) {

                final String jndiName = clz.getSimpleName() + "ImplRemote";

                return this.getEJBBean(jndiName);

            }

            @SuppressWarnings("unchecked")

            protected <T> T getEJBBean(final String jndiName) {

                T bean = null;

                try {

                    bean = (T) this.ctx.lookup(jndiName);

                } catch (NamingException e) {

                    e.printStackTrace();

                }

                return bean;

            }

            public abstract void init();

        }

 

8. EJB bean lifecycle

    a.stateless: new instance() -> dependency inject -> PostConstruct callback -> application invocation -> PreDestory callback;

    b.stateful: new instance() -> dependency inject -> PostConstruct callback -> ready status(app invoke) -> PrePassivate(opt.) -> Passive status -> PostActivate(opt.) -> ready status -> PreDestroy

    c.entity: new() -> new -> persist() -> managed -> remove() -> removed ->persist() -> managed -> persistence context ends -> detached -> merge() -> managed -> refresh() -> managed.

 

9. Setting jndi name pattern in OpenEJB

    a.put properties - openejb.jndiname.format={interfaceClass} in {OpenEJB_HOME}/conf/system.properties(create it if not existing)

 

10. Setting Oracle datasource

    a.add 'Resource' in openejb.xml;

        <Resource id="oracleDS" type="DataSource">

            JdbcDriver oracle.jdbc.driver.OracleDriver

            JdbcUrl jdbc:oracle:thin:@10.199.130.142:1521:apj

            UserName trs

            Password trs

            JtaManaged true

        </Resource>

    b.copy the ojdbc14.jar to {OpenEJB_HOME}/lib/;

    c.refer to the 'Resource' in persistence.xml;

        <persistence-unit name="oracle" transaction-type="JTA">

            <jta-data-source>oracleDS</jta-data-source>

            <properties>

                <property name="openjpa.Log" value="SQL=TRACE" />

                <property name="openjpa.jdbc.SynchronizeMappings" value="buildSchema(ForeignKeys=true)" />

            </properties>

        </persistence-unit>

 

11. setting deploy folders / projects:

<Deployments dir="apps/" />

<Deployments dir="c:\my\app\beans\" />

<Deployments jar="c:\my\app\superEjbs.jar" />