Michael Sikora on Java EE

Converting to JBoss-5.0.0.GA - Part 2

In this post I continue describing the conversion from glassfish to

JBoss-5.0.0.GA. This post covers the examples from chapter 5 to chapter 10 of my book. This has proved very straightforward with only a couple of items to take note of.

Native SQL

One problem I hit was in lab6 of chapter 5. This deals with native SQL queries in JPQL.

In JBoss if one field definition is specified in a @FieldResult, then all fields for that class need to be specified even if they map onto the same column name. For example we may have the query:

@SqlResultSetMapping(

name="CustomerAccountResults",

entities={@EntityResult(entityClass=ejb30.entity.Account.class,

fields={@FieldResult(name="id", column="ACC_ID"),

           @FieldResult(name="accountType", column="ACCOUNTTYPE"),

            @FieldResult(name="balance", column="BALANCE"),

           @FieldResult(name="customer", column="CUSTOMER_ID") } ),

          @EntityResult(entityClass=ejb30.entity.Customer.class)

         }

),

Because we need to add the first @FieldResult entry to map id to column ACC_ID, we need to add a @FieldResult entry for every field in Account. This applies for fields such as accountType and balance which map onto columns with the same name. According to the JPA spec such FieldResult mappings are optional.

If we dont have a FieldResult mapping in JBoss we get a runtime error along the lines:

[JDBCExceptionReporter] Column not found: balance6_0_

Messaging

Chapter 8 deals with JMS Messaging. To create JMS resources such as

a JMSQueue named BankServiceJMSQueue

a JMSTopic named BankServiceJMSTopic

a JMSConnectionFactory named BankServiceConnectionFactory

we first need to create the following chap08-service.xml file:

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

<server>

<mbean code="org.jboss.mq.server.jmx.Queue"

name="jboss.mq.destination:service=Queue,name=BankServiceJMSQueue">

<attribute name="JNDIName">BankServiceJMSQueue</attribute>

<depends optional-attribute-name="DestinationManager">

jboss.mq:service=DestinationManager</depends>

</mbean>

<mbean code="org.jboss.mq.server.jmx.Topic"

name="jboss.mq.destination:service=Topic,name=BankServiceJMSTopic">

<attribute name="JNDIName">BankServiceJMSTopic</attribute>

<depends optional-attribute-name="DestinationManager">

jboss.mq:service=DestinationManager</depends>

</mbean>

<mbean code="org.jboss.jms.server.connectionfactory.ConnectionFactory"

name="jboss.messaging.connectionfactory:service=BankServiceConnectionFactory"

xmbean-dd="xmdesc/ConnectionFactory-xmbean.xml">

<attribute name="JNDIBindings">

<bindings>

<binding>BankServiceConnectionFactory</binding>

</bindings>

</attribute>

<depends optional-attribute-name="ServerPeer">

jboss.messaging:service=ServerPeer

</depends>

<depends optional-attribute-name="Connector">

jboss.messaging:service=Connector,transport=bisocket

</depends>

<depends>jboss.messaging:service=PostOffice

</depends>

</mbean>

</server>

The above xml file can be named anything but must end in "-service.xml". We have chosen chap08-service.xml. This xml file is then copied to the deploy directory. We have the following ant target in our build file:

<target name="create-jms-resources">

<copy file="chap08-service.xml" todir="${jboss.home}/server/default/deploy"/>

</target>

That's it for now. My next post will deal with Web Services.

Configuring passivation parameters in JBoss 5.0.0.GA

One gotcha I came across was configuring passivation parameters in lab 5 of Chapter 2. There does not appear a way to do this in the administrator console. Instead you use the JBoss specific CacheConfig annotation in your stateful session bean as follows:

@Stateful

@CacheConfig(maxSize=2, idleTimeoutSeconds=15) // JBoss specific annotation

public class ShoppingCartBean implements ShoppingCart {

The default values are

maxSize=100000, idleTimeoutSeconds=300

Alternatively you can edit the ejb3-interceptors-aop.xml file in JBOSS_HOME/server/default/deploy directory. This will apply to all stateful session beans in the deployment.

Converting to JBoss-5.0.0.GA - Part 1

I have finally started converting the examples in my book from glassfish to JBoss-5.0.0.GA. I won't describe all the conversion steps in this blog, just JBoss features that differed from other Java EE containers, or gotchas that caught me out. I used JBoss in its standard packaging; using the default Hibernate persistence engine and the embedded Hypersonic (HSQL) relational database. In this post I'll cover chapters 2, 3 and 4. As before I avoided choosing an IDE, instead I converted the glassfish ant build scripts to run on JBoss. The conversion took the following steps:

(1)Create the JBOSS_HOME environment variable that points to the JBoss installation directory. In Windows do this from the System Control panel.

(2) Set the ant property jboss.home to the JBOSS_HOME environment variable in the env.properties file

(3) in build.xml file modify the classpath to use JBoss directories

${jboss.home}/lib and  ${jboss.home}/client

(4) in build.xml replace the glassfish asadmin tool for deployment with a simple copy of the EAR or JAR file to the 

${jboss.home}/server/default/deploy directory. 

.

JNDI

The very first example in chapter 2 has a Java client running outside an application client container invoke a stateless session bean using JNDI. Because of JNDI differences, for JBoss we need to have the statement

TimeService timeService = (TimeService) ctx.lookup("ejb30.session.TimeService");

replaced by

TimeService timeService = (TimeService) ctx.lookup("TimeServiceBean/remote");

in

Client.java.

In the above example we deployed the TimeService EJB packaged in a JAR file. If the EJB is packaged in an EAR file, which is the normal case, then the JNDI lookup would be "EAR file name/ejb name/remote" for remote interfaces or "EAR file name/ejb name/local" for local interfaces. So in lab3 of chapter 2 the JNDI lookup is:

TimeService timeService = (TimeService) ctx.lookup("TimeService/TimeServiceBean/remote");

PERSISTENCE

Chapter 3 deals with persistence which entails modifying the persistence.xml file. Following examples in JBoss documentation I initially tried

<persistence>

<persistence-unit name="BankService">

<provider>org.hibernate.ejb.HibernatePersistence</provider>

<jta-data-source>java:/DefaultDS</jta-data-source>

<properties>

<property name="hibernate.dialect" value="org.hibernate.dialect.HSQLDialect"/>

<property name="hibernate.hbm2ddl.auto" value="create-drop"/>

</properties>

</persistence-unit>

</persistence>

This gave the error

"org.jboss.xb.binding.JBossXBRuntimeException: Failed to resolve schema nsURI= location=persistence" at deploy time. I suspect the above persistence.xml file would work for JBoss version 4.3 and lower, but for version 5 you need to add header details in the <persistence> tag as follows:

<persistence

xmlns="http://java.sun.com/xml/ns/persistence"

xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_1_0.xsd"

version="1.0">

<persistence-unit name="BankService">

<provider>org.hibernate.ejb.HibernatePersistence</provider>

<jta-data-source>java:/DefaultDS</jta-data-source>

<properties>

<property name="hibernate.dialect" value="org.hibernate.dialect.HSQLDialect"/>

<property name="hibernate.hbm2ddl.auto" value="create-drop"/>

</properties>

</persistence-unit>

</persistence>

JBoss provides a GUI based tool, the HSQL Database Manager tool for querying tables created when persisting entities. This tool is accessed from the JBoss administrator console. To initiate the console enter

http://localhost:8080

in your web browser. Then click on the JMX Console link. This brings up the JMX Agent View screen. Then under the jboss subheading click on the database=localDB,service=Hypersonic link. On the resulting screen click on the Invoke button of the startDatabaseManager operation.

This will then bring up the HSQL Database Manager window. You can then perform standard SQL queries.

In lab4 of chapter 3 we use a strategy of GenerationType.AUTO to generate primary key values.

In JBoss (using default Hibernate persistence engine and HSQL database) specifying a primary key generation strategy of GenerationType.AUTO will default to an IDENTITY strategy. In this case HSQL will use an identity column for generating a primary key value. If a column has not been specified as an identity column then HSQL will use the primary key column as an identity column.

O/R Mapping

In chapter 4 lab1 the Customer.toString() method was modified so that addresses and accounts are not referenced. This is because these are lazily loaded by default, and would otherwise give the run time org.hibernate.LazyInitializationException. So the following code fragment

public String toString() {

return "[Customer Id =" + id + ",first name=" + firstName + ",last name="

+ lastName + ", referee=" + referee + ",addresses=" + addresses

+ ",accounts=" + accounts + "]";

was modified to

public String toString() {

return "[Customer Id =" + id + ",first name=" + firstName + ",last name="

+ lastName + ", referee=" + referee + ",addresses= {not initialized}"

+ ",accounts= {not initialized}" + "]";

In lab2 JBoss gives a deploy error of "org.hibernate.HibernateException: cannot simultaneously fetch multiple bags." This is a known Hibernate feature when using a bag (i.e. Collection or List) for eager fetches. For example the following fragment from the customer entity:

@OneToMany(mappedBy="customer", fetch=EAGER)

public Collection<Account> getAccounts() { return accounts; }

public void setAccounts(Collection<Account> accounts) { this.accounts = accounts; }

This can be resolved by (a) adding an @IndexColumn annotation or (b) using a Set instead. (a) is a Hibernate extension to Java EE, so I used option b, Sets.

That's all for this post.