2 Replies Latest reply on Dec 16, 2014 9:33 AM by realcrazybird

Single instance of Session EJB using EJB 2.1 on JBOSS 5.1.1 EAP

realcrazybird Dec 16, 2014 6:54 AM

Hello!

In our project we're using quite old infrastructure and technlogy - EJB2.1 on a JBOSS 5.1.1 EAP and we don't have the time or budget to upgrade to EJB 3.0 or later.

I'm using a MDB to process messages form a message queue. This message queue delegates work to a stateless session bean which creates objects in the database. Now I do have concurrency problems when the program runs (hibernate tries to create different Objects with the same primary key/id) and I want to ensure that there can only bw one instance of the EJB, which creates the objects.

I tried to modify my jboss.xml (which is packaged in my META-INF dir in the ejb-jar) in the following way (changes in bold font)

<?xml version="1.0"?>

<jboss xmlns="http://www.jboss.com/xml/ns/javaee"

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

xsi:schemaLocation="http://www.jboss.com/xml/ns/javaee

http://www.jboss.org/j2ee/schema/jboss_5_0.xsd"

version="3.0">

<enterprise-beans>

<message-driven>

<ejb-name>AMessageBean</ejb-name>

<configuration-name>Singleton Message Driven Bean</configuration-name>

<resource-adapter-name>activemq-rar-5.2.0.rar</resource-adapter-name>

<configuration-name>Singleton Message Driven Bean</configuration-name>

</message-driven>

<ejb-name>ASessionBean</ejb-name>

<local-jndi-name>local/ASessionBean</local-jndi-name>

<pool-config>

<pool-max-size>1</pool-max-size>

</pool-config>

</session>

</enterprise-beans>

</jboss>

but JBOSS seems to ignore this setting. Changing the "Standard Stateless SessionBean" container-configuration in the standardjboss.xml is not an options because I have other EJBs in the same applications which should not be limited to one instance at a time.

I would be thankful for any tips.

Stefan

1. Re: Single instance of Session EJB using EJB 2.1 on JBOSS 5.1.1 EAP

jaysensharma Dec 16, 2014 8:59 AM (in response to realcrazybird)

In "$JBOSS_HOME/docs/dtd/jboss_5_0.dtd" i see an option to define the "container-configuration" for individual session beans using jboss.xml something as following to override container provided settings. I did not test it though but it can be seen in doc [1].

<?xml version="1.0" encoding="UTF-8"?>
<jboss xmlns="http://www.jboss.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
      xsi:schemaLocation="http://www.jboss.com/xml/ns/javaee  http://www.jboss.org/j2ee/schema/jboss_5_1.xsd" version="5.1">
  <enterprise-beans>
      <session>
        <ejb-name>HelloSLSB</ejb-name>
          .
          .
        <configuration-name>Individual SLSB Config</configuration-name>
          .
          .
      </session>
  </enterprise-beans>

<!-- Overriding container configuration -->
  <container-configurations>
      <container-configuration extends="Standard Stateless SessionBean">
        <container-name>Individual SLSB Config</container-name>
        <container-pool-conf>
          <MaximumSize>20</MaximumSize>
        </container-pool-conf>
      </container-configuration>
  </container-configurations>
</jboss>

[1] 11.3.1.3. Container configuration information Says:

By placing a jboss.xml file in the EJB JAR META-INF directory, you can specify either overrides for container configurations in the standardjboss.xml file, or entirely new named container configurations. This provides great flexibility in the configuration of containers.

2. Re: Single instance of Session EJB using EJB 2.1 on JBOSS 5.1.1 EAP

realcrazybird Dec 16, 2014 9:33 AM (in response to realcrazybird)

Thanks, tried that but it seems that "container-configurations" is in the DTD but not in the Schema Definition. Why?
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