------
                                    Multi Datasource Web Application
                                    ------
                                    The Apache Onami developers team
                                    ------
                                     2014

~~
~~ Licensed to the Apache Software Foundation (ASF) under one
~~ or more contributor license agreements.  See the NOTICE file
~~ distributed with this work for additional information
~~ regarding copyright ownership.  The ASF licenses this file
~~ to you under the Apache License, Version 2.0 (the
~~ "License"); you may not use this file except in compliance
~~ with the License.  You may obtain a copy of the License at
~~
~~   http://www.apache.org/licenses/LICENSE-2.0
~~
~~ Unless required by applicable law or agreed to in writing,
~~ software distributed under the License is distributed on an
~~ "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
~~ KIND, either express or implied.  See the License for the
~~ specific language governing permissions and limitations
~~ under the License.
~~

Multi Datasource Web Application

* java code

+--------------------------------------+
public class BootstrapServletListener
    extends GuiceServletContextListener
{

    protected Injector getInjector()
    {
        final PersistenceModule persistenceModule = new PersistenceModule() {

            @Override
            protected void configurePersistence()
            {
                bindContainerManagedPersistenceUnitWithJndiName( "java:comp/env/foobar/mainPuJndiName" )
                    .annotatedWith(MainPU.class)
                    .useGlobalTransactionWithJndiName( "java:comp/env/UserTransaction" );

                bindContainerManagedPersistenceUnitWithJndiName( "java:comp/env/foobar/alternativePUJndiName" )
                    .annotatedWith(AlternativePU.class)
                    .useGlobalTransactionWithJndiName( "java:comp/env/UserTransaction" );

                bindContainerManagedPersistenceUnitWithJndiName( "java:comp/env/foobar/systemPuJndiName" )
                    .annotatedWith(SystemPU.class)
                    .useLocalTransaction();
            }

        };

        final ServletModule servletModule = new ServletModule()
        {
            filter("/*").through(PersistenceFilter.class);
        };

        return Guice.createInjector( servletModule, persistenceModule, getApplicationSpecificModules() );
    }

}
+--------------------------------------+

* web.xml

+--------------------------------------+
<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.5" 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/web-app_2_5.xsd">
    <display-name>FooBar App</display-name>
    <filter>
        <filter-name>guiceFilter</filter-name>
        <filter-class>com.google.inject.servlet.GuiceFilter</filter-class>
    </filter>
    <filter-mapping>
        <filter-name>guiceFilter</filter-name>
        <url-pattern>/*</url-pattern>
    </filter-mapping>
    <listener>
        <listener-class>foo.bar.BootstrapServletListener</listener-class>
    </listener>
    <!-- More config. -->
</web-app>
+--------------------------------------+

* persistence.xml

+--------------------------------------+
<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_2_0.xsd" version="2.0">
    <persistence-unit name="mainPuName" transaction-type="JTA">
        <!-- your configuration -->
    </peristence-unit>
    <persistence-unit name="alternativePuName" transaction-type="JTA">
        <!-- your configuration -->
    </peristence-unit>
    <persistence-unit name="systemPuName" transaction-type="RESOURCE_LOCAL">
        <!-- your configuration -->
    </peristence-unit>
</peristence>
+--------------------------------------+

* JNDI Binding

  In order to allow container managed persistence units the persistence unit must be bound in the JNDI framework.

  If your container follows the J2EE Standard 5.0 add the following to your web.xml

+--------------------------------------+
<peristence-unit-ref>
    <peristence-unit-ref-name>foobar/mainPuJndiName</peristence-unit-ref-name>
    <peristence-unit-name>mainPuName</peristence-unit-name>
</peristence-unit-ref>
<peristence-unit-ref>
    <peristence-unit-ref-name>foobar/alternativePuJndiName</peristence-unit-ref-name>
    <peristence-unit-name>alterantivePuName</peristence-unit-name>
</peristence-unit-ref>
<peristence-unit-ref>
    <peristence-unit-ref-name>foobar/systemPuJndiName</peristence-unit-ref-name>
    <peristence-unit-name>systemPuName</peristence-unit-name>
</peristence-unit-ref>
+--------------------------------------+

  Important: JBoss AS7.x do not support placing the JNDI binding in the web.xml.
  Instead add the following to your persistence.xml

+--------------------------------------+
<property name="jboss.entity.manager.factory.jndi.name" value="java:comp/env/foobar/mainPuJndiName" />
<property name="jboss.as.jpa.managed" value="true" />

<property name="jboss.entity.manager.factory.jndi.name" value="java:comp/env/foobar/alternativePuJndiName" />
<property name="jboss.as.jpa.managed" value="true" />

<property name="jboss.entity.manager.factory.jndi.name" value="java:comp/env/foobar/systemPuJndiName" />
<property name="jboss.as.jpa.managed" value="true" />
+--------------------------------------+

  Important: JBoss AS 7.x makes all datasources defined in the standalone.xml JTA managed. If you want one or more of
  the datasources to be resource local you must add the attribute "jta" to the datasource element.

+--------------------------------------+
<datasource jndi-name="java:jboss/datasources/systemDS" pool-name="systemDS" enabled="true" use-java-context="true" jta="false">
    ...
</datasource>
+--------------------------------------+

* Structure of the .war

+--------------------------------------+
+ app.war
|    + META-INF
|    |    + MANIFEST.MF
|    |    + persistence.xml
|    + WEB-INF
|    |    + classes
|    |    |    + META-INF
|    |    |    |    + MANIFEST.MF
|    |    |    + foo
|    |    |    |    + bar
|    |    |    |    |    + BootstrapServletListener.class
|    |    + lib
|    |    |    + guice.jar
|    |    |    + onami-persist.jar
+--------------------------------------+