Configure web applications in JBoss

When you deploy a web application in a JavaEE application server, it usually consist of a .war archive.

Sometimes, the web application needs some configuration parameters. The most common way to do this is to have <context-param> in web.xml. That is simple and works fine except that the web.xml file needs to be inside the .war archive. This makes it inconvenient to change a configuration parameter since you have to repack the .war archive. You also have to set the same value several times if several web applications share the same configuration.

It would be nice to be able to specify the configuration parameter values outside the .war archive, in a way so that several web applications in the same application server can use the same parameter value. Sadly, the JavaEE specification offers no simple way to do this portably.

However, I found a way to do it in JBoss 4.2.2. Create a file named something-service.xml in the JBoss deployment directory with the following structure:

<server>
<mbean code="org.jboss.naming.JNDIBindingServiceMgr"
       name="pm-urls:service=JNDIBindingServiceMgr">
    <attribute name="BindingsConfig" serialDataType="jbxb">
    <jndi:bindings
        xmlns:xs="http://www.w3.org/2001/XMLSchema-instance"
        xmlns:jndi="urn:jboss:jndi-binding-service:1.0"
        xs:schemaLocation="urn:jboss:jndi-binding-service:1.0 resource:jndi-binding-service_1_0.xsd">
    <jndi:binding name="myapp/BackendHost"><jndi:value>somehost</jndi:value></jndi:binding>
    <jndi:binding name="myapp/BackendPort"><jndi:value type="java.lang.Integer">4711</jndi:value></jndi:binding>
    </jndi:bindings>
    </attribute>
    <depends>jboss:service=Naming</depends>
</mbean>
</server> 

Then lookup the configuration parameters using JNDI in the web application(s):

InitialContext initCtx = new InitialContext();
String backendHost = (String)initCtx.lookup("myapp/BackendHost");
int backendPort = (Integer)initCtx.lookup("myapp/BackendPort");

Se some documentation about this.