Overview

JBoss AS offers several mechanisms to retrieve components by name. Every JBoss AS instance has it's own local JNDI namespace (java:) which is unique per JVM. The layout of this namespace is primarily governed by the Java EE specification. Applications which share the same JBoss AS instance can use this namespace to intercommunicate. In addition to local JNDI, a variety of mechanisms exist to access remote components.

• Client JNDI - This is a mechanism by which remote components can be accessed using the JNDI APIs, but without network round-trips. This approach is the most efficient, and removes a potential single point of failure. For this reason, it is highly recommended to use Client JNDI over traditional remote JNDI access. However, to make this possible, it does require that all names follow a strict layout, so user customizations are not possible. Currently only access to remote EJBs is supported via the ejb: namespace. Future revisions will likely add a JMS client JNDI namespace.

• Traditional Remote JNDI - This is a more familiar approach to EE application developers, where the client performs a remote component name lookup against a server, and a proxy/stub to the component is serialized as part of the name lookup and returned to the client. The client then invokes a method on the proxy which results in another remote network call to the underlying service. In a nutshell, traditional remote JNDI involves two calls to invoke an EE component, whereas Client JNDI requires one. It does however allow for customized names, and for a centralized directory for multiple application servers. This centralized directory is, however, a single point of failure. 

• EE Application Client / Server-To-Server Delegation - This approach is where local names are bound as an alias to a remote name using one of the above mechanisms. This is useful in that it allows applications to only ever reference standard portable Java EE names in both code and deployment descriptors. It also allows for the application to be unaware of network topology details/ This can even work with Java SE clients by using the little known EE Application Client feature. This feature allows you to run an extremely minimal AS server around your application, so that you can take advantage of certain core services such as naming and injection.  

Local JNDI

The Java EE platform specification defines the following JNDI contexts:

• java:comp - The namespace is scoped to the current component (i.e. EJB)

• java:module - Scoped to the current module

• java:app - Scoped to the current application

• java:global - Scoped to the application server

In addition to the standard namespaces, AS7 also provides the following two global namespaces:

• java:jboss

• java:/

AS 7.1 also provides the java:jboss/exported context, entries bound to this context are accessible over remote JNDI.

<web-app version="3.0"
         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_3_0.xsd">
    <env-entry>
        <env-entry-name>java:global/mystring</env-entry-name>
        <env-entry-type>java.lang.String</env-entry-type>
        <env-entry-value>Hello World</env-entry-value>
    </env-entry>
    <env-entry>
        <env-entry-name>hello</env-entry-name>
        <env-entry-type>java.lang.String</env-entry-type>
        <env-entry-value>Hello Module</env-entry-value>
    </env-entry>
</web-app>

<subsystem xmlns="urn:jboss:domain:naming:1.1" >
  <bindings>
    <simple name="java:global/a" value="100" type="int" />
    <simple name="java:global/jbossDocs" value="https://docs.jboss.org" type="java.net.URL" />
    <object-factory name="java:global/b" module="com.acme" class="org.acme.MyObjectFactory" />
    <lookup name="java:global/c" lookup="java:global/b" />
 </bindings>
</subsystem>

/subsystem=naming/binding=java\:global\/mybinding:add(binding-type=simple, type=long, value=1000)

/subsystem=naming/binding=*:read-operation-description(name=add)

Remote JNDI

AS 7.1 supports two different types of remote JNDI. The old jnp based JNDI implementation used in previous JBoss versions is no longer supported.

<dependency>
  <groupId>org.jboss.as</groupId>
  <artifactId>jboss-as-ejb-client-bom</artifactId>
  <version>7.1.0.Final</version>
  <type>pom</type>
  <scope>compile</scope>
</dependency>

final Properties env = new Properties();
env.put(Context.INITIAL_CONTEXT_FACTORY, org.jboss.naming.remote.client.InitialContextFactory.class.getName());
env.put(Context.PROVIDER_URL, "remote://localhost:4447");
remoteContext = new InitialContext(env);