Hi,

In this article we will discuss how can we load jars residing over NFS in JBoss AS-7 classpath. In some development environment, when there are multiple jars and properties files are being used by multiple servers, it is good to put all of them in a central repository, so that if the files (jar/properties files/xmls) are modified, all the servers will pickup the latest version and there will be less overhead related to copying the latest versions to individual servers

NFS allows a user on a client computer to access files over a network in a manner similar to how local storage is accessed. I installed NFS using below link :

Remote_Disk_Access_with_NFS#Installing_NFS

As JBoss AS-7 has introduced a module structure to load your custom jars. One can quickly create a custom module and put the required jars in them, with appropriate entries in module.xml . But in this case we would be needing an additional module directory, which would be residing over NFS server and we would map this to our local (client) server.

Step-1: Modify standalone.sh and add a separate module directory. To do this navigate to $JBOSS_HOME/bin and edit the file.

Search for keyword “module” and it should look like below :

..
if [ "x$JBOSS_MODULEPATH" = "x" ]; then
    JBOSS_MODULEPATH="$JBOSS_HOME/modules"
fi
..

Edit the above section of your “standalone.sh” script and then add the “:” separated path of your module directories as following

..
JBOSS_MODULEPATH=/mnt/nfs:$JBOSS_HOME/modules

#if [ "x$JBOSS_MODULEPATH" = "x" ]; then
  #  JBOSS_MODULEPATH="$JBOSS_HOME/modules"
#fi
..

Here /mnt/nfs/ is the directory, where our new module directory would be residing.

Step-2 : On the shared mount create below directory structure :

..
/mnt/nfs/
├── aaa
   └── bbb
       └── ccc
           └── main
               ├── module.xml
               ├── utility_JAR.jar

..

where

module.xml :

..

<?xml version="1.0" encoding="UTF-8"?>
<module xmlns="urn:jboss:module:1.1" name="aaa.bbb.ccc">
   <resources>
       <resource-root path="utility_JAR.jar"/>
   </resources>
</module>

..

Step-3 : Now lets create a simple application which would be using utility_JAR.jar (ClassLoaderTestWAR.war). The war file will have below structure :”

..
ClassLoaderTestWAR.war/
├── index.jsp
├── WEB-INF
   ├── jboss-deployment-structure.xml
   ├── web.xml
..

Where :

index.jsp :

..
<html>
     <head><title>ClassLoader Demo</title></head>
     <body bgcolor="maroon" text="white">
            <center>
                    <h1>Class Loader Demo..</h1>


<%
       aaa.bbb.TestUtility utility=new aaa.bbb.TestUtility();
       String whichClassLoader=utility.sayWhichClassLoader();
       System.out.println("nnt -----> "+whichClassLoader);
       out.println("<h1>"+whichClassLoader+"</h1>");
%>

      </body>
</html>
..

jboss-deployment-structure.xml :

..

<?xml version="1.0" encoding="UTF-8"?>
<jboss-deployment-structure>
 <deployment>
   <dependencies>
       <module name="aaa.bbb.ccc" />
   </dependencies>
 </deployment>
</jboss-deployment-structure>

..

web.xml :

..

<web-app>
   <welcome-file-list>
       <welcome-file>index.jsp</welcome-file>
   </welcome-file-list>
</web-app>

..

Step-4 : Now deploy the application and start the JBoss AS-7 server.

Step-5 : Access the application using : http://localhost:8080/ClassLoaderTestWAR

You will see something like below :

If the above output comes that means the jar was loaded from our new module directory, which resides over NFS.

Regards,
Middlewaremagic Team 🙂

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