Clustering and Session Replication Using Glassfish 3.1

Sometimes we need to replicate sessions between clustered environment to make sure session failovers. In this tutorial im trying to clustered 2 Glassfish instances located in the same computer, create a simple webapps and try to see whether session in instance 1 replicated to instance 2. I dont know why but Glassfish 3.0 seems doesnt support clustering so im using Glassfish version 3.1 instead.

Lets start by starting Glassfish, go to /bin and start it from command promt by typing asadmin start-domain domain1.

After it started, go to Glassfish console from your browser. Glassfish console URL will be http://localhost:4848/. Login and start creating a cluster from Clusters menu.

Start your cluster,

congratulation, you have started your cluster. Lets see details from each instances,

it shows your instance’s http port.

To test our session replication, i create a simple web application using Netbeans 6.9.
First is a simple jsp file, index.jsp

<%@page import="java.util.Enumeration"%>
<%@page contentType="text/html" pageEncoding="UTF-8"%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
    "http://www.w3.org/TR/html4/loose.dtd">

<html>
    <head>
        <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
        <title>JSP Page</title>
    </head>
    <body>
        <h1>Session Form</h1>

        <%
                    if (request.getParameter("sessionName") != null && request.getParameter("sessionValue") != null) {
                        HttpSession httpSession = request.getSession();
                        httpSession.setAttribute(request.getParameter("sessionName"), request.getParameter("sessionValue"));
                    }
        %>

        <form action="index.jsp" method="POST">

            your session name : <input type="text" name="sessionName" /> <br />
            your session value : <input type="text" name="sessionValue" /> <br />
            <input type="submit" />

        </form>

        <h1>Your Sessions</h1>

        <%
                    Enumeration sessionNames = session.getAttributeNames();
                    while (sessionNames.hasMoreElements()) {
                        String mySessionName = sessionNames.nextElement().toString();
                        String mySession = request.getSession().getAttribute(mySessionName).toString();
                        out.print(mySessionName+ " --> "+mySession + " <br />");
                    }
        %>

    </body>
</html>

And the most important is the web.xml configuration,

<?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">
    <distributable id="sessionDistribute" />
    <session-config>
        <session-timeout>
            30
        </session-timeout>
    </session-config>
    <welcome-file-list>
        <welcome-file>index.jsp</welcome-file>
    </welcome-file-list>
</web-app>

Build it into a war app and deploy it to our clustered environment, always make sure the Availability option checked as enabled.

After you launch it, input some value to jsp page in instance1 and save it. It will save your values to a session.

open instance2′s jsp page and check whether your instance1′s session is there.

As you can see, your sessions from instance 1 is replicated and available from instance 2.

Have fun using Glassfish. :)

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