JMXConnector con=JMXConnectorFactory.connect
              (new JMXServiceURL("rmi", "alfheim.dit.upm.es", 1099, "server"));
MBeanServerConnection serverconn=con.getMBeanServerConnection();
ObjectName memoryObjName=    
                 ObjectName.getInstance(ManagementFactory.MEMORY_MXBEAN_NAME);
Object compositeData=serverconn.getAttribute(memoryObjName, "HeapMemoryUsage");
MemoryUsage usage=MemoryUsage.from((CompositeData)compositeData);
System.out.println("Committed memory (Bytes): "+usage.getCommitted());

Example 4: Using a connector to get the (remote) reference.