As stated in Configuration MBeans, the AMX API allows client applications to connect to Application Server instances using the DAS. All AMX connections are established to the DAS only: AMX does not support direct connections to individual server instances. This makes it simple to interact with all servers, clusters, and so on, with a single connection.
Sample code for connecting to the DAS is shown in Connecting to the DAS. The com.sun.appserv.management.helper.Connect class (see http://glassfish.dev.java.net/nonav/javaee5/amx/javadoc/com/sun/appserv/management/helper/Connect.html) is also available.