Grails 2.5.4: Get all logged in users with HttpSessionListener - grails

Question

I'm trying to get all the current user sessions using the app-info plugin but it doesn't compile in Grails 2.5.4. Is there another way to get this information? I'm new to Grails.
This link has some information including a reference to the app-info plugin but it's old and I wasn't able to get anything to compile.
UPDATE
I've added this custom class in src\groovy\UserSessions:
package usersessions
import javax.servlet.http.HttpSessionEvent
import javax.servlet.http.HttpSessionListener
//import org.apache.shiro.subject.PrincipalCollection
//import org.apache.shiro.subject.SimplePrincipalCollection;
//import org.apache.shiro.subject.support.DefaultSubjectContext
class MyHttpSessionListener implements HttpSessionListener {
private static List activeUsers = Collections.synchronizedList(new ArrayList());
#Override
public void sessionCreated(HttpSessionEvent event) { }
#Override
public void sessionDestroyed(HttpSessionEvent event) {
String userName = getCurrentUserName(event)
if (userName == null) {
return
}
MyHttpSessionListener.userLoggedOut(userName)
}
public static void userLoggedIn(String userName) {
if (!activeUsers.contains(userName)) {
activeUsers.add(userName)
}
}
public static void userLoggedOut(String userName) {
activeUsers.remove(userName)
}
public static List getCurrentUserNames() {
return Collections.unmodifiableList(activeUsers);
}
/*
private String getCurrentUserName(HttpSessionEvent event) {
PrincipalCollection currentUser = (PrincipalCollection) event.getSession().getAttribute(DefaultSubjectContext.PRINCIPALS_SESSION_KEY);
if (currentUser == null) {
return null
}
return (String) currentUser.getPrimaryPrincipal();
}
*/
}
Added this to /scripts/_Events.groovy
import groovy.xml.StreamingMarkupBuilder
eventWebXmlEnd = {String tmpfile ->
def root = new XmlSlurper().parse(webXmlFile)
root.appendNode {
'listener' {
'listener-class' (
'usersessions.MyHttpSessionListener'
)
}
}
webXmlFile.text = new StreamingMarkupBuilder().bind {
mkp.declareNamespace(
"": "http://java.sun.com/xml/ns/javaee")
mkp.yield(root)
}
}
Added this to resources.groovy
myHttpSessionListener(usersessions.MyHttpSessionListener)
/* shiroAuthenticator(ModularRealmAuthenticator) {
authenticationStrategy = ref("shiroAuthenticationStrategy")
authenticationListeners = [ ref("authListener") ]
}
*/
Added this to my controller:
package usersessions
class NewController extends MyHttpSessionListener {
def index() {
myHttpSessionListener.userLoggedIn("user1")
render "Users "+ getCurrentUserNames()
}
}
It compiles and the app runs but I don't see how to get sessions in the listener? The controller gives an error when I load it:
No such property: myHttpSessionListener for class: usersessions.NewController
UPDATE 2
I changed the controller to use this code to test creating a sessions and it works:
def index() {
String randomString = org.apache.commons.lang.RandomStringUtils.random(3, true, true)
userLoggedIn(randomString)
render "Users "+ getCurrentUserNames()
}