ZK Session-backed registry

asked 2011-08-18 03:45:17 +0800

avidD
166 ● 2

Hello,
I want to use a singleton registry that manages process-scoped and session-scoped attributes. The purpose of this registry is to avoid explicitly using session attributes scattered all over the application. It would give me typed properties instead of having to cast everywhere and I would not have to use String attribute keys all over the code.

I have an abstract registry class that defines the properties and I have an implementation ZKSessionRegistry that ought to be backed by ZK sessions. However, this unfortunately does not work as expected. Here comes the problem:

I must initialize my registry with session scoped properties when a new session is created. This includes, for instance, a lock manager. I tried to do this initialization using two listeners which both did not work. Here are the two alternative listeners:

public class SessionInitListener implements SessionInit {
public void init(Session session, Object request) throws Exception {
Registry registry = (Registry)Registry.instance();
registry.setLockManager(
new SessionLockManager(((javax.servlet.http.HttpSession)session.getNativeSession()).getId(), LockManager.instance()));
}
}

public class SessionListener extends HttpSessionListener {
public void sessionCreated(HttpSessionEvent event) {
LOG.info("Session created, registering lock manager.");
Registry registry = (Registry)Registry.instance();
registry.setLockManager(
new SessionLockManager(event.getSession().getId(), LockManager.instance()));
}
...
}

And this is part of the ZKSessionRegistry:
...
public void setLockManager(SessionLockManager lockManager) {
LOG.debug("Set lock manager for session: " + Sessions.getCurrent(true));
Sessions.getCurrent(true).setAttribute(SES_ATT_LOCK_MANAGER, lockManager);
}

It turns out that in both cases, the servlet-API session listener and the ZK SessionInit, the ZK session does not exist at the time of firing the listener. Unfortunately, I could not find any hint (by keyword search) in the ZK documentation about the session lifecycle. Is there any listener which fires _after_ the session is created?

Regards and thanks beforehand,
David