public boolean isActive() {
        // Check if subscription is approved and configured (if required)
        if (state != State.subscribed) {
            return false;
        }
        // Check if the subscription has expired
        if (expire != null && new Date().after(expire)) {
            // TODO This checking does not replace the fact that we need to implement expiration.
            // TODO A thread that checks expired subscriptions and removes them is needed.
            return false;
        }
        return true;
    }
Returns true if the subscription is active. A subscription is considered active if it
has not expired, it has been approved and configured.

@return true if the subscription is active.
xmppserver/src/main/java/org/jivesoftware/openfire/pubsub/NodeSubscription.java