<p>I'm new to Spring Security. How do I add an event listener which will be called as a user logs in successfully? Also I need to get some kind of unique session ID in this listener which should be available further on. I need this ID to synchronize with another server.</p>

You need to define a Spring Bean which implements
ApplicationListener
.
Then, in your code, do something like this:
```
```
public void onApplicationEvent(ApplicationEvent appEvent)
{
    if (appEvent instanceof AuthenticationSuccessEvent)
    {
        AuthenticationSuccessEvent event = (AuthenticationSuccessEvent) appEvent;
        UserDetails userDetails = (UserDetails) event.getAuthentication().getPrincipal();

        // ....
    }
}
```
```
Then, in your applicationContext.xml file, just define that bean and it will automatically start receiving events :)