How determinate that a browser stopped

[Rogatkin, Dmitry M]

We develop a chat servlet. The servlet is invoked by a chat applet and uses standard request/response input and output streams to communicate with applet, so until a chat is active, the servlet doesn't return. But if a browser stops the applet, or a browser crashed, the servlet has no idea what happened and can continue sending data. No any exception happens. Some trick was found, like an attempt to read something from the applet (in such case) can rise an exception, but it looks like a hacker's approach. Does somebody know better solution?   Dmitry.