Alive check thread when reading from socket

[Michal Glowacki]

I have an application that connects to remote socket and waits for xml messages. I need also to check if the time between those messages is not bigger than x seconds. I never wrote threaded application in java, could anyone help me? I am even more confused because of socket reading. Not sure how can I pause it and switch the thread. This is code snippet:

    
private void run() {		
		while(true) {			
			try {
				readMessages();
			} catch (Exception e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}			
		}
}

private void readMessages() throws Exception {
		BufferedReader br = new BufferedReader(
				new InputStreamReader(socket.getInputStream()));
	    String line = null;
	    StringBuffer buf = new StringBuffer();
		while ((line = br.readLine()) != null && br.ready()) {			
			buf.append(line);
		}
		System.out.println(buf);
		processMessage(buf.toString());
}

[Ulf Dittmer]

For an introduction to Java sockets see http://java.sun.com/docs/books/tutorial/networking/sockets/index.html. It contains a working client/server pair.

Also read Don't println to a Socket; it looks as if the code you posted is susceptible to that problem.

[Michal Glowacki]

Ulf Dittmer wrote:For an introduction to Java sockets see http://java.sun.com/docs/books/tutorial/networking/sockets/index.html. It contains a working client/server pair.

Also read Don't println to a Socket; it looks as if the code you posted is susceptible to that problem.

I am sorry Ulf but I don't know how it applies to my question/problem. I am wondering, how to swap to check-alive-thread when awaiting an input from server socket. So, my app is continously awaiting data from socket, but another thread should make a check fx each second if the waiting time not exceeded x seconds.

[Nitesh Kant]

Michal Glowacki wrote:I am wondering, how to swap to check-alive-thread when awaiting an input from server socket. So, my app is continously awaiting data from socket, but another thread should make a check fx each second if the waiting time not exceeded x seconds.

There is no need for swaping the thread reading the data. All it needs to do is have a state variable (volatile) that tells whether it has received any data or not.
As soon as you start reading start a Timer (simplest approach) which checks for the state variable every "x" minutes [Every X minutes if you want to keep the socket reader alive forever and it should get something every x seconds]. If the state variable says that the data is not received the interrupt the reader thread or inform the admin, as your application demands.

[Michal Glowacki]

Thanks Nitesh, this is what I needed!