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POJava multithreaded server - each connection returns data. Processing on main thread?
 

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  1. POJava multithreaded server - each connection returns data. Processing on main thread?
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    <p>I am writing a client with an integrated server that should wait indefinitely for new connections - and handle each on a Thread.</p> <p>I want to process the received byte array in a system wide available message handler <strong>on the main thread</strong>. However, currently the processing is obviously done on the client thread.</p> <p>I've looked at Futures, submit() of ExecutorService, but as I create my Client-Connections within the Server, the data would be returned to the Server thread. How can I return it from there onto the main thread (in a synchronized packet store maybe?) to process it without blocking the server?</p> <p>My current implementation looks like this:</p> <pre><code> public class Server extends Thread { private int port; private ExecutorService threadPool; public Server(int port) { this.port = port; // 50 simultaneous connections threadPool = Executors.newFixedThreadPool(50); } public void run() { try{ ServerSocket listener = new ServerSocket(this.port); System.out.println("Listening on Port " + this.port); Socket connection; while(true){ try { connection = listener.accept(); System.out.println("Accepted client " + connection.getInetAddress()); connection.setSoTimeout(4000); ClientHandler conn_c= new ClientHandler(connection); threadPool.execute(conn_c); } catch (IOException e) { System.out.println("IOException on connection: " + e); } } } catch (IOException e) { System.out.println("IOException on socket listen: " + e); e.printStackTrace(); threadPool.shutdown(); } } } class ClientHandler implements Runnable { private Socket connection; ClientHandler(Socket connection) { this.connection=connection; } @Override public void run() { try { // Read data from the InputStream, buffered int count; byte[] buffer = new byte[8192]; InputStream is = connection.getInputStream(); ByteArrayOutputStream out = new ByteArrayOutputStream(); // While there is data in the stream, read it while ((count = is.read(buffer)) &gt; 0) { out.write(buffer, 0, count); } is.close(); out.close(); System.out.println("Disconnect client " + connection.getInetAddress()); connection.close(); // handle the received data MessageHandler.handle(out.toByteArray()); } catch (IOException e) { System.out.println("IOException on socket read: " + e); e.printStackTrace(); } return; } } </code></pre> <p><strong>Update:</strong> The robust way seems to be what TomTom suggested - using the newer java.nio instead. As this project is of limited use and more of an experiment, I'd like to know the best way using it with java.io/java.net :)</p>
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    1. COSo why exactly would you want to process these on main thread? NIO does allow you to do non-blocking processing (and libraries like Netty make it easier to use), but is there specific reason to avoid multi-threaded approach?
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    2. COEach of these incoming messages might produce new outgoing connections and thus, new incoming connections on this server and I would like to avoid running everything after message capture in new threads
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