PHP tcp connection to Java server hangs on socket_read()

Question

I'm trying to create a PHP client to connect to a simple java server, send some data, and receive a response back. The java server responds fine when interacting with a simple client coded in Java, but once a request is sent from a PHP client it hangs indefinitely when socket_read() is called. If this line is commented out the data arrives just fine, but when its not it doesnt seem as though the Java server receives the data at all. This is very similar to this previously asked question: Simple Java TCP Server and PHP Client Problems but as far as I can tell my code is nearly identical in operation to the solution given.

The java server is multithreaded, that is for other parts of the program and I dont beleive that is causing the issue. The php script has a UI hooked into it for testing. Anyone know whats going on?

Java Server:

    import java.io.*;
    import java.net.*;
    import java.lang.*;

    class TCPRelayServer
    {
        String clientSentence;
        String responseString;
        ServerSocket socket;
        Socket connection;

       public void TCPRelayServer() throws Exception{
             System.out.println("Created Relay");
        }

        public void run() throws Exception{            
                clientSentence = "";
                responseString = "";
                // Open socket to all localhost connections on port
                socket = new ServerSocket(9090, 100, InetAddress.getByName(null));
                socket.setSoTimeout(5000);

             while(true)
             {
                try{
                    System.out.println("**Relay Server**  Relay Server Waiting");

                    // Setup buffers and connection
                    connection = socket.accept();
                    InputStreamReader inputStream = new InputStreamReader(connection.getInputStream());
                    BufferedReader input = new BufferedReader(inputStream);
                    DataOutputStream response = new DataOutputStream(connection.getOutputStream());

                    // Get server input
                    clientSentence = input.readLine();
                    System.out.println("**Relay Server**  Received: " + clientSentence);

                    // Perform logic
                    responseString = clientSentence.toUpperCase() + "
";

                    // send response
                    response.writeBytes("IT WORKED!
");
                    response.flush();
                    response.close();

                }
                catch(Exception e){
                    continue;
                }
             }
        }
    }

    class Relay implements Runnable {

        Thread runner;
        public Relay() {
        }
        public Relay(String threadName) {
            runner = new Thread(this, threadName); // (1) Create a new thread.
            System.out.println(runner.getName());
            runner.start(); // (2) Start the thread.
        }
        public void run(){
            //Display info about this particular thread
            System.out.println("Thread Started: " + Thread.currentThread());

            TCPRelayServer relay = new TCPRelayServer();
            try{
                relay.run();
            }
            catch(Exception e){
                System.out.println("Relay Server Failed to Run");
                return;
            }
        }
    }

    public class Triplestore {

        public static void main(String[] args) {
            Relay RELAY = new Relay("Relay");
            //Server SERVER = new Server("Server");
            //Client CLIENT = new Client("Client");

            //Display info about the main thread
            System.out.println("Main Thread: " + Thread.currentThread());

            while(true){

            }
        }
    }

PHP Client:


    
    


    
    
        
            Port Number: 
            


            Message: 
            

            
        

             
           
    FAILED Reason: socket_create() - " . socket_strerror(socket_last_error()) . "
";
                } else {
                    echo "
   OK
";
                }

                // Connect to address on port
                echo "Connecting to '$address' on port '$service_port'...";
                $connect = @socket_connect($socket, $address, $port);
                if ($connect === false) {
                    echo "
   FAILED 
   Reason: socket_connect() - " . socket_strerror(socket_last_error($socket)) . "
";
                } else {
                    echo "
   OK
";
                }


                // Send Message
                echo "Sending message...";
                $sent = @socket_sendto($socket, $message, strlen($message), MSG_EOF, $address, $port);
                if ($sent === false) {
                    echo "
   FAILED
   Reason: socket_write() - " . socket_strerror(socket_last_error($socket)) . "
";
                } else {
                    echo "
   OK
";
                }

                // Read Response
                echo "Reading response...
";

                //$line = socket_read($socket, 1024, PHP_NORMAL_READ);
                //$output .= $line;


                while($next = socket_read($socket, 4096, PHP_NORMAL_READ)){
                    $output .= $str;
                    if($next == "" || strpos($output,"
") !== false)
                        break;
                }

                echo 'Output: ' . $output;
                if ($output === false) {
                    echo "
   FAILED 
   Reason: socket_read() - " . socket_strerror(socket_last_error($socket)) . "
";
                } else {
                    echo "   " . $output . "
";
                }

                // Close Socket
                echo "Closing socket...";
                socket_close($socket);
                echo "
   OK
";
            }
            else{
                echo "Please enter a port number and message.
";
            }
        ?>

goat · Accepted Answer

you use readline() in java, which blocks until it finds a new line. I don't think you ever send a new line terminated string in your php code. So, both your java and php code should be blocking indefinitely.

PHP tcp connection to Java server hangs on socket_read()

Answers (1)

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