Problem serializing and unSerializing.

Question

Hello,
I am experiencing some problems with a client/server application I am writing.
After I open a Socket the server application has to send to the client a comment and an object in certain time intervals.
Here is the code on the server side:
    class Client {
         Socket client;
         BufferedReader in;
     PrintStream out;
         public Client (Socket client){
              this.client = client;
              System.out.println("New Connection: " + client.getInetAddress() + ":" + client.getPort());
              try{
                   in = new BufferedReader(new InputStreamReader(client.getInputStream()));
                   out = new PrintStream(client.getOutputStream(),true);
              } catch(IOException e){
                   System.out.println(e.getMessage());
         public boolean send(Object obj,String name){
              try{
                   System.out.println("Sending Obj: " + name);
                   out.println("Sending\t"+obj.getClass().getName()+"\t"+name);
                   ObjectOutputStream outS = new ObjectOutputStream(client.getOutputStream());
                   outS.writeObject(obj);
                   outS.flush();
                   System.out.println("obj sent");
              } catch(Exception e){
                        System.out.println("Error Sending Obj: " + e.getMessage());
                        return false;
              return true;
}and here is the code on the client side:
     private void connect (String IP,int Port){
          try {
               ss = new Socket();
               ss.bind(null);
               ss.setSoTimeout(10000);
               ss.connect(new InetSocketAddress(IP,Port));
          in = new BufferedReader(new InputStreamReader(ss.getInputStream()));
              out = new PrintStream(ss.getOutputStream(),true);
              inHandler = new inComing();
              inHandler.start();
          } catch (IOException e){
               System.out.println(e.getMessage());
     class inComing extends Thread {
          boolean running = true;
          ObjectInputStream oin;
          public void run(){
               String str;
               do {
                    try {
                         in = new BufferedReader(new InputStreamReader(ss.getInputStream()));
                         str = in.readLine();
                         System.out.println(str);
                         oin = new ObjectInputStream(ss.getInputStream());
                         Semaforo APP = (Semaforo)oin.readObject();
                         SEM.setStatus(APP.getStatus());
                         SEM.setPowerOn(APP.isPowerOn());
                         System.out.println("obj received");
                    }catch (Exception e) {
                         System.out.println(e.getMessage());
               } while(running);
}the output on the client side is for example:
Sending MyPackages.CElements.Semaforo Semaforo
obj received
Sending MyPackages.CElements.Semaforo Semaforo
obj received
Sending MyPackages.CElements.Semaforo Semaforo
obj received
Sending MyPackages.CElements.Semaforo Semaforo
obj received
Sending MyPackages.CElements.Semaforo Semaforo
obj received
Sending MyPackages.CElements.Semaforo Semaforo
obj received
Sending MyPackages.CElements.Semaforo Semaforo
obj received
Sending MyPackages.CElements.Semaforo Semaforo
invalid stream header: 7372001D
MyPackages.CElements.SemaforoxrJWindow;Lwt/Dialog$ModalExclusionType;Lsq~invalid stream header: 00000003
ardsqq�ntext;L.AbstractDocument$AbstractElement��x��7��QLapos���$�invalid stream header: 53656E64
ing MyPackages.CElements.Semaforo Semaforo
invalid stream header: 78000000
Ldrenqinvalid stream header: 7871007E
}�� header: 00740007
tabSizesrvax.swing.text.AbstractDocument$AbstractElement��x��7��erqsocket closed
So you can see it worked fine for some time and then there are some errors, it happens that after some time it starts working fine again.
I really can not understand what is wrong especially for this random behavior, I really can not predict when it works and when it will not.
Can someone help me?
Thanks
Carlo

Answer 1

I solved the problem not opening multiple streams over the same Socket, now the server will send the comments simply serializing a string object, this way it works fine and it is a more solid solution, I can not explain why I had such a insane idea!
Then I tried to do it in a clean way, creating the ObjectInput/outputStream only once when I start the Socket, but I am experiencing a strange problem.
Here is the code on the server side:
   class Client {
         Socket client;
         BufferedReader in;
          ObjectOutputStream outS;
         boolean running = true;
         int i = 0;
         public Client (Socket client){
              this.client = client;
              System.out.println("New Connection: " + client.getInetAddress() + ":" + client.getPort());
              try{
                   in = new BufferedReader(new InputStreamReader(client.getInputStream()));
                   outS = new ObjectOutputStream(client.getOutputStream());
              } catch(IOException e){
                   System.out.println(e.getMessage());
         public boolean send(Object obj,String name){
              try{
                   System.out.println("Sending Obj: " + name +"  " + i);
                   //ObjectOutputStream outS = new ObjectOutputStream(client.getOutputStream());
                   outS.writeObject("Sending\t"+obj.getClass().getName()+"\t"+name+"  " + i);
                   i++;
                   System.out.println("Status: " + ((Semaforo)obj).getStatus());
                   outS.writeObject(obj);
                   outS.flush();
                   System.out.println("obj sent");
              } catch(Exception e){
                        System.out.println("Error Sending Obj: " + e.getMessage());
                        return false;
              return true;
}And on the client side:
private void connect (String IP,int Port){
          try {
               ss = new Socket();
               ss.bind(null);
               ss.setSoTimeout(10000);
               ss.connect(new InetSocketAddress(IP,Port));
              out = new PrintStream(ss.getOutputStream(),true);
              inHandler = new inComing();
              inHandler.start();
          } catch (IOException e){
               System.out.println(e.getMessage());
     class inComing extends Thread {
          boolean running = true;
          ObjectInputStream oin;
          BufferedReader in;
          String str;
          Semaforo APP;
          Object obj;
          public inComing(){
               try {
                    oin = new ObjectInputStream(ss.getInputStream());
               } catch (IOException e){
                    System.out.println(e.getMessage());
          public void run(){
               obj = new Object();
               do {
                    try {
                         //oin = new ObjectInputStream(ss.getInputStream());
                         obj = oin.readObject();
                         System.out.println("recived new Obj: " + obj.getClass().getName());
                         System.out.println((String)obj);
                         obj = oin.readObject();
                         System.out.println("recived new Obj: " + obj.getClass().getName());
                         System.out.println("Status: " + ((Semaforo)obj).getStatus());
                         System.out.println("obj received");
                    }catch (Exception e) {
                         System.out.println("read error: " + e.getMessage());
               } while(running);
}The output on the srver side is:
Pronto a ricevere connessioni
New Connection: /127.0.0.1:4932
Pronto a ricevere connessioni
Sending Obj: Semaforo 0
Status: 2
obj sent
Sending Obj: Semaforo 1
Status: 1
obj sent
Sending Obj: Semaforo 2
Status: 0
obj sent
Sending Obj: Semaforo 3
Status: 1
obj sent
on the Client side the output is:
recived new Obj: java.lang.String
Sending MyPackages.CElements.Semaforo Semaforo 0
recived new Obj: MyPackages.CElements.Semaforo
Status: 2
obj received
recived new Obj: java.lang.String
Sending MyPackages.CElements.Semaforo Semaforo 1
recived new Obj: MyPackages.CElements.Semaforo
Status: 2
obj received
recived new Obj: java.lang.String
Sending MyPackages.CElements.Semaforo Semaforo 2
recived new Obj: MyPackages.CElements.Semaforo
Status: 2
obj received
recived new Obj: java.lang.String
Sending MyPackages.CElements.Semaforo Semaforo 3
recived new Obj: MyPackages.CElements.Semaforo
Status: 2
obj received
The strange thing is that it updates correctly the sting object, but it updates the Semaforo object only the first time, after the status does not change, If I create a new ObjectOutput/InputStream every time it works.
Do you have any idea?
Thanks
Carlo