[java] Java and Sockets

Quote:

Original post by jolyqr I'm quite new in Java. What do you mean by "serializable "? Indeed I have met this word lots of time, but I have never got its meaning...

Quote:

Original post by Son of Cain Yes, a class that implements the java.io.Serializable interfaced can be serialized and sent through a stream of bytes. The ObjectInputStream is used to read Objects from a stream, while the ObjectOutputStream is the counterpart, used to write them. Any property declared with the keyword "transient" in the Serializable class is not considered for serialization. RMI - Remote Method Invocation - uses this concept to serve Remote Objects for the applications' clients. I must remind you that serialization and de-serialization is an expensive operation; beware on how you use it, and for what you use it. You can always encapsulate data into datagrams, or even better, into NIO's ByteBuffer instances, and use asynchronous communication for maximum performance. Son Of Cain

Quote:

Original post by rip-off Yet another disclamier from me, but shouldnt you be able to wrap the input/output streams of the socket in ObjectInputStream and ObjectOutputStreams ? Something like *** Source Snippet Removed *** The Objects you send might have to be serializable or something, my java is a bit rusty...

Quote:

Original post by jolyqr Could you tell me more about the last concepts?

public interface NetworkCommand extends java.io.Serializable {}

public class BasicCommand implements NetworkCommand {    // These attributes won't be sent to the stream (serialized)  private transient Object localCopyOfObject;  private static transient int count = 0;  private int order;  private String command;    // ...}

Socket socket;ObjectInputStream ois = new ObjectInputStream( socket.getInputStream() );ObjectOutputStream oos = new ObjectOutputStream( socket.getOutputStream() );// These methods block while reading/writting data, so you better put them in their own threadsois.readObject();oos.writeObject(new BasicCommand());

public class NetworkInputHandler implements Runnable {    private Socket socket;  private boolean running;  private Queue < NetworkCommand > commands;  public NetworkHandler(Socket s) {    this.socket = s;    running = true;  }    public void run() {    ObjectInputStream ois = new ObjectInputStream(socket.getInputStream());    while ( running ) {      Object input = ois.readObject();            // process object and put it into queue      // ...    }  }  }

Quote:

Original post by jolyqr basically, when i'm trying to send an object, i've got the following excepttion java.io.NotSerializableException: org.unisoft.client.Table the type of the object i would like to send is Table. The client and the server have got a copy of that class.

Quote:

Original post by rip-off Quote: Original post by jolyqr basically, when i'm trying to send an object, i've got the following excepttion java.io.NotSerializableException: org.unisoft.client.Table the type of the object i would like to send is Table. The client and the server have got a copy of that class. If you look at the most important line of that exception information (the first one ), it says "java.io.NotSerializableException: org.unisoft.client.Table" This means the class "Table" is "NotSerializable", so you cannot send it via the methods I described. I don't use java often enough to give a detailed work-around, but you need to copy all the important data from the Table object into a class you define and send that. Another problem here is that Table sounds like quite a large, complex object. Perhaps you could allow the client to send a command specifying exactly the data it wants from the table, and send only that data instead of the entire object.