Strainu onLine

The most common way to make a server in Java is to create a thread pool and associate each request with a thread. Java5 offers a special class called Executor that can help you with the task. However, if you ever needed to make a server which can handle thousands of connections, you know this solution doesn’t scale very well. Most processors can’t handle more than a few hundreds of threads.
The solution is to use non-blocking sockets, a feature introduced in java 1.4 (the java.nio package). However, this has an important drawback: you can’t use the getInputStream(), getOutputStream() functions from the Socket class to serialize objects. The reason is simple: with non-blocking sockets, there is no way the system can guarantee that the whole object has been sent/received.
You can however „trick” the virtual machine by using explicit Streams. You have a simple example below. We try to send an object with the Message type.

• The sending end
  
Message outgoingMessage;
SocketChannel socketChannel;
//we open the channel and connect
ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
ObjectOutputStream objectOutputStream = new ObjectOutputStream(byteArrayOutputStream);
objectOutputStream.writeObject(outgoingMessage);
objectOutputStream.flush();
socketChannel.write(ByteBuffer.wrap(byteArrayOutputStream.toByteArray()));

• The receiving end
  
SocketChannel socketChannel;
ByteBuffer data;
//we open the channel and connect
socketChannel.read(data);
ByteArrayInputStream byteArrayInputStream = new ByteArrayInputStream(data.array());
ObjectInputStream objectInputStream = new ObjectInputStream(byteArrayInputStream);
Message message = (Message)objectInputStream.readObject();


The code works if you receive the whole object or more than one object (the readObject() function reads exactly one object). However, I had some issues with reconstructing the object if it arrived in multiple pieces. Any suggestions on that part would be useful.
Here are some resources that I found useful: a discussion at forum.java.sun.com and another discution about the subject.