How to generate a new rhread for every request

Question

Hello,
I'm trying to write a server side program that does the following, recieves a Single connection from a client, client sends a request to the server side program, the server side program sends to a third party(back end) and waits for a reply.
The problem i am facing is the following, I want to for each message(request) recieved from the Client to generate a new thread and establish a new connection with the third party, I have tried creating a new thread for the communication with the third party, in this case if the response from backend takes time I will still be able to recieve other requests from the client. But I dont know how to return the message that his been to the Father thread. The reason why I am doing this is that I dont want the same thread that recieves the request from client to wait until the reply for the previous thread is sent.
Here's the code which I have been trying to implement.
ClientCommunicator {
Socket soc= new Socket(IPAddress,port);
Thread backEndComm= new Thread (new BackEndCommunicator
(soc,"Message To Back End"));
backEndComm.setPriority(8);
backEndComm.start();
public class BackEndCommunicator implements Runnable
Socket socket;
String messageToBeSentToBE= "";
public BackEndCommunicator(Socket socket, String messageTOBE)
this.socket= socket;
messageToBeSentToBE= messageTOBE;
public void run()
PrintWriter outtBackEnd= null;
BufferedReader innBackEnd= null;
String replyFromBE= "";
try
outtBackEnd= new PrintWriter(new OutputStreamWriter(socket.getOutputStream()));
outtBackEnd.println(messageToBeSentToBE);
outtBackEnd.flush();
innBackEnd= new BufferedReader(new InputStreamReader(socket.getInputStream()));
replyFromBE= innBackEnd.readLine();
How can I return the String "replyFromBE" to the ClientCommunicator class so it can be sent to the client as soon as recieved from the back end.
regards,
[email protected]

Answer 1

I assume the problem you are having is that your ClientCommunicator thread is blocking in a read and has no way of receiving notification from the other thread. Seems like you have a couple options at least.
1. Use non-blocking IO and a selector to do service both the client socket and the backend socket. Usually, NIO is more of a pain than it is worth unless you need to service hundreds of connections at once, but I think that in this case where you know that there are only two connections it might be easy enough to use.
2. A second option would be to avoid blocking on the read by using the available method on the input stream to first determine if you can actually read anything. This would allow you to wait with a small timeout on a monitor that the backend communicator could notify when it receives a response. This is not the ideal solution because you are limiting how fast you respond to the client and could be using more cpu time than necessary. However, it might be a lot easier to implement and could be adequate for what you need.
First solution is more elegant but potentially not worth the trouble. Second solution is less elegant, but may be good enough.