CODEWITHSUNDEEP
javasocketstcpclient-server
user3717434
user3717434

Reputation: 225

Java TCP Connection From Server through Client

How can a Server open a TCP connection through a Client which was connected to server before? Let say we have simple server like the code shows below; server waits for client connections and a handler thread serves connected clients. Client as below, every time wants to do an operation with the server, reestablish the connection, communicate with server and then close the connection. So, if server would like to open a TCP connection through the client(when there is no an active connection from client to server), how it can be done?

Server Code

public class DServer {
    public static void main(String[] args) {
        ServerSocket serverSocket = new ServerSocket(7800);
        while(true) {
            Socket socket = serverSocket.accept();
            System.out.println("Server established a new connection");
            HandleConnection handler = new HandleConnection(socket);
            handler.start();
        }
    }
}

Client Code

public class DClient{
    public static void main(String[] args) {
        Socket socket = new Socket("localhost", 7800);
        ObjectOutputStream out = new ObjectOutputStream(socket.getOutputStream());
        ObjectInputStream in = new ObjectInputStream(socket.getInputStream());

        //for every operation you do, first reestablish the connection,
        //communicate with server, then close the connection.

    }
}

Upvotes: 0

Views: 760

Answers (2)

Vinod Kumawat
Vinod Kumawat

Reputation: 741

There is solution to create proxy server which is manage the both request client and server which called middleware for both client request. In network programming it must required to fist server start and then client request because client server architecture.

Upvotes: 0

Aurand
Aurand

Reputation: 5547

I think you have some fundamental misunderstandings about what a client is and what a server is in a networking sense.

The server is the application listening for connections. The client is the application creating connections to the server. If you want both of your applications to be able to initiate communication at will, then your applications will need to be both clients and servers.

So your "DClient" application will need to have a ServerSocket. You "DClient" application can then inform your "DServer" application of it's host and port for when "DServer" wants to create a connection (note that things like NATing can make this sort of thing problematic if both applications are not in the same network).

Alternately, depending on your use case, you could just leave the connection from client to server open. This is the more usual approach to letting the server push data.

Upvotes: 1

Related Questions