Deploy simple server code to Heroku

Question

I recently visited heroku.com site and tried to deploy my first java program there , I actually had a good start using their java deployment tutorial, and had it run ok. now I have a server code which I need to deploy there , I tried to follow the example but I had some question in mind like,

1- what will be the host in this case , I already tried the app link as if its the host but it throws errors ,

here is my sample server code

public class DateServer {

    /** Runs the server. */
    public static void main(String[] args) throws IOException {
        ServerSocket listener = new ServerSocket(6780);
        try {
            while (true) {
                Socket socket = listener.accept();
                try {
                    PrintWriter out = new PrintWriter(socket.getOutputStream(), true);
                    out.println(new Date().toString());
                } finally {
                    socket.close();
                }
            }
        } finally {
            listener.close();
        }
    }
}

here is my client code

public class DateClient {

    /** Runs the client as an application. First it displays a dialog box asking for the IP address or hostname of a host running the date server, then connects to it and displays the date that it serves. */
    public static void main(String[] args) throws IOException {
        //I used my serverAddress is my external ip address 
        Socket s = new Socket(serverAddress, 6780);
        BufferedReader input = new BufferedReader(new InputStreamReader(s.getInputStream()));
        String answer = input.readLine();
        JOptionPane.showMessageDialog(null, answer);
        System.exit(0);
    }
}

I followed this tutorial https://devcenter.heroku.com/articles/java at their site to upload my server code is there something else I need to do ?!

thanks in advance

ryanbrainard · Accepted Answer · 2013-05-16 06:02:14Z

6

On Heroku, your application must bind to the HTTP port provided in the $PORT environment variable. Given this, the two major problems in your application code above are 1) you are binding to a hardcoded port (6780) and 2) your application is using TCP instead of HTTP. As shown in the tutorial, use something like Jetty to accomplish the HTTP equivalent of your application and use System.getenv("PORT") to bind to the right port, like this:

import java.util.Date;
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.*;
import org.eclipse.jetty.server.Server;
import org.eclipse.jetty.servlet.*;

public class HelloWorld extends HttpServlet {

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp)
            throws ServletException, IOException {
        resp.getWriter().print(new Date().toString());
    }

    public static void main(String[] args) throws Exception{
        Server server = new Server(Integer.valueOf(System.getenv("PORT")));
        ServletContextHandler context = new ServletContextHandler(ServletContextHandler.SESSIONS);
        context.setContextPath("/");
        server.setHandler(context);
        context.addServlet(new ServletHolder(new HelloWorld()),"/*");
        server.start();
        server.join();   
    }
}

answered May 16, 2013 at 6:02

ryanbrainard

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2 Comments

Aamer Over a year ago

ok but will be the client code a normal http connection in this case?! this actually fairly simple example, what I am really doing is building multiplayer game where clients can connect to server and play so I am interested about ur client code after ur change in the server code thanks in advance ? please remember that I am intending to extend the code to support multiplayer so any help would be appreciated

ryanbrainard Over a year ago

Yes, your client would need to be using HTTP as well. Heroku applications can make outbound TCP connections (e.g. to a database), but all inbound connections need to be over HTTP. See info about Heroku HTTP routing for more details.

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