如何实现 2 个不同的服务器，它们由具有相同 object 的客户端调用

Question

Hy, i´m doing some exercises, heres the background to know. imagine you are a travel agency

-you have to search for the cheapest flight for your customers

-they tell you how many miles they gone flight

-which area they wanna sit, default - business - firstclass.

travel agency is the client

and there are 2 airlines where we can choose.

this 2 airlines airline1: dreamLine (Server1), cloudLine(Server2),

this servers get a request via commandline/client and calculate their value and return it to the client. just for example server1 should return 200€ and server 2 should return 600 €, calculation isnt the problem more how 2 servers can work sequential or simultaniously

my problem here is i dont know where i should start by separating the servers. i have implemented already both servers but i get some errors, because i need to make a queue or implement a further Handler which tells which server should start or which server should end first or do anything. i tried it already with just one server, this works, but 2 idk i think they issue is this that there are 2 sockets opened and this isnt allowed but i didnt found any info for a client which sends a request to 2 different servers, just the other way, many clients to one server, but this isnt what im searchin for

would be great if u can tell me what i should search for, when i wanna work with n servers and just 1 client

got already various errors once -Address already in use: JVM_Bind more -server timed out and so on

here my test classes client:

public class Client {

public static void main(String[] args) throws UnknownHostException, IOException {
    int number, temp, temp1, more;
    Scanner sc = new Scanner(System.in);
    Socket s = new Socket("localhost", 1342);
    Scanner sc1 = new Scanner(s.getInputStream());

    System.out.println("enter any number");

    number = sc.nextInt();
    PrintStream p = new PrintStream(s.getOutputStream());
    p.println(number);
    temp = sc1.nextInt();
    System.out.println(temp);
    sc.close();
    s.close();
    sc1.close();
    p.close();


    Scanner sc2 = new Scanner(System.in);
    Socket s2 = new Socket("localhost", 1343);
    Scanner sc3 = new Scanner(s.getInputStream());

    System.out.println("enter any number");

    number = sc.nextInt();
    PrintStream p1 = new PrintStream(s2.getOutputStream());
    p1.println(number);
    more = sc3.nextInt();
    System.out.println(temp);

    System.out.println(temp+ " " +more);
}

}

server 1:

public class Server {

public static void main(String[] args) throws IOException {
    int number;
    int temp;
    ServerSocket s1 = new ServerSocket(1342);
    Socket ss = s1.accept();
    Scanner sc = new Scanner(ss.getInputStream());
    number = sc.nextInt();
    temp = number*2;
    PrintStream p = new PrintStream(ss.getOutputStream());
    p.println(temp);
}

}

server2:

public class Server2 {

public static void main(String[] args) throws IOException {
    int number;
    int temp;
    ServerSocket s1 = new ServerSocket(1343);
    Socket ss = s1.accept();
    Scanner sc = new Scanner(ss.getInputStream());
    number = sc.nextInt();
    temp = number*10;
    PrintStream p = new PrintStream(ss.getOutputStream());
    p.println(temp);
}

}

cant find the error what i miss

Answer 1

You can use one socket client to connect to multiple servers with a procedure like this:

1. Connect to server1 with ip address : port <> (open) .
2. Request data to server1 >> (write) .
3. Wait response from server1 << (read) .
4. disconnect from server1 <> (close) .

Repeat the steps above for the server2. Remember: You must close the connection to server1, before using the same socket client for server2.

Answer 2

free for all client server example with 2 servers and only 1 client: before u run the client, u have to run the servers first than u can start with the client

public class Client {

public static void main(String[] args) throws UnknownHostException, IOException, InterruptedException {
    int number, temp, temp1, more;
    Scanner sc = new Scanner(System.in);
    Socket s = new Socket("localhost", 1342);
    Scanner sc1 = new Scanner(s.getInputStream());

    System.out.println("enter any number");

    number = sc.nextInt();
    PrintStream p = new PrintStream(s.getOutputStream());
    p.println(number);
    temp = sc1.nextInt();
    System.out.println(temp);
    s.close();
    System.out.println("Server 1 closed!");

    Scanner scc = new Scanner(System.in);
    s = new Socket("localhost", 2555);
    Scanner sc2 = new Scanner(s.getInputStream());

    System.out.println("enter any number");

    number = scc.nextInt();
    p = new PrintStream(s.getOutputStream());
    p.println(number);
    more = sc2.nextInt();
    System.out.println(more);

    System.out.println(temp+ " " +more);
}

}

public class Server {

public static void main(String[] args) throws IOException {
    int number;
    int temp;
    ServerSocket s1 = new ServerSocket(1342);
    Socket ss = s1.accept();
    Scanner sc = new Scanner(ss.getInputStream());
    number = sc.nextInt();
    temp = number*2;
    PrintStream p = new PrintStream(ss.getOutputStream());
    p.println(temp);
}

}

public class Server2 {

public static void main(String[] args) throws IOException {
    int number;
    int temp;
    ServerSocket s1 = new ServerSocket(2555);
    Socket ss = s1.accept();
    Scanner sc = new Scanner(ss.getInputStream());
    number = sc.nextInt();
    temp = number*10;
    PrintStream p = new PrintStream(ss.getOutputStream());
    p.println(temp);
}

}