[TOREVIEW] PROTOCOL written + Code for Client and Server

specs/jlheig/Code/Client/Client.iml

@@ -0,0 +1,11 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<module type="JAVA_MODULE" version="4">
+  <component name="NewModuleRootManager" inherit-compiler-output="true">
+    <exclude-output />
+    <content url="file://$MODULE_DIR$">
+      <sourceFolder url="file://$MODULE_DIR$/src" isTestSource="false" />
+    </content>
+    <orderEntry type="inheritedJdk" />
+    <orderEntry type="sourceFolder" forTests="false" />
+  </component>
+</module>

specs/jlheig/Code/Client/src/Client.java

@@ -0,0 +1,92 @@
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.io.PrintWriter;
+import java.net.Socket;
+import java.util.Scanner;
+import java.util.logging.Level;
+import java.util.logging.Logger;
+
+public class Client {
+    public static void main(String[] args) throws IOException {
+        Client client = new Client();
+        Scanner scan = new Scanner(System.in);
+
+        if(args.length == 0){
+            System.out.println("Error, we need 1 argument to serve as the server adress");
+            return;
+        }
+
+        String server = args[0];
+        client.connect(server, PORT);
+        boolean stayConnected = true;
+        String input;
+        do{
+            input = scan.nextLine();
+
+            if(input.compareTo(QUIT) == 0){
+                stayConnected = false;
+            }
+
+            client.writer.println(input);
+            client.writer.flush();
+
+        }while(stayConnected);
+
+        client.disconnect();
+    }
+
+    private static String QUIT = "QUIT";
+    private static int PORT = 3334;
+
+    private Logger logger = Logger.getLogger(Client.class.getName());
+
+    Socket clientSocket;
+    PrintWriter writer;
+    BufferedReader reader;
+    boolean isConnected = false;
+
+    public void connect(String server, int port) throws IOException{
+        try{
+            clientSocket = new Socket(server, port);
+            writer = new PrintWriter(clientSocket.getOutputStream());
+            reader = new BufferedReader(new InputStreamReader(clientSocket.getInputStream()));
+            isConnected = true;
+        }
+        catch (IOException e){
+            logger.log(Level.SEVERE, "Impossible to connect to the server", e.getMessage());
+        }
+
+        new Thread(new listener()).start();
+    }
+
+    public void disconnect() throws IOException {
+        try {
+            if (isConnected) {
+                logger.log(Level.INFO, "Client wants to quit");
+                isConnected = false;
+                writer.close();
+                reader.close();
+                clientSocket.close();
+            }
+        }
+        catch (IOException e){
+            logger.log(Level.SEVERE, "Error while disconnecting", e.getMessage());
+        }
+    }
+
+    class listener implements Runnable {
+        public void run(){
+            String resp;
+            try{
+                while((isConnected && (resp = reader.readLine()) != null)){
+                    System.out.println(resp);
+                }
+            }
+            catch (IOException e){
+                logger.log(Level.SEVERE, "Error while listening", e.getMessage());
+                isConnected = false;
+            }
+        }
+    }
+}

specs/jlheig/Code/Server/Server.iml

@@ -0,0 +1,11 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<module type="JAVA_MODULE" version="4">
+  <component name="NewModuleRootManager" inherit-compiler-output="true">
+    <exclude-output />
+    <content url="file://$MODULE_DIR$">
+      <sourceFolder url="file://$MODULE_DIR$/src" isTestSource="false" />
+    </content>
+    <orderEntry type="inheritedJdk" />
+    <orderEntry type="sourceFolder" forTests="false" />
+  </component>
+</module>

specs/jlheig/Code/Server/src/Server.java

@@ -0,0 +1,111 @@
+import java.io.*;
+import java.net.*;
+
+public class Server {
+    public static void main(String[] args) throws IOException {
+        Server server = new Server();
+        while (true){
+            server.waitForClients();
+        }
+    }
+
+    private static String HELP = "HELP";
+    private static String QUIT = "QUIT";
+    private static int PORT = 3334;
+
+    private static String ADD = "ADD";
+    private static String SUB = "SUB";
+    private static String MULT = "MULT";
+    private static String DIV = "DIV";
+
+    public void waitForClients() throws IOException {
+        ServerSocket server = new ServerSocket(PORT);
+        Socket calculator = server.accept();
+
+        SocketAddress address = calculator.getRemoteSocketAddress();
+
+        if(address instanceof InetSocketAddress){
+            InetAddress addressInet = ((InetSocketAddress)address).getAddress();
+            if(addressInet instanceof Inet4Address){
+                System.out.println("Listening in IPV4 at : " + addressInet + " Port : " + PORT);
+            }
+            else if(addressInet instanceof Inet6Address){
+                System.out.println("Listening in IPV6 at : " + addressInet + " Port : " + PORT);
+            }
+            else{
+                System.err.println("Wrong IP address");
+            }
+        }
+        else{
+            System.err.println("Wrong internet protocol socket");
+        }
+
+        PrintWriter writer = new PrintWriter(new OutputStreamWriter(calculator.getOutputStream()));
+        BufferedReader reader = new BufferedReader(new InputStreamReader(calculator.getInputStream()));
+
+        writer.println("Hello, please enter the calculation you want to do : ");
+        writer.flush();
+
+        String input = reader.readLine();
+        while(input != null){
+            String[] inputSplitted = input.split(" ");
+
+            if(inputSplitted.length == 1){
+                String command = inputSplitted[0];
+                if(command.compareTo(HELP) == 0){
+                    writer.println("Supported operations : ADD, SUB, MULT, DIV");
+                    writer.println("All operations require only 2 arguments");
+                    writer.println("If you want to quit use command QUIT");
+                }
+                else if(command.compareTo(QUIT) == 0){
+                    writer.println("Closing the connection...");
+                    reader.close();
+                    writer.close();
+                    calculator.close();
+                    server.close();
+                    return;
+                }
+                else{
+                    writer.println("Error, unsupported command, please use HELP");
+                }
+            }
+            else if(inputSplitted.length == 3){
+                String operation = inputSplitted[0];
+                int n1 = Integer.parseInt(inputSplitted[1]);
+                int n2 = Integer.parseInt(inputSplitted[2]);
+
+                if(operation.compareTo(ADD) == 0){
+                    writer.println("Result : " + (n1 + n2));
+                }
+                else if(operation.compareTo(SUB) == 0){
+                    writer.println("Result : " + (n1 - n2));
+                }
+                else if(operation.compareTo(MULT) == 0){
+                    writer.println("Result : " + (n1 * n2));
+                }
+                else if(operation.compareTo(DIV) == 0){
+                    try {
+                        writer.println("Result : " + (n1 / n2));
+                    }
+                    catch (ArithmeticException e){
+                        writer.println("Error, " + e.getMessage() + " please enter a valid divide operation");
+                    }
+                }
+                else{
+                    writer.println("Error, unsupported operation, please use HELP");
+                }
+            }
+            else{
+                writer.println("Error, wrong number of arguments, please use HELP");
+            }
+            writer.flush();
+            input = reader.readLine();
+        }
+
+        reader.close();
+        writer.close();
+        calculator.close();
+        server.close();
+
+    }
+}

specs/jlheig/PROTOCOL.md

@@ -0,0 +1,55 @@
+# RES - Exercise-protocol-Design 2021
+
+Authors : Jean-Luc Blanc
+
+Date : 31.03.2021
+
+------
+
+### What transport protocol do we use?
+
+TCP/IP, most used and popular one. It is also the default one with Java sockets.
+
+### How does the client find the server?
+
+When you start a server, it shows the port its listening to. So the client simply has to connect to that port through the right ip adress.
+
+### Who speaks first?
+
+There are no right or wrongs, but usually clients speak first, this therefor allows the server to decide to accept or not the connection of the client
+
+### What is the sequence of messages exchanged by the client and the server?
+
+1. Server listens to a port
+2. Client try connecting to the server
+3. Server accepts
+4. Server is waiting for a calculation
+5. Client sends one
+6. Server receives it and compute it
+7. Server sends an answer to the client
+8. Client receives it
+9. Client can either ask a new calculation or simply disconnect
+
+### What happens when a message is received from the other party?
+
+Depends on what message was send : 
+* if the message sent is an invalid command, we send an error message
+* if the message is a valid command then we simply send the answer to the calculation
+
+### What is the syntax of the messages? How do we generate and parse them?
+
+That's an arbitrary choice, I would go for that : 
+* add n1 n2
+* sub n1 n2
+* mult n1 n2
+* div n1 n2
+
+Most basic operations can be decomposed in this form : 
+* operation
+* number on the left
+* number on the right
+
+### Who closes the connection and when?
+
+The client decides when to close the connection
+