The name request should repeated until the message type of the response is equal to MessageType.USER_NAME.

Question about the task

Chat (part 8)

Java Multithreading, Level 6, Lesson 15

Resolved

This just seems to be a small thing, but I can't get it validated. I already tried several different writings:

boolean isUserName = request.getType() == (MessageType.USER_NAME);
boolean isUserName = request.getType() == (MessageType.USER_NAME) ? true : false;
boolean isUserName = request.getType().equals (MessageType.USER_NAME) ? true : false;

What exactly is the validator looking for?

The Handler class must implement the client communication protocol.
Let's identify independent stages of the protocol and implement them in separate methods:
The first stage is the handshake (in which the server meets the client).
We'll implement it in the private String method serverHandshake(Connection connection) throws IOException,
ClassNotFoundException method. The method takes a connection as an argument, and returns the name of the new client.

The implementation should:
1) Generate and send a username request
2) Get the client's response
3) Verify that the response has a username
4) Extract the name from the response, and verify that it is not empty and is not already being used (use connectionMap)
5) Add the new user and connection to connectionMap
6) Send an informational message to the client, informing it that the name was accepted
7) If any verification step fails, request the client's name again
8) Return the accepted name as the return value

Requirements:

The Handler class must have a private String serverHandshake(Connection connection) method.
The serverHandshake() method should send a name request using the Connection class's send() method.
The name request should repeated until the message type of the response is equal to MessageType.USER_NAME.
If an empty name is received in response, the name request must be repeated.
If the name already exists in connectionMap, the name request must be repeated.
Once all the checks have been passed, the serverHandshake() method should add a new (name, connection) pair to connectionMap and send a message indicating that the name was accepted.
The serverHandshake() method should return the name of the client with which the new connection was established.

package com.codegym.task.task30.task3008; /* The server's main class. */ import java.io.IOException; import java.net.ServerSocket; import java.net.Socket; import java.util.Map; import java.util.concurrent.ConcurrentHashMap; import java.util.concurrent.ConcurrentMap; public class Server { private static Map<String, Connection> connectionMap = new ConcurrentHashMap<>(); public static void main(String[] args) { int serverport = ConsoleHelper.readInt(); try { ServerSocket serverSocket = new ServerSocket(serverport); ConsoleHelper.writeMessage("Server is running."); try { while (true) { Socket newSocket = serverSocket.accept(); Handler newHandler = new Handler(newSocket); newHandler.start(); } } catch (Exception e) { serverSocket.close(); e.printStackTrace(); } } catch (IOException e) { ConsoleHelper.writeMessage("Failure initializing ServerSocket."); } } private static class Handler extends Thread{ private Socket socket; Handler(Socket socket){ this.socket = socket; } private String serverHandshake(Connection connection) throws IOException, ClassNotFoundException{ String clientName; while(true) { connection.send(new Message(MessageType.NAME_REQUEST, "Please enter valid username.")); Message request = connection.receive(); boolean isUserName = request.getType() == (MessageType.USER_NAME) ? true : false; boolean isNotEmpty = request.getData().trim().length() == 0 ? false : true; boolean isNotUsed = !connectionMap.containsKey(request.getData()); if(isUserName && isNotEmpty && isNotUsed){ connectionMap.put(request.getData(), connection); connection.send(new Message(MessageType.NAME_ACCEPTED, "Username accepted.")); return request.getData(); } } } } public static void sendBroadcastMessage(Message message){ for(String key : connectionMap.keySet()){ try { connectionMap.get(key).send(message); } catch (IOException e) { ConsoleHelper.writeMessage("Message could not be sent to " + key); } } } }

Comments (4)

Popular
New
Old

You must be signed in to leave a comment

Fadi Alsaidi

Level 34 , Carrollton, TX, USA

5 December 2021, 15:37

I dont see any logic that would handle entering the wrong message type. I would suggest you create a logic that would check message type & throws a new IOException for entering the wrong message type and calling the same "server Handshake" method again. otherwise if a user input the wrong message type, then that would be the end of your program.

Jurij Thmsn

Level 29 , Flensburg, Germany

6 December 2021, 15:12

Thanks for your answer. I don't understand - if the MessageType wasn't the right one wouldn't the while loop just repeat again?

Guadalupe Gagnon

Level 37 , Tampa, United States

3 December 2021, 15:25

solution

I don't know specifically what is wrong, but here are some ideas: - It doesn't say to send a String with the name request. This isn't a problem in real world code, but the it could potentially be causing a rejection from the validator. Try only sending the name request without:

new Message(MessageType.NAME_REQUEST)

- same with MessageType.NAME_ACCEPTED line (line 62) As a tip: Instead of using booleans you can just use the continue keyword. That may make the code easier to read, understand, and debug:

if(request.getType() != MessageType.USER_NAME) continue;
// etc.

I didn't audit the your entire project, so if this doesn't help then there may be an issue in a completely different part of your project throwing off the validator.

Jurij Thmsn

Level 29 , Flensburg, Germany

6 December 2021, 15:18

Thanks for your answer! I Just wrote all conditions with if statements and continue and it validated. I don't really understand why it didn't work with the booleans and a combined if statement. In my eyes the logic stays the same? The if-continue construct is clearer and probably faster(because if first condition fails, less code os executed) but I think the logic is the same isn't it? Is it just the validator being picky or am I misunderstanding something? Anyways, sometimes I just have to accept such things and not get stuck to long with these things. Thanks fo your time, again.