Live Support Chat Server

Service oriented architecture with two backends:

• ChatServer:
  • publishes user join requests in Redis pub/sub, users channel
  • enables User and Support to exchange messages via chat using WebSockets
• Subscriber:
  • subscribes to users channel in Redis pub/sub and forwards user join requests to UI using WebSockets

Requirements for running the whole project:

• Docker engine

Instructions:

• clone the repo
• cd into repo
• start docker engine
• run: docker-compose up (it starts ChatServer, Subscriber and Redis in three different docker containers which are connected via docker network)

Protocol and flow description for building UI:

1. Register User in ChatServer by sending HTTP request to: GET localhost:9000/user/join/{userName}
   • Expect JSON response:

   {
       "userId": "9d6d2db0cdb84d8ba67105670d94d641",
       "username": "Nika",
       "chatId": "d2464b5386044daf9e36ffd414260f67"
   }

2. Initiate WebSocket connection for User in ChatServer by sending request to: GET localhost:9000/chat/{chatId}
   • server immediately starts sending ping message for each second, UI must respond with: pong:user (covers heartbeat functionality)
   • for requesting to join, send message:

   {
       "type": "Join",
       "args": {
           "userId": "9d6d2db0cdb84d8ba67105670d94d641",
           "username": "Nika",
           "from": "User"
       }
   }

   • Expect JSON response:

   {
       "type": "UserJoined",
       "args": {
           "username": "Nika",
           "userId": "9d6d2db0cdb84d8ba67105670d94d641",
           "chatId": "d2464b5386044daf9e36ffd414260f67"
       }
   }

3. Initiate WebSocket connection for Support in Subscriber by sending request to: GET localhost:9001/users
   • server immediately starts sending ping message for each second, UI must respond with: pong:support (covers heartbeat functionality)
   • for loading pending users send this WS message, it also subscribes to Redis PubSub and reads newly joined users

     {
         "type": "Load"
     }

   • Expect one re more JSON WebSocket messages (TODO - consider sending one message with list of users instead of single message for each user): for pending users

     {
         "username": "Nika",
         "userId": "9d6d2db0cdb84d8ba67105670d94d641",
         "chatId": "d2464b5386044daf9e36ffd414260f67"
     }

     for newly joined users

     {
         "type": "UserJoined",
         "args": {
             "username": "Dodo",
             "userId": "b646273c1f8840b1ad296b40ef62f2c5",
             "chatId": "2500f760be124d299f214c5f3aa0ecf2"
          }
     }

   • once Support clicks to the special user request, UI must send the JoinUser as websocket message so that it gets filtered out for other Support agents, at the same time UI must send another request to ChatServer - step 4 (details in step 4) JoinUser looks like

    {
        "type": "JoinUser",
        "args": {
            "userId": "8e0a7c3e1b2f489f8ce129a5167f71b5",
            "chatId": "0765d196ec4e4d108b9e4b6fca7c8254",
            "username": "Zaza"
        }
    }

   as a response the backend sends following WebSocket message:

   {
       "type": "RemoveUser",
       "args": {
           "userId": "8e0a7c3e1b2f489f8ce129a5167f71b5"
       }
   }

   This message will be broadcasted to all support UI-s and Frontend will be able to drop this user from the list
4. Initiate WebSocket connection for Support in ChatServer by sending request to: GET localhost:9000/chat/{chatId}
   • attach request body:

   {
       "type": "Join",
       "args": {
           "userId" : "9d6d2db0cdb84d8ba67105670d94d641",
           "supportUserName": "Vika",
           "username": "Nika",
           "from": "Support"    
       }
   }

• Expect JSON response:

  {
      "type": "SupportJoinedUser",
      "args": {
          "supportId": "1939d1c378ea45809521c16668c21c10",
          "supportUserName": "Kiku",
          "username": "f3eb5276f29c4971827d31acd12327a7",
          "userId": "Gela",
          "chatId": "91a68f25d5e5444aaaa5dc47ebf7d893"
      }
  }

5. Send chat message to Support from User by sending the following WebSocket text message on the opened WS connection:

   {
       "type": "ChatMessage",
       "args": {
           "userId": "9d6d2db0cdb84d8ba67105670d94d641",
           "supportId": "7c270542e64a4dfbb2bc1c7793746674",
           "content": "Hey, I want to transfer money offshore, how can I do it via internet bank?",
           "from": "User"    
       }
   }

   • Expect JSON response for both User and Support WebSocket connections:

    {
        "type": "ChatMessage",
        "args": {
            "userId": "9d6d2db0cdb84d8ba67105670d94d641",
            "supportId": "7c270542e64a4dfbb2bc1c7793746674",
            "content": "hey",
            "timestamp": "2023-10-22T18:18:59.360855Z",
            "from": "User"
        }
    }

6. Send chat message to User from Support by sending the following WebSocket text message on the opened WS connection:

   {
       "type": "ChatMessage",
       "args": {
           "userId": "9d6d2db0cdb84d8ba67105670d94d641",
           "supportId": "7c270542e64a4dfbb2bc1c7793746674",
           "supportUserName": "Vika",
           "content": "Hello, please navigate to Transfer and then select Offshore :)",
           "from": "Support"    
       }
   }

   • Expect JSON response for both User and Support WebSocket connections:

    {
        "type": "ChatMessage",
        "args": {
            "userId": "f49f3cc665af4cb38092af714a4c87fa",
            "supportId": "7c270542e64a4dfbb2bc1c7793746674",
            "content": "Hello, please navigate to Transfer and then select Offshore :)",
            "timestamp": "2023-10-22T18:19:19.119515Z",
            "from": "Support"
        }
   }

Each chat expires after two minutes of inactivity. Also, WebSocket connection automatically closes after 120 seconds of inactivity.

In case User or Support refreshes browser backend either loads:

• conversation history (if the chat is still active)
• message about chat expiration (if the chat was expired)

7. In case User refreshes browser the UI must send new Join (re-join) WebSocket text message:

   {   
       "type": "Join",
       "args": {
           "userId": "8b5ee49aa3bb45e1a8719179e5e25c12",
           "supportId": "7c270542e64a4dfbb2bc1c7793746674",
           "username": "Nika",
           "from": "User"
       }
   }

   • Expect JSON response:

   {
       "type": "ChatHistory",
       "args": {
           "messages": [
               {
                   "userId": "718b568c22f6460ca46a07cfc6aae3ba",
                   "supportId": "35eda9304e554514915fdbb8f26b710d",
                   "content": "Hey, I want to tranasfer money offshore, how can I do it via internet bank?",
                   "timestamp": "2023-10-22T18:36:54.834408Z",
                   "from": "User"
               },
               {
                   "userId": "718b568c22f6460ca46a07cfc6aae3ba",
                   "supportId": "35eda9304e554514915fdbb8f26b710d",
                   "content": "Hello, please navigate to Transfer and then select Offshore :)",
                   "timestamp": "2023-10-22T18:37:10.219775Z",
                   "from": "Support"
               }
           ]
       }
   }

8. Same message is loaded for Support, however a bit different Join (re-join) WebSocket text message must be sent:

   {   
       "type": "Join",
       "args": {
           "userId": "8b5ee49aa3bb45e1a8719179e5e25c12",
           "supportId": "7c270542e64a4dfbb2bc1c7793746674",
           "username": "Nika",
           "supportUserName": "Vika",
           "from": "Support"
       }
   }