• Client uses a Websocket to connect to 'websocket service'
• Client can register with a login and password using identity service
• Any service can get user id by using identity service

# Download this project
git clone https://github.com/MaximRobota/websocket-chat

Before running services, you should set the database config with yours or set the your database config with my values on .env

MYSQL_HOST=db
MYSQL_USER=user
MYSQL_PASSWORD=devpass
MYSQL_PORT=3398
MYSQL_DB=mysql_database

cd websocket-chat
docker-compose build
docker-compose up

├── identity-service                // Our API core handlers
├── message-persistence-service     // Check and save events
├── websocket-service               // Two-way interactive communication session between the user's browser and a server
├── tests
├── docker-compose.yml

/auth/register (name, pass) -> token
/auth/login (name, pass) -> token
/auth/getIdByToken -> int (id)

• Uses kafka to post messages that need saving (queue “message_save”)
• Listens to kafka (queue “message_events”)
• Checks that a user is a valid user (id service) and only then posts the message to “message_save”
• Sends updates about messages to correct users
• If a user with an invalid token sends a message ignore it and log a warning to stdout

• Listens on “message_save” queue
• Saves messages to database and rollback if an error occurs:
• In case of an error log error to stdout
• Send a message error to “message_events”
• In case of message is saved send message id and other data to “message_events”

• Redis can be used as a key-value storage by websocket service:
  • Save user id and message UUID (provided by the client)
  • Is required to keep track on which messages are sent by which users

• Connect to a websocket
• Sends message text, user_to_id and a random UUID (generated by client)
• The message UUID is used to identify the message until the message is actually allotted a database id (until it is saved)

1. Client sends:

{ 
	uuid: “a62f2bf7-cfe7-48d6x-ad53-956e41b0769b”,
	Message: “hi”,
	user_to : 2
}

With jwt_token in headers (at connection time)

1. Websocket service:

   1. Marks the message UUID as the one sent by a user with some id (1? - get the id by token).

   2. When a message is saved Websocket service gets a message on “message_events” queue :

   {
   	uuid: “a62f2bf7-cfe7-48d6x-ad53-956e41b0769b”,
   	state: “Saved”
   }
   

2. Websocket service looks up the corresponding websocket handle to send the event (saved)to the correct user and sends

   {
   	uuid: “a62f2bf7-cfe7-48d6x-ad53-956e41b0769b”,
   	state: “Saved”
   }
   

3. Client gets the message and can identify the correct message to mark it as “successfully sent”.

General:

• Every service is a docker container.
• Every service is written in python 3 (3.7 +)
• Use docker-compose to run the whole stack
• Expect every service to run on the same host (localhost)
• Every service runs on some port
• This port is defined as an environment variable (ENV_VAR)
• Docker-compose.yaml should define the ports for each service (do not hardcode the port values, use environment variables only)

Example:

import os 
os.environ[“KAFKA_PORT”] / os.environ[“ID_SERVICE_PORT”]/ ...


web_socket_service:
	Image:
Build: ..

Environment:
	KAFKA_PORT: 9092
persistence_service:
	Image:
Build: ..

Environment:
	KAFKA_PORT: 9092 

• Docker-compose -f docker_compose.yaml up
• Python3 client_test.py
• Registers 2 users,
• User 1 sends a message to user 2
• assert ( wait for 20 secs) that the message is saved
• Message uuid matches the one we created
• Message state is “saved”

• Use docker-compose up to start for all services
• JWT Authentication
• Flask app for identity service
• Create schema for database MySql
• Implement Kafka Producer / Consumer
• 2 processes
  1. sends a message
  2. prints the received message
• Implement Redis (did not find application in the project)
• Implement Kubernetes (basic test without using CP3-WS)