For handling a mailing queue architecture, RabbitMQ was chosen with a Direct Exchange and single 'outbox' queue. The outbox queue can receive many messages and routes it to the Direct Exchange, using the same routing key for every message. The Direct exchange will then dispatch in a load balance in a round-robin configuration to all Mailgun API tool processes. Ideally they would POST request the API asynchronously to handle many emails at the same time. When the server cannot handle anymore load, more mail tool nodes should be added. The benefit of this configuration is that the queue does not have to handle any load other than sending messages, while a cluster of consumer API nodes can wait for the email response and put it in a success or failure queue when done.
Notes: Git commits contain each part of the assignment in isolation, some code was removed to build new features on top of old parts.
- Install RabitMQ with
brew install rabbitmq - Start the service with
brew services start rabbitmq - Optionally access the RabbitMQ admin panel at
http://localhost:15672/with user 'guest' and pass 'guest' - In the base directory run
lein with-profile mailtool:outbox uberjarto create jars for both the outbox queue and mailtool - Run the outbox to initialize the RabbitMQ queue,
java -jar target/outbox.jar --address DUMMY_ADDRESS - Run as many mail tool services as needed, replacing the APIKEY and SANDBOXDOMAINS
java -jar target/mailtool.jar -k APIKEY -d SANDBOXDOMAIN - Run the outbox again to send four example emails round robin to the mail tools,
java -jar target/outbox.jar --address RECIPIENT_EMAIL_ADDRESS
- Success and failure queues
- Master slave cluster configuration for high availability of queue watching process with RabbitMQ that replaces master with slave when master fails.