Challenge Sportsbook (2019)

A code challenge for a certain company

Objective

Build a service that:

• allows players to place bets
• flag players who place stakes above a configurable threshold, within a certain time frame (non-overlapping time windows)
• when a player crosses a threshold a notification must be generated
• notifications must be:
  • persisted in a sql or nosql layer
  • available via websocket
• must be easily deployable

Architecture

The image above shows the system architecture built for the sake of this exercise, it includes:

• Web service (Spring REST API):
  • stakes placement
  • threshold notifications webhook dispatcher
  • threshold notifications websocket
  • mongoDB persistence layer for both stakes and threshold notifications
• App (HTML + javascript):
  • web page connected to the notification websocket which displays threshold notifications in real-time
• Threshold engine (Kafka Streams):
  • real-time threshold engine
  • configurable threshold limit and window size (based on java.time.Duration.parse())
• Messaging Bus (Kafka):
  • links the web service and the threshold engine

Additionally, the system is fully containerized and deployable using docker-compose.

Running it

Requirements

• building
  • maven
  • jdk >= 11
• deploying
  • docker
  • docker-compose

Build

mvn clean package

Deploy

docker-compose up -d

Notifications Webpage

localhost:8080/index.html

Using it

The logic behind the service is pretty straight forward, places from different players come in, if a player crossed the defined threshold, a notification is generated into the message bus and, consequently to the websocket and all webhooks registered.

Below are the REST API interactions for placing bets and registering/deleting web hooks.

Place stakes

curl --location --request POST 'localhost:8080/stakes/placeStake' \
--header 'Content-Type: application/json' \
--data-raw '{
	"account": "Alice",
	"stake": 55
}'

Register notifications webhook

curl --location --request POST 'localhost:8080/notifications/registerWebhook' \
--header 'Content-Type: application/json' \
--data-raw '{
	"url": "https://some.webhook.endpoint"
}'

Delete a webhook

curl --location --request PUT 'localhost:8080/notifications/deleteWebHook/02170326-71d4-4734-a5a9-bd03ab790d31'

Websocket

The socket is available at http://localhost:8080/topic/notifications