User Service

User Service is an application for handling and processing Events via socket connections.

Supported events are

• Follow
• Unfollow
• Broadcast
• Private Message
• Status Update

Implementation details

On app start two sockets are initialized one for clients another for events.

The events arrive out of order but app should deliver them by order. EventsBuffer class is taking care of this by using BlockingQueue with a comparator. Capacity of the queue is configurable and is exported to JMX so it can be changed during runtime.

Key Classes

• SocketServer basically all functionality related to opening and reading sockets
• EventsBuffer dealing with events order and pushing them to event processors
• ClientStore holding all connected clients and removes them when connection is closed
• FollowerStore holding data about which followers (who follows whom)

Technology stack

• Java 8
• Spring
• Javaslang
• Lombock
• Guava
• Junit, Mockito, Assertj

Build and Run

To build and run jar file

./gradlew build

java -jar build/libs/user-service-0.1-SNAPSHOT.jar

To build and run Docker

./gradlew buildDocker

docker run -p 9090:9090 -p 9099:9099 soundcloud/user-service:1.0-SNAPSHOT

NOTE: You should have Lombock plugin installed to build and run the app with IDE

Known issues

While running with docker follower-maze-2.0.jar is failing while waiting for remaining notifications with ಠ_ಠ SOMETHING WENT WRONG ಠ_ಠ

Configuration

1. buffer.capacity - default 1000. Represents capacity of the buffer. When size of buffer gets to the limit half of the buffer is being flushed (events are being send)
2. buffer.scheduleFixedRate - default 2000 (2sec). Used for flushing events buffer if there are no incoming events.
3. socket.address - default localhost. Socket address
4. socket.eventPort - default 9090. Socket address
5. socket.clientPort - default 9099. Socket address

The app uses application.yml in classpath by default

If you need custom configuration use

-Dspring.config.location=/path

For changing log lvl you can use

-Dlogging.level.org.springframework=DEBUG

Finally :)

Hope you have enjoyed reviewing my code as much as I writing it :)