We will describe a project's architecture that aims to have a design that let scale functionalities without too much accidental complexity. The architecture picks ideas from DDD and CQRS.

1. A production project’s
architecture
with Clojure :)
February 2016 @jordillonch

2. introduction
• inspired by horus
• why?

3. some concepts and libraries

4. domain
• contexts
• modules
• application services
• value objects/aggregates
• interfaces for repositories and external services
• buses
• command bus
• oracle
• domain event publisher

5. infrastructure
• http rest api server
• rabbitmq workers
• key/value database
• relational database
• non blocking promises

6. libraries
• com.stuartsierra/component: managing the lifecycle and dependencies of software components which have runtime state
• co.paralleluniverse/pulsar: provides high-performance lightweight threads, Go-like channels, Erlang-like actors, and other
asynchronous programming tools
• prismatic/schema: declarative data description and validation
• funcool/catacumba: web toolkit
• com.taoensso/timbre: logging and profiling
• hikari-cp: high-performance JDBC connection pool
• slingshot: enhanced throw and catch for Clojure
• com.gearswithingears/shrubbery: mocking
• com.novemberain/langohr: RabbitMQ client
• com.taoensso/carmine: Redis client

7. how it looks?

8. contexts
leaderboard
board
year
month
friends
shared infrastructure
storage
storage score
schema
finder updater
reseter repository
schema
lister updater
repository
finder updater
deleter repository
logic blocks

9. shared infrastructure
buses
logger
jdbc connection
pool
command bus
domain event
publisher
oracle
oauth2 access
token repository http server api
http server api
oauth2
domain event
backup
infrastructure

10. some examples

11. leaderboard score updater
controller
command bus
command
handler
updater
repository

12. controller
oracle
oracle handler
finder
repository
leaderboard score finder

13. show me the code!

14. some interesting points

15. • Stuart Sierra component
• lifecycle and dependencies management of runtime state
• rapid workflow
• component next
• adaptation of Stuart Sierra components map definition
• simplifiers
• bus handlers
• api rest routing
components

16. • value objects/aggregates definition
• validation
• coercion
schema

17. command bus
• use of promises
• 2 modes of use:
• fire and forget
• wait response

18. • behaviour
• mocking
• stubs generation
• acceptance
• system setup
• system reset
test

19. enhanced throw and catch
• slingshot