The basic setup is from the valuable spray template. The example covers
- REST-Services with Spray
- an event-driven architecture based on Akka
- persistence with squeryl
- Testing with Specs2
The project layout is corresponding to the classic maven style directory structure. All source code is located in src/main/scala and src/test/scala, respectively.
The source code is organized in the following packages:
- api: The rest service stuff, i.e. definition of routes, Json marshallers
- core: the rest agnostic business logic: message objects, operations
- domain: the domain model as case class(es)
- database: Squeryl schema definition, database configuration
- a Request hits the defined routes in the webservice actor
- the Request is converted to a message object
- An intermediate Actor is created per request to handle the completion of the request (pre request pattern)
- the Message object is passed to the business logic actor via the per request Actor
- the business logic actor mainly triggers the database interaction
- the resulting data is passed back to the per request actor which completes the request
Performance and stability are pretty hard achieve in this setup. First I implemented the ask pattern, but the system crashed under heavy load. That is not tolerable in any serious system. Fiddling with akka settings doesn't help (or I couln't figure out how to configure everything correctly).
Then I switched to the pre request pattern. That solved the performance and stability problems for me as the blocking part of the system is encapsulated in a separate Actor per request. The overall performance is quite good now. Reading access gets up to 2000 req/s on a i5, which is quite nice.
Testing is broken right now.
The project is built using sbt. Use
sbt gen-idea
to create Idea project files.
The project is released under the MIT license.