Shopping Cart

This is a study on how to implement a minimal (but realistic) shopping cart system with DDD and eventsourcing. Plus, within this project I'd like to explore some issues eventually raising when introducing Scala into a fairly large enterprise with a solid Java culture.

The following technologies has been used:

• Akka 2.3.9 as a core framework (using Scala 2.11.x);
• Spray 1.3.3 for the REST layer;
• ScalaTest 2.2.x for testing.

What's included so far?

The project so far is divided into two distinct modules:

• core contains the domain-specific parts of the application. Every specific actor should have a decent test suite, i.e. ShoppingCartAggregate has its own ShoppingCartAggregateSpec;
• server contains the REST service. The current implementation uses Spray but, at this time, it is far from satisfactory.

How to run it?

TODO (complete)

Right now you could analyse the system behaviour using the specs available on project.

Getting started

If yout already know about Scala & SBT you can skip this section.

Since this is an SBT project, you'll probably need a recent version of Intellij IDEA (tested on 14.x) with Scala plugin in order to open it in a IDE. IDEA can also run Spec tests, so it's highly recommended.

Using a command line is easier to start:

1. Run ./activator on the project directory and wait until internet has been downloaded
2. When the prompt appears, run test in order to excute all tests.

When tests are successful, you should see something similar to:

[info] Run completed in 2 seconds, 538 milliseconds.
[info] Total number of tests run: 21
[info] Suites: completed 4, aborted 0
[info] Tests: succeeded 21, failed 0, canceled 0, ignored 0, pending 0

If you want to play around while having your tests running at every changes, prepend test command with ~, i.e.

~ test
[info] MoneySpec:
[info] Money
[info] - should be created from a String
[info] - should be summable
[info] - should be subtractable
[info] - should be rounded as 2 decimals half-even
[info] - should be comparable
[info] PingPongActorSpec:
[info] A Ping actor
[INFO] [12/18/2014 21:27:22.335] [MySpec-akka.actor.default-dispatcher-3] [akka://MySpec/user/$a] In PingActor - received message: pong
[info] - must send back a ping on a pong
[info] A Pong actor
[INFO] [12/18/2014 21:27:22.340] [MySpec-akka.actor.default-dispatcher-4] [akka://MySpec/user/$b] In PongActor - received message: ping
[info] - must send back a pong on a ping
[info] ShoppingCartSpec:
[info] A shopping cart
[info] - must add a product
[info] - must refuse to add a product when it's not available
[info] - must add a product with a quantity
[info] - must sum quantities of the same product
[info] - must remove an existing product
[info] - must do nothing if asked to remove a product that is not present
[info] - must subtract quantities of the same product
[info] - must remove product from cart is its quantity is 0
[info] - must be cleared
[info] - must reject unknown commands
[info] A persistence cart
[info]   must recover the previous state 
[info]   - when is non empty
[INFO] [12/18/2014 21:27:23.580] [BrgActorySystem-akka.actor.default-dispatcher-5] [akka://BrgActorySystem/user/$a] Message [akka.persistence.JournalProtocol$WriteMessagesSuccessful$] from Actor[akka://BrgActorySystem/system/journal#866893466] to Actor[akka://BrgActorySystem/user/$a#-965529725] was not delivered. [1] dead letters encountered. This logging can be turned off or adjusted with configuration settings 'akka.log-dead-letters' and 'akka.log-dead-letters-during-shutdown'.
[INFO] [12/18/2014 21:27:23.580] [BrgActorySystem-akka.actor.default-dispatcher-5] [akka://BrgActorySystem/user/$a] Message [akka.persistence.JournalProtocol$WriteMessageSuccess] from Actor[akka://BrgActorySystem/system/testActor2#-630366286] to Actor[akka://BrgActorySystem/user/$a#-965529725] was not delivered. [2] dead letters encountered. This logging can be turned off or adjusted with configuration settings 'akka.log-dead-letters' and 'akka.log-dead-letters-during-shutdown'.
[INFO] [12/18/2014 21:27:23.580] [BrgActorySystem-akka.actor.default-dispatcher-5] [akka://BrgActorySystem/user/$l] Message [akka.persistence.JournalProtocol$ReplayMessagesSuccess$] from Actor[akka://BrgActorySystem/system/journal#866893466] to Actor[akka://BrgActorySystem/user/$l#128166001] was not delivered. [3] dead letters encountered. This logging can be turned off or adjusted with configuration settings 'akka.log-dead-letters' and 'akka.log-dead-letters-during-shutdown'.
[info]   - when is recovered once it's started again
[info] ShoppingCartHandlerSpec:
[info] A shopping cart handler actor
[info] - must create a cart actor on demand
[info] - must forward commands to a specific actor
[info] Run completed in 2 seconds, 376 milliseconds.
[info] Total number of tests run: 21
[info] Suites: completed 4, aborted 0
[info] Tests: succeeded 21, failed 0, canceled 0, ignored 0, pending 0
[info] All tests passed.
[success] Total time: 3 s, completed Dec 18, 2014 9:27:23 PM
1. Waiting for source changes... (press enter to interrupt)