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scalaakkaactor

Data store in an actor system

I'm working on an event processing pipeline based on Akka actors. I have 3 actors for each step of the pipeline: FilterWorker, EnrichWorker and ProcessWorker; plus a supervisor actor that makes sure the events are sent from one step of the pipeline to the next.

The enrich step might need to query some external database for extra data or even create new data that I'll want to persist. For example, the enrich step of a web analytics system might want to enrich a click event with the user that made the click and store that user information in a database.

Keeping in mind that example, I see the following options:

1.Use a singleton; e.g. UserStore that keeps in memory all the users gathered so far and saves them to the database once in a while; has all the logic to fetch users that are not yet in memory. Doesn't seem like a good idea to use a singleton in an actor system however (?).

  1. Use a store actor. Use tell to add a new user and ask to fetch it.

Is there a better pattern for this?

Thanks!

Solution

  • In order to not leave this unanswered, I went with my second option and johanandren's suggestion of having an Actor fill the data store role. Works pretty well!