Skunk

Install

libraryDependencies += "dev.hnaderi" %% "edomata-skunk" % "0.12.4"

or for integrated modules:

libraryDependencies += "dev.hnaderi" %% "edomata-skunk-circe" % "0.12.4"
libraryDependencies += "dev.hnaderi" %% "edomata-skunk-upickle" % "0.12.4"

or for scala.js

libraryDependencies += "dev.hnaderi" %%% "edomata-skunk" % "0.12.4"

Imports

import edomata.skunk.*

Defining codecs

given BackendCodec[Event] = CirceCodec.jsonb // or .json
given BackendCodec[Notification] = CirceCodec.jsonb

when using cqrs style:

given BackendCodec[State] = CirceCodec.jsonb 

Persisted snapshots (event sourcing only)

if you want to use persisted snapshots, you need to provide codec for your state model too.

given BackendCodec[State] = CirceCodec.jsonb 

Compiling application to a service

You need to use a driver to build your backend, there are two skunk drivers available:

1. SkunkDriver event sourcing driver
   
2. SkunkCQRSDriver cqrs driver

val app  = ??? // your application from previous chapter
val pool : Resource[IO, Session[IO]] = ??? // create your own session pool

val buildBackend = Backend
  .builder(AccountService)               // 1
  .use(SkunkDriver("domainname", pool))  // 2
  // .persistedSnapshot(maxInMem = 200)  // 3
  .inMemSnapshot(200)
  .withRetryConfig(retryInitialDelay = 2.seconds)
  .build

val application = buildBackend.use { backend =>
  val service = backend.compile(app)
  // compiling your application will give you a function
  // that takes a messages and does everything required,
  // and returns result.

  service(
    CommandMessage("abc", Instant.now, "a", "receive")
  ).flatMap(IO.println)
}

1. use your domain as described in previous chapter.
2. domainname is used as schema name in postgres.
3. feel free to navigate available options in backend builder.