Skunk

Install

libraryDependencies += "io.github.beyond-scale-group" %% "edomata-skunk" % "0.12.23-1-9975025-SNAPSHOT"

or for integrated modules:

libraryDependencies += "io.github.beyond-scale-group" %% "edomata-skunk-circe" % "0.12.23-1-9975025-SNAPSHOT"
libraryDependencies += "io.github.beyond-scale-group" %% "edomata-skunk-jsoniter" % "0.12.23-1-9975025-SNAPSHOT"
libraryDependencies += "io.github.beyond-scale-group" %% "edomata-skunk-upickle" % "0.12.23-1-9975025-SNAPSHOT"

or for scala.js

libraryDependencies += "io.github.beyond-scale-group" %%% "edomata-skunk" % "0.12.23-1-9975025-SNAPSHOT"

Imports

import edomata.backend.Backend
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.

Table prefix mode

By default, each aggregate gets its own PostgreSQL schema (e.g. "domainname".journal). If you prefer to keep all tables in a single schema (e.g. when using Flyway migrations), you can use prefix-based naming instead:

import edomata.backend.PGNamespace

val buildBackend = Backend
  .builder(AccountService)
  .use(SkunkDriver.from(PGNamespace.prefixed("domainname"), pool))
  .inMemSnapshot(200)
  .build

This creates tables named domainname_journal, domainname_outbox, etc. in the current schema, and skips the CREATE SCHEMA statement.

You can also use PGNaming directly for more control:

import edomata.backend.PGNaming

// Schema mode (default behavior)
SkunkDriver.from(PGNaming.schema("domainname"), pool)

// Prefix mode
SkunkDriver.from(PGNaming.prefixed("domainname"), pool)

Using with Flyway

If you manage your database schema with Flyway (or another migration tool), you can extract the DDL and disable automatic table creation:

1. Generate migration SQL

Use PGSchema to generate DDL statements for your migration files:

import edomata.backend.{PGNaming, PGSchema}

// For event sourcing
val ddl = PGSchema.eventsourcing(
  PGNaming.prefixed("accounts"),
  eventType = "jsonb",
  notificationType = "jsonb",
  snapshotType = "jsonb"
)
ddl.foreach(println)

// For CQRS
val cqrsDdl = PGSchema.cqrs(
  PGNaming.prefixed("accounts"),
  stateType = "jsonb",
  notificationType = "jsonb"
)

Copy the output into a Flyway migration file (e.g. V1__create_accounts_tables.sql).

2. Disable automatic setup

Pass skipSetup = true to prevent the driver from executing any DDL:

val buildBackend = Backend
  .builder(AccountService)
  .use(SkunkDriver.from(PGNaming.prefixed("accounts"), pool, skipSetup = true))
  .inMemSnapshot(200)
  .build

This ensures Flyway has full control over your database schema.