building the longevity context

Once we have your domain model in place, we are ready to build our LongevityContext, which we do in SimblContextImpl.scala:

import longevity.context.LongevityContext
import scala.concurrent.ExecutionContext.Implicits.global
import scala.concurrent.Future
import simbl.domain.SimblDomainModel

val longevityContext = LongevityContext[Future, SimblDomainModel]()

You can configure the longevity context with one of any number of effects. In this guide, we choose to use Scala futures. For other options, see the section on effects in the user manual.

The longevity context provides a variety of tools that are tailored to your model. The most important of these is the Repo, which you can use to do standard CRUD operations (create/retrieve/update/delete) with your persistent objects, as well as executing queries that return more than one result.

Longevity uses Typesafe Config to configure the longevity context. Typically, the configuration is drawn from the application.conf resource file. The longevity configuration for Simple Blogging looks this:

longevity.backEnd = InMem
longevity.autoOpenConnection = true
longevity.autoCreateSchema = true
longevity.optimisticLocking = false
longevity.writeTimestamps = false

longevity.cassandra.autoCreateKeyspace = true
longevity.cassandra.address = "127.0.0.1"
longevity.cassandra.useCredentials = no
longevity.cassandra.username = nil
longevity.cassandra.password = nil
longevity.cassandra.keyspace = simbl_main
longevity.cassandra.replicationFactor = 1

longevity.mongodb.uri = "mongodb://127.0.0.1:27017"
longevity.mongodb.db = simbl_main

longevity.jdbc.url = "jdbc:sqlite:simbl_main.db"

longevity.test.cassandra.autoCreateKeyspace = true
longevity.test.cassandra.address = "127.0.0.1"
longevity.test.cassandra.useCredentials = no
longevity.test.cassandra.username = nil
longevity.test.cassandra.password = nil
longevity.test.cassandra.keyspace = simbl_test
longevity.test.cassandra.replicationFactor = 1

longevity.test.mongodb.uri = "mongodb://127.0.0.1:27017"
longevity.test.mongodb.db = simbl_test

longevity.test.jdbc.url = "jdbc:sqlite:simbl_test.db"

Here, you need to specify the back end in configuration property longevity.backEnd. Your choices are currently Cassandra, InMem, MongoDB, and SQLite. We use InMem out of the box. If you want to try Cassandra or MongoDB, you will need to set up a database system to connect to. The SQLite back end will work without any extra setup, as all you need to run SQLite is the right jar on your classpath.

You can find configurations for main and test databases for the various back ends in the config file. If you want to experiment with adjusting the persistence strategy to use a real database, you may need to adjust this configuration.