scala support

build.sbt

@@ -86,10 +86,13 @@ headerSources in Compile ++= {
 }
 
 lazy val root = (project in file("."))
+// Don't forget to add your sbt module here!
+// A missing module here can lead to failing Travis test results
   .aggregate(`proxy-core`,
              `proxy-cassandra`,
              `proxy-postgres`,
              `java-support`,
+             `scala-support`,
              `java-shopping-cart`,
              `akka-client`,
              operator,
@@ -630,6 +633,70 @@ lazy val `java-support` = (project in file("java-support"))
     )
   )
 
+lazy val `scala-support` = (project in file("scala-support"))
+  .enablePlugins(AkkaGrpcPlugin, BuildInfoPlugin)
+  .settings(
+    name := "cloudstate-scala-support",
+    common,
+    crossPaths := false,
+    publishMavenStyle := true,
+    publishTo := sonatypePublishTo.value,
+    buildInfoKeys := Seq[BuildInfoKey](name, version),
+    buildInfoPackage := "io.cloudstate.scalasupport",
+    // Generate javadocs by just including non generated Java sources
+    sourceDirectories in (Compile, doc) := Seq((javaSource in Compile).value),
+    sources in (Compile, doc) := {
+      val javaSourceDir = (javaSource in Compile).value.getAbsolutePath
+      (sources in (Compile, doc)).value.filter(_.getAbsolutePath.startsWith(javaSourceDir))
+    },
+    // javadoc (I think java 9 onwards) refuses to compile javadocs if it can't compile the entire source path.
+    // but since we have java files depending on Scala files, we need to include ourselves on the classpath.
+    dependencyClasspath in (Compile, doc) := (fullClasspath in Compile).value,
+    javacOptions in (Compile, doc) ++= Seq(
+        "-overview",
+        ((javaSource in Compile).value / "overview.html").getAbsolutePath,
+        "-notimestamp",
+        "-doctitle",
+        "CloudState Scala Support"
+      ),
+    libraryDependencies ++= Seq(
+        // Remove these explicit gRPC/netty dependencies once akka-grpc 0.7.1 is released and we've upgraded to using that
+        "io.grpc" % "grpc-core" % GrpcJavaVersion,
+        "io.grpc" % "grpc-netty-shaded" % GrpcJavaVersion,
+        "com.typesafe.akka" %% "akka-stream" % AkkaVersion,
+        "com.typesafe.akka" %% "akka-slf4j" % AkkaVersion,
+        "com.typesafe.akka" %% "akka-discovery" % AkkaVersion,
+        "com.typesafe.akka" %% "akka-http" % AkkaHttpVersion,
+        "com.typesafe.akka" %% "akka-http-spray-json" % AkkaHttpVersion,
+        "com.typesafe.akka" %% "akka-http-core" % AkkaHttpVersion,
+        "com.typesafe.akka" %% "akka-http2-support" % AkkaHttpVersion,
+        "com.google.protobuf" % "protobuf-java" % ProtobufVersion % "protobuf",
+        "com.google.protobuf" % "protobuf-java-util" % ProtobufVersion,
+        "org.scalatest" %% "scalatest" % ScalaTestVersion % Test,
+        "com.typesafe.akka" %% "akka-testkit" % AkkaVersion % Test,
+        "com.typesafe.akka" %% "akka-stream-testkit" % AkkaVersion % Test,
+        "com.typesafe.akka" %% "akka-http-testkit" % AkkaHttpVersion % Test,
+        "com.thesamet.scalapb" %% "scalapb-runtime" % scalapb.compiler.Version.scalapbVersion % "protobuf",
+        "org.slf4j" % "slf4j-simple" % "1.7.26",
+        "com.fasterxml.jackson.core" % "jackson-databind" % "2.9.9.3"
+      ),
+    javacOptions in Compile ++= Seq("-encoding", "UTF-8"),
+    akkaGrpcGeneratedSources in Compile := Seq(AkkaGrpc.Server),
+    akkaGrpcGeneratedLanguages in Compile := Seq(AkkaGrpc.Scala), // FIXME should be Java, but here be dragons
+
+    // Work around for https://github.com/akka/akka-grpc/pull/673
+    (PB.targets in Compile) := {
+      val old = (PB.targets in Compile).value
+      val ct = crossTarget.value
+
+      old.map(_.copy(outputPath = ct / "akka-grpc" / "main"))
+    },
+    PB.protoSources in Compile ++= {
+      val baseDir = (baseDirectory in ThisBuild).value / "protocols"
+      Seq(baseDir / "protocol", baseDir / "frontend")
+    }
+  )
+
 lazy val `java-shopping-cart` = (project in file("samples/java-shopping-cart"))
   .dependsOn(`java-support`)
   .enablePlugins(AkkaGrpcPlugin, AssemblyPlugin)
@@ -659,6 +726,29 @@ lazy val `java-shopping-cart` = (project in file("samples/java-shopping-cart"))
     }
   )
 
+lazy val `scala-shopping-cart` = (project in file("samples/scala-shopping-cart"))
+  .dependsOn(`scala-support`)
+  .enablePlugins(AkkaGrpcPlugin)
+  .settings(
+    name := "scala-shopping-cart",
+    PB.generate in Compile := (PB.generate in Compile).dependsOn(PB.generate in (`scala-support`, Compile)).value,
+    PB.protoSources in Compile ++= {
+      val baseDir = (baseDirectory in ThisBuild).value / "protocols"
+      Seq(baseDir / "frontend", baseDir / "example")
+    },
+    mainClass in assembly := Some("io.cloudstate.samples.shoppingcart.Main"),
+    assemblyJarName in assembly := "scala-shopping-cart.jar",
+    test in assembly := {},
+    // logLevel in assembly := Level.Debug,
+    assemblyMergeStrategy in assembly := {
+      /*ADD CUSTOMIZATIONS HERE*/
+      //case PathList("META-INF", "io.netty.versions.properties") => MergeStrategy.last
+      case x =>
+        val oldStrategy = (assemblyMergeStrategy in assembly).value
+        oldStrategy(x)
+    }
+  )
+
 lazy val `akka-client` = (project in file("samples/akka-client"))
   .enablePlugins(AkkaGrpcPlugin)
   .settings(
@@ -720,7 +810,7 @@ lazy val `tck` = (project in file("tck"))
     fork in test := true,
     parallelExecution in IntegrationTest := false,
     executeTests in IntegrationTest := (executeTests in IntegrationTest)
-        .dependsOn(`proxy-core` / assembly, `java-shopping-cart` / assembly)
+        .dependsOn(`proxy-core` / assembly, `java-shopping-cart` / assembly, `scala-shopping-cart` / assembly)
         .value
   )
 

samples/scala-shopping-cart/src/main/scala/io/cloudstate/samples/shoppingcart/Main.scala

@@ -0,0 +1,14 @@
+package io.cloudstate.samples.shoppingcart
+
+import com.example.shoppingcart.ShoppingcartProto
+import io.cloudstate.javasupport._
+
+object Main extends App {
+  new CloudState()
+    .registerEventSourcedEntity(
+      classOf[ShoppingCartEntity],
+      ShoppingcartProto.javaDescriptor.findServiceByName("ShoppingCart"),
+      com.example.shoppingcart.persistence.DomainProto.javaDescriptor
+    )
+    .start
+}

samples/scala-shopping-cart/src/main/scala/io/cloudstate/samples/shoppingcart/ShoppingCartEntity.scala

@@ -0,0 +1,76 @@
+package io.cloudstate.samples.shoppingcart
+
+import com.example.shoppingcart.persistence.{
+  Cart => DCart,
+  ItemAdded => DItemAdded,
+  ItemRemoved => DItemRemoved,
+  LineItem => DLineItem
+}
+import com.example.shoppingcart.{
+  AddLineItem => SAddLineItem,
+  Cart => SCart,
+  LineItem => SLineItem,
+  RemoveLineItem => SRemoveLineItem
+}
+import com.google.protobuf.Empty
+import io.cloudstate.javasupport.EntityId
+import io.cloudstate.javasupport.eventsourced._
+
+import scala.collection.mutable
+
+/** An event sourced entity. */
+@EventSourcedEntity
+class ShoppingCartEntity(@EntityId val entityId: String) {
+
+  private val cart = mutable.LinkedHashMap.empty[String, SLineItem]
+
+  @Snapshot
+  def snapshot: DCart =
+    DCart(cart.values.map(convert).toSeq)
+
+  @SnapshotHandler
+  def handleSnapshot(cart: DCart): Unit = {
+    this.cart.clear()
+    cart.items.foreach { item =>
+      this.cart.put(item.productId, convert(item))
+    }
+  }
+
+  @EventHandler
+  def itemAdded(itemAdded: DItemAdded): Unit = {
+    val item = cart
+      .get(itemAdded.getItem.productId)
+      .fold(convert(itemAdded.getItem))(
+        item => item.copy(quantity = item.quantity + itemAdded.item.fold(0)(_.quantity))
+      )
+    cart.put(item.productId, item)
+  }
+
+  @EventHandler
+  def itemRemoved(itemRemoved: DItemRemoved): Unit = cart.remove(itemRemoved.productId)
+
+  @CommandHandler
+  def getCart: SCart = SCart(cart.values.toSeq)
+
+  @CommandHandler
+  def addItem(item: SAddLineItem, ctx: CommandContext): Empty = {
+    if (item.quantity <= 0) ctx.fail("Cannot add negative quantity of to item" + item.productId)
+    ctx.emit(
+      DItemAdded(Some(DLineItem(item.productId, item.name, item.quantity)))
+    )
+    Empty.getDefaultInstance
+  }
+
+  @CommandHandler
+  def removeItem(item: SRemoveLineItem, ctx: CommandContext): Empty = {
+    if (!cart.contains(item.productId)) {
+      ctx.fail("Cannot remove item " + item.productId + " because it is not in the cart.")
+    }
+    ctx.emit(DItemRemoved(item.productId))
+    Empty.getDefaultInstance
+  }
+
+  private def convert(item: DLineItem) = SLineItem(item.productId, item.name, item.quantity)
+
+  private def convert(item: SLineItem) = DLineItem(item.productId, item.name, item.quantity)
+}

scala-support/src/main/java/io/cloudstate/javasupport/ClientActionContext.java

@@ -0,0 +1,29 @@
+package io.cloudstate.javasupport;
+
+/**
+ * Context that provides client actions, which include failing and forwarding.
+ *
+ * <p>These contexts are typically made available in response to commands.
+ */
+public interface ClientActionContext extends Context {
+  /**
+   * Fail the command with the given message.
+   *
+   * @param errorMessage The error message to send to the client.
+   */
+  RuntimeException fail(String errorMessage);
+
+  /**
+   * Instruct the proxy to forward handling of this command to another entity served by this
+   * stateful function.
+   *
+   * <p>The command will be forwarded after successful completion of handling this command,
+   * including any persistence that this command does.
+   *
+   * <p>{@link ServiceCall} instances can be created using the {@link ServiceCallFactory} obtained
+   * from any (including this) contexts {@link Context#serviceCallFactory()} method.
+   *
+   * @param to The service call to forward command processing to.
+   */
+  void forward(ServiceCall to);
+}