rustedbones / akka-http-scalapb

akka-http protobuf binary and json marshalling/unmarshalling for ScalaPB messages



Scala CI Maven Central Software License

akka-http protobuf and json marshalling/unmarshalling for ScalaPB messages


Version Release date Akka Http version ScalaPB version Scala versions
0.2.2 2020-05-10 10.1.11 0.10.3 (0.10.1 json4s) 2.13.2, 2.12.11
0.2.1 2019-07-13 10.1.8 0.9.0 (0.9.2 json4s) 2.13.0, 2.12.8, 2.11.12
0.2.0 2019-06-22 10.1.8 0.9.0 (0.9.2 json4s) 2.13.0, 2.12.8, 2.11.12
0.1.0 2019-01-27 10.1.7 0.8.4 (0.7.2 json4s) 2.12.8, 2.11.12

The complete list can be found in the CHANGELOG file.

Getting akka-http-scalapb

Libraries are published to Maven Central. Add to your build.sbt:

libraryDependencies += "fr.davit" %% "akka-http-scalapb"        % <version> // binary & json support

Important: Since akka-http 10.1.0, akka-stream transitive dependency is marked as provided. You should now explicitly include it in your build.

[...] we changed the policy not to depend on akka-stream explicitly anymore but mark it as a provided dependency in our build. That means that you will always have to add a manual dependency to akka-stream. Please make sure you have chosen and added a dependency to akka-stream when updating to the new version

libraryDependencies += "com.typesafe.akka" %% "akka-stream" % <version> // Only Akka 2.5 supported

For more details, see the akka-http 10.1.x release notes

Quick start

For the examples, we are using the following proto domain model

message Item {
  string name = 1;
  int64 id    = 2;

message Order {
  reapeated Item items = 1;

The implicit marshallers and unmarshallers for your generated proto classes are defined in ScalaPBSupport. You simply need to have them in scope.

import akka.http.scaladsl.server.Directives
import fr.davit.akka.http.scaladsl.marshallers.scalapb.ScalaPBSupport

class MyProtoService extends Directives with ScalaPBSupport {

  // format: OFF
  val route =
    get {
      pathSingleSlash {
        complete(Item("thing", 42))
    } ~
    post {
      entity(as[Order]) { order =>
        val itemsCount = order.items.size
        val itemNames =", ")
        complete(s"Ordered $itemsCount items: $itemNames")
  // format: ON

Marshalling/Unmarshalling of the generated classes depends on the Accept/Content-Type header sent by the client:

  • Content-Type: application/json: json
  • Content-Type: application/x-protobuf: binary
  • Content-Type: application/x-protobuffer: binary
  • Content-Type: application/protobuf: binary
  • Content-Type: application/ binary

No Accept header or matching several (eg Accept: application/*) will take the 1st matching type from the above list.

Json only

If you are using scalaPB for json (un)marshalling only, you can use ScalaPBJsonSupport from the sub module

libraryDependencies += "fr.davit" %% "akka-http-scalapb-json4s"        % <version> // json support only

Binary only

If you are using scalaPB for binary (un)marshalling only, you can use ScalaPBBinarySupport form the sub module

libraryDependencies += "fr.davit" %% "akka-http-scalapb-binary"        % <version> // binary support only


Only json (un)marshallers are able to support collections of proto messages as root object.

Entity streaming (http chunked transfer) is at the moment not supported by the library.