Is it possible to write a upickle Serializer for akka - scala

Question

I would like to implement an akka Serializer using upickle but I'm not sure its possible. To do so I would need to implement a Serializer something like the following:
import akka.serialization.Serializer
import upickle.default._
class UpickleSerializer extends Serializer {
def includeManifest: Boolean = true
def identifier = 1234567
def toBinary(obj: AnyRef): Array[Byte] = {
writeBinary(obj) // ???
}
def fromBinary(bytes: Array[Byte], clazz: Option[Class[_]]): AnyRef = {
readBinary(bytes) // ???
}
}
The problem is I cannot call writeBinary/readBinary without having the relevant Writer/Reader. Is there a way I can look these up based on the object class?

Answer 1

Take a look at following files, you should get some ideas!
CborAkkaSerializer.scala
LocationAkkaSerializer.scala
Note: These serializers are using cbor

Answer 2

I found a way to do it using reflection. I base the solution on the assumption that any object that needs to be serialized should have defined a ReadWriter in its companion object:
class UpickleSerializer extends Serializer {
private var map = Map[Class[_], ReadWriter[AnyRef]]()
def includeManifest: Boolean = true
def identifier = 1234567
def toBinary(obj: AnyRef): Array[Byte] = {
implicit val rw = getReadWriter(obj.getClass)
writeBinary(obj)
}
def fromBinary(bytes: Array[Byte], clazz: Option[Class[_]]): AnyRef = {
implicit val rw = lookup(clazz.get)
readBinary[AnyRef](bytes)
}
private def getReadWriter(clazz: Class[_]) = map.get(clazz) match {
case Some(rw) => rw
case None =>
val rw = lookup(clazz)
map += clazz -> rw
rw
}
private def lookup(clazz: Class[_]) = {
import scala.reflect.runtime._
val rootMirror = universe.runtimeMirror(clazz.getClassLoader)
val classSymbol = rootMirror.classSymbol(clazz)
val moduleSymbol = classSymbol.companion.asModule
val moduleMirror = rootMirror.reflectModule(moduleSymbol)
val instanceMirror = rootMirror.reflect(moduleMirror.instance)
val members = instanceMirror.symbol.typeSignature.members
members.find(_.typeSignature <:< typeOf[ReadWriter[_]]) match {
case Some(rw) =>
instanceMirror.reflectField(rw.asTerm).get.asInstanceOf[ReadWriter[AnyRef]]
case None =>
throw new RuntimeException("Not found")
}
}
}