!per #3652 Custom snapshot and persistent message serialization

- Protobuf serializer for Persistent message
- Configurable serializer for Persistent message's payload
- Configurable serializer for snapshots

akka-docs/rst/scala/code/docs/persistence/PersistenceSerializerDocSpec.scala

@@ -0,0 +1,50 @@
+/**
+ * Copyright (C) 2009-2013 Typesafe Inc. <http://www.typesafe.com>
+ */
+
+package docs.persistence
+
+import com.typesafe.config._
+
+import org.scalatest.WordSpec
+
+import akka.actor.ActorSystem
+import akka.serialization.{ Serializer, SerializationExtension }
+
+class PersistenceSerializerDocSpec extends WordSpec {
+
+  val customSerializerConfig =
+    """
+      //#custom-serializer-config
+      akka.actor {
+        serializers {
+          my-payload = "docs.persistence.MyPayloadSerializer"
+          my-snapshot = "docs.persistence.MySnapshotSerializer"
+        }
+        serialization-bindings {
+          "docs.persistence.MyPayload" = my-payload
+          "docs.persistence.MySnapshot" = my-snapshot
+        }
+      }
+      //#custom-serializer-config
+    """.stripMargin
+
+  SerializationExtension(ActorSystem("doc", ConfigFactory.parseString(customSerializerConfig)))
+}
+
+class MyPayload
+class MySnapshot
+
+class MyPayloadSerializer extends Serializer {
+  def identifier: Int = 77124
+  def includeManifest: Boolean = false
+  def toBinary(o: AnyRef): Array[Byte] = ???
+  def fromBinary(bytes: Array[Byte], manifest: Option[Class[_]]): AnyRef = ???
+}
+
+class MySnapshotSerializer extends Serializer {
+  def identifier: Int = 77125
+  def includeManifest: Boolean = false
+  def toBinary(o: AnyRef): Array[Byte] = ???
+  def fromBinary(bytes: Array[Byte], manifest: Option[Class[_]]): AnyRef = ???
+}