c

akka.serialization

SerializerWithStringManifest

abstract class SerializerWithStringManifest extends Serializer

A Serializer represents a bimap between an object and an array of bytes representing that object.

For serialization of data that need to evolve over time the SerializerWithStringManifest is recommended instead of Serializer because the manifest (type hint) is a String instead of a Class. That means that the class can be moved/removed and the serializer can still deserialize old data by matching on the String. This is especially useful for Akka Persistence.

The manifest string can also encode a version number that can be used in fromBinary to deserialize in different ways to migrate old data to new domain objects.

If the data was originally serialized with Serializer and in a later version of the system you change to SerializerWithStringManifest the manifest string will be the full class name if you used includeManifest=true, otherwise it will be the empty string.

Serializers are loaded using reflection during akka.actor.ActorSystem start-up, where two constructors are tried in order:

  • taking exactly one argument of type akka.actor.ExtendedActorSystem; this should be the preferred one because all reflective loading of classes during deserialization should use ExtendedActorSystem.dynamicAccess (see akka.actor.DynamicAccess), and
  • without arguments, which is only an option if the serializer does not load classes using reflection.

Be sure to always use the akka.actor.DynamicAccess for loading classes! This is necessary to avoid strange match errors and inequalities which arise from different class loaders loading the same class.

Source
Serializer.scala
Linear Supertypes
Serializer, AnyRef, Any
Known Subclasses
ReplicatedDataSerializer, ReplicatorMessageSerializer, MessageSerializer, MiscMessageSerializer
Ordering
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  2. By Inheritance
Inherited
  1. SerializerWithStringManifest
  2. Serializer
  3. AnyRef
  4. Any
Implicitly
  1. by any2stringadd
  2. by StringFormat
  3. by Ensuring
  4. by ArrowAssoc
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Visibility
  1. Public
  2. All

Instance Constructors

  1. new SerializerWithStringManifest()

Abstract Value Members

  1. abstract def fromBinary(bytes: Array[Byte], manifest: String): AnyRef

    Produces an object from an array of bytes, with an optional type-hint; the class should be loaded using ActorSystem.dynamicAccess.

    Produces an object from an array of bytes, with an optional type-hint; the class should be loaded using ActorSystem.dynamicAccess.

    It's recommended to throw java.io.NotSerializableException in fromBinary if the manifest is unknown. This makes it possible to introduce new message types and send them to nodes that don't know about them. This is typically needed when performing rolling upgrades, i.e. running a cluster with mixed versions for while. NotSerializableException is treated as a transient problem in the TCP based remoting layer. The problem will be logged and message is dropped. Other exceptions will tear down the TCP connection because it can be an indication of corrupt bytes from the underlying transport.

  2. abstract def identifier: Int

    Completely unique value to identify this implementation of Serializer, used to optimize network traffic.

    Completely unique value to identify this implementation of Serializer, used to optimize network traffic. Values from 0 to 40 are reserved for Akka internal usage.

    Definition Classes
    SerializerWithStringManifest → Serializer
  3. abstract def manifest(o: AnyRef): String

    Return the manifest (type hint) that will be provided in the fromBinary method.

    Return the manifest (type hint) that will be provided in the fromBinary method. Use "" if manifest is not needed.

  4. abstract def toBinary(o: AnyRef): Array[Byte]

    Serializes the given object into an Array of Byte

    Serializes the given object into an Array of Byte

    Definition Classes
    SerializerWithStringManifest → Serializer

Concrete Value Members

  1. final def fromBinary(bytes: Array[Byte], manifest: Option[Class[_]]): AnyRef

    Produces an object from an array of bytes, with an optional type-hint; the class should be loaded using ActorSystem.dynamicAccess.

    Produces an object from an array of bytes, with an optional type-hint; the class should be loaded using ActorSystem.dynamicAccess.

    Definition Classes
    SerializerWithStringManifest → Serializer
  2. final def fromBinary(bytes: Array[Byte], clazz: Class[_]): AnyRef

    Java API: deserialize with type hint

    Java API: deserialize with type hint

    Definition Classes
    Serializer
  3. final def fromBinary(bytes: Array[Byte]): AnyRef

    Java API: deserialize without type hint

    Java API: deserialize without type hint

    Definition Classes
    Serializer
  4. final def includeManifest: Boolean

    Returns whether this serializer needs a manifest in the fromBinary method

    Returns whether this serializer needs a manifest in the fromBinary method

    Definition Classes
    SerializerWithStringManifest → Serializer