Serialization Interfaces
For complex objects, the following interfaces are used for serialization and deserialization.
java.io.Serializablejava.io.Externalizablecom.hazelcast.nio.serialization.DataSerializablecom.hazelcast.nio.serialization.IdentifiedDataSerializablecom.hazelcast.nio.serialization.Portable, and- Custom Serialization (using
StreamSerializer,ByteArraySerializer)
When Hazelcast serializes an object into Data:
(1) It first checks whether the object is an instance of com.hazelcast.nio.serialization.DataSerializable.
(2) If the above check fails, then Hazelcast checks if it is an instance of com.hazelcast.nio.serialization.Portable.
(3) If the above check fails, then Hazelcast checks whether the object is a well-known type like String, Long, or Integer, or if it is a user-specified type like ByteArraySerializer or StreamSerializer.
(4) If the above checks fail, Hazelcast will use Java serialization.
If all of the above checks do not work, then serialization will fail. When a class implements multiple interfaces, the above steps are important to determine the serialization mechanism that Hazelcast will use. When a class definition is required for any of these serializations, all the classes needed by the application should be on the classpath because Hazelcast does not download them automatically.