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Comparing Serialization Interfaces

The table below provides a comparison between the interfaces listed in the previous section to help you in deciding which interface to use in your applications.

Serialization Interface	Advantages	Disadvantages
Serializable	A standard and basic Java interface Requires no implementation	More time and CPU usage More space occupancy Not supported by Native clients
Externalizable	A standard Java interface More CPU and memory usage efficient than Serializable	Serialization interface must be implemented Not supported by Native clients
DataSerializable	More CPU and memory usage efficient than Serializable	Specific to Hazelcast Not supported by Native clients
IdentifiedDataSerializable	More CPU and memory usage efficient than Serializable Reflection is not used during deserialization Supported by all Native Clients	Specific to Hazelcast Serialization interface must be implemented A Factory and configuration must be implemented
Portable	More CPU and memory usage efficient than Serializable Reflection is not used during deserialization Versioning is supported Partial deserialization is supported during Queries Supported by all Native Clients	Specific to Hazelcast Serialization interface must be implemented A Factory and configuration must be implemented Class definition is also sent with data but stored only once per class
Custom Serialization	Does not require class to implement an interface Convenient and flexible Can be based on StreamSerializer ByteArraySerializer	Serialization interface must be implemented Plug in and configuration is required
Compact Serialization (BETA)	More memory usage efficient than Portable Convenient, flexible, and can be used with no configuration Does not require class to implement an interface Supports schema evolution Partial deserialization is supported during queries and indexing	Specific to Hazelcast Schema is not part of the data but schema distribution may incur costs on short-lived use cases The format is in the BETA state and no compatibility guarantees are given yet Currently, not supported by the Hazelcast SQL engine

Serialization Interface

Advantages

Disadvantages

Serializable

A standard and basic Java interface
Requires no implementation

More time and CPU usage
More space occupancy
Not supported by Native clients

Externalizable

A standard Java interface
More CPU and memory usage efficient than Serializable

Serialization interface must be implemented
Not supported by Native clients

DataSerializable

More CPU and memory usage efficient than Serializable

Specific to Hazelcast
Not supported by Native clients

IdentifiedDataSerializable

More CPU and memory usage efficient than Serializable
Reflection is not used during deserialization
Supported by all Native Clients

Specific to Hazelcast
Serialization interface must be implemented
A Factory and configuration must be implemented

Portable

More CPU and memory usage efficient than Serializable
Reflection is not used during deserialization
Versioning is supported
Partial deserialization is supported during Queries
Supported by all Native Clients

Specific to Hazelcast
Serialization interface must be implemented
A Factory and configuration must be implemented
Class definition is also sent with data but stored only once per class

Custom Serialization

Does not require class to implement an interface
Convenient and flexible
Can be based on StreamSerializer ByteArraySerializer

Serialization interface must be implemented
Plug in and configuration is required

Compact Serialization (BETA)

More memory usage efficient than Portable
Convenient, flexible, and can be used with no configuration
Does not require class to implement an interface
Supports schema evolution
Partial deserialization is supported during queries and indexing

Specific to Hazelcast
Schema is not part of the data but schema distribution may incur costs on short-lived use cases
The format is in the BETA state and no compatibility guarantees are given yet
Currently, not supported by the Hazelcast SQL engine

Let’s dig into the details of the above serialization mechanisms in the following sections.