Chapter 7. The Externalizable API
An
Externalizer is a class that can:
- Marshall a given object type to a byte array.
- Unmarshall the contents of a byte array into an instance of the object type.
Externalizers are used by Red Hat JBoss Data Grid and allow users to specify how their object types are serialized. The marshalling infrastructure used in JBoss Data Grid builds upon JBoss Marshalling and provides efficient payload delivery and allows the stream to be cached. The stream caching allows data to be accessed multiple times, whereas normally a stream can only be read once.
The Externalizable interface uses and extends serialization. This interface is used to control serialization and deserialization in JBoss Data Grid.
7.1. Customize Externalizers
As a default in Red Hat JBoss Data Grid, all objects used in a distributed or replicated cache must be serializable. The default Java serialization mechanism can result in network and performance inefficiency. Additional concerns include serialization versioning and backwards compatibility.
For enhanced throughput, performance or to enforce specific object compatibility, use a customized externalizer. Customized externalizers for JBoss Data Grid can be used in one of two ways:
- Use an Externalizable Interface. For details, see Chapter 7, The Externalizable API.
- Use an advanced externalizer.
