public interface AdvancedExternalizer<T> extends Externalizer<T>
AdvancedExternalizerprovides an alternative way to provide externalizers for marshalling/unmarshalling user defined classes that overcome the deficiencies of the more user-friendly externalizer definition model explained in
Externalizer. The first noticeable difference is that this method does not require user classes to be annotated in anyway, so it can be used with classes for which source code is not available or that cannot be modified. The bound between the externalizer and the classes that are marshalled/unmarshalled is set by providing an implementation for
getTypeClasses()which should return the list of classes that this externalizer can marshall. Secondly, in order to save the maximum amount of space possible in the payloads generated, this externalizer method requires externalizer implementations to provide a positive identified via
getId()implementations or via XML/programmatic configuration that identifies the externalizer when unmarshalling a payload. In order for this to work however, this externalizer method requires externalizers to be registered on cache manager creation time via XML or programmatic configuration. On the contrary, externalizers based on
SerializeWithrequire no pre-registration whatsoever. Internally, Infinispan uses this advanced externalizer mechanism in order to marshall/unmarshall internal classes. Finally,
AbstractExternalizerprovides default implementations for some of the methods defined in this interface and so it's generally recommended that implementations extend that abstract class instead of implementing
AdvancedExternalizerdirectly. Even though
Serializableindirectly, there's no requirement for the advanced externalizer to be marshalled, because the pre-registration done on startup allows the marshaller to identify the externalizer from the given id.
|Modifier and Type||Method and Description|
Returns an integer that identifies the externalizer type.
Returns a collection of Class instances representing the types that this AdvancedExternalizer can marshall.
Set<Class<? extends T>> getTypeClasses()
AdvancedExternalizershould read the contents of the incoming buffer. Using a positive integer allows for very efficient variable length encoding of numbers, and it's much more efficient than shipping
AdvancedExternalizerimplementation class information around. Negative values are not allowed. Implementers of this interface can use any positive integer as long as it does not clash with any other identifier in the system. You can find information on the pre-assigned identifier ranges in here. It's highly recommended that maintaining of these identifiers is done in a centralized way and you can do so by making annotations reference a set of statically defined identifiers in a separate class or interface. Such class/interface gives a global view of the identifiers in use and so can make it easier to assign new ids. Implementors can optionally avoid giving a meaningful implementation to this method (i.e. return null) and instead rely on XML or programmatic configuration to provide the AdvancedExternalizer id. If no id can be determined via the implementation or XML/programmatic configuration, an error will be reported. If an id has been defined both via the implementation and XML/programmatic configuration, the value defined via XML/programmatic configuration will be used ignoring the other.
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