org.axonframework.serialization.upcasting

Interface Upcaster<T>

Type Parameters:

T - The data format that this upcaster uses to represent the data

All Known Subinterfaces:

EventUpcaster

All Known Implementing Classes:

ContextAwareEventMultiUpcaster, ContextAwareSingleEntryMultiUpcaster, ContextAwareSingleEntryUpcaster, ContextAwareSingleEventUpcaster, EventMultiUpcaster, EventTypeUpcaster, EventUpcasterChain, GenericUpcasterChain, NoOpEventUpcaster, SingleEntryMultiUpcaster, SingleEntryUpcaster, SingleEventUpcaster

Functional Interface:

This is a functional interface and can therefore be used as the assignment target for a lambda expression or method reference.

@FunctionalInterface
public interface Upcaster<T>

Interface for Upcasters. An upcaster is the mechanism used to convert deprecated (typically serialized) objects and convert them into the current format. If the serializer itself is not able to cope with the changed formats (XStream, for example, will allow for some changes by using aliases), the Upcaster will allow you to configure more complex structural transformations.

Upcasters work on intermediate representations of the object to upcast. In some cases, this representation contains a byte array, while in other cases they contain an object structure. For performance reasons, it is advisable to ensure that all upcasters in the same upcaster chain (where one's output is another's input) use the same intermediate representation content type.

Since:

3.0

Author:

Rene de Waele

Method Summary

Modifier and Type	Method and Description
Stream<T>	upcast(Stream<T> intermediateRepresentations) Apply this upcaster to a stream of intermediateRepresentations and return the altered stream.

Method Detail

upcast

Stream<T> upcast(Stream<T> intermediateRepresentations)

Apply this upcaster to a stream of intermediateRepresentations and return the altered stream.

To upcast an object an upcaster should apply a mapping function to the input stream (Stream.map(java.util.function.Function)). To remove an object from the stream the upcaster should filter the input stream (Stream.filter(java.util.function.Predicate)). To split an input object into more than one objects use Stream.flatMap(java.util.function.Function).

In some cases the upcasting result of an Upcaster may depend on more than one input object. In that case an Upcaster may store state in the method during upcasting or even read ahead in the stream.

Parameters:

intermediateRepresentations - The input stream of representations of objects

Returns:

the output stream of representations after applying the upcast function