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Interface ChangeCallback

All Known Implementing Classes:

AbstractChangeCallback

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 ChangeCallback

Describes a callback for receiving streaming changes.

Implementations of this callback performing internal paging may return false from onChange(Change) to indicate no more changes are desired. Such implementations are encouraged to also implement the PagedCallback interface to allow the system to optimise output handling, where possible, based on the page being requested.

Note: Implementors are strongly encouraged to extend from AbstractChangeCallback. This interface will change, over time, and any class implementing it directly will be broken by such changes. Extending from the abstract class will help prevent such breakages.

See Also:

AbstractChangeCallback

Method Summary

Modifier and Type	Method and Description
boolean	onChange(Change change) Provides a change to the callback for processing.
default void	onEnd(ChangeSummary summary) Called after the final change has been streamed.
default void	onStart(ChangeContext context) Called before the first change is streamed.

Method Detail

onChange

boolean onChange(@Nonnull
                 Change change)
          throws IOException

Provides a change to the callback for processing.

If the callback is performing internal paging, it may signal the end of the page by returning false here. When doing so, onEnd(ChangeSummary) will never receive true for truncation.

Parameters:

change - the change to process

Returns:

true if additional changes should be provided; otherwise, false if the callback has received as many changes as desired

Throws:

IOException - may be thrown by implementations which perform I/O

onEnd

default void onEnd(@Nonnull
                   ChangeSummary summary)
            throws IOException

Called after the final change has been streamed.

Note: If there were no changes, this method may be called immediately after onStart(ChangeContext) without any calls to onChange(Change).

Parameters:

summary - summarizes the request and the streamed changes

Throws:

IOException - may be thrown by implementations which perform I/O.

onStart

default void onStart(@Nonnull
                     ChangeContext context)
              throws IOException

Called before the first change is streamed.

Parameters:

context - provides details about the request for which changes are being streamed

Throws:

IOException - may be thrown by implementations which perform I/O.