= EntityChangesSubscriber
:Notice: Licensed to the Apache Software Foundation (ASF) under one or more contributor license agreements. See the NOTICE file distributed with this work for additional information regarding copyright ownership. The ASF licenses this file to you under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at. http://www.apache.org/licenses/LICENSE-2.0 . Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR  CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.

SPI to receive a summary of the number of entities that have changed as the result of an interaction (action invocation or property edit).

One use case is for performance profiling: to determine the "footprint" of an interaction, which will have a direct impact on the response time of that interaction.

Only those entities that have publishing enabled (using * _DomainObject#entityChangePublishing()_ ) are included.

== API

[source,java]
.EntityChangesSubscriber.java
----
interface EntityChangesSubscriber {
  void onChanging(EntityChanges entityChanges)     // <.>
}
----

<.> xref:#onChanging_EntityChanges[onChanging(EntityChanges)]
+
--
Receives all changing entities (with publishing enabled using _DomainObject#entityChangePublishing()_ ) as an instance of xref:refguide:applib:index/services/publishing/spi/EntityChanges.adoc[EntityChanges] .
--

== Members

[#onChanging_EntityChanges]
=== onChanging(EntityChanges)

Receives all changing entities (with publishing enabled using _DomainObject#entityChangePublishing()_ ) as an instance of xref:refguide:applib:index/services/publishing/spi/EntityChanges.adoc[EntityChanges] .

The callback is called at the end of the transaction, during the pre-commit phase.

include::hooks/EntityChangesSubscriber_010-implementation.adoc[]

include::hooks/EntityChangesSubscriber_020-examples-and-usage.adoc[]
