/
StreamDeferrer.java
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/
StreamDeferrer.java
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/*
* Copyright 2016 Deutsche Nationalbibliothek
*
* Licensed 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.
*/
package org.metafacture.flowcontrol;
import org.metafacture.framework.FluxCommand;
import org.metafacture.framework.StreamReceiver;
import org.metafacture.framework.annotations.Description;
import org.metafacture.framework.annotations.In;
import org.metafacture.framework.annotations.Out;
import org.metafacture.framework.helpers.DefaultStreamPipe;
/**
* Defers all stream events until an <i>end-record</i> is received. Once the
* event is received {@code StreamDeferrer} forwards all events it has received
* before the <i>end-record</i> event to the next downstream module. The
* <i>end-record</i> event is forwarded immediately.
* <p>
* The {@code StreamDeferrer} is useful when merging two or more streams of
* events into one. The module is intended to be added at the end of each flow.
* There it ensures that the events for each record are forwarded consecutively
* to the merged flow without them being mixed with events belonging to a record
* from another stream.
*
* @author Christoph Böhme
*/
@Description("Defers all stream events until an end-record event is received")
@FluxCommand("defer-stream")
@In(StreamReceiver.class)
@Out(StreamReceiver.class)
public class StreamDeferrer extends DefaultStreamPipe<StreamReceiver> {
private final StreamBuffer buffer = new StreamBuffer();
/**
* Creates an instance of {@link StreamDeferrer}.
*/
public StreamDeferrer() {
}
@Override
public void startRecord(final String identifier) {
buffer.clear();
buffer.startRecord(identifier);
}
@Override
public void endRecord() {
buffer.endRecord();
buffer.replay();
}
@Override
public void startEntity(final String name) {
buffer.startEntity(name);
}
@Override
public void endEntity() {
buffer.endEntity();
}
@Override
public void literal(final String name, final String value) {
buffer.literal(name, value);
}
@Override
protected void onSetReceiver() {
buffer.setReceiver(getReceiver());
}
@Override
protected void onResetStream() {
buffer.clear();
}
@Override
protected void onCloseStream() {
buffer.clear();
}
}