StreamingAemWriter.java
/* Copyright 2002-2022 CS GROUP
* Licensed to CS GROUP (CS) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* CS 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.
*/
package org.orekit.files.ccsds.ndm.adm.aem;
import java.io.IOException;
import org.hipparchus.exception.LocalizedCoreFormats;
import org.orekit.errors.OrekitException;
import org.orekit.errors.OrekitMessages;
import org.orekit.files.ccsds.definitions.FrameFacade;
import org.orekit.files.ccsds.section.Header;
import org.orekit.files.ccsds.utils.generation.Generator;
import org.orekit.propagation.Propagator;
import org.orekit.propagation.SpacecraftState;
import org.orekit.propagation.sampling.OrekitFixedStepHandler;
import org.orekit.time.AbsoluteDate;
/**
* A writer for AEM files.
*
* <p> Each instance corresponds to a single AEM file.
*
* <p> This class can be used as a step handler for a {@link Propagator}.
*
* <pre>{@code
* Propagator propagator = ...; // pre-configured propagator
* AEMWriter aemWriter = ...; // pre-configured writer
* try (Generator out = ...; // set-up output stream
* StreamingAemWriter sw = new StreamingAemWriter(out, aemWriter)) { // set-up streaming writer
*
* // write segment 1
* propagator.getMultiplexer().add(step, sw.newSegment());
* propagator.propagate(startDate1, stopDate1);
*
* ...
*
* // write segment n
* propagator.getMultiplexer().clear();
* propagator.getMultiplexer().add(step, sw.newSegment());
* propagator.propagate(startDateN, stopDateN);
*
* }
* }</pre>
* @author Bryan Cazabonne
* @author Luc Maisonobe
* @see <a href="https://public.ccsds.org/Pubs/504x0b1c1.pdf">CCSDS 504.0-B-1 Attitude Data Messages</a>
* @see AemWriter
* @since 10.2
*/
public class StreamingAemWriter implements AutoCloseable {
/** Generator for AEM output. */
private final Generator generator;
/** Writer for the AEM message format. */
private final AemWriter writer;
/** Header. */
private final Header header;
/** Current metadata. */
private final AemMetadata metadata;
/** Indicator for writing header. */
private boolean headerWritePending;
/** Simple constructor.
* @param generator generator for AEM output
* @param writer writer for the AEM message format
* @param header file header (may be null)
* @param template template for metadata
* @since 11.0
*/
public StreamingAemWriter(final Generator generator, final AemWriter writer,
final Header header, final AemMetadata template) {
this.generator = generator;
this.writer = writer;
this.header = header;
this.metadata = template.copy(header == null ? writer.getDefaultVersion() : header.getFormatVersion());
this.headerWritePending = true;
}
/**
* Create a writer for a new AEM attitude ephemeris segment.
* <p> The returned writer can only write a single attitude ephemeris segment in an AEM.
* This method must be called to create a writer for each attitude ephemeris segment.
* @return a new AEM segment writer, ready for use.
*/
public SegmentWriter newSegment() {
return new SegmentWriter();
}
/** {@inheritDoc} */
@Override
public void close() throws IOException {
writer.writeFooter(generator);
}
/** A writer for a segment of an AEM. */
public class SegmentWriter implements OrekitFixedStepHandler {
/**
* {@inheritDoc}
*
* <p> Sets the {@link AemMetadataKey#START_TIME} and {@link AemMetadataKey#STOP_TIME} in this
* segment's metadata if not already set by the user. Then calls {@link AemWriter#writeHeader(Generator, Header)
* writeHeader} if it is the first segment) and {@link AemWriter#writeMetadata(Generator, AemMetadata)} to start the segment.
*/
@Override
public void init(final SpacecraftState s0, final AbsoluteDate t, final double step) {
try {
final AbsoluteDate date = s0.getDate();
if (t.isBefore(date)) {
throw new OrekitException(OrekitMessages.NON_CHRONOLOGICALLY_SORTED_ENTRIES,
date, t, date.durationFrom(t));
}
if (headerWritePending) {
// we write the header only for the first segment
writer.writeHeader(generator, header);
headerWritePending = false;
}
metadata.setStartTime(date);
metadata.setUseableStartTime(null);
metadata.setUseableStopTime(null);
metadata.setStopTime(t);
if (metadata.getEndpoints().getFrameA() == null ||
metadata.getEndpoints().getFrameA().asSpacecraftBodyFrame() == null) {
// the external frame must be frame A
metadata.getEndpoints().setFrameA(FrameFacade.map(s0.getAttitude().getReferenceFrame()));
} else {
// the external frame must be frame B
metadata.getEndpoints().setFrameB(FrameFacade.map(s0.getAttitude().getReferenceFrame()));
}
writer.writeMetadata(generator, metadata);
writer.startAttitudeBlock(generator);
} catch (IOException e) {
throw new OrekitException(e, LocalizedCoreFormats.SIMPLE_MESSAGE, e.getLocalizedMessage());
}
}
/** {@inheritDoc}. */
@Override
public void handleStep(final SpacecraftState currentState) {
try {
writer.writeAttitudeEphemerisLine(generator, metadata, currentState.getAttitude().getOrientation());
} catch (IOException e) {
throw new OrekitException(e, LocalizedCoreFormats.SIMPLE_MESSAGE, e.getLocalizedMessage());
}
}
/** {@inheritDoc}. */
@Override
public void finish(final SpacecraftState finalState) {
try {
writer.endAttitudeBlock(generator);
} catch (IOException e) {
throw new OrekitException(e, LocalizedCoreFormats.SIMPLE_MESSAGE, e.getLocalizedMessage());
}
}
}
}