StreamingOemWriter.java
/* Contributed in the public domain.
* 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.odm.oem;
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.ndm.odm.OdmHeader;
import org.orekit.files.ccsds.utils.generation.Generator;
import org.orekit.frames.Frame;
import org.orekit.propagation.Propagator;
import org.orekit.propagation.SpacecraftState;
import org.orekit.propagation.sampling.OrekitFixedStepHandler;
import org.orekit.time.AbsoluteDate;
import org.orekit.utils.TimeStampedPVCoordinates;
/**
* A writer for OEM files.
*
* <p> Each instance corresponds to a single OEM file. A new OEM ephemeris segment is
* started by calling {@link #newSegment()}.
*
* <p>
* The segments returned by this class can be used as step handlers for a {@link Propagator}.
* </p>
*
* <pre>{@code
* Propagator propagator = ...; // pre-configured propagator
* OEMWriter aemWriter = ...; // pre-configured writer
* try (Generator out = ...; // set-up output stream
* StreamingOemWriter sw = new StreamingOemWriter(out, oemWriter, header, metadata)) { // 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 Evan Ward
* @see <a href="https://public.ccsds.org/Pubs/502x0b2c1.pdf">CCSDS 502.0-B-2 Orbit Data
* Messages</a>
* @see <a href="https://public.ccsds.org/Pubs/500x0g4.pdf">CCSDS 500.0-G-4 Navigation
* Data Definitions and Conventions</a>
* @see OemWriter
*/
public class StreamingOemWriter implements AutoCloseable {
/** Generator for OEM output. */
private final Generator generator;
/** Writer for the OEM message format. */
private final OemWriter writer;
/** Header. */
private final OdmHeader header;
/** Current metadata. */
private final OemMetadata metadata;
/** If the propagator's frame should be used. */
private final boolean useAttitudeFrame;
/** If acceleration should be included in the output. */
private final boolean includeAcceleration;
/** Indicator for writing header. */
private boolean headerWritePending;
/**
* Construct a writer that for each segment uses the reference frame of the
* first state's attitude.
*
* @param generator generator for OEM output
* @param writer writer for the AEM message format
* @param header file header (may be null)
* @param template template for metadata
* @since 11.0
* @see #StreamingOemWriter(Generator, OemWriter, OdmHeader, OemMetadata, boolean)
*/
public StreamingOemWriter(final Generator generator, final OemWriter writer,
final OdmHeader header, final OemMetadata template) {
this(generator, writer, header, template, true);
}
/**
* Construct a writer that writes position, velocity, and acceleration at
* each time step.
*
* @param generator generator for OEM output
* @param writer writer for the AEM message format
* @param header file header (may be null)
* @param template template for metadata
* @param useAttitudeFrame if {@code true} then the reference frame for each
* segment is taken from the first state's attitude.
* Otherwise the {@code template}'s reference frame
* is used, {@link OemMetadata#getReferenceFrame()}.
* @see #StreamingOemWriter(Generator, OemWriter, OdmHeader, OemMetadata, boolean, boolean)
* @since 11.1.2
*/
public StreamingOemWriter(final Generator generator, final OemWriter writer,
final OdmHeader header, final OemMetadata template,
final boolean useAttitudeFrame) {
this(generator, writer, header, template, useAttitudeFrame, true);
}
/**
* Simple constructor.
*
* @param generator generator for OEM output
* @param writer writer for the AEM message format
* @param header file header (may be null)
* @param template template for metadata
* @param useAttitudeFrame if {@code true} then the reference frame for
* each segment is taken from the first state's
* attitude. Otherwise the {@code template}'s
* reference frame is used, {@link
* OemMetadata#getReferenceFrame()}.
* @param includeAcceleration if {@code true} then acceleration is included
* in the OEM file produced. Otherwise only
* position and velocity is included.
* @since 11.1.2
*/
public StreamingOemWriter(final Generator generator, final OemWriter writer,
final OdmHeader header, final OemMetadata template,
final boolean useAttitudeFrame,
final boolean includeAcceleration) {
this.generator = generator;
this.writer = writer;
this.header = header;
this.metadata = template.copy(header == null ? writer.getDefaultVersion() : header.getFormatVersion());
this.useAttitudeFrame = useAttitudeFrame;
this.includeAcceleration = includeAcceleration;
this.headerWritePending = true;
}
/**
* Create a writer for a new OEM ephemeris segment.
* <p> The returned writer can only write a single ephemeris segment in an OEM.
* This method must be called to create a writer for each ephemeris segment.
* @return a new OEM 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 OEM. */
public class SegmentWriter implements OrekitFixedStepHandler {
/** Reference frame of this segment. */
private Frame frame;
/** Empty constructor.
* <p>
* This constructor is not strictly necessary, but it prevents spurious
* javadoc warnings with JDK 18 and later.
* </p>
* @since 12.0
*/
public SegmentWriter() {
// nothing to do
}
/**
* {@inheritDoc}
*
* <p>Writes the header automatically on first segment.
* Sets the {@link OemMetadataKey#START_TIME} and {@link OemMetadataKey#STOP_TIME} in this
* segment's metadata if not already set by the user.
*/
@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 (useAttitudeFrame) {
frame = s0.getAttitude().getReferenceFrame();
metadata.setReferenceFrame(FrameFacade.map(frame));
} else {
frame = metadata.getFrame();
}
writer.writeMetadata(generator, metadata);
writer.startData(generator);
} catch (IOException e) {
throw new OrekitException(e, LocalizedCoreFormats.SIMPLE_MESSAGE, e.getLocalizedMessage());
}
}
/** {@inheritDoc}. */
@Override
public void handleStep(final SpacecraftState currentState) {
try {
final TimeStampedPVCoordinates pv =
currentState.getPVCoordinates(frame);
writer.writeOrbitEphemerisLine(generator, metadata, pv, includeAcceleration);
} catch (IOException e) {
throw new OrekitException(e, LocalizedCoreFormats.SIMPLE_MESSAGE, e.getLocalizedMessage());
}
}
/** {@inheritDoc}. */
@Override
public void finish(final SpacecraftState finalState) {
try {
writer.endData(generator);
} catch (IOException e) {
throw new OrekitException(e, LocalizedCoreFormats.SIMPLE_MESSAGE, e.getLocalizedMessage());
}
}
}
}