nl.esi.metis.aisparser.provenance.VDMMessageProvenance Maven / Gradle / Ivy

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This package supports the parsing of AIS messages in Java. AIS, the Automatic Identification System, is a system aiming at improving maritime safety by exchanging messages between ships, other vehicles in particular aircraft involved in search-and-rescue (SAR), and (fixed) base stations. To be precise, this package support the ITU-R M.1371-4 AIS standard. See our extensive javadoc and in particular the class AISParser for more information on how to use this package. The parser was used in the Poseidon project, and is improved in the Metis project to better handle uncertain information. Both projects were led by the Embedded Systems Institute. In both projects Thales Nederlands was the carrying industrial partner, and multiple Dutch universities participated.

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/* ESI AIS Parser
 * 
 * Copyright 2011/2012 by Pierre van de Laar & Pierre America (Embedded Systems Institute)
 * Copyright 2008 by Brian C. Lane 
 * All Rights Reserved
 * 
 */
package nl.esi.metis.aisparser.provenance;

import java.util.ArrayList;
import java.util.List;

import nl.esi.metis.aisparser.annotations.Annotation;

/** An object of this class indicates that information is contained in an VDM message that was obtained from one or more sources together.
 * @author Pierre America
 * @author Pierre van de Laar
 */
public class VDMMessageProvenance implements Provenance {

	/** The time when the information was created. */
	private double time;

	/** Returns the time stamp when the information item was created. */
	public double getTime() {
		return time;
	}

	/** Returns a description of the provenance of the information item. 
	 * In this case, it mentions the sources that are combined to form the current VDM message. */
	public String getProvenanceTree(String layout) {
		StringBuilder sb = new StringBuilder(layout + "VDMMessage combines\n");
		final String newLayout = layout + " - ";
		for(Provenance p : parts)
		{
			if (p == null)
			{
				sb.append(newLayout + "null\n");
			}
			else
			{
				sb.append(p.getProvenanceTree(newLayout) +"\n");
			}
		}
		return sb.toString();
	}

	/** This array contains the provenance objects for all the parts of the VDM message */
	private VDMLineProvenance[] parts;
	
	/** Returns the provenance objects for all the parts of the VDM message. */
	public VDMLineProvenance[] getParts ()  {
		return parts;
	}
	
	/** The annotations associated with this VDM Message */
	private List annotations = new ArrayList();

	/** Returns the annotations associated with this VDM message. */
	@Override
	public List getAnnotations() {
		List retval = new ArrayList();
		retval.addAll(annotations);
		for(Provenance p: parts)
		{
			/* TODO: should the same remarks with every VDM line be removed? I.e. to prevent the following messages?
			 * VDMMessage combines
			 *  - C:\Metis\AIS\AISHub\2011\201112201030.nmea:3702
			 *  - C:\Metis\AIS\AISHub\2011\201112201030.nmea:3703
			 * Deviation from standard: Use of '' instead of ('A' or 'B') as channel identifiers.
			 * Deviation from standard: Use of '' instead of ('A' or 'B') as channel identifiers.
			 *
			 * VDMMessage combines
			 *  - C:\Metis\AIS\AISHub\2011\201112201030.nmea:4379
			 *  - C:\Metis\AIS\AISHub\2011\201112201030.nmea:4380
			 * Well known deviation from standard: Use of '2' instead of 'B' as channel identifiers.
			 * Well known deviation from standard: Use of '2' instead of 'B' as channel identifiers.
			 */
			if (p != null)	// Feedback by YALTES - 01/15/2013
			{
				retval.addAll(p.getAnnotations());
			}
		}
		return retval;
	}

	private String channelId;
	/** Get Channel Identifier of VDM Message
	 * @return channel id 
	 */
	public String getChannelId() {
		return channelId;
	}

	
	/** Constructs a provenance object describing an VDM message that was obtained from one or more parts together.
	 * @param parts the provenance objects for all the parts of the VDM message
	 */
	public VDMMessageProvenance (VDMLineProvenance[] parts, List annotations, String channelId)
	{
		this.parts = parts;
		this.annotations = annotations;
		this.channelId = channelId;
		
		//bounded linear search to find first time
		int x = 0;
		int y = parts.length;
		while(x != y)
		{
			if(parts[x]== null)
			{
				x++;
			}
			else
			{
				y=x;
			}
		}
		if(x < parts.length)
		{
			time = parts[x].getTime();
		}
		else
		{
			time = 0;
		}
	}
	
	/** Get Number Of Parts of VDM Message
	 * @return number of parts 
	 */
	public int nrOfParts()
	{
		return parts.length;
	}

}