nl.esi.metis.aisparser.impl.AISMessageIllegalImpl Maven / Gradle / Ivy

Go to download

Show more of this group Show more artifacts with this name
Show all versions of EsiAisParser Show documentation

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.

The newest version!

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

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

import nl.esi.metis.aisparser.AISMessageIllegal;
import nl.esi.metis.aisparser.Sixbit;
import nl.esi.metis.aisparser.annotations.AISNoCompleteMessageIdAnnotation;
import nl.esi.metis.aisparser.annotations.AISNoCompleteRepeatIndicatorAnnotation;
import nl.esi.metis.aisparser.annotations.AISNoCompleteUserIdAnnotation;
import nl.esi.metis.aisparser.annotations.Annotation;
import nl.esi.metis.aisparser.provenance.AISMessageProvenance;
import nl.esi.metis.aisparser.provenance.VDMMessageProvenance;

//TODO also store content of inconsistent message?

/** AIS Message Inconsistent
 * Class to store AIS Messages that don't adhere to the standard
 */
class AISMessageIllegalImpl implements AISMessageIllegal {
	private static final int MESSAGEID_FROM = 1;
	private static final int MESSAGEID_TO = 6;

	private int messageID;
	/** messageID
	 * @return int value of messageID (6 bits [1,6])
	 */
	public int getMessageID() { return messageID; }


	private static final int REPEATINDICATOR_FROM = 7;
	private static final int REPEATINDICATOR_TO = 8;

	private int repeatIndicator;
	/** repeatIndicator
	 * @return int value of repeatIndicator (2 bits [7,8])
	 */
	public int getRepeatIndicator() { return repeatIndicator; }


	private static final int USERID_FROM = 9;
	private static final int USERID_TO = 38;

	private int userID;
	/** userID
	 * @return int value of userID (30 bits [9,38])
	 */
	public int getUserID() { return userID; }
	

	/** The provenance */
	private VDMMessageProvenance provenance;

	/** The annotations */
	protected List annotations = new ArrayList();
	
	/** Returns the provenance, i.e., a description of where the AIS message came from, including a time stamp.
	 * @return the provenance
	 */
	public AISMessageProvenance getProvenance() {
		return new AISMessageProvenance(provenance, annotations);
	}
	

	/** Constructs an object representing an illegal message.
     * @param content the content of the message
     * @param prov the provenance of the message
     */
	public AISMessageIllegalImpl(Sixbit content, VDMMessageProvenance prov)
	{
    	this.provenance = prov;

    	if (content.length() < MESSAGEID_TO){
    		messageID = content.getIntFromTo(MESSAGEID_FROM,content.length());		//TODO: Is this the correct interpretation, or should we provide a range of possible values (depending on the possible values the missing bits could have)
    		annotations.add(new AISNoCompleteMessageIdAnnotation(content.length()));
    		annotations.add(new AISNoCompleteRepeatIndicatorAnnotation(0));
    		annotations.add(new AISNoCompleteUserIdAnnotation(0));
    	}
    	else {
    		messageID = content.getIntFromTo(MESSAGEID_FROM,MESSAGEID_TO);
    		
	    	if (content.length() < REPEATINDICATOR_TO)
	    	{
	    		repeatIndicator = content.getIntFromTo(REPEATINDICATOR_FROM,content.length()); //TODO: Is this the correct interpretation, or should we provide a range of possible values (depending on the possible values the missing bits could have)
	    		annotations.add(new AISNoCompleteRepeatIndicatorAnnotation(content.length()+1-REPEATINDICATOR_FROM));
	    		annotations.add(new AISNoCompleteUserIdAnnotation(0));
	    	}
	    	else {
	    		repeatIndicator = content.getIntFromTo(REPEATINDICATOR_FROM,REPEATINDICATOR_TO);

	    		assert (content.length() < USERID_TO); 
	    		userID = content.getIntFromTo(USERID_FROM,content.length()); //TODO: Is this the correct interpretation, or should we provide a range of possible values (depending on the possible values the missing bits could have)
	    		annotations.add(new AISNoCompleteUserIdAnnotation(content.length()+1-USERID_FROM));
	    	}
    	}
	}

    /**
     * Generates a String representing the parsed AISMessage 
     * Format:
     * all fields are shown in the order and units as specified by the standard separated by SEPARATORs
     * @see java.lang.Object#toString()
     */
    public String toString()
    {
    	return  Integer.toString(messageID) + AISMessageImpl.SEPARATOR +
    			Integer.toString(repeatIndicator) + AISMessageImpl.SEPARATOR +
    			Integer.toString(userID) + AISMessageImpl.SEPARATOR ;
    }
}