mil.navy.nps.dis
Class EventID

java.lang.Object
  mil.navy.nps.dis.PduElement
      mil.navy.nps.dis.EventID

All Implemented Interfaces:

java.lang.Cloneable, SerializationInterface

public class EventID

extends PduElement

Record for event identification.

Version:

1.0

Author:

Don McGregor (http://www.npsnet.org/~mcgredo)

Location:

Web: http://www.web3d.org/WorkingGroups/vrtp/mil/navy/nps/dis/EventID.java

or locally: ~/mil/navy/nps/dis/EventID.java

Hierarchy Diagram:

Summary:

The event identification shall be specified by the Event Identifier Record.

Explanation:

The record shall consist of a Simulation Address Record and an Event Number. The latter is uniquely assigned within the host by the simulation application that initiates the sequence of events. The Event Identifier Record shall be set to one for each exercise and incremented by one for each fire event or collision event. In the case where all possible values are exhausted, the numbers may be reused, beginning at one.

Note that I've flattened the object, such that the site and application ID are in this object, rather than in an object/class of their own. This is a questionable move.

It inherits from PduElement, the abstract class that all non-PDUs inherit from. As usual, it knows how to serialize and deserialize itself, clone itself, etc.

The event ID is used to keep events straight. It is employed in the fire and detonation PDUs, for example.

This is extremely similar to the EventID class. It includes a hash function for the object, in case we want to use this as a key in a hash table.

History:

12Dec96 /Don McGregor /New

10Mar97 /Don McGregor /Cleaned up for javadoc

16Apr97 /Don McGregor /PrintStream passed to printValues

12Aug97 /Don McGregor /elaborated printValues

8Dec97 /Ronan Fauglas /changes for documentation templates + complements in documentation

11Dec97 /Ronan Fauglas /changed access methods: thisVariable() --> getThisVariable()

11Dec97 /Ronan Fauglas /changed instance variable from "" to protected

11Dec97 /Ronan Fauglas /changed entity 2 event in event accessor method...

References:

DIS Data Dictionary :Event Identifier Record

DIS-Java-VRML Working Group: http://www.web3d.org/WorkingGroups/vrtp/dis-java-vrml/

DIS specification : IEEE 1278.1, Section 5.3.18

See Also:

PduElement, SerializationInterface, EntityStatePdu

Field Summary

protected UnsignedShort	applicationID Application Identifier Field - Each simulation application at a DIS site shall be assigned an application identifier unique within that site.
protected UnsignedShort	eventID Event Indentifier Field - A general purpose Identifier used to uniquely identify up to 65535 items.
protected UnsignedShort	siteID Site Identifier Field - Each DIS site shall be assigned a unique Site Identifier.
protected static int	sizeOf Constant value--size of an EventID as written out to the wire.

Constructor Summary

EventID()
Default constructor--fills with zeros for all values.

EventID(short pSiteID, short pApplicationID, short pEventID)

Method Summary

java.lang.Object	clone() Makes deep copies of all the instance variables, so we don't have two objects pointing to the same data.
void	deSerialize(java.io.DataInputStream inputStream) Deserialize our data from the input stream.
boolean	equals(java.lang.Object obj) Makes a "numeric equality" test.
UnsignedShort	getApplicationID()
UnsignedShort	getEventID()
UnsignedShort	getSiteID()
int	hashCode() This provides a hash code for the object.
int	length() Returns the length of the object when serialized in a stream.
void	printValues(int indentLevel, java.io.PrintStream printStream) Prints the generated serialized object for debugging.
void	serialize(java.io.DataOutputStream outputStream) Serialize our data out to the stream.
void	setApplicationID(int pApplicationID)
void	setApplicationID(UnsignedShort pApplicationID)
void	setEventID(int pEventID)
void	setEventID(UnsignedShort pEventID)
void	setSiteID(int pSiteID)
void	setSiteID(UnsignedShort pSiteID)

Methods inherited from class java.lang.Object

finalize, getClass, notify, notifyAll, toString, wait, wait, wait

Field Detail

siteID

protected UnsignedShort siteID

Site Identifier Field - Each DIS site shall be assigned a unique Site Identifier.

applicationID

protected UnsignedShort applicationID

Application Identifier Field - Each simulation application at a DIS site shall be assigned an application identifier unique within that site.

eventID

protected UnsignedShort eventID

Event Indentifier Field - A general purpose Identifier used to uniquely identify up to 65535 items.

Value:

The event number field of shall be set to one for each exercise and incremented by one for each fire event, collision event or electromagnetic mission event. In the case where all values are exhausted, the numbers may be reused, beginning again at one.

sizeOf

protected static final int sizeOf

Constant value--size of an EventID as written out to the wire. Here: sizeOf = 6 bytes

See Also:

Constant Field Values

Constructor Detail

EventID

public EventID()

Default constructor--fills with zeros for all values.

EventID

public EventID(short pSiteID,
               short pApplicationID,
               short pEventID)

Method Detail

clone

public java.lang.Object clone()

Description copied from class: PduElement

Makes deep copies of all the instance variables, so we don't have two objects pointing to the same data. The accessor methods make copies of the objects, rather than returning the objects themselves. The runtime provides the right object type with the call to super.clone(), and we cast it to our type. Subclasses should do the same thing, and all these ivars will be taken care of automatically.

Overrides:

clone in class PduElement

Returns:

a clone of this instance

See Also:

Object

serialize

public void serialize(java.io.DataOutputStream outputStream)

Description copied from class: PduElement

Serialize our data out to the stream. Subclasses of us should call super.Serialize() to make sure the superclasse's data is serialized out. The order in which instance variables are serialized is significant. They must be serialized in the same order they appear in the DIS spec. Prints out some information during execution if debugging flag is set.

Specified by:

serialize in interface SerializationInterface

Specified by:

serialize in class PduElement

Parameters:

outputStream - the stream to which this object is serialized

deSerialize

public void deSerialize(java.io.DataInputStream inputStream)

Description copied from class: PduElement

Deserialize our data from the input stream. Subclasses of us should call super.deSerialize to make sure the superclass's data are properly affected. The order in which instance variables are serialized is significant. They must be deSerialized in the same order as they have been serialized as specified by the DIS spec.

Specified by:

deSerialize in interface SerializationInterface

Specified by:

deSerialize in class PduElement

Parameters:

inputStream - the stream from which this object is initialized

length

public int length()

Description copied from class: PduElement

Returns the length of the object when serialized in a stream.

Specified by:

length in class PduElement

Returns:

the length of the object when serialized in a stream

printValues

public void printValues(int indentLevel,
                        java.io.PrintStream printStream)

Description copied from class: PduElement

Prints the generated serialized object for debugging.

Specified by:

printValues in class PduElement

Parameters:

indentLevel - number of spaces to indent for visibility

hashCode

public int hashCode()

This provides a hash code for the object. A Hash code is a handy way to uniquely identify entities.

• The problem:
  There's a problem with the core API, since there are 48 bits of information in the object, but the hash code has only 32 bits to put things in. Hence we must make sure that our entities won't interfere between each others.
• The solution:
  The solution right now is to ignore the application ID when generating the hash code. Furthermore, the entity ID is in the upper 16 bits, while the site ID is in the lower 16 bits. The idea is that this will help spread out the hash code a bit more, since there are probably many more entities than sites, and putting the part with more information in the MSB helps spread things out.

Returns:

a hash code value for this object

See Also:

EntityID.hashCode()

equals

public boolean equals(java.lang.Object obj)

Makes a "numeric equality" test.

Parameters:

obj - the object want to be compared with this object.

Returns:

yes if the object in parameter is of the same type and if the numerical values of both objects are equal.

getSiteID

public UnsignedShort getSiteID()

setSiteID

public void setSiteID(UnsignedShort pSiteID)

setSiteID

public void setSiteID(int pSiteID)

getApplicationID

public UnsignedShort getApplicationID()

setApplicationID

public void setApplicationID(UnsignedShort pApplicationID)

setApplicationID

public void setApplicationID(int pApplicationID)

getEventID

public UnsignedShort getEventID()

setEventID

public void setEventID(UnsignedShort pEventID)

setEventID

public void setEventID(int pEventID)