net.sf.jrtps.message

Class NackFrag

java.lang.Object

net.sf.jrtps.message.SubMessage

net.sf.jrtps.message.NackFrag

public class NackFrag
extends SubMessage

The NackFrag Submessage is used to communicate the state of a Reader to a Writer. When a data change is sent as a series of fragments, the NackFrag Submessage allows the Reader to inform the Writer about specific fragment numbers it is still missing. see 8.3.7.10 NackFrag, 9.4.5.13 NackFrag Submessage

Author:

mcr70

Nested Class Summary

Nested classes/interfaces inherited from class net.sf.jrtps.message.SubMessage

SubMessage.Kind

Field Summary

Fields

Modifier and Type	Field and Description
static int	KIND

Fields inherited from class net.sf.jrtps.message.SubMessage

header

Constructor Summary

Constructors

Constructor and Description
NackFrag(SubMessageHeader smh, RTPSByteBuffer bb)

Method Summary

Modifier and Type	Method and Description
int	getCount() A counter that is incremented each time a new NackFrag message is sent.
SequenceNumberSet	getFragmentNumberState() Communicates the state of the reader to the writer.
EntityId	getReaderId() Identifies the Reader entity that requests to receive certain fragments.
EntityId	getWriterId() Identifies the Writer entity that is the target of the NackFrag message.
SequenceNumber	getWriterSequenceNumber() The sequence number for which some fragments are missing.
void	writeTo(RTPSByteBuffer bb) Writes this SubMessage into given RTPSByteBuffer.

Methods inherited from class net.sf.jrtps.message.SubMessage

getHeader, getKind, toString

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

KIND

public static final int KIND

See Also:

Constant Field Values

Constructor Detail

NackFrag

public NackFrag(SubMessageHeader smh,
                RTPSByteBuffer bb)

Method Detail

getReaderId

public EntityId getReaderId()

Identifies the Reader entity that requests to receive certain fragments.

Returns:

EntityId of the reader

getWriterId

public EntityId getWriterId()

Identifies the Writer entity that is the target of the NackFrag message. This is the Writer Entity that is being asked to re-send some fragments.

Returns:

EntityId of the writer

getWriterSequenceNumber

public SequenceNumber getWriterSequenceNumber()

The sequence number for which some fragments are missing.

Returns:

sequence number

getFragmentNumberState

public SequenceNumberSet getFragmentNumberState()

Communicates the state of the reader to the writer. The fragment numbers that appear in the set indicate missing fragments on the reader side. The ones that do not appear in the set are undetermined (could have been received or not).

Returns:

SequenceNumberSet indicating missing fragments

getCount

public int getCount()

A counter that is incremented each time a new NackFrag message is sent. Provides the means for a Writer to detect duplicate NackFrag messages that can result from the presence of redundant communication paths.

Returns:

a count

writeTo

public void writeTo(RTPSByteBuffer bb)

Description copied from class: SubMessage

Writes this SubMessage into given RTPSByteBuffer.

Specified by:

writeTo in class SubMessage

Parameters:

bb - RTPSByteBuffer