net.sf.jrtps.udds

Class DataReader<T>

java.lang.Object

net.sf.jrtps.udds.Entity<T,PublicationData>

net.sf.jrtps.udds.DataReader<T>

Type Parameters:

T - Type of the DataReader. Type may be obtained from an external tool like IDL compiler, or it may be more dynamically constructed Object that is used with uDDS.

public class DataReader<T>
extends Entity<T,PublicationData>

This class represents a strongly typed DataReader in spirit of DDS specification. DataReader maintains a history cache where it keeps Samples received from writers on the network. There are two ways to get these Samples from DataReader. One is by using any of the get methods, and the other is by registering a SampleListener.

Author:

mcr70

Field Summary

Fields

Modifier and Type	Field and Description
protected RTPSReader<T>	rtps_reader RTPSReader associated with this DataReader

Fields inherited from class net.sf.jrtps.udds.Entity

communicationListeners

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	DataReader(Participant p, Class<T> type, RTPSReader<T> reader) Constructor with null typeName
protected	DataReader(Participant p, Class<T> type, String typeName, RTPSReader<T> reader) Constructor for DataReader.

Method Summary

Modifier and Type	Method and Description
void	addSampleListener(SampleListener<T> listener) Adds a SampleListener to this DataReader
void	addWriterListener(WriterLivelinessListener wl) Adds a WriterListener to this DataReader.
void	clear(List<Sample<T>> samples) Clears Samples from the history cache.
Instance<T>	getInstance(Sample<T> sample) Gets an Instance of given Sample.
Set<Instance<T>>	getInstances() Gets a Set of instances this DataReader knows.
List<Sample<T>>	getSamples() Gets all the samples this DataReader knows about.
List<Sample<T>>	getSamplesSince(Sample<T> s) Gets all the Samples that have been received after given Sample.
void	removeSampleListener(SampleListener<T> listener) Removes a given SampleListener from this DataReader.
void	removeWriterListener(WriterLivelinessListener wl) Removes a WriterListener from this DataReader.
void	setContentFilter(ContentFilter<T> cf) Sets a ContentFilter.

Methods inherited from class net.sf.jrtps.udds.Entity

addCommunicationListener, getGuid, getParticipant, getTopicName, getType, getTypeName, removeCommunicationListener

Methods inherited from class java.lang.Object

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

Field Detail

rtps_reader

protected final RTPSReader<T> rtps_reader

RTPSReader associated with this DataReader

Constructor Detail

DataReader

protected DataReader(Participant p,
                     Class<T> type,
                     RTPSReader<T> reader)

Constructor with null typeName

Parameters:

p - Participant

type - Class of the type this DataReader handles

reader - RTPSReader used

DataReader

protected DataReader(Participant p,
                     Class<T> type,
                     String typeName,
                     RTPSReader<T> reader)

Constructor for DataReader.

Parameters:

p - Participant that created this DataReader

type - Type of this DataReader

typeName - Name of the type. If null, fully qualified class name is used

reader - associated RTPSReader

Method Detail

addSampleListener

public void addSampleListener(SampleListener<T> listener)

Adds a SampleListener to this DataReader

Parameters:

listener - Listener to add

addWriterListener

public void addWriterListener(WriterLivelinessListener wl)

Adds a WriterListener to this DataReader.

Parameters:

wl - WriterListener to add

getInstances

public Set<Instance<T>> getInstances()

Gets a Set of instances this DataReader knows.

Returns:

a Set of instances

getInstance

public Instance<T> getInstance(Sample<T> sample)

Gets an Instance of given Sample. Due to asynchronous nature of DDS applications, instance might be disposed after the Sample has been passed to application. In that case, this method will return null.

   App                      DataReader                  RTPSReader
    |------- getSamples() ----->|                           |
    |<------ samples -----------|                           |
    |                           |<-------- dispose ---------|
    |------- getInstance() ---->|                           |
    |<------ null --------------|                           |
    |                           |                           |
 

Parameters:

sample - a Sample, whose instance is retrieved

Returns:

Instance of given Sample, or null if there is no such Instance available.

getSamples

public List<Sample<T>> getSamples()

Gets all the samples this DataReader knows about. Samples are returned in the order they have been received.

Returns:

all the Samples

getSamplesSince

public List<Sample<T>> getSamplesSince(Sample<T> s)

Gets all the Samples that have been received after given Sample.

Parameters:

s - a Sample to compare.

Returns:

all the samples that have been received after given Sample

clear

public void clear(List<Sample<T>> samples)

Clears Samples from the history cache. Once cleared, they cannot be retrieved from the cache anymore. Note, that clearing samples from readers history cache is not the same thing as writer disposing. Reader clearing samples is merely a local operation while writer disposal is a global operation affecting all the entities in the network. Clearing can be thought of as a manual resource control on reader side.

Parameters:

samples - a List of Samples to clear.

removeSampleListener

public void removeSampleListener(SampleListener<T> listener)

Removes a given SampleListener from this DataReader.

Parameters:

listener - A listener to remove

removeWriterListener

public void removeWriterListener(WriterLivelinessListener wl)

Removes a WriterListener from this DataReader.

Parameters:

wl - WriterListener to remove

setContentFilter

public void setContentFilter(ContentFilter<T> cf)

Sets a ContentFilter. ContentFilterProperty from ContentFilter will be sent to writers. Writers that support writer side filtering will be able to apply filtering if the parameters of ContentFilterProperty match.

Parameters:

cf - ContentFilter to set