org.omg.dds.sub

Interface DataReader<TYPE>

Type Parameters:

TYPE - The concrete type of the data to be read.

All Superinterfaces:

AutoCloseable, Closeable, DDSObject, DomainEntity<DataReaderListener<TYPE>,DataReaderQos>, Entity<DataReaderListener<TYPE>,DataReaderQos>

public interface DataReader<TYPE>
extends DomainEntity<DataReaderListener<TYPE>,DataReaderQos>

A DataReader allows the application (1) to declare the data it wishes to receive (i.e., make a subscription) and (2) to access the data received by the attached Subscriber. A DataReader refers to exactly one TopicDescription (either a Topic, a ContentFilteredTopic, or a MultiTopic) that identifies the data to be read. The subscription has a unique resulting type. The data reader may give access to several instances of the resulting type, which can be distinguished from each other by their keys. All operations except for the inherited operations Entity.setQos(org.omg.dds.core.EntityQos), Entity.getQos(), Entity.setListener(java.util.EventListener), Entity.getListener(), Entity.enable(), getStatusCondition(), and Entity.close() may fail with the exception NotEnabledException. All sample-accessing operations, namely all variants of read() or take(), may fail with the exception PreconditionNotMetException. Access to the Data Data is made available to the application by the following operations on DataReader objects: read(), take(), and the other methods beginning with those prefixes.. The general semantics of the "read" operations is that the application only gets access to the corresponding data; the data remains the middleware's responsibility and can be read again. The semantics of the "take" operations is that the application takes full responsibility for the data; that data will no longer be accessible to the DataReader. Consequently, it is possible for a DataReader to access the same sample multiple times but only if all previous accesses were read operations. Each of these operations returns an ordered collection of Samples (data values and associated meta-information). Each data value represents an atom of data information (i.e., a value for one instance). This collection may contain samples related to the same or different instances (identified by the key). Multiple samples can refer to the same instance if the settings of the History allow for it.

Nested Class Summary

Nested Classes

Modifier and Type	Interface and Description
static interface	DataReader.Selector<T> Selector class encapsulates different ways of selecting samples from a DataReader.

Method Summary

Methods

Modifier and Type	Method and Description
<OTHER> DataReader<OTHER>	cast() Cast this data reader to the given type, or throw an exception if the cast fails.
void	closeContainedEntities() This operation closes all the entities that were created by means of the "create" operations on the DataReader.
QueryCondition<TYPE>	createQueryCondition(String queryExpression, List<String> queryParameters) This operation creates a QueryCondition.
QueryCondition<TYPE>	createQueryCondition(Subscriber.DataState states, String queryExpression, List<String> queryParameters) This operation creates a QueryCondition.
ReadCondition<TYPE>	createReadCondition(Subscriber.DataState states) This operation creates a ReadCondition.
TYPE	getKeyValue(TYPE keyHolder, InstanceHandle handle) This operation can be used to retrieve the instance key that corresponds to an instance handle.
LivelinessChangedStatus	getLivelinessChangedStatus() This operation allows access to the LIVELINESS_CHANGED communication status.
PublicationBuiltinTopicData	getMatchedPublicationData(InstanceHandle publicationHandle) This operation retrieves information on a publication that is currently "associated" with the DataReader; that is, a publication with a matching Topic and compatible QoS that the application has not indicated should be "ignored" by means of DomainParticipant.ignorePublication(InstanceHandle).
Set<InstanceHandle>	getMatchedPublications() This operation retrieves the list of publications currently "associated" with the DataReader; that is, publications that have a matching Topic and compatible QoS that the application has not indicated should be "ignored" by means of DomainParticipant.ignorePublication(InstanceHandle).
Subscriber	getParent()
RequestedDeadlineMissedStatus	getRequestedDeadlineMissedStatus() This operation allows access to the REQUESTED_DEADLINE_MISSED communication status.
RequestedIncompatibleQosStatus	getRequestedIncompatibleQosStatus() This operation allows access to the REQUESTED_INCOMPATIBLE_QOS communication status.
SampleLostStatus	getSampleLostStatus() This operation allows access to the SAMPLE_LOST communication status.
SampleRejectedStatus	getSampleRejectedStatus() This operation allows access to the SAMPLE_REJECTED communication status.
StatusCondition<DataReader<TYPE>>	getStatusCondition() This operation allows access to the StatusCondition associated with the Entity.
SubscriptionMatchedStatus	getSubscriptionMatchedStatus() This operation allows access to the SUBSCRIPTION_MATCHED communication status.
TopicDescription<TYPE>	getTopicDescription()
ModifiableInstanceHandle	lookupInstance(ModifiableInstanceHandle handle, TYPE keyHolder) This operation takes as a parameter an instance and returns a handle that can be used in subsequent operations that accept an instance handle as an argument.
InstanceHandle	lookupInstance(TYPE keyHolder) This operation takes as a parameter an instance and returns a handle that can be used in subsequent operations that accept an instance handle as an argument.
Sample.Iterator<TYPE>	read() This operation accesses a collection of samples from this DataReader.
Sample.Iterator<TYPE>	read(DataReader.Selector<TYPE> query) This operation accesses a collection of samples from this DataReader.
Sample.Iterator<TYPE>	read(int maxSamples) This operation accesses a collection of samples from this DataReader.
List<Sample<TYPE>>	read(List<Sample<TYPE>> samples) This operation accesses a collection of samples from this DataReader.
List<Sample<TYPE>>	read(List<Sample<TYPE>> samples, DataReader.Selector<TYPE> selector) This operation accesses a collection of samples from this DataReader.
boolean	readNextSample(Sample<TYPE> sample) This operation copies the next, non-previously accessed sample from this DataReader.
DataReader.Selector<TYPE>	select() Provides a DataReader.Selector that can be used to refine what read() or take() methods return.
Sample.Iterator<TYPE>	take() This operation accesses a collection of samples from this DataReader.
Sample.Iterator<TYPE>	take(DataReader.Selector<TYPE> query) This operation accesses a collection of samples from this DataReader.
Sample.Iterator<TYPE>	take(int maxSamples) This operation accesses a collection of samples from this DataReader.
List<Sample<TYPE>>	take(List<Sample<TYPE>> samples) This operation accesses a collection of samples from this DataReader.
List<Sample<TYPE>>	take(List<Sample<TYPE>> samples, DataReader.Selector<TYPE> query) This operation accesses a collection of samples from this DataReader.
boolean	takeNextSample(Sample<TYPE> sample) This operation copies the next, non-previously accessed sample from this DataReader and "removes" it from the DataReader so it is no longer accessible.
void	waitForHistoricalData(Duration maxWait) This operation is intended only for DataReader entities for which Durability.getKind() is not Durability.Kind.VOLATILE.
void	waitForHistoricalData(long maxWait, TimeUnit unit) This operation is intended only for DataReader entities for which Durability.getKind() is not Durability.Kind.VOLATILE.

Methods inherited from interface org.omg.dds.core.Entity

close, enable, getInstanceHandle, getListener, getQos, getStatusChanges, retain, setListener, setListener, setQos, setQos

Methods inherited from interface org.omg.dds.core.DDSObject

getEnvironment

Method Detail

cast

<OTHER> DataReader<OTHER> cast()

Cast this data reader to the given type, or throw an exception if the cast fails.

Type Parameters:

OTHER - The type of the data subscribed to by this reader, according to the caller.

Returns:

this data reader

Throws:

ClassCastException - if the cast fails

createReadCondition

ReadCondition<TYPE> createReadCondition(Subscriber.DataState states)

This operation creates a ReadCondition. The returned ReadCondition will be attached and belong to the DataReader.

Parameters:

states - The returned condition will only trigger on samples with one of these sample states, view states, and instance states.

createQueryCondition

QueryCondition<TYPE> createQueryCondition(String queryExpression,
                                        List<String> queryParameters)

This operation creates a QueryCondition. The returned QueryCondition will be attached and belong to the DataReader. It will trigger on any sample state, view state, or instance state.

Parameters:

queryExpression - The returned condition will only trigger on samples that pass this content-based filter expression.

queryParameters - A set of parameter values for the queryExpression.

See Also:

createQueryCondition(org.omg.dds.sub.Subscriber.DataState, String, List)

createQueryCondition

QueryCondition<TYPE> createQueryCondition(Subscriber.DataState states,
                                        String queryExpression,
                                        List<String> queryParameters)

This operation creates a QueryCondition. The returned QueryCondition will be attached and belong to the DataReader.

Parameters:

states - The returned condition will only trigger on samples with one of these sample states, view states, and instance states.

queryExpression - The returned condition will only trigger on samples that pass this content-based filter expression.

queryParameters - A set of parameter values for the queryExpression.

See Also:

createQueryCondition(String, List)

closeContainedEntities

void closeContainedEntities()

This operation closes all the entities that were created by means of the "create" operations on the DataReader. That is, it closes all contained ReadCondition and QueryCondition objects.

Throws:

PreconditionNotMetException - if the any of the contained entities is in a state where it cannot be closed.

getTopicDescription

TopicDescription<TYPE> getTopicDescription()

Returns:

the TopicDescription associated with the DataReader. This is the same TopicDescription that was used to create the DataReader.

getSampleRejectedStatus

SampleRejectedStatus getSampleRejectedStatus()

This operation allows access to the SAMPLE_REJECTED communication status.

See Also:

org.omg.dds.core.status

getLivelinessChangedStatus

LivelinessChangedStatus getLivelinessChangedStatus()

This operation allows access to the LIVELINESS_CHANGED communication status.

See Also:

org.omg.dds.core.status

getRequestedDeadlineMissedStatus

RequestedDeadlineMissedStatus getRequestedDeadlineMissedStatus()

This operation allows access to the REQUESTED_DEADLINE_MISSED communication status.

See Also:

org.omg.dds.core.status

getRequestedIncompatibleQosStatus

RequestedIncompatibleQosStatus getRequestedIncompatibleQosStatus()

This operation allows access to the REQUESTED_INCOMPATIBLE_QOS communication status.

See Also:

org.omg.dds.core.status

getSubscriptionMatchedStatus

SubscriptionMatchedStatus getSubscriptionMatchedStatus()

This operation allows access to the SUBSCRIPTION_MATCHED communication status.

See Also:

org.omg.dds.core.status

getSampleLostStatus

SampleLostStatus getSampleLostStatus()

This operation allows access to the SAMPLE_LOST communication status.

See Also:

org.omg.dds.core.status

waitForHistoricalData

void waitForHistoricalData(Duration maxWait)
                           throws TimeoutException

This operation is intended only for DataReader entities for which Durability.getKind() is not Durability.Kind.VOLATILE. As soon as an application enables a non-VOLATILE DataReader it will start receiving both "historical" data, i.e., the data that was written prior to the time the DataReader joined the domain, as well as any new data written by the DataWriter entities. There are situations where the application logic may require the application to wait until all "historical" data is received. This is the purpose of this operation. The operation blocks the calling thread until either all "historical" data is received, or else the duration specified by the max_Wait parameter elapses, whichever happens first.

Throws:

TimeoutException - if maxWait elapsed before all the data was received.

See Also:

waitForHistoricalData(long, TimeUnit)

waitForHistoricalData

void waitForHistoricalData(long maxWait,
                         TimeUnit unit)
                           throws TimeoutException

This operation is intended only for DataReader entities for which Durability.getKind() is not Durability.Kind.VOLATILE. As soon as an application enables a non-VOLATILE DataReader it will start receiving both "historical" data, i.e., the data that was written prior to the time the DataReader joined the domain, as well as any new data written by the DataWriter entities. There are situations where the application logic may require the application to wait until all "historical" data is received. This is the purpose of this operation. The operation blocks the calling thread until either all "historical" data is received, or else the duration specified by the max_Wait parameter elapses, whichever happens first.

Throws:

TimeoutException - if maxWait elapsed before all the data was received.

See Also:

waitForHistoricalData(Duration)

getMatchedPublications

Set<InstanceHandle> getMatchedPublications()

This operation retrieves the list of publications currently "associated" with the DataReader; that is, publications that have a matching Topic and compatible QoS that the application has not indicated should be "ignored" by means of DomainParticipant.ignorePublication(InstanceHandle). The handles returned in the 'publicationHandles' list are the ones that are used by the DDS implementation to locally identify the corresponding matched DataWriter entities. These handles match the ones that appear in Sample.getInstanceHandle() when reading the "DCPSPublications" built-in topic. The operation may fail if the infrastructure does not locally maintain the connectivity information.

Returns:

a new collection containing a copy of the information.

See Also:

getMatchedPublicationData(InstanceHandle)

getMatchedPublicationData

PublicationBuiltinTopicData getMatchedPublicationData(InstanceHandle publicationHandle)

This operation retrieves information on a publication that is currently "associated" with the DataReader; that is, a publication with a matching Topic and compatible QoS that the application has not indicated should be "ignored" by means of DomainParticipant.ignorePublication(InstanceHandle). The operation getMatchedPublications() can be used to find the publications that are currently matched with the DataReader.

Parameters:

publicationHandle - a handle to the publication, the data of which is to be retrieved.

Returns:

a new object containing a copy of the information.

Throws:

IllegalArgumentException - if the publicationHandle does not correspond to a publication currently associated with the DataReader.

UnsupportedOperationException - if the infrastructure does not hold the information necessary to fill in the publicationData.

See Also:

getMatchedPublications()

read

Sample.Iterator<TYPE> read()

This operation accesses a collection of samples from this DataReader. It behaves exactly like read(Selector) except that the collection of returned samples is not constrained by any Selector.

Returns:

a non-null unmodifiable iterator over loaned samples.

See Also:

read(Selector), read(List), read(List, Selector), readNextSample(Sample), take()

read

Sample.Iterator<TYPE> read(DataReader.Selector<TYPE> query)

This operation accesses a collection of samples from this DataReader. The returned samples will be limited by the given DataReader.Selector. The setting of the Presentation may impose further limits on the returned samples.

1. If Presentation.getAccessScope() is Presentation.AccessScopeKind.INSTANCE, then samples belonging to the same data instance are consecutive.
2. If Presentation.getAccessScope() is Presentation.AccessScopeKind.TOPIC and Presentation.isOrderedAccess() is set to false, then samples belonging to the same data instance are consecutive.
3. If Presentation.getAccessScope() is Presentation.AccessScopeKind.TOPIC and Presentation.isOrderedAccess() is set to true, then samples belonging to the same instance may or may not be consecutive. This is because to preserve order it may be necessary to mix samples from different instances.
4. If Presentation.getAccessScope() is Presentation.AccessScopeKind.GROUP and Presentation.isOrderedAccess() is set to false, then samples belonging to the same data instance are consecutive.
5. If Presentation.getAccessScope() is Presentation.AccessScopeKind.GROUP and Presentation.isOrderedAccess() is set to true, then the returned collection contains at most one sample. The difference in this case is due to the fact that it is required that the application is able to read samples belonging to different DataReader objects in a specific order.

In any case, the relative order between the samples of one instance is consistent with the DestinationOrder:

• If DestinationOrder.getKind() is DestinationOrder.Kind.BY_RECEPTION_TIMESTAMP, samples belonging to the same instances will appear in the relative order in which they were received (FIFO, earlier samples ahead of the later samples).
• If DestinationOrder.getKind() is DestinationOrder.Kind.BY_SOURCE_TIMESTAMP, samples belonging to the same instances will appear in the relative order implied by the result of Sample.getSourceTimestamp() (FIFO, smaller values of the source time stamp ahead of the larger values).

In addition to the sample data, the read operation also provides sample meta-information ("sample info"). See Sample. The returned samples are "loaned" by the DataReader. The use of this variant allows for zero-copy (assuming the implementation supports it) access to the data and the application will need to "return the loan" to the DataReader using the Sample.Iterator.close() operation. Some elements in the returned collection may not have valid data. If the instance state in the Sample is InstanceState.NOT_ALIVE_DISPOSED or InstanceState.NOT_ALIVE_NO_WRITERS, then the last sample for that instance in the collection, that is, the one with Sample.getSampleRank() == 0, does not contain valid data. Samples that contain no data do not count towards the limits imposed by the ResourceLimits. The act of reading a sample sets its sample state to SampleState.READ. If the sample belongs to the most recent generation of the instance, it will also set the view state of the instance to ViewState.NOT_NEW. It will not affect the instance state of the instance. If the DataReader has no samples that meet the constraints, the return value will be a non-null iterator that provides no samples.

Returns:

a non-null unmodifiable iterator over loaned samples.

See Also:

read(), read(List), read(List, Selector), readNextSample(Sample), take(Selector)

read

Sample.Iterator<TYPE> read(int maxSamples)

This operation accesses a collection of samples from this DataReader. It behaves exactly like read() except that the returned samples are no more than #maxSamples.

Returns:

a non-null unmodifiable iterator over loaned samples.

See Also:

read(), read(Selector), read(List, Selector), readNextSample(Sample), take(List)

read

List<Sample<TYPE>> read(List<Sample<TYPE>> samples)

This operation accesses a collection of samples from this DataReader. It behaves exactly like read() except that the returned samples are not "on loan" from the Service; they are deeply copied to the application. If the number of samples read are fewer than the current length of the list, the list will be trimmed to fit the samples read. If list is null, a new list will be allocated and its size may be zero or unbounded depending upon the number of samples read. If there are no samples, the list reference will be non-null and the list will contain zero samples. The read operation will copy the data and meta-information into the elements already inside the given collection, overwriting any samples that might already be present. The use of this variant forces a copy but the application can control where the copy is placed and the application will not need to "return the loan."

Returns:

samples, for convenience.

See Also:

read(), read(Selector), read(List, Selector), readNextSample(Sample), take(List)

read

List<Sample<TYPE>> read(List<Sample<TYPE>> samples,
                      DataReader.Selector<TYPE> selector)

This operation accesses a collection of samples from this DataReader. It behaves exactly like read(Selector) except that the returned samples are not "on loan" from the Service; they are deeply copied to the application. The number of samples are specified as the minimum of DataReader.Selector.getMaxSamples() and the length of the list. If the number of samples read are fewer than the current length of the list, the list will be trimmed to fit the samples read. If list is null, a new list will be allocated and its size may be zero or unbounded depending upon the number of samples read. If there are no samples, the list reference will be non-null and the list will contain zero samples. The read operation will copy the data and meta-information into the elements already inside the given collection, overwriting any samples that might already be present. The use of this variant forces a copy but the application can control where the copy is placed and the application will not need to "return the loan."

Returns:

samples, for convenience.

See Also:

read(), read(Selector), read(List), readNextSample(Sample), take(List, Selector)

take

Sample.Iterator<TYPE> take()

This operation accesses a collection of samples from this DataReader. It behaves exactly like take(Selector) except that the collection of returned samples is not constrained by any Selector.

Returns:

a non-null unmodifiable iterator over loaned samples.

See Also:

take(Selector), take(List), take(List, Selector), takeNextSample(Sample), read()

take

Sample.Iterator<TYPE> take(int maxSamples)

This operation accesses a collection of samples from this DataReader. It behaves exactly like take(Selector) except that the collection of returned samples is not constrained by any Selector. The number of samples accessible via the iterator will not be more than #maxSamples.

Returns:

a non-null unmodifiable iterator over loaned samples.

See Also:

take(Selector), take(List), take(List, Selector), takeNextSample(Sample), read()

take

Sample.Iterator<TYPE> take(DataReader.Selector<TYPE> query)

This operation accesses a collection of samples from this DataReader. The number of samples returned is controlled by the Presentation and other factors using the same logic as for read(Selector). The act of taking a sample removes it from the DataReader so it cannot be "read" or "taken" again. If the sample belongs to the most recent generation of the instance, it will also set the view state of the instance to ViewState.NOT_NEW. It will not affect the instance state of the instance. The behavior of the take operation follows the same rules than the read operation regarding the preconditions and postconditions for the arguments and return results. Similar to read, the take operation will "loan" elements to the application; this loan must then be returned by means of Sample.Iterator.close(). The only difference with read is that, as stated, the sample returned by take will no longer be accessible to successive calls to read or take. If the DataReader has no samples that meet the constraints, the return value will be a non-null iterator that provides no samples.

Returns:

a non-null unmodifiable iterator over loaned samples.

See Also:

take(), take(List), take(List, Selector), takeNextSample(Sample), read(Selector)

take

List<Sample<TYPE>> take(List<Sample<TYPE>> samples)

This operation accesses a collection of samples from this DataReader. It behaves exactly like take() except that the returned samples are not "on loan" from the Service; they are deeply copied to the application. The take operation will copy the data and meta-information into the elements already inside the given collection, overwriting any samples that might already be present. The use of this variant forces a copy but the application can control where the copy is placed and the application will not need to "return the loan."

Returns:

samples, for convenience.

See Also:

take(), take(Selector), take(List, Selector), takeNextSample(Sample), read(List)

take

List<Sample<TYPE>> take(List<Sample<TYPE>> samples,
                      DataReader.Selector<TYPE> query)

This operation accesses a collection of samples from this DataReader. It behaves exactly like take(Selector) except that the returned samples are not "on loan" from the Service; they are deeply copied to the application. The take operation will copy the data and meta-information into the elements already inside the given collection, overwriting any samples that might already be present. The use of this variant forces a copy but the application can control where the copy is placed and the application will not need to "return the loan."

Returns:

samples, for convenience.

See Also:

take(), take(Selector), take(List), takeNextSample(Sample), read(List, Selector)

readNextSample

boolean readNextSample(Sample<TYPE> sample)

This operation copies the next, non-previously accessed sample from this DataReader. The implied order among the samples stored in the DataReader is the same as for read(List, Selector). This operation is semantically equivalent to read(List, Selector) where DataReader.Selector.getMaxSamples() is 1, DataReader.Selector.getDataState() followed by Subscriber.DataState.getSampleStates() == SampleState.NOT_READ, DataReader.Selector.getDataState() followed by Subscriber.DataState.getViewStates() contains all view states, and DataReader.Selector.getDataState() followed by Subscriber.DataState.getInstanceStates() contains all instance states. This operation provides a simplified API to "read" samples avoiding the need for the application to manage iterators and specify queries. If there is no unread data in the DataReader, the operation will return false and the provided sample is not modified.

Returns:

true if data was read or false if no data was available.

See Also:

read(), read(Selector), read(List), read(List, Selector), takeNextSample(Sample)

takeNextSample

boolean takeNextSample(Sample<TYPE> sample)

This operation copies the next, non-previously accessed sample from this DataReader and "removes" it from the DataReader so it is no longer accessible. This operation is analogous to readNextSample(Sample) except for the fact that the sample is "removed" from the DataReader. This operation is semantically equivalent to take(List, Selector) where DataReader.Selector.getMaxSamples() is 1, DataReader.Selector.getDataState() followed by Subscriber.DataState.getSampleStates() == SampleState.NOT_READ, DataReader.Selector.getDataState() followed by Subscriber.DataState.getViewStates() contains all view states, and DataReader.Selector.getDataState() followed by Subscriber.DataState.getInstanceStates() contains all instance states. This operation provides a simplified API to "take" samples avoiding the need for the application to manage iterators and specify queries. If there is no unread data in the DataReader, the operation will return false and the provided sample is not modified.

Returns:

true if data was taken or false if no data was available.

See Also:

take(), take(Selector), take(List), take(List, Selector), readNextSample(Sample)

getKeyValue

TYPE getKeyValue(TYPE keyHolder,
               InstanceHandle handle)

This operation can be used to retrieve the instance key that corresponds to an instance handle. The operation will only fill the fields that form the key inside the keyHolder instance.

Parameters:

keyHolder - a container, into which this method shall place its result.

handle - a handle indicating the instance whose value this method should get.

Returns:

keyHolder, as a convenience to facilitate chaining.

Throws:

IllegalArgumentException - if the InstanceHandle does not correspond to an existing data object known to the DataReader. If the implementation is not able to check invalid handles, then the result in this situation is unspecified.

lookupInstance

ModifiableInstanceHandle lookupInstance(ModifiableInstanceHandle handle,
                                      TYPE keyHolder)

This operation takes as a parameter an instance and returns a handle that can be used in subsequent operations that accept an instance handle as an argument. The instance parameter is only used for the purpose of examining the fields that define the key. This operation does not register the instance in question. If the instance has not been previously registered, or if for any other reason the Service is unable to provide an instance handle, the Service will return a nil handle.

Parameters:

handle - a container, into which this method shall place its result.

keyHolder - a sample of the instance whose handle this method should look up.

Returns:

handle, if it is non-null, or a new object otherwise.

See Also:

lookupInstance(Object)

lookupInstance

InstanceHandle lookupInstance(TYPE keyHolder)

This operation takes as a parameter an instance and returns a handle that can be used in subsequent operations that accept an instance handle as an argument. The instance parameter is only used for the purpose of examining the fields that define the key. This operation does not register the instance in question. If the instance has not been previously registered, or if for any other reason the Service is unable to provide an instance handle, the Service will return a nil handle.

Parameters:

keyHolder - a sample of the instance whose handle this method should look up.

Returns:

an immutable handle to the instance.

See Also:

lookupInstance(ModifiableInstanceHandle, Object)

getStatusCondition

StatusCondition<DataReader<TYPE>> getStatusCondition()

Description copied from interface: Entity

This operation allows access to the StatusCondition associated with the Entity. The returned condition can then be added to a WaitSet so that the application can wait for specific status changes that affect the Entity.

Specified by:

getStatusCondition in interface Entity<DataReaderListener<TYPE>,DataReaderQos>

getParent

Subscriber getParent()

Specified by:

getParent in interface DomainEntity<DataReaderListener<TYPE>,DataReaderQos>

Returns:

the factory object that created this entity.

select

DataReader.Selector<TYPE> select()

Provides a DataReader.Selector that can be used to refine what read() or take() methods return.

Returns:

The DataReader.Selector object returned by this method is the default selector. By default it selects ResourceLimits.LENGTH_UNLIMITED samples. This is equivalent to calling read() without any parameters.