DDS::DataReader Class Reference
[DataReaders]

<<interface>> Allows the application to: (1) declare the data it wishes to receive (i.e. make a subscription) and (2) access the data received by the attached DDS::Subscriber. More...

#include <managed_subscription.h>

Inheritance diagram for DDS::DataReader:

List of all members.

Public Member Functions

ReadCondition^ create_readcondition (System::UInt32 sample_states, System::UInt32 view_states, System::UInt32 instance_states)

Creates a DDS::ReadCondition.

QueryCondition^ create_querycondition (System::UInt32 sample_states, System::UInt32 view_states, System::UInt32 instance_states, System::String^ query_expression, StringSeq^ query_parameters)

Creates a DDS::QueryCondition.

void delete_readcondition (ReadCondition^ %condition)

Deletes a DDS::ReadCondition or DDS::QueryCondition attached to the DDS::DataReader.

void delete_contained_entities ()

Deletes all the entities that were created by means of the "create" operations on the DDS::DataReader.

void wait_for_historical_data (Duration_t% max_wait)

Waits until all "historical" data is received for DDS::DataReader entities that have a non-VOLATILE PERSISTENCE Qos kind.

void get_matched_publications (InstanceHandleSeq^ publication_handles)

Retrieve the list of publications currently "associated" with this DDS::DataReader.

void get_matched_publication_data (PublicationBuiltinTopicData^ publication_data, InstanceHandle_t% publication_handle)

This operation retrieves the information on a publication that is currently "associated" with the DDS::DataReader.

ITopicDescription^ get_topicdescription ()

Returns the DDS::TopicDescription associated with the DDS::DataReader.

Subscriber^ get_subscriber ()

Returns the DDS::Subscriber to which the DDS::DataReader belongs.

void get_sample_rejected_status (SampleRejectedStatus% status)

Accesses the DDS::StatusKind::SAMPLE_REJECTED_STATUS communication status.

void get_liveliness_changed_status (LivelinessChangedStatus% status)

Accesses the DDS::StatusKind::LIVELINESS_CHANGED_STATUS communication status.

void get_requested_deadline_missed_status (RequestedDeadlineMissedStatus% status)

Accesses the DDS::StatusKind::REQUESTED_DEADLINE_MISSED_STATUS communication status.

void get_requested_incompatible_qos_status (RequestedIncompatibleQosStatus^ status)

Accesses the DDS::StatusKind::REQUESTED_INCOMPATIBLE_QOS_STATUS communication status.

void get_sample_lost_status (SampleLostStatus% status)

Accesses the DDS::StatusKind::SAMPLE_LOST_STATUS communication status.

void get_subscription_matched_status (SubscriptionMatchedStatus% status)

Accesses the DDS::StatusKind::SUBSCRIPTION_MATCHED_STATUS communication status.

virtual void get_datareader_cache_status (DataReaderCacheStatus% status)

<<eXtension>> Get the datareader cache status for this reader.

virtual void get_datareader_protocol_status (DataReaderProtocolStatus% status)

<<eXtension>> Get the datareader protocol status for this reader.

virtual void get_matched_publication_datareader_protocol_status (DataReaderProtocolStatus% status, InstanceHandle_t% publication_handle)

<<eXtension>> Get the datareader protocol status for this reader, per matched publication identified by the publication_handle.

void set_qos (DataReaderQos^ qos)

Sets the reader QoS.

void set_qos_with_profile (System::String^ library_name, System::String^ profile_name)

<<eXtension>> Change the QoS of this reader using the input XML QoS profile.

void get_qos (DataReaderQos^ qos)

Gets the reader QoS.

void set_listener (DataReaderListener^ l, StatusMask mask)

Sets the reader listener.

DataReaderListener^ get_listener ()

Get the reader listener.

template<typename T>

void read_untyped (DDS::LoanableSequence< T >^received_data, DDS::SampleInfoSeq^ info_seq, System::Int32 max_samples, System::UInt32 sample_states, System::UInt32 view_states, System::UInt32 instance_states)

Read data samples, if any are available.

template<typename T>

void take_untyped (DDS::LoanableSequence< T >^received_data, DDS::SampleInfoSeq^ info_seq, System::Int32 max_samples, System::UInt32 sample_states, System::UInt32 view_states, System::UInt32 instance_states)

Take data samples, if any are available.

template<typename T>

void read_w_condition_untyped (DDS::LoanableSequence< T >^received_data, DDS::SampleInfoSeq^ info_seq, System::Int32 max_samples, DDS::ReadCondition^ condition)

Read data samples, if any are available.

template<typename T>

void take_w_condition_untyped (DDS::LoanableSequence< T >^received_data, DDS::SampleInfoSeq^ info_seq, System::Int32 max_samples, DDS::ReadCondition^ condition)

Take data samples, if any are available.

void read_next_sample_untyped (System::Object^ received_data, DDS::SampleInfo^ sample_info)

Read data samples, if any are available.

void take_next_sample_untyped (System::Object^ received_data, DDS::SampleInfo^ sample_info)

Take data samples, if any are available.

template<typename T>

void read_instance_untyped (DDS::LoanableSequence< T >^received_data, DDS::SampleInfoSeq^ info_seq, System::Int32 max_samples, DDS::InstanceHandle_t% a_handle, System::UInt32 sample_states, System::UInt32 view_states, System::UInt32 instance_states)

Read data samples, if any are available.

template<typename T>

void take_instance_untyped (DDS::LoanableSequence< T >^received_data, DDS::SampleInfoSeq^ info_seq, System::Int32 max_samples, DDS::InstanceHandle_t% a_handle, System::UInt32 sample_states, System::UInt32 view_states, System::UInt32 instance_states)

Take data samples, if any are available.

template<typename T>

void read_next_instance_untyped (DDS::LoanableSequence< T >^received_data, DDS::SampleInfoSeq^ info_seq, System::Int32 max_samples, DDS::InstanceHandle_t% previous_handle, System::UInt32 sample_states, System::UInt32 view_states, System::UInt32 instance_states)

Read data samples, if any are available.

template<typename T>

void take_next_instance_untyped (DDS::LoanableSequence< T >^received_data, DDS::SampleInfoSeq^ info_seq, System::Int32 max_samples, DDS::InstanceHandle_t% previous_handle, System::UInt32 sample_states, System::UInt32 view_states, System::UInt32 instance_states)

Take data samples, if any are available.

template<typename T>

void read_next_instance_w_condition_untyped (DDS::LoanableSequence< T >^received_data, DDS::SampleInfoSeq^ info_seq, System::Int32 max_samples, DDS::InstanceHandle_t% previous_handle, DDS::ReadCondition^ condition)

Read data samples, if any are available.

template<typename T>

void take_next_instance_w_condition_untyped (DDS::LoanableSequence< T >^received_data, DDS::SampleInfoSeq^ info_seq, System::Int32 max_samples, DDS::InstanceHandle_t% previous_handle, DDS::ReadCondition^ condition)

Take data samples, if any are available.

template<typename T>

void return_loan_untyped (DDS::LoanableSequence< T >^received_data, DDS::SampleInfoSeq^ info_seq)

Return loaned sample data and meta-data.

void get_key_value_untyped (System::Object^ key_holder, DDS::InstanceHandle_t% handle)

Fill in the key fields of the given data sample.

virtual void enable () override

Enables the DDS::Entity.

virtual StatusCondition^ get_statuscondition () override

Allows access to the DDS::StatusCondition associated with the DDS::Entity.

virtual StatusMask get_status_changes () override

Retrieves the list of communication statuses in the DDS::Entity that are triggered.

virtual InstanceHandle_t get_instance_handle () override

Allows access to the DDS::InstanceHandle_t associated with the DDS::Entity.

Detailed Description

<<interface>> Allows the application to: (1) declare the data it wishes to receive (i.e. make a subscription) and (2) access the data received by the attached DDS::Subscriber.

QoS:: DDS::DataReaderQos

Status:: DDS::StatusKind::DATA_AVAILABLE_STATUS;
DDS::StatusKind::LIVELINESS_CHANGED_STATUS, DDS::LivelinessChangedStatus;
DDS::StatusKind::REQUESTED_DEADLINE_MISSED_STATUS, DDS::RequestedDeadlineMissedStatus;
DDS::StatusKind::REQUESTED_INCOMPATIBLE_QOS_STATUS, DDS::RequestedIncompatibleQosStatus;
DDS::StatusKind::SAMPLE_LOST_STATUS, DDS::SampleLostStatus;
DDS::StatusKind::SAMPLE_REJECTED_STATUS, DDS::SampleRejectedStatus;
DDS::StatusKind::SUBSCRIPTION_MATCHED_STATUS, DDS::SubscriptionMatchedStatus<BR>

Listener:: DDS::DataReaderListener

A DDS::DataReader refers to exactly one DDS::TopicDescription (either a DDS::Topic, a DDS::ContentFilteredTopic or a DDS::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 key.

DDS::DataReader is an abstract class. It must be specialised for each particular application data-type (see USER_DATA). The additional methods or functions that must be defined in the auto-generated class for a hypothetical application type Foo are specified in the generic type DDS::TypedDataReader.

The following operations may be called even if the DDS::DataReader is not enabled. Other operations will fail with the value DDS::Retcode_NotEnabled if called on a disabled DDS::DataReader:

All sample-accessing operations, namely: DDS::TypedDataReader::read, DDS::TypedDataReader::take, DDS::TypedDataReader::read_w_condition, and DDS::TypedDataReader::take_w_condition may fail with the error DDS::Retcode_PreconditionNotMet as described in DDS::Subscriber::begin_access.

See also:: Operations Allowed in Listener Callbacks

Examples:: HelloWorld_subscriber.cpp, and HelloWorldSupport.cpp.

Member Function Documentation

ReadCondition ^ DDS::DataReader::create_readcondition	(	System::UInt32	sample_states,
		System::UInt32	view_states,
		System::UInt32	instance_states
	)

Creates a DDS::ReadCondition.

The returned DDS::ReadCondition will be attached and belong to the DDS::DataReader.

Parameters:

	sample_states	<<in>> sample state of the data samples that are of interest
	view_states	<<in>> view state of the data samples that are of interest
	instance_states	<<in>> instance state of the data samples that are of interest

Returns:: return DDS::ReadCondition created. Returns NULL in case of failure.

QueryCondition ^ DDS::DataReader::create_querycondition	(	System::UInt32	sample_states,
		System::UInt32	view_states,
		System::UInt32	instance_states,
		System::String^	query_expression,
		StringSeq^	query_parameters
	)

Creates a DDS::QueryCondition.

The returned DDS::QueryCondition will be attached and belong to the DDS::DataReader.

Queries and Filters Syntax describes the syntax of query_expression and query_parameters.

Parameters:

	sample_states	<<in>> sample state of the data samples that are of interest
	view_states	<<in>> view state of the data samples that are of interest
	instance_states	<<in>> instance state of the data samples that are of interest
	query_expression	<<in>> Expression for the query. Cannot be NULL.
	query_parameters	<<in>> Parameters for the query expression. Cannot be NULL.

Returns:: return DDS::QueryCondition created. Returns NULL in case of failure.

void DDS::DataReader::delete_readcondition ( ReadCondition^ % condition )

Deletes a DDS::ReadCondition or DDS::QueryCondition attached to the DDS::DataReader.

Since DDS::QueryCondition specializes DDS::ReadCondition, it can also be used to delete a DDS::QueryCondition.

Precondition:: The DDS::ReadCondition must be attached to the DDS::DataReader, or the operation will fail with the error DDS::Retcode_PreconditionNotMet.

Parameters:

condition

<<in>> Condition to be deleted.

Exceptions:

One

of the Standard Return Codes, or DDS::Retcode_PreconditionNotMet

void DDS::DataReader::delete_contained_entities ( )

Deletes all the entities that were created by means of the "create" operations on the DDS::DataReader.

Deletes all contained DDS::ReadCondition and DDS::QueryCondition objects.

The operation will fail with DDS::Retcode_PreconditionNotMet if the any of the contained entities is in a state where it cannot be deleted.

Once DDS::DataReader::delete_contained_entities completes successfully, the application may delete the DDS::DataReader, knowing that it has no contained DDS::ReadCondition and DDS::QueryCondition objects.

Exceptions:

One

of the Standard Return Codes, or DDS::Retcode_PreconditionNotMet

void DDS::DataReader::wait_for_historical_data ( Duration_t% max_wait )

Waits until all "historical" data is received for DDS::DataReader entities that have a non-VOLATILE PERSISTENCE Qos kind.

This operation is intended only for DDS::DataReader entities that have a non-VOLATILE PERSISTENCE QoS kind.

As soon as an application enables a non-VOLATILE DDS::DataReader, it will start receiving both "historical" data, i.e. the data that was written prior to the time the DDS::DataReader joined the domain, as well as any new data written by the DDS::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 the DDS::DataReader::wait_for_historical_data operations.

The operation DDS::DataReader::wait_for_historical_data blocks the calling thread until either all "historical" data is received, or else duration specified by the max_wait parameter clapses, whichever happens first. A successful completion indicates that all the "historical" data was "received"; timing out indicates that max_wait elapsed before all the data was received.

Parameters:

max_wait

<<in>> Timeout value. Cannot be NULL.

Exceptions:

One

of the Standard Return Codes, DDS::Retcode_Timeout or DDS::Retcode_NotEnabled.

void DDS::DataReader::get_matched_publications ( InstanceHandleSeq^ publication_handles )

Retrieve the list of publications currently "associated" with this DDS::DataReader.

Matching publications are those in the same domain that have a matching DDS::Topic, compatible QoS common partition that the DDS::DomainParticipant has not indicated should be "ignored" by means of the DDS::DomainParticipant::ignore_publication operation.

The handles returned in the publication_handles' list are the ones that are used by the DDS implementation to locally identify the corresponding matched DDS::DataWriter entities. These handles match the ones that appear in the instance_handle field of the DDS::SampleInfo when reading the DDS::PublicationBuiltinTopicDataTypeSupport::PUBLICATION_TOPIC_NAME builtin topic

Parameters:

publication_handles

<<inout>>. The sequence will be grown if the sequence has ownership and the system has the corresponding resources. Use a sequence without ownership to avoid dynamic memory allocation. If the sequence is too small to store all the matches and the system can not resize the sequence, this method will fail with DDS::Retcode_OutOfResources.

The maximum number of matches possible is configured with DDS::DomainParticipantResourceLimitsQosPolicy. You can use a zero-maximum sequence without ownership to quickly check whether there are any matches without allocating any memory. Cannot be NULL..

Exceptions:

One

of the Standard Return Codes, or DDS::Retcode_OutOfResources if the sequence is too small and the system can not resize it, or DDS::Retcode_NotEnabled

void DDS::DataReader::get_matched_publication_data	(	PublicationBuiltinTopicData^	publication_data,
		InstanceHandle_t%	publication_handle
	)

This operation retrieves the information on a publication that is currently "associated" with the DDS::DataReader.

Publication with a matching DDS::Topic, compatible QoS and common partition that the application has not indicated should be "ignored" by means of the DDS::DomainParticipant::ignore_publication operation.

The publication_handle must correspond to a publication currently associated with the DDS::DataReader. Otherwise, the operation will fail with DDS::Retcode_BadParameter. Use the operation DDS::DataReader::get_matched_publications to find the publications that are currently matched with the DDS::DataReader.

Note: This operation does not retrieve the following information in DDS::PublicationBuiltinTopicData:

DDS::PublicationBuiltinTopicData::type_code
DDS::PublicationBuiltinTopicData::property

The above information is available through DDS::DataReaderListener::on_data_available() (if a reader listener is installed on the DDS::PublicationBuiltinTopicDataDataReader).

Parameters:

	publication_data	<<inout>>. The information to be filled in on the associated publication. Cannot be NULL.
	publication_handle	<<in>>. Handle to a specific publication associated with the DDS::DataWriter. Cannot be NULL.. Must correspond to a publication currently associated with the DDS::DataReader.

Exceptions:

One

of the Standard Return Codes or DDS::Retcode_NotEnabled

ITopicDescription ^ DDS::DataReader::get_topicdescription ( )

Returns the DDS::TopicDescription associated with the DDS::DataReader.

Returns that same DDS::TopicDescription that was used to create the DDS::DataReader.

Returns:: DDS::TopicDescription associated with the DDS::DataReader.

Subscriber ^ DDS::DataReader::get_subscriber ( )

Returns the DDS::Subscriber to which the DDS::DataReader belongs.

Returns:: DDS::Subscriber to which the DDS::DataReader belongs.

void DDS::DataReader::get_sample_rejected_status ( SampleRejectedStatus% status )

Accesses the DDS::StatusKind::SAMPLE_REJECTED_STATUS communication status.

Parameters:

status

<<inout>> DDS::SampleRejectedStatus to be filled in. Cannot be NULL.

Exceptions:

One

of the Standard Return Codes

void DDS::DataReader::get_liveliness_changed_status ( LivelinessChangedStatus% status )

Accesses the DDS::StatusKind::LIVELINESS_CHANGED_STATUS communication status.

Parameters:

status

<<inout>> DDS::LivelinessChangedStatus to be filled in. Cannot be NULL.

Exceptions:

One

of the Standard Return Codes

void DDS::DataReader::get_requested_deadline_missed_status ( RequestedDeadlineMissedStatus% status )

Accesses the DDS::StatusKind::REQUESTED_DEADLINE_MISSED_STATUS communication status.

Parameters:

status

<<inout>> DDS::RequestedDeadlineMissedStatus to be filled in. Cannot be NULL.

Exceptions:

One

of the Standard Return Codes

void DDS::DataReader::get_requested_incompatible_qos_status ( RequestedIncompatibleQosStatus^ status )

Accesses the DDS::StatusKind::REQUESTED_INCOMPATIBLE_QOS_STATUS communication status.

Parameters:

status

<<inout>> DDS::RequestedIncompatibleQosStatus to be filled in. Cannot be NULL.

Exceptions:

One

of the Standard Return Codes

void DDS::DataReader::get_sample_lost_status ( SampleLostStatus% status )

Accesses the DDS::StatusKind::SAMPLE_LOST_STATUS communication status.

Parameters:

status

<<inout>> DDS::SampleLostStatus to be filled in. Cannot be NULL.

Exceptions:

One

of the Standard Return Codes

void DDS::DataReader::get_subscription_matched_status ( SubscriptionMatchedStatus% status )

Accesses the DDS::StatusKind::SUBSCRIPTION_MATCHED_STATUS communication status.

Parameters:

status

<<inout>> DDS::SubscriptionMatchedStatus to be filled in. Cannot be NULL.

Exceptions:

One

of the Standard Return Codes

virtual void DDS::DataReader::get_datareader_cache_status ( DataReaderCacheStatus% status ) [virtual]

<<eXtension>> Get the datareader cache status for this reader.

Parameters:

status

<<inout>> DDS::DataReaderCacheStatus to be filled in. Cannot be NULL.

Exceptions:

One

of the Standard Return Codes or DDS::Retcode_NotEnabled.

virtual void DDS::DataReader::get_datareader_protocol_status ( DataReaderProtocolStatus% status ) [virtual]

<<eXtension>> Get the datareader protocol status for this reader.

Parameters:

status

<<inout>> DDS::DataReaderProtocolStatus to be filled in. Cannot be NULL.

Exceptions:

One

of the Standard Return Codes or DDS::Retcode_NotEnabled.

virtual void DDS::DataReader::get_matched_publication_datareader_protocol_status	(	DataReaderProtocolStatus%	status,
		InstanceHandle_t%	publication_handle
	)			`[virtual]`

<<eXtension>> Get the datareader protocol status for this reader, per matched publication identified by the publication_handle.

Note: Status for a remote entity is only kept while the entity is alive. Once a remote entity is no longer alive, its status is deleted.

Parameters:

	status	<<inout>>. The information to be filled in on the associated publication. Cannot be NULL.
	publication_handle	<<in>>. Handle to a specific publication associated with the DDS::DataWriter. Cannot be NULL.. Must correspond to a publication currently associated with the DDS::DataReader.

Exceptions:

One

of the Standard Return Codes or DDS::Retcode_NotEnabled

void DDS::DataReader::set_qos ( DataReaderQos^ qos )

Sets the reader QoS.

This operation modifies the QoS of the DDS::DataReader.

The DDS::DataReaderQos::user_data, DDS::DataReaderQos::deadline, DDS::DataReaderQos::latency_budget, DDS::DataReaderQos::time_based_filter, DDS::DataReaderQos::reader_data_lifecycle can be changed. The other policies are immutable.

Parameters:

qos

<<in>> The DDS::DataReaderQos to be set to. Policies must be consistent. Immutable policies cannot be changed after DDS::DataReader is enabled. The special value DDS::Subscriber::DATAREADER_QOS_DEFAULT can be used to indicate that the QoS of the DDS::DataReader should be changed to match the current default DDS::DataReaderQos set in the DDS::Subscriber. Cannot be NULL.

Exceptions:

One

of the Standard Return Codes, DDS::Retcode_ImmutablePolicy, or DDS::Retcode_InconsistentPolicy.

See also:

DDS::DataReaderQos for rules on consistency among QoS

set_qos (abstract)

DDS::DataReader::set_qos

Operations Allowed in Listener Callbacks

void DDS::DataReader::set_qos_with_profile	(	System::String^	library_name,
		System::String^	profile_name
	)

<<eXtension>> Change the QoS of this reader using the input XML QoS profile.

This operation modifies the QoS of the DDS::DataReader.

The DDS::DataReaderQos::user_data, DDS::DataReaderQos::deadline, DDS::DataReaderQos::latency_budget, DDS::DataReaderQos::time_based_filter, DDS::DataReaderQos::reader_data_lifecycle can be changed. The other policies are immutable.

Parameters:

	library_name	<<in>> Library name containing the XML QoS profile. If library_name is null RTI Data Distribution Service will use the default library (see DDS::Subscriber::set_default_library).
	profile_name	<<in>> XML QoS Profile name. If profile_name is null RTI Data Distribution Service will use the default profile (see DDS::Subscriber::set_default_profile).

Exceptions:

One

of the Standard Return Codes, DDS::Retcode_ImmutablePolicy, or DDS::Retcode_InconsistentPolicy.

See also:

DDS::DataReaderQos for rules on consistency among QoS

DDS::DataReader::set_qos

Operations Allowed in Listener Callbacks

void DDS::DataReader::get_qos ( DataReaderQos^ qos )

Gets the reader QoS.

This method may potentially allocate memory depending on the sequences contained in some QoS policies.

Parameters:

qos

<<inout>> The DDS::DataReaderQos to be filled up. Cannot be NULL.

Exceptions:

One

of the Standard Return Codes

See also:: get_qos (abstract)

void DDS::DataReader::set_listener	(	DataReaderListener^	l,
		StatusMask	mask
	)

Sets the reader listener.

Parameters:

	l	<<in>> DDS::DataReaderListener to set to
	mask	<<in>> DDS::StatusMask associated with the DDS::DataReaderListener.

Exceptions:

One

of the Standard Return Codes

See also:: set_listener (abstract)

DataReaderListener ^ DDS::DataReader::get_listener ( )

Get the reader listener.

Returns:: DDS::DataReaderListener of the DDS::DataReader.

See also:: get_listener (abstract)

template<typename T>

void DDS::DataReader::read_untyped	(	DDS::LoanableSequence< T >^	received_data,
		DDS::SampleInfoSeq^	info_seq,
		System::Int32	max_samples,
		System::UInt32	sample_states,
		System::UInt32	view_states,
		System::UInt32	instance_states
	)			`[explicit]`

Read data samples, if any are available.