17.1.4.9. Subscriber

class eprosima::fastdds::dds::Subscriber : public eprosima::fastdds::dds::DomainEntity

Class Subscriber, contains the public API that allows the user to control the reception of messages. This class should not be instantiated directly. DomainRTPSParticipant class should be used to correctly create this element.

Public Functions

inline virtual ~Subscriber()

Destructor.

virtual ReturnCode_t enable() override

This operation enables the Subscriber.

Returns

RETCODE_OK is successfully enabled. RETCODE_PRECONDITION_NOT_MET if the participant creating this Subscriber is not enabled.

const SubscriberQos &get_qos() const

Allows accessing the Subscriber Qos.

Returns

SubscriberQos reference

ReturnCode_t get_qos(SubscriberQos &qos) const

Retrieves the Subscriber Qos.

Parameters

qosSubscriberQos where the qos is returned

Returns

RETCODE_OK

ReturnCode_t set_qos(const SubscriberQos &qos)

Allows modifying the Subscriber Qos. The given Qos must be supported by the SubscriberQos.

Parameters

qos – new value for SubscriberQos

Returns

RETCODE_IMMUTABLE_POLICY if any of the Qos cannot be changed, RETCODE_INCONSISTENT_POLICY if the Qos is not self consistent and RETCODE_OK if the qos is changed correctly.

const SubscriberListener *get_listener() const

Retrieves the attached SubscriberListener.

Returns

Pointer to the SubscriberListener

ReturnCode_t set_listener(SubscriberListener *listener)

Modifies the SubscriberListener, sets the mask to StatusMask::all()

Parameters

listener – new value for SubscriberListener

Returns

RETCODE_OK

ReturnCode_t set_listener(SubscriberListener *listener, const StatusMask &mask)

Modifies the SubscriberListener.

Parameters
Returns

RETCODE_OK

DataReader *create_datareader(TopicDescription *topic, const DataReaderQos &reader_qos, DataReaderListener *listener = nullptr, const StatusMask &mask = StatusMask::all())

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

Parameters
  • topicTopic the DataReader will be listening.

  • reader_qos – QoS of the DataReader.

  • listener – Pointer to the listener (default: nullptr)

  • maskStatusMask that holds statuses the listener responds to (default: all).

Returns

Pointer to the created DataReader. nullptr if failed.

DataReader *create_datareader_with_profile(TopicDescription *topic, const std::string &profile_name, DataReaderListener *listener = nullptr, const StatusMask &mask = StatusMask::all())

This operation creates a DataReader. The returned DataReader will be attached and belongs to the Subscriber.

Parameters
  • topicTopic the DataReader will be listening.

  • profile_nameDataReader profile name.

  • listener – Pointer to the listener (default: nullptr)

  • maskStatusMask that holds statuses the listener responds to (default: all).

Returns

Pointer to the created DataReader. nullptr if failed.

ReturnCode_t delete_datareader(const DataReader *reader)

This operation deletes a DataReader that belongs to the Subscriber.

The delete_datareader operation must be called on the same Subscriber object used to create the DataReader. If delete_datareader is called on a different Subscriber, the operation will have no effect and it will return an error.

Parameters

readerDataReader to delete

Returns

RETCODE_PRECONDITION_NOT_MET if the datareader does not belong to this subscriber, RETCODE_OK if it is correctly deleted and RETCODE_ERROR otherwise.

DataReader *lookup_datareader(const std::string &topic_name) const

This operation retrieves a previously-created DataReader belonging to the Subscriber that is attached to a Topic with a matching topic_name. If no such DataReader exists, the operation will return nullptr.

If multiple DataReaders attached to the Subscriber satisfy this condition, then the operation will return one of them. It is not specified which one.

Parameters

topic_name – Name of the topic associated to the DataReader

Returns

Pointer to a previously created DataReader created on a Topic with that topic_name

ReturnCode_t get_datareaders(std::vector<DataReader*> &readers) const

This operation allows the application to access the DataReader objects.

Parameters

readers – Vector of DataReader where the list of existing readers is returned

Returns

RETCODE_OK

ReturnCode_t get_datareaders(std::vector<DataReader*> &readers, const std::vector<SampleStateKind> &sample_states, const std::vector<ViewStateKind> &view_states, const std::vector<InstanceStateKind> &instance_states) const

This operation allows the application to access the DataReader objects that contain samples with the specified sample_states, view_states, and instance_states.

Parameters
  • readers[out] Vector of DataReader where the list of existing readers is returned

  • sample_states – Vector of SampleStateKind

  • view_states – Vector of ViewStateKind

  • instance_states – Vector of InstanceStateKind

Returns

RETCODE_OK

bool has_datareaders() const

This operation checks if the subscriber has DataReaders

Returns

true if the subscriber has one or several DataReaders, false in other case

ReturnCode_t begin_access()

Indicates that the application is about to access the data samples in any of the DataReader objects attached to the Subscriber.

Returns

RETCODE_OK

ReturnCode_t end_access()

Indicates that the application has finished accessing the data samples in DataReader objects managed by the Subscriber.

Returns

RETCODE_OK

ReturnCode_t notify_datareaders() const

This operation invokes the operation on_data_available on the DataReaderListener objects attached to contained DataReader entities.

This operation is typically invoked from the on_data_on_readers operation in the SubscriberListener. That way the SubscriberListener can delegate to the DataReaderListener objects the handling of the data.

Returns

RETCODE_OK

ReturnCode_t delete_contained_entities()

Deletes all contained DataReaders. If the DataReaders have any QueryCondition or ReadCondition, they are deleted before the DataReader itself.

Returns

RETCODE_OK if successful, an error code otherwise

ReturnCode_t set_default_datareader_qos(const DataReaderQos &qos)

This operation sets a default value of the DataReader QoS policies which will be used for newly created DataReader entities in the case where the QoS policies are defaulted in the create_datareader operation.

This operation will check that the resulting policies are self consistent; if they are not, the operation will have no effect and return false.

The special value DATAREADER_QOS_DEFAULT may be passed to this operation to indicate that the default QoS should be reset back to the initial values the factory would use, that is the values that would be used if the set_default_datareader_qos operation had never been called.

Parameters

qos – new value for DataReaderQos to set as default

Returns

RETCODE_INCONSISTENT_POLICY if the Qos is not self consistent and RETCODE_OK if the qos is changed correctly.

const DataReaderQos &get_default_datareader_qos() const

This operation returns the default value of the DataReader QoS, that is, the QoS policies which will be used for newly created DataReader entities in the case where the QoS policies are defaulted in the create_datareader operation.

The values retrieved get_default_datareader_qos will match the set of values specified on the last successful call to get_default_datareader_qos, or else, if the call was never made, the default values.

Returns

Current default DataReaderQos.

DataReaderQos &get_default_datareader_qos()

This operation returns the default value of the DataReader QoS, that is, the QoS policies which will be used for newly created DataReader entities in the case where the QoS policies are defaulted in the create_datareader operation.

The values retrieved get_default_datareader_qos will match the set of values specified on the last successful call to get_default_datareader_qos, or else, if the call was never made, the default values.

Returns

Current default DataReaderQos.

ReturnCode_t get_default_datareader_qos(DataReaderQos &qos) const

This operation retrieves the default value of the DataReader QoS, that is, the QoS policies which will be used for newly created DataReader entities in the case where the QoS policies are defaulted in the create_datareader operation.

The values retrieved get_default_datareader_qos will match the set of values specified on the last successful call to get_default_datareader_qos, or else, if the call was never made, the default values.

Parameters

qosDataReaderQos where the default_qos is returned

Returns

RETCODE_OK

ReturnCode_t get_datareader_qos_from_profile(const std::string &profile_name, DataReaderQos &qos) const

Fills the DataReaderQos with the values of the XML profile.

Parameters
Returns

RETCODE_OK if the profile exists. RETCODE_BAD_PARAMETER otherwise.

const DomainParticipant *get_participant() const

This operation returns the DomainParticipant to which the Subscriber belongs.

Returns

DomainParticipant Pointer

const InstanceHandle_t &get_instance_handle() const

Returns the Subscriber’s handle.

Returns

InstanceHandle of this Subscriber.

Public Static Functions

static ReturnCode_t copy_from_topic_qos(DataReaderQos &reader_qos, const TopicQos &topic_qos)

Copies TopicQos into the corresponding DataReaderQos.

Parameters
  • reader_qos[inout]

  • topic_qos[in]

Returns

RETCODE_OK if successful, an error code otherwise