Subscribe to a ROS topic as data provider. More...

#include <fkie_message_filters/subscriber.h>

Inheritance diagram for fkie_message_filters::Subscriber< M, Translate >:

Collaboration diagram for fkie_message_filters::Subscriber< M, Translate >:

Public Types
using	Output = IO< Outputs... >
	Grouped output types. More...

Public Member Functions
	Subscriber () noexcept
	Constructs an empty subscriber. More...

	Subscriber (ros::NodeHandle &nh, const std::string &topic, uint32_t queue_size, const ros::TransportHints &transport_hints=ros::TransportHints(), ros::CallbackQueueInterface *callback_queue=nullptr) noexcept
	Constructor that subscribes to the given ROS topic. More...

Connection	connect_to_sink (Sink< Outputs... > &dst) noexcept
	Connect this source to a sink. More...

virtual void	disconnect () noexcept override
	Disconnect from all connected sinks. More...

void	disconnect_from_all_sinks () noexcept
	Disconnect from all connected sinks. More...

virtual void	reset () noexcept
	Reset filter state. More...

void	set_subscribe_options (ros::NodeHandle &nh, const std::string &topic, uint32_t queue_size, const ros::TransportHints &transport_hints=ros::TransportHints(), ros::CallbackQueueInterface *callback_queue=nullptr) noexcept
	Configure ROS topic that is to be subscribed. More...

virtual void	subscribe ()
	Subscribe to the configured ROS topic. More...

void	subscribe (ros::NodeHandle &nh, const std::string &topic, uint32_t queue_size, const ros::TransportHints &transport_hints=ros::TransportHints(), ros::CallbackQueueInterface *callback_queue=nullptr) noexcept
	Convenience function to subscribe to a ROS topic. More...

virtual void	subscribe_on_demand (PublisherBase &pub)
	Subscribe to the configured ROS topic whenever the given publisher is active. More...

virtual std::string	topic () const noexcept override
	Return the subscribed topic name. More...

virtual void	unsubscribe ()
	Unsubscribe from the configured ROS topic. More...

Static Public Attributes
static constexpr std::size_t	NUM_OUTPUTS
	Number of output arguments.

Protected Member Functions
virtual bool	is_configured () const noexcept override
	Check if the ROS subscriber is properly configured. More...

void	link_with_publisher (PublisherBase &pub)
	Add self to the list of subscribers which are controlled by a publisher. More...

void	send (const Outputs &... out)
	Pass data to all connected sinks. More...

virtual void	subscribe_impl () noexcept override
	Create a ROS subscriber. More...

void	unlink_from_publisher ()
	Remove self from the list of subscribers which are controlled by a publisher. More...

virtual void	unsubscribe_impl () noexcept override
	Shut the ROS subscriber down. More...

Detailed Description

template<class M, template< typename > class Translate = RosMessageEvent>
class fkie_message_filters::Subscriber< M, Translate >

Subscribe to a ROS topic as data provider.

This class together with the Publisher class is the generic interface between ROS and this library. All messages which are received on the subscribed topic will be passed to the connected sinks for further processing. For maximum flexibility, you can choose one of four ways how to pass the received message:

Subscriber<M, RosMessageEvent> will act as a source of ros::MessageEvent<const M> objects (default)
Subscriber<M, RosMessageConstPtr> will act as a source of M::ConstPtr objects (as of this writing, this is a boost::shared_ptr<const M>)
Subscriber<M, RosMessageStdSharedPtr> will act as a source of std::shared_ptr<const M> objects
Subscriber<M, RosMessage> will act as a source of plain M objects

Unlike regular ROS subscribers, this class can be associated with a publisher instance. In that case, the subscriber will delay subscription until the publisher is actively used and will unsubscribe (and stop passing data) as soon as the publisher becomes idle. This is a convenient method to save processing power if the filter pipeline is used only intermittently.

See also: CameraSubscriber, ImageSubscriber

Member Typedef Documentation

◆ Output

using fkie_message_filters::Source< Outputs >::Output = IO<Outputs...>

inherited

Grouped output types.

This type can be used to define sinks with matching types.

Constructor & Destructor Documentation

◆ Subscriber() [1/2]

template<class M , template< typename > class Translate = RosMessageEvent>

fkie_message_filters::Subscriber< M, Translate >::Subscriber ( )

noexcept

Constructs an empty subscriber.

You need to call set_subscribe_options() and either subscribe() or subscribe_on_demand() to actually subscribe to a ROS topic.

Exceptions: Does not throw any exceptions.

◆ Subscriber() [2/2]

template<class M , template< typename > class Translate = RosMessageEvent>

fkie_message_filters::Subscriber< M, Translate >::Subscriber	(	ros::NodeHandle &	nh,
		const std::string &	topic,
		uint32_t	queue_size,
		const ros::TransportHints &	transport_hints = `ros::TransportHints()`,
		ros::CallbackQueueInterface *	callback_queue = `nullptr`
	)

noexcept

Constructor that subscribes to the given ROS topic.

This constructor calls set_subscribe_options() and subscribe() for you.

nh ROS node handle to create the ROS subscription
topic name of the ROS topic, subject to remapping
queue_size size of the ROS subscription queue
transport_hints low-level transport hints for the ROS client library
callback_queue custom ROS callback queue

Exceptions: Does not throw any exceptions.

Member Function Documentation

◆ connect_to_sink()

Connection fkie_message_filters::Source< Outputs >::connect_to_sink ( Sink< Outputs... > & dst )

noexceptinherited

Connect this source to a sink.

Can be called multiple times to connect multiple sinks; in that case, the sinks receive data in the same order as they have been connected. This function does basically the same thing as Sink::connect_to_source(), only from the opposite point of view.

dst the sink that is to be connected

Returns: a connection object that can be used to monitor or sever the created connection

Exceptions: Does not throw any exceptions.

◆ disconnect()

virtual void fkie_message_filters::Source< Outputs >::disconnect ( )

overridevirtualnoexceptinherited

Disconnect from all connected sinks.

The source implementation calls disconnect_from_all_sinks().

Exceptions: Does not throw any exceptions.

Implements fkie_message_filters::FilterBase.

◆ disconnect_from_all_sinks()

void fkie_message_filters::Source< Outputs >::disconnect_from_all_sinks ( )

noexceptinherited

Disconnect from all connected sinks.

Severs the connection to all sinks, turning the send() method into a no-op.

Exceptions: Does not throw any exceptions.

◆ is_configured()

template<class M , template< typename > class Translate = RosMessageEvent>

virtual bool fkie_message_filters::Subscriber< M, Translate >::is_configured ( ) const

overrideprotectedvirtualnoexcept

Check if the ROS subscriber is properly configured.

Exceptions: Does not throw any exceptions.

Implements fkie_message_filters::SubscriberBase.

◆ link_with_publisher()

void fkie_message_filters::SubscriberBase::link_with_publisher ( PublisherBase & pub )

protectedinherited

Add self to the list of subscribers which are controlled by a publisher.

A subscriber can be linked with one publisher only. Any previously linked publisher is unlinked first.

pub publisher

Exceptions: Propagates exceptions raised by the implementation of the abstract class methods.

See also: PublisherBase::link_with_subscriber()

◆ reset()

virtual void fkie_message_filters::FilterBase::reset ( )

inlinevirtualnoexceptinherited

Reset filter state.

For stateful filters, this method resets the internal state as if the filter had just been created. Existing connections to sources and sinks are unaffected.

The default implementation does nothing.

Exceptions: Does not throw any exceptions.

Reimplemented in fkie_message_filters::Buffer< Inputs >, fkie_message_filters::Buffer< Inputs... >, fkie_message_filters::TfFilter< Inputs >, fkie_message_filters::TfFilter< Inputs... >, fkie_message_filters::Combiner< PolicyTmpl, IOs >, fkie_message_filters::Sequencer< Inputs >, and fkie_message_filters::Sequencer< Inputs... >.

◆ send()

void fkie_message_filters::Source< Outputs >::send ( const Outputs &... out )

protectedinherited

Pass data to all connected sinks.

out data

Exceptions: Does not throw any exceptions, but will propagate uncaught exceptions from filter callbacks.

◆ set_subscribe_options()

template<class M , template< typename > class Translate = RosMessageEvent>

void fkie_message_filters::Subscriber< M, Translate >::set_subscribe_options	(	ros::NodeHandle &	nh,
		const std::string &	topic,
		uint32_t	queue_size,
		const ros::TransportHints &	transport_hints = `ros::TransportHints()`,
		ros::CallbackQueueInterface *	callback_queue = `nullptr`
	)

noexcept

Configure ROS topic that is to be subscribed.

All arguments are passed to the ROS client library; see the ROS documentation for further information. Calling this method will automatically unsubscribe any previously subscribed ROS topic.

nh ROS node handle to create the ROS subscription
topic name of the ROS topic, subject to remapping
queue_size size of the ROS subscription queue
transport_hints low-level transport hints for the ROS client library
callback_queue custom ROS callback queue

Exceptions: Does not throw any exceptions.

◆ subscribe() [1/2]

void fkie_message_filters::SubscriberBase::subscribe ( )

virtualinherited

Subscribe to the configured ROS topic.

This method does nothing if no ROS topic was configured or if the subscriber is subscribed already. Cancels the effect of subscribe_on_demand(), i.e. the subscriber will remain subscribed permanently.

Exceptions: Propagates exceptions raised by the implementation of the abstract class methods.

◆ subscribe() [2/2]

template<class M , template< typename > class Translate = RosMessageEvent>

void fkie_message_filters::Subscriber< M, Translate >::subscribe	(	ros::NodeHandle &	nh,
		const std::string &	topic,
		uint32_t	queue_size,
		const ros::TransportHints &	transport_hints = `ros::TransportHints()`,
		ros::CallbackQueueInterface *	callback_queue = `nullptr`
	)

noexcept

Convenience function to subscribe to a ROS topic.

This function is equivalent to calling set_subscribe_options() and then subscribe().

nh ROS node handle to create the ROS subscription
topic name of the ROS topic, subject to remapping
queue_size size of the ROS subscription queue
transport_hints low-level transport hints for the ROS client library
callback_queue custom ROS callback queue

Exceptions: Does not throw any exceptions.

◆ subscribe_impl()

template<class M , template< typename > class Translate = RosMessageEvent>

virtual void fkie_message_filters::Subscriber< M, Translate >::subscribe_impl ( )

overrideprotectedvirtualnoexcept

Create a ROS subscriber.

Exceptions: Does not throw any exceptions.

Implements fkie_message_filters::SubscriberBase.

◆ subscribe_on_demand()

void fkie_message_filters::SubscriberBase::subscribe_on_demand ( PublisherBase & pub )

virtualinherited

Subscribe to the configured ROS topic whenever the given publisher is active.

This method does nothing if no ROS topic was configured. Otherwise, it will immediately subscribe or unsubscribe depending on the publisher's current state. If the publisher becomes active or inactive, the subscriber's state will update accordingly.

pub publisher

Exceptions: Propagates exceptions raised by the implementation of the abstract class methods.

◆ topic()

template<class M , template< typename > class Translate = RosMessageEvent>

virtual std::string fkie_message_filters::Subscriber< M, Translate >::topic ( ) const

overridevirtualnoexcept

Return the subscribed topic name.

Exceptions: Depends on the implementation.

Implements fkie_message_filters::SubscriberBase.

◆ unlink_from_publisher()

void fkie_message_filters::SubscriberBase::unlink_from_publisher ( )

protectedinherited

Remove self from the list of subscribers which are controlled by a publisher.

This will not affect the current subscription state. It will only prevent further updates from the previously linked publisher.

Exceptions: Does not throw any exceptions.

◆ unsubscribe()

void fkie_message_filters::SubscriberBase::unsubscribe ( )

virtualinherited

Unsubscribe from the configured ROS topic.

You can call subscribe() afterwards to re-subscribe to the ROS topic. This method does nothing if the subscriber is not subscribed to any ROS topic. Cancels the effect of subscribe_on_demand(), i.e. the subscriber will remain unsubscribed permanently.

Exceptions: Propagates exceptions raised by the implementation of the abstract class methods.

◆ unsubscribe_impl()

template<class M , template< typename > class Translate = RosMessageEvent>

virtual void fkie_message_filters::Subscriber< M, Translate >::unsubscribe_impl ( )

overrideprotectedvirtualnoexcept

Shut the ROS subscriber down.

Exceptions: Does not throw any exceptions.

Implements fkie_message_filters::SubscriberBase.

The documentation for this class was generated from the following file:

include/fkie_message_filters/subscriber.h

Public Types

Public Member Functions

Static Public Attributes

Protected Member Functions

Detailed Description

template<class M, template< typename > class Translate = RosMessageEvent> class fkie_message_filters::Subscriber< M, Translate >

Member Typedef Documentation

◆ Output

Constructor & Destructor Documentation

◆ Subscriber() [1/2]

◆ Subscriber() [2/2]

Member Function Documentation

◆ connect_to_sink()

◆ disconnect()

◆ disconnect_from_all_sinks()

◆ is_configured()

◆ link_with_publisher()

◆ reset()

◆ send()

◆ set_subscribe_options()

◆ subscribe() [1/2]

◆ subscribe() [2/2]

◆ subscribe_impl()

◆ subscribe_on_demand()

◆ topic()

◆ unlink_from_publisher()

◆ unsubscribe()

◆ unsubscribe_impl()

template<class M, template< typename > class Translate = RosMessageEvent>
class fkie_message_filters::Subscriber< M, Translate >