dds::topic::ContentFilteredTopic< T > Class Template Reference

ContentFilteredTopic is a specialization of TopicDescription that allows for content-based subscriptions. More...

#include "ContentFilteredTopic.hpp"

Inherits dds::topic::TopicDescription.

Public Types
typedef T	DataType

Public Member Functions
	ContentFilteredTopic (const Topic< T > &topic, const std::string &name, const dds::topic::Filter &filter)
const dds::domain::DomainParticipant &	domain_participant () const
const std::string &	filter_expression () const
const dds::core::StringSeq	filter_parameters () const
template<typename FWDIterator >
void	filter_parameters (const FWDIterator &begin, const FWDIterator &end)
bool	is_nil () const
const std::string &	name () const
bool	operator!= (const null_type nil) const
template<typename R >
bool	operator!= (const R &ref) const
DELEGATE *	operator-> ()
const DELEGATE *	operator-> () const
bool	operator== (const null_type) const
template<typename R >
bool	operator== (const R &ref) const
const dds::topic::Topic< T > &	topic () const
const std::string &	type_name () const

Detailed Description

template<typename T>
class dds::topic::ContentFilteredTopic< T >

ContentFilteredTopic is a specialization of TopicDescription that allows for content-based subscriptions.

ContentFilteredTopic describes a more sophisticated subscription which indicates that the Subscriber does not necessarily want to see all values of each instance published under the Topic. Rather, it only wants to see the values whose contents satisfy certain criteria. Therefore this class must be used to request content-based subscriptions.

The selection of the content is done using the SQL based filter with parameters to adapt the filter clause.

Example

// Default creation of a Topic
dds::domain::DomainParticipant participant(org::eclipse::cyclonedds::domain::default_id());
dds::topic::Topic<Foo::Bar> topic(participant, "TopicName");
 
// Creation of a ContentFilteredTopic (assume Foo::Bar contains long_1 element).
std::vector<std::string> params;
params.push_back("1");
dds::topic::Filter filter("long_1=%0", params);
dds::topic::ContentFilteredTopic<Foo::Bar> cfTopic(topic,
                                                   "ContentFilteredTopicName",
                                                   filter);
 
// The ContentFilteredTopic can be used to create readers
dds::sub::Subscriber subscriber(participant);
dds::sub::DataReader<Foo::Bar> reader(subscriber, cfTopic);

See also

Topic Definition

Definition at line 36 of file ContentFilteredTopic.hpp.

Member Typedef Documentation

DataType

template<typename T>

typedef T dds::topic::ContentFilteredTopic< T >::DataType

Convenience typedef for the type of the data sample.

Definition at line 86 of file ContentFilteredTopic.hpp.

Constructor & Destructor Documentation

ContentFilteredTopic()

template<typename T>

dds::topic::ContentFilteredTopic< T >::ContentFilteredTopic	(	const Topic< T > &	topic,
		const std::string &	name,
		const dds::topic::Filter &	filter
	)

Creates a ContentFilteredTopic be used as to perform content-based subscriptions.

The ContentFilteredTopic only relates to samples published under that Topic, filtered according to their content. The filtering is done by means of evaluating a logical expression that involves the values of some of the data-fields in the sample.

See SQL expression info

Parameters

topic	the related Topic
name	the name of the ContentFilteredTopic
filter	the filter expression

Exceptions

dds::core::Exception

Member Function Documentation

domain_participant()

const dds::domain::DomainParticipant& dds::topic::TopicDescription::domain_participant ( ) const

inherited

This operation returns the DomainParticipant associated with the TopicDescription.

Note that there is exactly one DomainParticipant associated with each TopicDescription.

Returns

the DomainParticipant

filter_expression()

template<typename T>

const std::string& dds::topic::ContentFilteredTopic< T >::filter_expression

(

)

const

Get the filter expression.

See SQL expression info

Returns

the filter expression

filter_parameters() [1/2]

template<typename T>

const dds::core::StringSeq dds::topic::ContentFilteredTopic< T >::filter_parameters

(

)

const

Get the filter expression parameters.

See SQL expression info

Returns

the filter parameters as a sequence

filter_parameters() [2/2]

template<typename T>

template<typename FWDIterator >

void dds::topic::ContentFilteredTopic< T >::filter_parameters	(	const FWDIterator &	begin,
		const FWDIterator &	end
	)

Sets the query parameters.

See SQL expression info

Template Parameters

begin	Iterator pointing to the beginning of the parameters to set
end	Iterator pointing to the end of the parameters to set

Returns

void

Exceptions

dds::core::Error	An internal error has occurred.
dds::core::NullReferenceError	The entity was not properly created and references to dds::core::null.

is_nil()

template<typename DELEGATE>

bool dds::core::Reference< DELEGATE >::is_nil ( ) const

inherited

Check if the referenced object is nil.

In other words, check if the reference is pointing to a null object.

Returns

true if the referenced object is null.

name()

const std::string& dds::topic::TopicDescription::name ( ) const

inherited

This operation returns the name used to create the TopicDescription.

Returns

the TopicDescription name

operator!=() [1/2]

template<typename DELEGATE>

bool dds::core::Reference< DELEGATE >::operator!= ( const null_type  nil ) const

inherited

Special operator!= used to check if this reference object does not equal the dds::core::null reference.

The non-null-check can be done like this:

if (r != dds::core::null) {
   // Use the dds reference object r
}

Returns

true if this reference is not null.

operator!=() [2/2]

template<typename DELEGATE>

template<typename R >

bool dds::core::Reference< DELEGATE >::operator!= ( const R &  ref ) const

inherited

Compares two Reference objects and returns true if they are not equal.

Inequality is based on the referential inequality of the object being pointed to.

Parameters

ref	the other Reference object

Returns

true when not equal

operator->() [1/2]

template<typename DELEGATE>

DELEGATE* dds::core::Reference< DELEGATE >::operator-> ( )

inherited

The operator->() is provided to be able to directly invoke functions on the delegate.

The decision to provide direct access to the delegate was motivated by the need for providing a way that was not invasive with respect to the CXXDDS API and yet would allow for vendor-specific extension. Thus vendor-specific extensions can be invoked on the Reference and on all its subclasses as follows:

my_dds_entity.standard_function();
my_dds_entity->vendor_specific_extension();

Returns

a reference to delegate.

operator->() [2/2]

template<typename DELEGATE>

const DELEGATE* dds::core::Reference< DELEGATE >::operator-> ( ) const

inherited

The operator->() is provided to be able to directly invoke functions on the delegate.

The decision to provide direct access to the delegate was motivated by the need for providing a way that was not invasive with respect to the CXXDDS API and yet would allow for vendor-specific extension. Thus vendor-specific extensions can be invoked on the Reference and on all its subclasses as follows:

my_dds_entity.standard_function();
my_dds_entity->vendor_specific_extension();

Returns

a reference to delegate.

operator==() [1/2]

template<typename DELEGATE>

bool dds::core::Reference< DELEGATE >::operator== ( const  null_type ) const

inherited

Special operator== used to check if this reference object equals the dds::core::null reference.

The null-check can be done like this:

if (r == dds::core::null) {
   // Do not use the dds reference object r in its current state
}

Returns

true if this reference is null.

operator==() [2/2]

template<typename DELEGATE>

template<typename R >

bool dds::core::Reference< DELEGATE >::operator== ( const R &  ref ) const

inherited

Compares two Reference objects and returns true if they are equal.

Equality is based on the referential equality of the object being pointed.

Parameters

ref	the other Reference object

Returns

true when equal

topic()

template<typename T>

const dds::topic::Topic<T>& dds::topic::ContentFilteredTopic< T >::topic

(

)

const

Return the associated Topic.

Returns

the Topic

Exceptions

dds::core::Error	An internal error has occurred.
dds::core::NullReferenceError	The entity was not properly created and references to dds::core::null.

type_name()

const std::string& dds::topic::TopicDescription::type_name ( ) const

inherited

This operation returns the registered name of the data type associated with the TopicDescription.

Returns

the type_name

---

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

• dds/topic/ContentFilteredTopic.hpp