<<interface>> Specialization of DDSTopicDescription that allows for content-based subscriptions. More...

Inheritance diagram for DDSContentFilteredTopic:

Public Member Functions
virtual const char *	get_filter_expression ()=0
	Get the `filter_expression`.

virtual DDS_ReturnCode_t	get_expression_parameters (DDS_StringSeq &parameters)=0
	Get the `expression_parameters`.

virtual DDS_ReturnCode_t	set_expression_parameters (const DDS_StringSeq &parameters)=0
	Set the `expression_parameters`.

virtual DDS_ReturnCode_t	append_to_expression_parameter (const DDS_Long index, const char *val)=0
	<<eXtension>> Appends a string term to the specified parameter string.

virtual DDS_ReturnCode_t	remove_from_expression_parameter (const DDS_Long index, const char *val)=0
	<<eXtension>> Removes a string term from the specified parameter string.

virtual DDSTopic *	get_related_topic ()=0
	Get the `related_topic`.

Public Member Functions inherited from DDSTopicDescription
virtual const char *	get_type_name ()=0
	Get the associated `type_name`.

virtual const char *	get_name ()=0
	Get the name used to create this DDSTopicDescription .

virtual DDSDomainParticipant *	get_participant ()=0
	Get the DDSDomainParticipant to which the DDSTopicDescription belongs.

Static Public Member Functions
static DDSContentFilteredTopic *	narrow (DDSTopicDescription *topic_description)
	Narrow the given DDSTopicDescription pointer to a DDSContentFilteredTopic pointer.

Detailed Description

<<interface>> Specialization of DDSTopicDescription that allows for content-based subscriptions.

It describes a more sophisticated subscription that indicates a DDSDataReader does not want to necessarily see all values of each instance published under the DDSTopic. Rather, it wants to see only the values whose contents satisfy certain criteria. This class therefore can be used to request content-based subscriptions.

The selection of the content is done using the filter_expression with parameters expression_parameters.

The filter_expression attribute is a string that specifies the criteria to select the data samples of interest. It is similar to the WHERE part of an SQL clause.

The expression_parameters attribute is a sequence of strings that give values to the 'parameters' (i.e. "%n" tokens) in the filter_expression. The number of supplied parameters must fit with the requested values in the filter_expression (i.e. the number of n tokens).

Queries and Filters Syntax describes the syntax of filter_expression and expression_parameters.

Note on Content-Based Filtering and Sparse Value Types

If you are a user of the Dynamic Data API, you may define sparse value types; that is, types for which every data sample need not include a value for every field defined in the type. (See DDS_TK_SPARSE and DDS_TypeCodeFactory::create_sparse_tc.) In order for a filter expression on a field to be well defined, that field must be present in the data sample. That means that you will only be able to perform a content-based filter on fields that are marked as DDS_TYPECODE_KEY_MEMBER or DDS_TYPECODE_NONKEY_REQUIRED_MEMBER.

Member Function Documentation

static DDSContentFilteredTopic* DDSContentFilteredTopic::narrow ( DDSTopicDescription * topic_description )

static

Narrow the given DDSTopicDescription pointer to a DDSContentFilteredTopic pointer.

Returns: DDSContentFilteredTopic if this DDSTopicDescription is a DDSContentFilteredTopic. Otherwise, return NULL.

virtual const char* DDSContentFilteredTopic::get_filter_expression ( )

pure virtual

Get the filter_expression.

Return the filter_expression associated with the DDSContentFilteredTopic.

Returns: the filter_expression.

virtual DDS_ReturnCode_t DDSContentFilteredTopic::get_expression_parameters ( DDS_StringSeq & parameters )

pure virtual

Get the expression_parameters.

Return the expression_parameters associated with the DDSContentFilteredTopic. expression_parameters is either specified on the last successful call to DDSContentFilteredTopic::set_expression_parameters or, if that method is never called, the parameters specified when the DDSContentFilteredTopic was created.

Parameters

parameters <<inout>> the filter expression parameters. The memory for the strings in this sequence is managed according to the conventions described in Conventions. In particular, be careful to avoid a situation in which RTI Connext allocates a string on your behalf and you then reuse that string in such a way that RTI Connext believes it to have more memory allocated to it than it actually does.

Returns: One of the Standard Return Codes

See Also: DDSDomainParticipant::create_contentfilteredtopic; DDSContentFilteredTopic::set_expression_parameters

virtual DDS_ReturnCode_t DDSContentFilteredTopic::set_expression_parameters ( const DDS_StringSeq & parameters )

pure virtual

Set the expression_parameters.

Change the expression_parameters associated with the DDSContentFilteredTopic.

Parameters

parameters <<in>> the filter expression parameters . Length of sequence cannot be greater than 100.

Returns: One of the Standard Return Codes

virtual DDS_ReturnCode_t DDSContentFilteredTopic::append_to_expression_parameter	(	const DDS_Long	index,
		const char *	val
	)

pure virtual

<<eXtension>> Appends a string term to the specified parameter string.

Appends the input string to the end of the specified parameter string, separated by a comma. If the original parameter string is enclosed in quotation marks (''), the resultant string will also be enclosed in quotation marks.

This method can be used in expression parameters associated with MATCH operators in order to add a pattern to the match pattern list. For example, if the filter expression parameter value is:

'IBM'

Then append_to_expression_parameter(0, "MSFT") would generate the new value:

'IBM,MSFT'

Parameters

index	<<in>> The index of the parameter string to be modified. The first index is index 0. When using the DDS_STRINGMATCHFILTER_NAME filter, `index` must be 0.
val	<<in>> The string term to be appended to the parameter string.

Returns: One of the Standard Return Codes

virtual DDS_ReturnCode_t DDSContentFilteredTopic::remove_from_expression_parameter	(	const DDS_Long	index,
		const char *	val
	)

pure virtual

<<eXtension>> Removes a string term from the specified parameter string.

Removes the input string from the specified parameter string. To be found and removed, the input string must exist as a complete term, bounded by comma separators or the strong boundary. If the original parameter string is enclosed in quotation marks (''), the resultant string will also be enclosed in quotation marks. If the removed term was the last entry in the string, the result will be a string of empty quotation marks.

This method can be used in expression parameters associated with MATCH operators in order to remove a pattern from the match pattern list. For example, if the filter expression paremeter value is:

'IBM,MSFT'

Then remove_from_expression_parameter(0, "IBM") would generate the expression:

'MSFT'

Parameters

index	<<in>> The index of the parameter string to be modified. The first index is index 0. When using the DDS_STRINGMATCHFILTER_NAME filter, `index` must be 0.
val	<<in>> The string term to be removed from the parameter string.

Returns: One of the Standard Return Codes

virtual DDSTopic* DDSContentFilteredTopic::get_related_topic ( )

pure virtual

Get the related_topic.

Return the DDSTopic specified when the DDSContentFilteredTopic was created.

Returns: The DDSTopic assocated with the DDSContentFilteredTopic.

Public Member Functions

Static Public Member Functions

Detailed Description

Member Function Documentation