org.omg.dds.topic

Interface ContentFilteredTopic<TYPE>

Type Parameters:

TYPE - The concrete type of the data that will be published and/ or subscribed by the readers and writers that use this topic description.

All Superinterfaces:

AutoCloseable, Closeable, DDSObject, TopicDescription<TYPE>

public interface ContentFilteredTopic<TYPE>
extends TopicDescription<TYPE>

ContentFilteredTopic is a specialization of TopicDescription that allows for content-based subscriptions. ContentFilteredTopic describes a more sophisticated subscription that indicates the subscriber does not want to necessarily see all values of each instance published under the Topic. 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 filterExpression with parameters expressionParameters.

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

Method Summary

Methods

Modifier and Type	Method and Description
List<String>	getExpressionParameters() This operation returns the expression parameters associated with the ContentFilteredTopic, that is, the parameters specified on the last successful call to setExpressionParameters(List), or if setExpressionParameters(List) was never called, the parameters specified when the ContentFilteredTopic was created.
String	getFilterExpression()
Topic<? extends TYPE>	getRelatedTopic()
void	setExpressionParameters(List<String> expressionParameters) This operation changes the expression parameters associated with the ContentFilteredTopic.

Methods inherited from interface org.omg.dds.topic.TopicDescription

cast, close, getName, getParent, getTypeName, getTypeSupport

Methods inherited from interface org.omg.dds.core.DDSObject

getEnvironment

Method Detail

getFilterExpression

String getFilterExpression()

Returns:

the filter expression associated with the ContentFilteredTopic, that is, the expression specified when the ContentFilteredTopic was created.

getExpressionParameters

List<String> getExpressionParameters()

This operation returns the expression parameters associated with the ContentFilteredTopic, that is, the parameters specified on the last successful call to setExpressionParameters(List), or if setExpressionParameters(List) was never called, the parameters specified when the ContentFilteredTopic was created.

Returns:

an unmodifiable list.

See Also:

setExpressionParameters(List)

setExpressionParameters

void setExpressionParameters(List<String> expressionParameters)

This operation changes the expression parameters associated with the ContentFilteredTopic.

See Also:

getExpressionParameters()

getRelatedTopic

Topic<? extends TYPE> getRelatedTopic()

Returns:

the Topic associated with the ContentFilteredTopic, that is, the Topic specified when the ContentFilteredTopic was created.