MultiTopic is a specialization of TopicDescription that allows subscriptions to combine/filter/rearrange data coming from several org.omg.dds.topic.Topics. More...

Inheritance diagram for org.omg.dds.topic.MultiTopic< TYPE >:

Collaboration diagram for org.omg.dds.topic.MultiTopic< TYPE >:

Public Member Functions
public< OTHER > TopicDescription< OTHER >	cast ()
	Cast this topic description to the given type, or throw an exception if the cast fails. More...

void	close ()
	Dispose the resources held by this object. More...

ServiceEnvironment	getEnvironment ()

List< String >	getExpressionParameters ()
	This operation returns the expression parameters associated with the MultiTopic, 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 MultiTopic was created. More...

String	getName ()
	Returns the name used to create the TopicDescription. More...

DomainParticipant	getParent ()
	Returns the org.omg.dds.domain.DomainParticipant to which the TopicDescription belongs. More...

String	getSubscriptionExpression ()

String	getTypeName ()
	Returns the type name used to create the TopicDescription. More...

TypeSupport< TYPE >	getTypeSupport ()
	Returns the org.omg.dds.type.TypeSupport used to create this TopicDescription. More...

void	setExpressionParameters (List< String > expressionParameters)
	This operation changes the expression parameters associated with the MultiTopic. More...

void	setExpressionParameters (String... expressionParameters)
	This operation changes the expression parameters associated with the MultiTopic. More...

Detailed Description

MultiTopic is a specialization of TopicDescription that allows subscriptions to combine/filter/rearrange data coming from several org.omg.dds.topic.Topics.

MultiTopic allows a more sophisticated subscription that can select and combine data received from multiple topics into a single resulting type (specified by the inherited typeName). The data will then be filtered (selection) and possibly rearranged (aggregation/projection) according to a subscriptionExpression with parameters expressionParameters.

The subscriptionExpression is a string that identifies the selection and rearrangement of data from the associated topics. It is similar to an SQL clause where the SELECT part provides the fields to be kept, the FROM part provides the names of the topics that are searched for those fields, and the WHERE clause gives the content filter. The Topics combined may have different types but they are restricted in that the type of the fields used for the NATURAL JOIN operation must be the same.
The expressionParameters attribute is a sequence of strings that give values to the "parameters" (i.e., "%n" tokens) in the subscriptionExpression. The number of supplied parameters must fit with the requested values in the subscriptionExpression (i.e., the number of "%n" tokens).
org.omg.dds.sub.DataReader entities associated with a MultiTopic are alerted of data modifications by the usual Listener or org.omg.dds.core.Condition mechanisms whenever modifications occur to the data associated with any of the topics relevant to the MultiTopic.
DataReader entities associated with a MultiTopic access instances that are "constructed" at the DataReader side from the instances written by multiple DataWriter entities. The MultiTopic access instance will begin to exist as soon as all the constituting Topic instances are in existence. The org.omg.dds.sub.ViewState and org.omg.dds.sub.InstanceState are computed from the corresponding states of the constituting instances:
- The viewState of the MultiTopic instance is NEW if at least one of the constituting instances has viewState = NEW, otherwise it will be NOT_NEW.
- The instanceState of the MultiTopic instance is "ALIVE" if the instanceStates of all the constituting Topic instances are ALIVE. It is "NOT_ALIVE_DISPOSED" if at least one of the constituting Topic instances is NOT_ALIVE_DISPOSED. Otherwise, it is NOT_ALIVE_NO_WRITERS.

NOTE: MultiTopic is currently not supported by OpenSplice!

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.

Definition at line 73 of file MultiTopic.java.

Member Function Documentation

◆ cast()

public<OTHER> TopicDescription<OTHER> org.omg.dds.topic.TopicDescription< TYPE >.cast ( )

inherited

Cast this topic description to the given type, or throw an exception if the cast fails.

Parameters

<OTHER> The type of the data exchanged on this topic, according to the caller.

Returns: this topic description

Exceptions

ClassCastException if the cast fails

◆ close()

void org.omg.dds.topic.TopicDescription< TYPE >.close ( )

inherited

Dispose the resources held by this object.

A TopicDescription cannot be closed if it is in use by any org.omg.dds.pub.DataWriters or org.omg.dds.sub.DataReaders. With respect to org.omg.dds.topic.Topics specifically: a Topic cannot be closed if it has any remaining org.omg.dds.topic.ContentFilteredTopics or org.omg.dds.topic.MultiTopics related to it.

See also: org.omg.dds.core.Entity::close()

Implemented in org.opensplice.dds.topic.ContentFilteredTopicImpl< TYPE >, and org.opensplice.dds.topic.TopicDescriptionExt< TYPE >.

◆ getEnvironment()

ServiceEnvironment org.omg.dds.core.DDSObject.getEnvironment ( )

inherited

Returns: the org.omg.dds.core.ServiceEnvironment object that directly or indirectly was used to create this object.

◆ getExpressionParameters()

List<String> org.omg.dds.topic.MultiTopic< TYPE >.getExpressionParameters ( )

This operation returns the expression parameters associated with the MultiTopic, 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 MultiTopic was created.

Returns: an unmodifiable list.

See also: #setExpressionParameters(List)

◆ getName()

String org.omg.dds.topic.TopicDescription< TYPE >.getName ( )

inherited

Returns the name used to create the TopicDescription.

Returns: the name.

Implemented in org.opensplice.dds.topic.TopicImpl< TYPE >, and org.opensplice.dds.topic.ContentFilteredTopicImpl< TYPE >.

◆ getParent()

DomainParticipant org.omg.dds.topic.TopicDescription< TYPE >.getParent ( )

inherited

Returns the org.omg.dds.domain.DomainParticipant to which the TopicDescription belongs.

Returns: the org.omg.dds.domain.DomainParticipant

Implemented in org.opensplice.dds.topic.TopicImpl< TYPE >, org.opensplice.dds.topic.ContentFilteredTopicImpl< TYPE >, and org.omg.dds.topic.Topic< TYPE >.

◆ getSubscriptionExpression()

String org.omg.dds.topic.MultiTopic< TYPE >.getSubscriptionExpression ( )

Returns: the subscription expression associated with the MultiTopic, that is, the expression specified when the MultiTopic was created.

◆ getTypeName()

String org.omg.dds.topic.TopicDescription< TYPE >.getTypeName ( )

inherited

Returns the type name used to create the TopicDescription.

Returns: the type name

Implemented in org.opensplice.dds.topic.TopicImpl< TYPE >, and org.opensplice.dds.topic.ContentFilteredTopicImpl< TYPE >.

◆ getTypeSupport()

TypeSupport<TYPE> org.omg.dds.topic.TopicDescription< TYPE >.getTypeSupport ( )

inherited

Returns the org.omg.dds.type.TypeSupport used to create this TopicDescription.

Returns: the org.omg.dds.type.TypeSupport.

Implemented in org.opensplice.dds.topic.TopicImpl< TYPE >, and org.opensplice.dds.topic.ContentFilteredTopicImpl< TYPE >.

◆ setExpressionParameters() [1/2]

void org.omg.dds.topic.MultiTopic< TYPE >.setExpressionParameters ( List< String > expressionParameters )

This operation changes the expression parameters associated with the MultiTopic.

Parameters

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

See also: getExpressionParameters()

◆ setExpressionParameters() [2/2]

void org.omg.dds.topic.MultiTopic< TYPE >.setExpressionParameters ( String... expressionParameters )

This operation changes the expression parameters associated with the MultiTopic.

Parameters

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

See also: getExpressionParameters()

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

java5/common/java/code/org/omg/dds/topic/MultiTopic.java

Public Member Functions

Detailed Description

Member Function Documentation

◆ cast()

◆ close()

◆ getEnvironment()

◆ getExpressionParameters()

◆ getName()

◆ getParent()

◆ getSubscriptionExpression()

◆ getTypeName()

◆ getTypeSupport()

◆ setExpressionParameters() [1/2]

◆ setExpressionParameters() [2/2]