DDS::Topic Class Reference

Topic is the basic description of data to be published or subscribed. More...

Inheritance diagram for DDS::Topic:

Public Member Functions
const char *	get_type_name ()
	This operation returns type_name of the provided Topic.
const char *	get_name ()
	This operation returns topic name of the provided Topic.
DomainParticipant *	get_participant ()
	This operation returns DomainParticipant that owns the Topic.
StatusMask	get_status_changes ()
	This returns the list of triggered communication statuses in the Topic. More...
ReturnCode_t	enable ()
	Enables the Topic. More...
ReturnCode_t	set_qos (const TopicQos &qos)
	Sets the TopicQos values. More...
ReturnCode_t	get_qos (TopicQos &qos)
	Returns the current TopicQos settings held in the Topic t. More...
ReturnCode_t	set_listener (TopicListener *a_listener, StatusMask mask)
	Installs a TopicListener on Topic t. More...
TopicListener *	get_listener ()
	This operation returns the currently installed TopicListener. More...
ReturnCode_t	get_inconsistent_topic_status (InconsistentTopicStatus *a_status)
	Provides access to the InconsistentTopicStatus of the Topic. More...
Public Member Functions inherited from DDS::Entity
virtual StatusCondition *	get_statuscondition ()
	Gets the StatusCondition associated with this Entity. NOTE: The entity maintains ownership of the statuscondition, and it remains valid only as long as the Entity is valid. Destroying the Entity also destroys the status condition.
virtual InstanceHandle_t	get_instance_handle ()
	Gets the handle that locally identifies this Entity.

Detailed Description

Topic is the basic description of data to be published or subscribed.

A topic is identified by a name and a type. A Topic is created by calling DomainParticipant::create_topic(). Prior to creating a Topic, the associated data type must be registered with the DomainParticipant via a call to the TypeSupport::register_type() function. [The register_type() function is auto-generated 'type-specific' code.]

Member Function Documentation

ReturnCode_t DDS::Topic::enable ( )

virtual

Enables the Topic.

A Topic is created either enabled or not based on the DomainParticipantQos setting entity_factory. When a Topic is not enabled, only the following sub-set of all Topic operations are legal:

• operations to get and set QoS policies,
• get_name(), get_type_name(), get_participant()
• get_statuscondition(),
• get_status_changes(),

Any other operation may return the NOT_ENABLED error. Topic::enable() may be called on an already enabled Topic [it will have no effect].

Reimplemented from DDS::Entity.

ReturnCode_t DDS::Topic::get_inconsistent_topic_status

(

InconsistentTopicStatus *

a_status

)

Provides access to the InconsistentTopicStatus of the Topic.

As a side-effect, this routine will reset the total_count_change status field to zero.

TopicListener* DDS::Topic::get_listener

(

)

This operation returns the currently installed TopicListener.

Note

Because the infrastructure makes a copy of the listener provided in Topic::set_listener(), the returned structure pointer will not match the pointer originally provided. However, the function pointers within the structure will match. Also, the application should not free the data referenced by the returned pointer.

ReturnCode_t DDS::Topic::get_qos

(

TopicQos &

qos

)

Returns the current TopicQos settings held in the Topic t.

This routine copies the Topic QoS properites into qos.

Note

The qos structure may contain sequences or strings that are populated with dynamic memory. The caller is responsible for freeing the dynamic memory of these items.
For example, the sequence 'qos->topic_data' may have dynamically allocated memory assigned. This can be released by a call to seq_clear(&qos->topic_data).

StatusMask DDS::Topic::get_status_changes ( )

virtual

This returns the list of triggered communication statuses in the Topic.

If the Topic is not enabled, all statuses will be untriggered.

Implements DDS::Entity.

ReturnCode_t DDS::Topic::set_listener	(	TopicListener *	a_listener,
		StatusMask	mask
	)

Installs a TopicListener on Topic t.

Only one listener may be attached to a Topic at a time. A call to set_listener() will replace any current listener with a_listener.

a_listener can be NULL, which indicates a listener that does nothing.

The infrastructure will make an internal copy of the listener structure so that it need not be persisted by the application.

ReturnCode_t DDS::Topic::set_qos

(

const TopicQos &

qos

)

Sets the TopicQos values.

These QoS values affect the behavior of the Topic.