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RTI Connext C API
Version 6.1.2
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DDS_Entity, DDS_Listener and related items. More...
Data Structures | |
| struct | DDS_Listener |
| <<interface>> Abstract base class for all Listener interfaces. More... | |
Macros | |
| #define | DDS_Listener_INITIALIZER |
| Initialize the DDS_Listener::listener_data pointer to NULL. More... | |
Typedefs | |
| typedef struct DDS_EntityImpl | DDS_Entity |
| <<interface>> Abstract base class for all the DDS objects that support QoS policies, a listener, and a status condition. More... | |
| typedef struct DDS_DomainEntityImpl | DDS_DomainEntity |
| <<interface>> Abstract base class for all DDS entities except for the DDS_DomainParticipant. More... | |
Functions | |
| DDS_ReturnCode_t | DDS_Entity_enable (DDS_Entity *self) |
| Enables the DDS_Entity. More... | |
| DDS_StatusCondition * | DDS_Entity_get_statuscondition (DDS_Entity *self) |
| Allows access to the DDS_StatusCondition associated with the DDS_Entity. More... | |
| DDS_StatusMask | DDS_Entity_get_status_changes (DDS_Entity *self) |
| Retrieves the list of communication statuses in the DDS_Entity that are triggered. More... | |
| DDS_InstanceHandle_t | DDS_Entity_get_instance_handle (DDS_Entity *self) |
| Allows access to the DDS_InstanceHandle_t associated with the DDS_Entity. More... | |
| DDS_EntityKind_t | DDS_Entity_get_entity_kind (DDS_Entity *self) |
| Allows access to the DDS_InstanceHandle_t associated with the DDS_Entity. More... | |
DDS_Entity, DDS_Listener and related items.
DDS_Entity subtypes are created and destroyed by factory objects. With the exception of DDS_DomainParticipant, whose factory is DDS_DomainParticipantFactory, all DDS_Entity factory objects are themselves DDS_Entity subtypes as well.
Important: all DDS_Entity delete operations are inherently thread-unsafe. The user must take extreme care that a given DDS_Entity is not destroyed in one thread while being used concurrently (including being deleted concurrently) in another thread. An operation's effect in the presence of the concurrent deletion of the operation's target DDS_Entity is undefined.
| #define DDS_Listener_INITIALIZER |
Initialize the DDS_Listener::listener_data pointer to NULL.
| typedef struct DDS_EntityImpl DDS_Entity |
<<interface>> Abstract base class for all the DDS objects that support QoS policies, a listener, and a status condition.
All operations except for set_qos(), get_qos(), set_listener(), get_listener() and enable(), may return the value DDS_RETCODE_NOT_ENABLED.
Each derived entity provides the following operations specific to its role in RTI Connext.
This operation sets the QoS policies of the DDS_Entity. Each of the derived entity classes provides this operation: DDS_Entity classes (DDS_DomainParticipant, DDS_Topic, DDS_Publisher, DDS_DataWriter, DDS_Subscriber, and DDS_DataReader) so that the policies that are meaningful to each DDS_Entity can be set. For example, see DDS_DomainParticipant_set_qos.
set_qos() is invoked after the DDS_Entity is enabled and it attempts to change the value of an immutable policy, the operation will fail and return DDS_RETCODE_IMMUTABLE_POLICY. set_qos() operation will also fail if it specifies a set of values that, once combined with the existing values, would result in an inconsistent set of policies. In this case, the operation will fail and return DDS_RETCODE_INCONSISTENT_POLICY. set_qos() operation succeeds. This is indicated by a return code of DDS_RETCODE_OK. In all other cases, none of the policies are modified. Each derived DDS_Entity class (DDS_DomainParticipant, DDS_Topic, DDS_Publisher, DDS_DataWriter, DDS_Subscriber, DDS_DataReader) has a corresponding special value of the QoS (DDS_PARTICIPANT_QOS_DEFAULT, DDS_PUBLISHER_QOS_DEFAULT, DDS_SUBSCRIBER_QOS_DEFAULT, DDS_TOPIC_QOS_DEFAULT, DDS_DATAWRITER_QOS_DEFAULT, DDS_DATAREADER_QOS_DEFAULT). This special value may be used as a parameter to the set_qos operation to indicate that the QoS of the DDS_Entity should be changed to match the current default QoS set in the DDS_Entity's factory. The operation set_qos cannot modify the immutable QoS, so a successful return of the operation indicates that the mutable QoS for the Entity has been modified to match the current default for the DDS_Entity's factory.
The set of policies specified in the qos parameter are applied on top of the existing QoS, replacing the values of any policies previously set.
Possible error codes returned in addition to Standard Return Codes : DDS_RETCODE_IMMUTABLE_POLICY, DDS_RETCODE_INCONSISTENT_POLICY.
This operation allows access to the existing set of QoS policies for the DDS_Entity. This operation must be provided by each of the derived DDS_Entity classes (DDS_DomainParticipant, DDS_Topic, DDS_Publisher, DDS_DataWriter, DDS_Subscriber, and DDS_DataReader), so that the policies that are meaningful to each DDS_Entity can be retrieved. For example, see DDS_DomainParticipant_get_qos
Possible error codes are Standard Return Codes.
This operation installs a DDS_Listener on the DDS_Entity. The listener will only be invoked on the changes of communication status indicated by the specified mask.
This operation must be provided by each of the derived DDS_Entity classes (DDS_DomainParticipant, DDS_Topic, DDS_Publisher, DDS_DataWriter, DDS_Subscriber, and DDS_DataReader), so that the listener is of the concrete type suitable to the particular DDS_Entity.
There are two components involved when setting up listeners: the listener itself and the mask. Both of these can be NULL.
Listeners for some Entities derive from the Connext DDS Listeners for related Entities. This means that the derived Listener has all of the methods of its parent class. You can install Listeners at all levels of the object hierarchy. At the top is the DomainParticipantListener; only one can be installed in a DomainParticipant. Then every Subscriber and Publisher can have their own Listener. Finally, each Topic, DataReader and DataWriter can have their own listeners. All are optional.
Suppose, however, that an Entity does not install a Listener, or installs a Listener that does not have particular communication status selected in the bitmask. In this case, if/when that particular status changes for that Entity, the corresponding Listener for that Entity's parent is called. Status changes are "propagated" from child Entity to parent Entity until a Listener is found that is registered for that status. Connext DDS will give up and drop the status-change event only if no Listeners have been installed in the object hierarchy to be called back for the specific status.
The following table describes the effect of different combinations of Listeners and Status Bit Masks considering the hierarchical processing.
| No Bits Set in Mask | Some/All Bits Set in Mask | |
|---|---|---|
| Listener is Specified | Connext DDS finds the next most relevant listener for the changed status | For the statuses that are enabled in the mask, the most relevant listener will be called. The 'statusChangedFlag' for the relevant status is reset |
| Listener is NULL | Connext DDS behaves as if the listener is not installed and finds the next most relevant listener for that status | Connext DDS behaves as if the listener is installed, but the callback is doing nothing. This is called a "nil" listener |
set_listener() will replace it with the new one. Consequently, if the value NULL is passed for the listener parameter to the set_listener operation, any existing listener will be removed. This operation allows access to the existing DDS_Listener attached to the DDS_Entity.
This operation must be provided by each of the derived DDS_Entity classes (DDS_DomainParticipant, DDS_Topic, DDS_Publisher, DDS_DataWriter, DDS_Subscriber, and DDS_DataReader) so that the listener is of the concrete type suitable to the particular DDS_Entity.
If no listener is installed on the DDS_Entity, this operation will return NULL.
| typedef struct DDS_DomainEntityImpl DDS_DomainEntity |
<<interface>> Abstract base class for all DDS entities except for the DDS_DomainParticipant.
Its sole purpose is to conceptually express that DDS_DomainParticipant is a special kind of DDS_Entity that acts as a container of all other DDS_Entity but itself cannot contain other DDS_DomainParticipant.
| DDS_ReturnCode_t DDS_Entity_enable | ( | DDS_Entity * | self | ) |
Enables the DDS_Entity.
This operation enables the Entity. Entity objects can be created either enabled or disabled. This is controlled by the value of the ENTITY_FACTORY QoS policy on the corresponding factory for the DDS_Entity.
By default, ENTITY_FACTORY is set so that it is not necessary to explicitly call DDS_Entity_enable on newly created entities.
The DDS_Entity_enable operation is idempotent. Calling enable on an already enabled Entity returns OK and has no effect.
If a DDS_Entity has not yet been enabled, the following kinds of operations may be invoked on it:
Other operations may explicitly state that they may be called on disabled entities; those that do not will return the error DDS_RETCODE_NOT_ENABLED.
It is legal to delete an DDS_Entity that has not been enabled by calling the proper operation on its factory.
Entities created from a factory Entity that is disabled are created disabled, regardless of the setting of the DDS_EntityFactoryQosPolicy.
Calling enable on an Entity whose factory Entity is not enabled will fail and return DDS_RETCODE_PRECONDITION_NOT_MET.
If DDS_EntityFactoryQosPolicy::autoenable_created_entities is TRUE, the enable operation on a factory will automatically enable all entities created from that factory (for example, enabling a DDS_Publisher will enable all its contained DDS_DataWriter objects)
Listeners associated with an entity are not called until the entity is enabled.
Conditions associated with a disabled entity are "inactive," that is, they have a trigger_value == FALSE.
| self | <<in>> Cannot be NULL. |
| DDS_StatusCondition* DDS_Entity_get_statuscondition | ( | DDS_Entity * | self | ) |
Allows access to the DDS_StatusCondition associated with the DDS_Entity.
The returned condition can then be added to a DDS_WaitSet so that the application can wait for specific status changes that affect the DDS_Entity.
| self | <<in>> Cannot be NULL. |
| DDS_StatusMask DDS_Entity_get_status_changes | ( | DDS_Entity * | self | ) |
Retrieves the list of communication statuses in the DDS_Entity that are triggered.
That is, the list of statuses whose value has changed since the last time the application read the status using the get_*_status() function.
When the entity is first created or if the entity is not enabled, all communication statuses are in the "untriggered" state so the list returned by the get_status_changes operation will be empty.
The list of statuses returned by the get_status_changes operation refers to the status that are triggered on the Entity itself and does not include statuses that apply to contained entities.
| self | <<in>> Cannot be NULL. |
| DDS_InstanceHandle_t DDS_Entity_get_instance_handle | ( | DDS_Entity * | self | ) |
Allows access to the DDS_InstanceHandle_t associated with the DDS_Entity.
This operation returns the DDS_InstanceHandle_t that represents the DDS_Entity.
| self | <<in>> Cannot be NULL. |
| DDS_EntityKind_t DDS_Entity_get_entity_kind | ( | DDS_Entity * | self | ) |
Allows access to the DDS_InstanceHandle_t associated with the DDS_Entity.
This operation returns the DDS_InstanceHandle_t that represents the DDS_Entity.
| self | <<in>> Cannot be NULL. |