Status Kinds

Kinds of communication status. More...

Macros
#define	DDS_STATUS_MASK_NONE
	No bits are set. More...
#define	DDS_STATUS_MASK_ALL
	All bits are set. More...

Typedefs
typedef DDS_UnsignedLong	DDS_StatusMask
	A bit-mask (list) of concrete status types, i.e. DDS_StatusKind[]. More...

Enumerations
enum	DDS_StatusKind {   DDS_INCONSISTENT_TOPIC_STATUS, DDS_OFFERED_DEADLINE_MISSED_STATUS, DDS_REQUESTED_DEADLINE_MISSED_STATUS, DDS_OFFERED_INCOMPATIBLE_QOS_STATUS,   DDS_REQUESTED_INCOMPATIBLE_QOS_STATUS, DDS_SAMPLE_LOST_STATUS, DDS_SAMPLE_REJECTED_STATUS, DDS_DATA_ON_READERS_STATUS,   DDS_DATA_AVAILABLE_STATUS, DDS_LIVELINESS_LOST_STATUS, DDS_LIVELINESS_CHANGED_STATUS, DDS_PUBLICATION_MATCHED_STATUS,   DDS_SUBSCRIPTION_MATCHED_STATUS, DDS_INSTANCE_REPLACED_STATUS, DDS_RELIABLE_READER_ACTIVITY_CHANGED_STATUS }
	Type for status kinds. More...

Detailed Description

Kinds of communication status.

Entity:

DDS_Entity

QoS:

QoS Policies

Listener:

DDS_Listener Each concrete DDS_Entity is associated with a set of Status objects whose value represents the communication status of that entity. Each status value can be accessed with a corresponding functionon the DDS_Entity. RTI Connext Micro supports a subset of these statuses. When these status values change, the proper DDS_Listener objects are invoked to asynchronously inform the application. An application is notified of communication status by means of the DDS_Listener mechanism. The statuses may be classified into:

• read communication statuses: i.e., those that are related to arrival of data, namely DDS_DATA_ON_READERS_STATUS and DDS_DATA_AVAILABLE_STATUS.
• plain communication statuses: i.e., all the others. Read communication statuses are treated slightly differently than the others because they don't change independently. In other words, at least two changes will appear at the same time ( DDS_DATA_ON_READERS_STATUS and DDS_DATA_AVAILABLE_STATUS) and even several of the last kind may be part of the set. This 'grouping' has to be communicated to the application. For each plain communication status, there is a corresponding structure to hold the status value. These values contain the information related to the change of status, as well as information related to the statuses themselves (e.g., contains cumulative counts).
  

  "Status Values"

Changes in Status

Associated with each one of an DDS_Entity's communication status is a logical StatusChangedFlag. This flag indicates whether that particular communication status has changed since the last time the status was read by the application. The way the status changes is slightly different for the Plain Communication Status and the Read Communication status.

"StatusChangedFlag indicates if status has changed"

Changes in plain communication status

For the plain communication status, the StatusChangedFlag flag is initially set to FALSE. It becomes TRUE whenever the plain communication status changes and it is reset to DDS_BOOLEAN_FALSE each time the application accesses the plain communication status via the proper get_<plain communication status>() operation on the DDS_Entity. The communication status is also reset to FALSE whenever the associated listener operation is called as the listener implicitly accesses the status which is passed as a parameter to the operation. The fact that the status is reset prior to calling the listener means that if the application calls the get_<plain communication status> from inside the listener it will see the status already reset. An exception to this rule is when the associated listener is the 'nil' listener. The 'nil' listener is treated as a NOOP and the act of calling the 'nil' listener does not reset the communication status.

"Changes in StatusChangedFlag for plain communication status"

Changes in read communication status

For the read communication status, the StatusChangedFlag flag is initially set to FALSE. The StatusChangedFlag becomes TRUE when either a data-sample arrives or else the DDS_ViewStateKind, DDS_SampleStateKind, or DDS_InstanceStateKind of any existing sample changes for any reason other than a call to DDS_DataReader_read_next_sample, or DDS_DataReader_take_next_sample. Specifically any of the following events will cause the StatusChangedFlag to become TRUE:

• The arrival of new data.
• A change in the DDS_InstanceStateKind of a contained instance. This can be caused by either:
  • The arrival of the notification that an instance has been disposed by:
    • the DDS_DataWriter that owns it if OWNERSHIP QoS kind= DDS_EXCLUSIVE_OWNERSHIP_QOS
    • or by any DDS_DataWriter if OWNERSHIP QoS kind= DDS_SHARED_OWNERSHIP_QOS
  • The loss of liveliness of the DDS_DataWriter of an instance for which there is no other DDS_DataWriter.
  • The arrival of the notification that an instance has been unregistered by the only DDS_DataWriter that is known to be writing the instance.

Depending on the kind of StatusChangedFlag, the flag transitions to FALSE again as follows:

• The DDS_DATA_AVAILABLE_STATUS StatusChangedFlag becomes FALSE when either the corresponding listener operation (on_data_available) is called or the read_next_sample or take_next_sample operation is called on the associated DDS_DataReader.
• The DDS_DATA_ON_READERS_STATUS StatusChangedFlag becomes FALSE when any of the following events occurs:
  • The corresponding listener operation (on_data_on_readers) is called.
  • The on_data_available listener operation is called on any DDS_DataReader belonging to the DDS_Subscriber.
  • The read or take operation (or their variants) is called on any DDS_DataReader belonging to the DDS_Subscriber.

"Changes in StatusChangedFlag for read communication status"

See Also

DDS_Listener

Macro Definition Documentation

#define DDS_STATUS_MASK_NONE

No bits are set.

#define DDS_STATUS_MASK_ALL

All bits are set.

Typedef Documentation

typedef DDS_UnsignedLong DDS_StatusMask

A bit-mask (list) of concrete status types, i.e. DDS_StatusKind[].

The bit-mask is an efficient and compact representation of a fixed-length list of DDS_StatusKind values. Bits in the mask correspond to different statuses. You can choose which changes in status will trigger a callback by setting the corresponding status bits in this bit-mask and installing callbacks for each of those statuses. The bits that are true indicate that the listener will be called back for changes in the corresponding status. For example:

DDS_StatusMask mask = DDS_REQUESTED_DEADLINE_MISSED_STATUS | 
 DDS_DATA_AVAILABLE_STATUS; 
 datareader->set_listener(listener, mask); 

or

DDS_StatusMask mask = DDS_REQUESTED_DEADLINE_MISSED_STATUS | 
 DDS_DATA_AVAILABLE_STATUS; 
 datareader = subscriber->create_datareader(topic, 
 DDS_DATAREADER_QOS_DEFAULT, 
 listener, mask);

Enumeration Type Documentation

enum DDS_StatusKind

Type for status kinds.

Each concrete DDS_Entity is associated with a set of *Status objects whose values represent the communication status of that DDS_Entity. The communication statuses whose changes can be communicated to the application depend on the DDS_Entity. Each status value can be accessed with a corresponding functionon the DDS_Entity. The changes on these status values cause activation of the corresponding trigger invocation of the proper DDS_Listener objects to asynchronously inform the application.

See Also

DDS_Entity, DDS_Listener

Enumerator
DDS_INCONSISTENT_TOPIC_STATUS	Another topic exists with the same name but different characteristics. Entity: DDS_Topic Status: DDS_InconsistentTopicStatus Listener: DDS_TopicListener
DDS_OFFERED_DEADLINE_MISSED_STATUS	The deadline that the DDS_DataWriter has committed through its DDS_DeadlineQosPolicy was not respected for a specific instance. Entity: DDS_DataWriter QoS: DEADLINE Status: DDS_OfferedDeadlineMissedStatus Listener: DDS_DataWriterListener
DDS_REQUESTED_DEADLINE_MISSED_STATUS	The deadline that the DDS_DataReader was expecting through its DDS_DeadlineQosPolicy was not respected for a specific instance. Entity: DDS_DataReader QoS: DEADLINE Status: DDS_RequestedDeadlineMissedStatus Listener: DDS_DataReaderListener
DDS_OFFERED_INCOMPATIBLE_QOS_STATUS	A QosPolicy value was incompatible with what was requested. Entity: DDS_DataWriter Status: DDS_OfferedIncompatibleQosStatus Listener: DDS_DataWriterListener
DDS_REQUESTED_INCOMPATIBLE_QOS_STATUS	A QosPolicy value was incompatible with what is offered. Entity: DDS_DataReader Status: DDS_RequestedIncompatibleQosStatus Listener: DDS_DataReaderListener
DDS_SAMPLE_LOST_STATUS	A sample has been lost (i.e. was never received). Entity: DDS_Subscriber Status: DDS_SampleLostStatus Listener: DDS_SubscriberListener
DDS_SAMPLE_REJECTED_STATUS	A (received) sample has been rejected. Entity: DDS_DataReader QoS: RESOURCE_LIMITS Status: DDS_SampleRejectedStatus Listener: DDS_DataReaderListener
DDS_DATA_ON_READERS_STATUS	New data is available. Entity: DDS_Subscriber Listener: DDS_SubscriberListener
DDS_DATA_AVAILABLE_STATUS	One or more new data samples have been received. Entity: DDS_DataReader Listener: DDS_DataReaderListener
DDS_LIVELINESS_LOST_STATUS	The liveliness that the DDS_DataWriter has committed to through its DDS_LivelinessQosPolicy was not respected, thus DDS_DataReader entities will consider the DDS_DataWriter as no longer alive. Entity: DDS_DataWriter QoS: LIVELINESS Status: DDS_LivelinessLostStatus Listener: DDS_DataWriterListener
DDS_LIVELINESS_CHANGED_STATUS	The liveliness of one or more DDS_DataWriter that were writing instances read through the DDS_DataReader has changed. Some DDS_DataWriter have become alive or not_alive. Entity: DDS_DataReader QoS: LIVELINESS Status: DDS_LivelinessChangedStatus Listener: DDS_DataReaderListener
DDS_PUBLICATION_MATCHED_STATUS	The DDS_DataWriter has found DDS_DataReader that matches the DDS_Topic and has compatible QoS. Entity: DDS_DataWriter Status: DDS_PublicationMatchedStatus Listener: DDS_DataWriterListener
DDS_SUBSCRIPTION_MATCHED_STATUS	The DDS_DataReader has found DDS_DataWriter that matches the DDS_Topic and has compatible QoS. Entity: DDS_DataReader Status: DDS_SubscriptionMatchedStatus Listener: DDS_DataReaderListener
DDS_INSTANCE_REPLACED_STATUS	The DDS_DataReader has replaced an instance. Entity: DDS_DataReader Status: DDS_DataReaderInstanceReplacedStatus Listener: DDS_DataReaderListener
DDS_RELIABLE_READER_ACTIVITY_CHANGED_STATUS	The DDS_DataWriter has detected a change of activity in a reliable DDS_DataReader. Entity: DDS_DataWriter Status: DDS_ReliableReaderActivityChangedStatus Listener: DDS_DataWriterListener