RTI Connext DDS Micro C++ API
Version 4.0.1
|
Information that accompanies each sample that is read
or taken
.
More...
#include <dds_c_subscription.h>
Public Attributes | |
DDS_SampleStateKind | sample_state |
The sample state of the sample. | |
DDS_ViewStateKind | view_state |
The view state of the instance. | |
DDS_InstanceStateKind | instance_state |
The instance state of the instance. | |
struct DDS_Time_t | source_timestamp |
The timestamp when the sample was written by a DataWriter. | |
DDS_InstanceHandle_t | instance_handle |
Identifies locally the corresponding instance. | |
DDS_InstanceHandle_t | publication_handle |
Identifies locally the DataWriter that modified the instance. | |
DDS_Boolean | valid_data |
Indicates whether the DataSample contains data or else it is only used to communicate a change in the instance_state of the instance. | |
struct DDS_Time_t | reception_timestamp |
<<eXtension>> The timestamp when the sample was committed by a DataReader. | |
DDS_EncapsulationId_t | encapsulation_id |
Information that accompanies each sample that is read
or taken
.
The DDS_SampleInfo contains information pertaining to the associated Data
instance sample including:
the sample_state
of the Data
value (i.e., if it has already been read or not)
the view_state
of the related instance (i.e., if the instance is new or not)
the instance_state
of the related instance (i.e., if the instance is alive or not)
the valid_data
flag. This flag indicates whether there is data associated with the sample. Some samples do not contain data indicating only a change on the instance_state
of the corresponding instance.
source_timestamp
of the sample. This is the timestamp provided by the DDSDataWriter at the time the sample was produced. instance_state
and view_state
of a single instance"DDS_SampleStateKind DDS_SampleInfo::sample_state |
The sample state of the sample.
Indicates whether or not the corresponding data sample has already been read.
DDS_ViewStateKind DDS_SampleInfo::view_state |
The view state of the instance.
Indicates whether the DDSDataReader has already seen samples for the most-current generation of the related instance.
DDS_InstanceStateKind DDS_SampleInfo::instance_state |
The instance state of the instance.
Indicates whether the instance is currently in existence or, if it has been disposed, the reason why it was disposed.
struct DDS_Time_t DDS_SampleInfo::source_timestamp |
The timestamp when the sample was written by a DataWriter.
DDS_InstanceHandle_t DDS_SampleInfo::instance_handle |
Identifies locally the corresponding instance.
DDS_InstanceHandle_t DDS_SampleInfo::publication_handle |
Identifies locally the DataWriter that modified the instance.
DDS_Boolean DDS_SampleInfo::valid_data |
Indicates whether the DataSample
contains data or else it is only used to communicate a change in the instance_state
of the instance.
Normally each DataSample
contains both a DDS_SampleInfo and some Data. However there are situations where a DataSample
contains only the DDS_SampleInfo and does not have any associated data. This occurs when the RTI Connext DDS Micro notifies the application of a change of state for an instance that was caused by some internal mechanism (such as a timeout) for which there is no associated data. An example of this situation is when the RTI Connext DDS Micro detects that an instance has no writers and changes the corresponding instance_state to DDS_NOT_ALIVE_NO_WRITERS_INSTANCE_STATE.
The application can distinguish whether a particular DataSample
has data by examining the value of the valid_data
flag. If this flag is set to DDS_BOOLEAN_TRUE, then the DataSample
contains valid Data. If the flag is set to DDS_BOOLEAN_FALSE, the DataSample
contains no Data.
To ensure correctness and portability, the valid_data
flag must be examined by the application prior to accessing the Data associated with the DataSample
and if the flag is set to DDS_BOOLEAN_FALSE, the application should not access the Data associated with the DataSample
, that is, the application should access only the DDS_SampleInfo.
struct DDS_Time_t DDS_SampleInfo::reception_timestamp |
<<eXtension>> The timestamp when the sample was committed by a DataReader.
DDS_EncapsulationId_t DDS_SampleInfo::encapsulation_id |
The transport encapsulation the sample was received as