RTI Connext Java API
Version 6.1.2
|
Information that accompanies each sample that is read
or taken
.
More...
Public Member Functions | |
Object | copy_from (Object other) |
Public Attributes | |
int | sample_state |
The sample state of the sample. More... | |
int | view_state |
The view state of the instance. More... | |
int | instance_state |
The instance state of the instance. More... | |
final Time_t | source_timestamp |
The timestamp when the sample was written by a DataWriter. More... | |
final InstanceHandle_t | instance_handle |
Identifies locally the corresponding instance. More... | |
final InstanceHandle_t | publication_handle |
Identifies locally the DataWriter that modified the instance. More... | |
int | disposed_generation_count |
The disposed generation count of the instance at the time of sample reception. More... | |
int | no_writers_generation_count |
The no writers generation count of the instance at the time of sample reception. More... | |
int | sample_rank |
The sample rank of the sample. More... | |
int | generation_rank |
The generation rank of the sample. More... | |
int | absolute_generation_rank |
The absolute generation rank of the sample. More... | |
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. More... | |
final Time_t | reception_timestamp |
<<extension>> The timestamp when the sample was committed by a DataReader. More... | |
final SequenceNumber_t | publication_sequence_number |
<<extension>> The publication sequence number. More... | |
final SequenceNumber_t | reception_sequence_number |
<<extension>> The reception sequence number when sample was committed by a DataReader More... | |
final GUID_t | original_publication_virtual_guid |
<<extension>> The original publication virtual GUID. More... | |
final SequenceNumber_t | original_publication_virtual_sequence_number |
<<extension>> The original publication virtual sequence number. More... | |
final GUID_t | related_original_publication_virtual_guid |
<<extension>> The original publication virtual GUID of a related sample. More... | |
final SequenceNumber_t | related_original_publication_virtual_sequence_number |
<<extension>> The original publication virtual sequence number of a related sample. More... | |
int | flag |
<<extension>> Flags associated with the sample. More... | |
GUID_t | source_guid |
<<extension>> The application logical data source associated with the sample. More... | |
GUID_t | related_source_guid |
<<extension>> The application logical data source that is related to the sample. More... | |
GUID_t | related_subscription_guid |
<<extension>> The related_reader_guid associated with the sample. More... | |
final GUID_t | topic_query_guid |
<<extension>> The GUID of the com.rti.dds.subscription.TopicQuery that is related to the sample. More... | |
CoherentSetInfo_t | coherent_set_info |
<<extension>> The information about the coherent set that this sample is a part of. More... | |
Information that accompanies each sample that is read
or taken
.
The com.rti.dds.subscription.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)
instance_state
of the related instance (i.e., if the instance is alive or not) instance_state
of the corresponding instance. disposed_generation_count
and no_writers_generation_count
for the related instance at the time the sample was received. These counters indicate the number of times the instance had become ALIVE (with instance_state=
com.rti.dds.subscription.InstanceStateKind.ALIVE_INSTANCE_STATE) at the time the sample was received. The sample_rank
and generation_rank
of the sample within the returned sequence. These ranks provide a preview of the samples that follow within the sequence returned by the read
or take
operations.
absolute_generation_rank
of the sample within the com.rti.dds.subscription.DataReader. This rank provides a preview of what is available within the com.rti.dds.subscription.DataReader. source_timestamp
of the sample. This is the timestamp provided by the com.rti.dds.publication.DataWriter at the time the sample was produced. For each instance, RTI Connext internally maintains two counts, the com.rti.dds.subscription.SampleInfo.disposed_generation_count and com.rti.dds.subscription.SampleInfo.no_writers_generation_count, relative to each DataReader:
The com.rti.dds.subscription.SampleInfo.disposed_generation_count and com.rti.dds.subscription.SampleInfo.no_writers_generation_count available in the com.rti.dds.subscription.SampleInfo capture a snapshot of the corresponding counters at the time the sample was received.
The com.rti.dds.subscription.SampleInfo.sample_rank and com.rti.dds.subscription.SampleInfo.generation_rank available in the com.rti.dds.subscription.SampleInfo are computed based solely on the actual samples in the ordered collection returned by read or take.
The com.rti.dds.subscription.SampleInfo.generation_rank is computed using the formula:
generation_rank = (MRSIC.disposed_generation_count + MRSIC.no_writers_generation_count) - (S.disposed_generation_count + S.no_writers_generation_count)
The com.rti.dds.subscription.SampleInfo.absolute_generation_rank available in the com.rti.dds.subscription.SampleInfo indicates the difference in "generations" between the sample (S) and the Most Recent Sample of the same instance that the middleware has received (MRS). That is, it counts the number of times the instance transitioned from not-alive to alive in the time from the reception of the S to the time when the read or take was called.
absolute_generation_rank = (MRS.disposed_generation_count + MRS.no_writers_generation_count) - (S.disposed_generation_count + S.no_writers_generation_count)
These counters and ranks allow the application to distinguish samples belonging to different "generations" of the instance. Note that it is possible for an instance to transition from not-alive to alive (and back) several times before the application accesses the data by means of read or take. In this case, the returned collection may contain samples that cross generations (i.e. some samples were received before the instance became not-alive, other after the instance re-appeared again). Using the information in the com.rti.dds.subscription.SampleInfo, the application can anticipate what other information regarding the same instance appears in the returned collection, as well as in the infrastructure and thus make appropriate decisions.
For example, an application desiring to only consider the most current sample for each instance would only look at samples with sample_rank == 0. Similarly, an application desiring to only consider samples that correspond to the latest generation in the collection will only look at samples with generation_rank == 0. An application desiring only samples pertaining to the latest generation available will ignore samples for which absolute_generation_rank != 0. Other application-defined criteria may also be used.
instance_state
and view_state
of a single instanceObject copy_from | ( | Object | other | ) |
Implementation of the Copyable
interface.
Implements Copyable.
References SampleInfo.absolute_generation_rank, SampleInfo.coherent_set_info, InstanceHandle_t.copy_from(), SampleInfo.disposed_generation_count, SampleInfo.flag, SampleInfo.generation_rank, SampleInfo.instance_handle, SampleInfo.instance_state, Time_t.nanosec, SampleInfo.no_writers_generation_count, SampleInfo.original_publication_virtual_guid, SampleInfo.original_publication_virtual_sequence_number, SampleInfo.publication_handle, SampleInfo.publication_sequence_number, SampleInfo.reception_sequence_number, SampleInfo.reception_timestamp, SampleInfo.related_original_publication_virtual_guid, SampleInfo.related_original_publication_virtual_sequence_number, SampleInfo.related_source_guid, SampleInfo.related_subscription_guid, SampleInfo.sample_rank, SampleInfo.sample_state, Time_t.sec, SampleInfo.source_guid, SampleInfo.source_timestamp, SampleInfo.topic_query_guid, SampleInfo.valid_data, and SampleInfo.view_state.
int sample_state |
The sample state of the sample.
Indicates whether or not the corresponding data sample has already been read.
Referenced by SampleInfo.copy_from().
int view_state |
The view state of the instance.
Indicates whether the com.rti.dds.subscription.DataReader has already seen samples for the most-current generation of the related instance.
Referenced by SampleInfo.copy_from().
int 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.
Referenced by SampleInfo.copy_from().
final Time_t source_timestamp |
The timestamp when the sample was written by a DataWriter.
Referenced by SampleInfo.copy_from().
final InstanceHandle_t instance_handle |
Identifies locally the corresponding instance.
Referenced by SampleInfo.copy_from().
final InstanceHandle_t publication_handle |
Identifies locally the DataWriter that modified the instance.
The publication_handle
is the same com.rti.dds.infrastructure.InstanceHandle_t that is returned by the operation com.rti.dds.subscription.DataReader.get_matched_publications and can also be used as a parameter to the operation com.rti.dds.subscription.DataReader.get_matched_publication_data.
Referenced by SampleInfo.copy_from().
int disposed_generation_count |
The disposed generation count of the instance at the time of sample reception.
Indicates how many times the instance_state
of the corresponding instance changed from com.rti.dds.subscription.InstanceStateKind.NOT_ALIVE_DISPOSED_INSTANCE_STATE to com.rti.dds.subscription.InstanceStateKind.ALIVE_INSTANCE_STATE. The counter is reset when the instance resource is reclaimed (removed from the DataReader cache).
Referenced by SampleInfo.copy_from().
int no_writers_generation_count |
The no writers generation count of the instance at the time of sample reception.
Indicates how many times the instance_state
of the corresponding instance changed from com.rti.dds.subscription.InstanceStateKind.NOT_ALIVE_NO_WRITERS_INSTANCE_STATE to com.rti.dds.subscription.InstanceStateKind.ALIVE_INSTANCE_STATE. The counter is reset when the instance resource is reclaimed (removed from the DataReader cache).
Referenced by SampleInfo.copy_from().
int sample_rank |
The sample rank of the sample.
Indicates the number of samples related to the same instance that follow in the collection returned by read
or take
.
Referenced by SampleInfo.copy_from().
int generation_rank |
The generation rank of the sample.
Indicates the generation difference (number of times the instance was NOT_ALIVE and become alive again) between the time the sample was received and the time the most recent sample in the collection related to the same instance was received.
Referenced by SampleInfo.copy_from().
int absolute_generation_rank |
The absolute generation rank of the sample.
Indicates the generation difference (number of times the instance was disposed and become alive again) between the time the sample was received, and the time the most recent sample (which may not be in the returned collection) related to the same instance was received.
Referenced by SampleInfo.copy_from().
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.
Normally each DataSample
contains both a com.rti.dds.subscription.SampleInfo and some Data. However there are situations where a DataSample
contains only the com.rti.dds.subscription.SampleInfo and does not have any associated data. This occurs when the RTI Connext 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 detects that an instance has no writers and changes the corresponding instance_state to com.rti.dds.subscription.InstanceStateKind.NOT_ALIVE_NO_WRITERS_INSTANCE_STATE.
The application can distinguish whether a particular DataSample
has data by examining the value of the com.rti.dds.subscription.SampleInfo.valid_data
. If this flag is set to com.rti.dds.infrastructure.true, then the DataSample
contains valid Data. If the flag is set to com.rti.dds.infrastructure.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 com.rti.dds.infrastructure.false, the application should not access the Data associated with the DataSample
, that is, the application should access only the com.rti.dds.subscription.SampleInfo.
Referenced by SampleInfo.copy_from().
final Time_t reception_timestamp |
<<extension>> The timestamp when the sample was committed by a DataReader.
Referenced by SampleInfo.copy_from().
final SequenceNumber_t publication_sequence_number |
<<extension>> The publication sequence number.
Referenced by SampleInfo.copy_from().
final SequenceNumber_t reception_sequence_number |
<<extension>> The reception sequence number when sample was committed by a DataReader
Referenced by SampleInfo.copy_from().
final GUID_t original_publication_virtual_guid |
<<extension>> The original publication virtual GUID.
If the com.rti.dds.infrastructure.PresentationQosPolicy::access_scope of the com.rti.dds.publication.Publisher is com.rti.dds.infrastructure.PresentationQosPolicyAccessScopeKind.PresentationQosPolicyAccessScopeKind.GROUP_PRESENTATION_QOS, this field contains the com.rti.dds.publication.Publisher virtual GUID that uniquely identifies the DataWriter group.
Referenced by SampleInfo.copy_from().
final SequenceNumber_t original_publication_virtual_sequence_number |
<<extension>> The original publication virtual sequence number.
If the com.rti.dds.infrastructure.PresentationQosPolicy::access_scope of the com.rti.dds.publication.Publisher is com.rti.dds.infrastructure.PresentationQosPolicyAccessScopeKind.PresentationQosPolicyAccessScopeKind.GROUP_PRESENTATION_QOS, this field contains the com.rti.dds.publication.Publisher virtual sequence number that uniquely identifies a sample within the DataWriter group.
Referenced by SampleInfo.copy_from().
final GUID_t related_original_publication_virtual_guid |
<<extension>> The original publication virtual GUID of a related sample.
Referenced by SampleInfo.copy_from().
final SequenceNumber_t related_original_publication_virtual_sequence_number |
<<extension>> The original publication virtual sequence number of a related sample.
Referenced by SampleInfo.copy_from(), and Requester< TReq, TRep >.createReplySample().
int flag |
<<extension>> Flags associated with the sample.
The flags can be set by using the field com.rti.dds.infrastructure.WriteParams_t.flag when writing a sample using the method com.rti.ndds.example.FooDataWriter.write_w_params.
Referenced by SampleInfo.copy_from().
GUID_t source_guid |
<<extension>> The application logical data source associated with the sample.
The source_guid can be set by using the field com.rti.dds.infrastructure.WriteParams_t.source_guid when writing a sample using the method com.rti.ndds.example.FooDataWriter.write_w_params.
Referenced by SampleInfo.copy_from().
GUID_t related_source_guid |
<<extension>> The application logical data source that is related to the sample.
The related_source_guid can be set by using the field com.rti.dds.infrastructure.WriteParams_t.related_source_guid when writing a sample using the method com.rti.ndds.example.FooDataWriter.write_w_params.
Referenced by SampleInfo.copy_from().
GUID_t related_subscription_guid |
<<extension>> The related_reader_guid associated with the sample.
The related_reader_guid can be set by using the field com.rti.dds.infrastructure.WriteParams_t.related_reader_guid when writing a sample using the method com.rti.ndds.example.FooDataWriter.write_w_params.
Referenced by SampleInfo.copy_from().
final GUID_t topic_query_guid |
<<extension>> The GUID of the com.rti.dds.subscription.TopicQuery that is related to the sample.
This GUID indicates whether a sample is part of the response to a com.rti.dds.subscription.TopicQuery or a regular ("live") sample:
Referenced by SampleInfo.copy_from().
CoherentSetInfo_t coherent_set_info |
<<extension>> The information about the coherent set that this sample is a part of.
This field is set for all samples that are part of a coherent set. Coherent sets are initiated using the operation com.rti.dds.publication.Publisher.begin_coherent_changes and finalized using the operation com.rti.dds.publication.Publisher.end_coherent_changes.
Referenced by SampleInfo.copy_from().