To understand the flow of messages during discovery, you can increase the verbosity of the messages logged by Connext DDS so that you will see whenever a new entity is discovered, and whenever there is a match between a local entity and a remote entity.
This can be achieved with the logging API:
NDDSConfigLogger::get_instance()->set_verbosity_by_category (NDDS_CONFIG_LOG_CATEGORY_ENTITIES, NDDS_CONFIG_LOG_VERBOSITY_STATUS_REMOTE);
Using the scenario in the summary diagram in Discovery Traffic Summary, these are the messages as seen on DomainParticipant A:
[D0049|ENABLE]DISCPluginManager_onAfterLocalParticipantEnabled:announcing new local participant: 0XA0A01A1,0X5522,0X1,0X1C1
[D0049|ENABLE]DISCPluginManager_onAfterLocalParticipantEnabled:at {46c614d9,0C43B2DC}
(The above messages mean: First participant A DATA sent out when participant A is enabled.)
DISCSimpleParticipantDiscoveryPluginReaderListener_onDataAvailable:discovered new participant: host=0x0A0A01A1, app=0x0000552B, instance=0x00000001
DISCSimpleParticipantDiscoveryPluginReaderListener_onDataAvailable:at {46c614dd,8FA13C1F}
DISCParticipantDiscoveryPlugin_assertRemoteParticipant:plugin discovered/updated remote participant: 0XA0A01A1,0X552B,0X1,0X1C1
DISCParticipantDiscoveryPlugin_assertRemoteParticipant:at {46c614dd,8FACE677}
DISCParticipantDiscoveryPlugin_assertRemoteParticipant:plugin accepted new remote participant: 0XA0A01A1,0X552B,0X1,0X1C1
DISCParticipantDiscoveryPlugin_assertRemoteParticipant:at {46c614dd,8FACE677}
(The above messages mean: Received participant B DATA.)
DISCSimpleParticipantDiscoveryPlugin_remoteParticipantDiscovered:re-announcing participant self: 0XA0A01A1,0X5522,0X1,0X1C1
DISCSimpleParticipantDiscoveryPlugin_remoteParticipantDiscovered:at {46c614dd,8FC02AF7}
(The above messages mean: Resending participant A DATA to the newly discovered remote participant.)
PRESPsService_linkToLocalReader:assert remote 0XA0A01A1,0X552B,0X1,0X200C2, local 0x000200C7 in reliable reader service PRESPsService_linkToLocalWriter:assert remote 0XA0A01A1,0X552B,0X1,0X200C7, local 0x000200C2 in reliable writer service PRESPsService_linkToLocalWriter:assert remote 0XA0A01A1,0X552B,0X1,0X4C7, local 0x000004C2 in reliable writer service PRESPsService_linkToLocalWriter:assert remote 0XA0A01A1,0X552B,0X1,0X3C7, local 0x000003C2 in reliable writer service PRESPsService_linkToLocalReader:assert remote 0XA0A01A1,0X552B,0X1,0X4C2, local 0x000004C7 in reliable reader service PRESPsService_linkToLocalReader:assert remote 0XA0A01A1,0X552B,0X1,0X3C2, local 0x000003C7 in reliable reader service PRESPsService_linkToLocalReader:assert remote 0XA0A01A1,0X552B,0X1,0X100C2, local 0x000100C7 in best effort reader service
(The above messages mean: Automatic matching of the discovery readers and writers. A built-in remote endpoint's object ID always ends with Cx.)
DISCSimpleParticipantDiscoveryPluginReaderListener_onDataAvailable:discovered modified participant: host=0x0A0A01A1, app=0x0000552B, instance=0x00000001
DISCParticipantDiscoveryPlugin_assertRemoteParticipant:plugin discovered/updated remote participant: 0XA0A01A1,0X552B,0X1,0X1C1
DISCParticipantDiscoveryPlugin_assertRemoteParticipant:at {46c614dd,904D876C}
(The above messages mean: Received participant B DATA.)
DISCPluginManager_onAfterLocalEndpointEnabled:announcing new local publication: 0XA0A01A1,0X5522,0X1,0X80000003
DISCPluginManager_onAfterLocalEndpointEnabled:at {46c614d9,1013B9F0}
DISCSimpleEndpointDiscoveryPluginPDFListener_onAfterLocalWriterEnabled:announcing new publication: 0XA0A01A1,0X5522,0X1,0X80000003
DISCSimpleEndpointDiscoveryPluginPDFListener_onAfterLocalWriterEnabled:at {46c614d9,101615EB}
(The above messages mean: Publication C DATA has been sent.)
DISCSimpleEndpointDiscoveryPlugin_subscriptionReaderListenerOnDataAvailable:discovered subscription: 0XA0A01A1,0X552B,0X1,0X80000004
DISCSimpleEndpointDiscoveryPlugin_subscriptionReaderListenerOnDataAvailable:at {46c614dd,94FAEFEF}
DISCEndpointDiscoveryPlugin_assertRemoteEndpoint:plugin discovered/updated remote endpoint: 0XA0A01A1,0X552B,0X1,0X80000004
DISCEndpointDiscoveryPlugin_assertRemoteEndpoint:at {46c614dd,950203DF}
(The above messages mean: Receiving subscription D DATA from Node B.)
PRESPsService_linkToLocalWriter:assert remote 0XA0A01A1,0X552B,0X1,0X80000004, local 0x80000003 in best effort writer service
(The above message means: User-created DataWriter C and DataReader D are matched.)
[D0049|DELETE_CONTAINED]DISCPluginManager_onAfterLocalEndpointDeleted:announcing disposed local publication: 0XA0A01A1,0X5522,0X1,0X80000003
[D0049|DELETE_CONTAINED]DISCPluginManager_onAfterLocalEndpointDeleted:at {46c61501,288051C8}
[D0049|DELETE_CONTAINED]DISCSimpleEndpointDiscoveryPluginPDFListener_onAfterLocalWriterDeleted:announcing disposed publication: 0XA0A01A1,0X5522,0X1,0X80000003
[D0049|DELETE_CONTAINED]DISCSimpleEndpointDiscoveryPluginPDFListener_onAfterLocalWriterDeleted:at {46c61501,28840E15}
(The above messages mean: Publication C DATA(delete) has been sent.)
DISCPluginManager_onBeforeLocalParticipantDeleted:announcing before disposed local participant: 0XA0A01A1,0X5522,0X1,0X1C1
DISCPluginManager_onBeforeLocalParticipantDeleted:at {46c61501,28A11663}
(The above messages mean: Participant A DATA(delete) has been sent.)
DISCParticipantDiscoveryPlugin_removeRemoteParticipantsByCookie:plugin removing 3 remote entities by cookie
DISCParticipantDiscoveryPlugin_removeRemoteParticipantsByCookie:at {46c61501,28E38A7C}
DISCParticipantDiscoveryPlugin_removeRemoteParticipantI:plugin discovered disposed remote participant: 0XA0A01A1,0X552B,0X1,0X1C1
DISCParticipantDiscoveryPlugin_removeRemoteParticipantI:at {46c61501,28E68E3D}
DISCParticipantDiscoveryPlugin_removeRemoteParticipantI:remote entity removed from database: 0XA0A01A1,0X552B,0X1,0X1C1
DISCParticipantDiscoveryPlugin_removeRemoteParticipantI:at {46c61501,28E68E3D}
(The above messages mean: Removing discovered entities from local database, before shutting down.)
As you can see, the messages are encoded, since they are primarily used by RTI support personnel.
For more information on the message logging API, see Controlling Messages from Connext DDS.
If you notice that a remote entity is not being discovered, check the QoS related to discovery (see Discovery-Related QoS).
If a remote entity is discovered, but does not match with a local entity as expected, check the QoS of both the remote and local entity.
© 2018 RTI