Detecting Leaving Domains

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Wed, 11/09/2016 - 02:40
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bonjefir
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Posts: 55
Detecting Leaving Domains

Hi everybody,

I have written a simple application which discover all domains with the help of dds::topic::ParticipantBuiltinTopicData. When a domain joins my LAN network, my program detects it but it cannot detect leaving domains. Is there any way to detect leaving domains? 

I bring some of my application code below for further uses:

// By default, the participant is enabled upon construction.
 // At that time our listeners for the builtin topics have not
 // been installed, so we disable the participant until we
 // set up the listeners.
 dds::domain::qos::DomainParticipantFactoryQos factoryQos =
 dds::domain::DomainParticipant::participant_factory_qos();
 factoryQos << dds::core::policy::EntityFactory::ManuallyEnable();
 factoryQos->resource_limits.max_objects_per_thread(4096);
 dds::domain::DomainParticipant::participant_factory_qos(factoryQos);dds::domain::qos::DomainParticipantQos dpQos = dds::core::QosProvider::Default()
 .participant_qos(rti::core::builtin_profiles::qos_lib::baseline());dpQos->discovery_config.ignore_default_domain_announcements(false);
 dpQos->discovery_config.participant_liveliness_assert_period(dds::core::Duration(1,0));
 dpQos->discovery_config.participant_liveliness_lease_duration(dds::core::Duration(10,0));
 // quickly detect the loss of liveness of remote participants
 dpQos->discovery_config.max_liveliness_loss_detection_period(dds::core::Duration(5,0));
 dpQos->discovery_config.asynchronous_publisher().disable_asynchronous_write(false);
 dpQos->discovery_config.publication_writer_publish_mode().Asynchronous();
 dpQos->discovery_config.subscription_writer_publish_mode().Asynchronous();dpQos->resource_limits.type_code_max_serialized_length(65535);
 dpQos->resource_limits.deserialized_type_object_dynamic_allocation_threshold(1024);
 dpQos->resource_limits.type_object_max_deserialized_length(dds::core::LENGTH_UNLIMITED);
 dpQos->resource_limits.type_object_max_serialized_length(12288);
 dpQos->resource_limits.participant_property_list_max_length(1024);
 dpQos->resource_limits.participant_property_string_max_length(32768);// Don't ignore the local loopback
 std::map<std::string,std::string> dpPropertyMap = {{"dds.transport.UDPv4.builtin.ignore_loopback_interface", "0"},{"dds.transport.UDPv4.builtin.recv_socket_buffer_size", "1048576"}};
 dpQos << rti::core::policy::Property(dpPropertyMap.begin(),dpPropertyMap.end());
 dp = dds::domain::DomainParticipant(DEFAULT_DISCOVERY_DOMAIN,dpQos);builtin_subscriber = dds::sub::builtin_subscriber(dp);// Get builtin subscriber's datareader for participants.
 participant_reader = rti::sub::find_datareader_by_topic_name< dds::sub::DataReader<dds::topic::ParticipantBuiltinTopicData> >(
 builtin_subscriber,
 dds::topic::participant_topic_name());// Set a waitset for reading participants
 // Get status conditions.
 // Each entity may have an attached Status Condition. To modify the
 // statuses we need to get the reader's Status Conditions first.
 // By instantiating a StatusCondition we are obtaining a reference to this
 // reader's StatusCondition
 dds::core::cond::StatusCondition participants_status_condition(participant_reader);
 discovery_Waitset = new dds::core::cond::WaitSet();
 discovery_Waitset->attach_condition(participants_status_condition);// Done! All the listeners are installed, so we can enable the participant now.
 dp.enable();

Thanks in advance for your help.

Bonjefir

 

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Sat, 11/12/2016 - 03:48
bonjefir
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Last seen: 4 years 5 months ago
Joined: 08/13/2014
Posts: 55

Hi,

I found a way to find local domains (in a host) by use of "dds::domain::find(domain_id)", but this function cannot find all domains in a local network consisting of several PCs. Is there anything like this function for all domains?

Bonjefir

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Sat, 12/03/2016 - 00:22
Fernando Garcia
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Joined: 05/18/2011
Posts: 199

Hi Bonjefir,

I assume that you want to do something similar to what RTI Admin Console does, which is (unless otherwise specified) to discover all the participants that are available in all the domains and once you know that, find out the domains that are in use.

As specified in the description of  default_domain_announcement_period in the DDS_DiscoveryConfigQosPolicy:

you can get information about participants running in different DDS domains by creating a participant in DDS domain 0 and implementing the on_data_available callback (see DATA_AVAILABLE Status) in the ParticipantBuiltinTopicData built-in DataReader's listener (see Built-in DataReaders) 

 

You can learn the domain ID associated with a participant by looking at the domain_id in the ParticipantBuiltinTopicData.

Let me know if this helps.

Thanks,
Fernando.

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Sat, 12/03/2016 - 22:57
bonjefir
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Last seen: 4 years 5 months ago
Joined: 08/13/2014
Posts: 55

Hi Fernando,

First of all, thanks for your answer. Second, I can detect all domain participant with a waitset on participant builtin reader (codes are given below). But I can not detect whether they are alive or not. That's my problem. I would be very grateful if you can let me know how to solve it.

// We only process newly seen participant
dds::sub::LoanedSamples<dds::topic::ParticipantBuiltinTopicData> samples = participant_reader.select()
.state(dds::sub::status::DataState::new_instance())
.take();
for (const auto& it : samples)
{
if (!it.info().valid()) {
continue;
}
addDomainID(it.data()->domain_id());
}

Best Regards,

Bonjefir

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