Subscriber Use Cases

The following #includes are needed for the examples on this page

#include <dds/sub/ddssub.hpp>
#include <dds/domain/ddsdomain.hpp>
#include <dds/core/ddscore.hpp>

Setting up a subscriber

• Set up participant

• Create a Subscriber with each of the available constructors

      // Create the participant
      dds::domain::DomainParticipant participant(0);
  
      // When not explicitly provided to the constructor, the 
      // created Subscriber's QoS is default, has a NULL listener, and a status mask
      // dds::core::status::StatusMask::all()
  
      // Creating a Subscriber
      dds::sub::Subscriber subscriber1(participant);    
  
      // Creating a Subscriber with modified QoS
      dds::sub::qos::SubscriberQos qos;
      qos << dds::core::policy::Presentation::GroupAccessScope(true, false);
      dds::sub::Subscriber subscriber2(participant, qos);
  
      // Creating a Subscriber with modified QoS and a listener
      ExampleSubscriberListener *listener = new ExampleSubscriberListener;
      dds::sub::Subscriber subscriber3(participant, qos, listener);
  
      // Creating a Subscriber with modified QoS, a listener, and a sample_rejected() 
      // status mask
      dds::sub::Subscriber subscriber4(
         participant, qos, listener, dds::core::status::StatusMask::sample_rejected());
  
      // Creating an entity with a listener automatically retains the entity, so 
      // we must either explicitly close the Subscriber...
      subscriber3.close();
      
      // ... or set the listener to null
      subscriber4.listener(NULL, dds::core::status::StatusMask::none());

Looking up Subscribers

• Lookup Subscribers

  void howto_lookup_subscribers()
  {
      dds::domain::DomainParticipant participant(0);
  
      // Create three Subscribers and retain them
      create_and_retain_subscriber(participant);
      create_and_retain_subscriber(participant);
      create_and_retain_subscriber(participant);
  
      // We don't have any references to the created Subscribers but we can look 
      // them up using the participant that they were created with
      std::vector<dds::sub::Subscriber> subscribers1;
  
      // subscriber_count will equal 3 and subscribers1 will hold a reference to 
      // each of the three subscribers that were created
      int subscriber_count = 
          rti::sub::find_subscribers(participant, std::back_inserter(subscribers1));
  
      // rti::sub::subscribers also takes a forward iterator and a max number of
      // subscribers to look up
      std::vector<dds::sub::Subscriber> subscribers2(2, dds::sub::Subscriber(dds::core::null));
  
      // subscriber_count will equal 2 because we're only asking for 2
      subscriber_count = 
          rti::sub::find_subscribers(participant, subscribers2.begin(), 2);
  
      // We retained the subscribers so we must close them now
      for (std::vector<dds::sub::Subscriber>::iterator it = subscribers1.begin();
            it != subscribers1.end(); 
            it++) {
          (*it).close();
      }
  }
  
  void create_and_retain_subscriber(dds::domain::DomainParticipant &participant)
  {
      dds::sub::Subscriber subscriber(participant);
      subscriber.retain();
  }

Tearing down a subscriber

• See Tearing Down An Entity for eamples of the various ways to teardown a Subscriber