Topic Use Cases

Working with topics. More...

Working with topics.

Registering a user data type

• Set up participant
• Register user data type of type T under the name "My_Type"

  const char* type_name = "My_Type";
  DDS_ReturnCode_t retcode;
  
  retcode = FooTypeSupport_register_type(participant, type_name);
  
  if (retcode != DDS_RETCODE_OK) {
       printf("***Error: failed to register type\n");
  }

Setting up a topic

• Set up participant
• Ensure user data type is registered
• Create a DDS_Topic under the name "my_topic"

  const char* topic_name = "my_topic";
  const char* type_type = "My_Type";   /* user data type */
  struct DDS_TopicQos topic_qos = DDS_TopicQos_INITIALIZER;
  DDS_Topic* topic;
  struct DDS_TopicListener topic_listener = DDS_TopicListener_INITIALIZER;
  
  /* MyTopicListener_InconsistentTopic function is user defined to match
     DDS_TopicListener_InconsistentTopicCallback */
  topic_listener.on_inconsistent_topic = MyTopicListener_InconsistentTopic;
  
  retcode = DDS_DomainParticipant_get_default_topic_qos(participant, 
                                              &topic_qos);
  
  if (retcode != DDS_RETCODE_OK) {
      printf("***Error: failed to get default topic qos\n");
  }
  
  topic = DDS_DomainParticipant_create_topic(participant, 
                                             topic_name,
                                             type_name,
                                             &topic_qos,
                                             &topic_listener /* or NULL */,
                                       DDS_STATUS_MASK_ALL);
  
  if (topic == NULL) {
      printf("***Error: failed to create topic\n");
  }

Tearing down a topic

• Delete DDS_Topic:

  DDS_ReturnCode_t retcode;
  
  retcode = DDS_DomainParticipant_delete_topic(participant, topic);
  
  if (retcode != DDS_RETCODE_OK) {
      printf("***Error: failed to delete topic\n");
  }