2.4. Create an Application

The rest of this guide will walk you through the steps to create an application and will provide example code snippets. It assumes that you have defined your types (see Define a Data Type) and have used rtiddsgen to generate their support code (see Generate Type Support Code with rtiddsgen).

2.4.1. Registry Configuration

The Connext Micro architecture defines a run-time (RT) component interface that provides a generic framework for organizing and extending functionality of an application. An RT component is created and deleted with an RT component factory. Each RT component factory must be registered within an RT registry in order for its components to be usable by an application.

The DomainParticipantFactory, in addition to its standard role of creating and deleting DomainParticipants, contains the RT registry where an application registers the components it will use.

Every DDS application must register these components:

• Writer History. Queue of written samples of a DataWriter. Must be registered with the name DDSHST_WRITER_DEFAULT_HISTORY_NAME.

• Reader History. Queue of received samples of a DataReader. Must be registered with the name DDSHST_READER_DEFAULT_HISTORY_NAME.

In addition, an application typically registers a discovery plugin in order to discover other DDS applications on a network:

• Discovery (DPDE or DPSE). Discovery component. Choose either dynamic (DPDE) or static (DPSE) endpoint discovery.

Example source:

• Get the RT Registry from the DomainParticipantFactory singleton:

  DDS_DomainParticipantFactory *factory = NULL;
  RT_Registry_T *registry = NULL;
  
  factory = DDS_DomainParticipantFactory_get_instance();
  registry = DDS_DomainParticipantFactory_get_registry(factory);
  

• Register the Writer History and Reader History components with the registry:

  /* Register Writer History */
  if (!RT_Registry_register(registry, DDSHST_WRITER_DEFAULT_HISTORY_NAME,
                            WHSM_HistoryFactory_get_interface(), NULL, NULL))
  {
      /* failure */
  }
  
  /* Register Reader History */
  if (!RT_Registry_register(registry, DDSHST_READER_DEFAULT_HISTORY_NAME,
                            RHSM_HistoryFactory_get_interface(), NULL, NULL))
  {
      /* failure */
  }
  

Only one discovery component can be registered, either DPDE or DPSE. Each has its own properties that can be configured upon registration.

• Register DPDE for dynamic participant, dynamic endpoint discovery:

  struct DPDE_DiscoveryPluginProperty discovery_plugin_properties =
      DPDE_DiscoveryPluginProperty_INITIALIZER;
  
  /* Configure properties */
  discovery_plugin_properties.participant_liveliness_assert_period.sec = 5;
  discovery_plugin_properties.participant_liveliness_assert_period.nanosec = 0;
  discovery_plugin_properties.participant_liveliness_lease_duration.sec = 30;
  discovery_plugin_properties.participant_liveliness_lease_duration.nanosec = 0;
  
  /* Register DPDE with updated properties. The name is arbitrary, but
   * cannot exceed 7 ASCIIZ characters.
  if (!RT_Registry_register(registry,
                            "dpde",
                            DPDE_DiscoveryFactory_get_interface(),
                            &discovery_plugin_properties._parent,
                            NULL))
  {
      /* failure */
  }
  

• Register DPSE for dynamic participant, static endpoint discovery:

  struct DPSE_DiscoveryPluginProperty discovery_plugin_properties =
      DPSE_DiscoveryPluginProperty_INITIALIZER;
  
  /*  Configure properties */
  discovery_plugin_properties.participant_liveliness_assert_period.sec = 5;
  discovery_plugin_properties.participant_liveliness_assert_period.nanosec = 0;
  discovery_plugin_properties.participant_liveliness_lease_duration.sec = 30;
  discovery_plugin_properties.participant_liveliness_lease_duration.nanosec = 0;
  
  /* Register DPSE with updated properties. The name is arbitrary, but
   * cannot exceed 7 ASCIIZ characters.
   */
  if (!RT_Registry_register(registry,
                            "dpse",
                            DPSE_DiscoveryFactory_get_interface(),
                            &discovery_plugin_properties._parent,
                            NULL))
  {
      printf("failed to register dpse\n");
      goto done;
  }
  

For more information, see Application Generation Using XML.