.. _dds_layers_domain_participant:

DomainParticipant
==================

A ``DomainParticipant`` is the entry point of the application to a domain.
Every DomainParticipant is linked to a single domain from its creation, and contains all the Entities related to that domain.
It also acts as a factory for :ref:`dds_layers_publication_publisher`, :ref:`dds_layers_subscription_subscriber` and :ref:`dds_layers_topic` entities.

The behavior of the DomainParticipant can be modified with the QoS values specified on :ref:`dds_layers_domain_participant_qos`.
The QoS values can be set at the creation of the DomainParticipant.

As an Entity, DomainParticipant accepts a :ref:`dds_layers_domain_participant_listener` that will be notified of status changes on the DomainParticipant instance.

.. _dds_layers_domain_participant_qos:

DomainParticipantQos
--------------------

``DomainParticipantQos`` controls the behavior of the DomainParticipant.
Internally it contains the following :ref:`dds_layers_infrastructure_policies` objects:

* ``participant_name`` as ``memory::container::StaticString256``
    The name of the DomainParticipant.
* ``entity_factory_qos`` as :ref:`entityfactoryqospolicy`
    Defines if the DomainParticipant will automatically enable created subentities or not.
* ``wire_protocol_qos`` as :ref:`dds_layers_infrastructure_safedds_policies_domainparticipantwireprotocolconfigqospolicy`
    The configuration of the wire protocol.
* ``allocations`` as :ref:`dds_layers_infrastructure_safedds_policies_domainparticipantallocationsqospolicy`
    Defines the memory configuration of the DomainParticipant.

.. note::

   Check :ref:`architecture_platform_memory_management` to understand how memory is managed in Safe DDS.


Example
^^^^^^^

.. literalinclude:: ../../../code/policies_examples/main.cpp
   :language: c++
   :dedent: 8
   :start-after: // DDS_DOMAINPARTICIPANT_QOS
   :end-before: //! DDS_DOMAINPARTICIPANT_QOS