.. _architecture_dds:

DDS module
==========

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            fill: #aaa;
            stroke: #888 !important;
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            opacity: 1;
            transition: opacity 0.1s;
        }

        svg:hover .layer_group:not(#dds_group) {
            opacity: 0.6;
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        .layer_group:hover:not(#system_group):not(#toolchain_group) {
            opacity: 1 !important;
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   :file: ../figures/svg_href_loader.html

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Safe DDS implements the `DDS (Data Distribution Service) Specification <https://www.omg.org/spec/DDS/About-DDS/>`__ specification defined by the `Object Management Group (OMG) <https://www.omg.org/>`__.

In order to provide flexibility and portability, two different DDS APIs are provided:

* A classic, factory-based API for DDS that employs controlled memory allocations.
* A modern C++, object-oriented API for DDS that ensures zero memory allocations.

These Safe DDS APIs are documented in the :ref:`DDS Layer <dds>` section.
The :ref:`DDS Layer <dds>` section also provides a detailed description of the DDS concepts and the DDS API.

Both APIs uses the same underlying DDS implementation, which is based in the concepts defined by the OMG's DDS Specification:

* :ref:`dds_layers_infrastructure_policies`
* :ref:`dds_layers_infrastructure_status`
* :ref:`dds_layers_domain`
* :ref:`dds_layers_infrastructure_entities`
   * :ref:`dds_layers_topic`
   * :ref:`dds_layers_publication_publisher`
   * :ref:`dds_layers_subscription_subscriber`
   * :ref:`dds_layers_publication_datawriter`
   * :ref:`dds_layers_subscription_datareader`
   * :ref:`typesupport`

.. note::

    For reference, the current implementation is compliant with OMG DDS specification v1.4 and OMG DDSI-RTPS specification v2.5.

.. _architecture_dds_classic:

Classic DDS API
---------------

.. include:: ../safety_manual/rules/RULE_CLASSIC_API.inc

The classic DDS API is a factory-based API that provides a controlled memory allocation via :ref:`dds_layers_infrastructure_safedds_preallocmemoryconfig` and related QoS policies, as explained in :ref:`architecture_platform_memory_management` section (see :ref:`DDS Layer <dds>`).
A example of use of this API can be seen in the :ref:`getting_started` section as well as in:


* :ref:`DomainParticipant creation reference <dds_layers_create_domain_participant_classic>`
* :ref:`Topic creation reference <dds_layers_create_topic_classic>`
* :ref:`Publisher creation reference <dds_layers_create_publisher_classic>`
* :ref:`Subscriber creation reference <dds_layers_create_subscriber_classic>`
* :ref:`DataWriter creation reference <dds_layers_create_datawriter_classic>`
* :ref:`DataReader creation reference <dds_layers_create_datareader_classic>`

.. _architecture_dds_static:

Static DDS API
--------------

.. include:: ../safety_manual/rules/RULE_CLASSIC_API.inc

The static DDS API is a modern C++, object-oriented API that ensures zero memory allocation by providing a sightly different API from that of the :ref:`architecture_dds_classic` (see :ref:`DDS Layer <dds>` for more information).
The usage of this API is documented in:

* :ref:`StaticDomainParticipant creation reference <dds_layers_create_domain_participant_static>`
* :ref:`StaticTopic creation reference <dds_layers_create_topic_static>`
* :ref:`StaticPublisher creation reference <dds_layers_create_publisher_static>`
* :ref:`StaticSubscriber creation reference <dds_layers_create_subscriber_static>`
* :ref:`StaticDataWriter creation reference <dds_layers_create_datawriter_static>`
* :ref:`StaticDataReader creation reference <dds_layers_create_datareader_static>`