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Why Connext?
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ROS 2 uses the `Data Distribution Service (DDS) <https://www.omg.org/omg-dds-portal/>`__
as its underlying communication middleware. ROS 2 shares many concepts with
DDS, such as the following:

* Both use a publish-subscribe communication model.
* Nodes in ROS 2 are equivalent to |DPs| in DDS.
* Messages in ROS 2 are equivalent to samples in DDS.

This means a |CONNEXT| DDS application can interoperate with ROS 2
systems, bringing high performance and full access to DDS Quality of Service
(QoS) settings and capabilities that are used in countless critical systems
around the world. 

For an in-depth review of ROS 2, visit
https://docs.ros.org/en/kilted/Concepts.html.

Using |CONNEXT| as your ROS 2 middleware (RMW) layer allows you to use features
unique to *Connext*, including the
`RTI Security Plugins 
<https://community.rti.com/static/documentation/connext-dds/7.3.0/doc/manuals/connext_dds_secure/getting_started_guide/index.html>`_, 
`Real-Time WAN Transport 
<https://community.rti.com/static/documentation/connext-dds/7.3.0/doc/manuals/connext_dds_professional/users_manual/users_manual/PartRealtimeWAN.htm>`_, 
`Simple Participant Discovery 2.0 
<https://community.rti.com/static/documentation/connext-dds/7.3.0/doc/manuals/connext_dds_professional/users_manual/users_manual/Simple_Participant_Discovery_2.htm>`_, 
`Admin Console 
<https://community.rti.com/static/documentation/connext-dds/7.3.0/doc/manuals/connext_dds_professional/tools/admin_console/index.html>`_, 
`Routing Service 
<https://community.rti.com/static/documentation/connext-dds/7.3.0/doc/manuals/connext_dds_professional/services/routing_service/index.html>`_, 
and more.

This document explains how ROS 2 and |CONNEXT| work together, the relationship
between different ROS 2 distributions and |CONNEXT| versions, and the factors
that influence compatibility:

* :numref:`ros-connextrmw-install` and :numref:`ros-connextrmw-use` describe
  how to use ROS 2 with the |CONNEXT| RMW. 
* :numref:`getting-started-connext` and
  :numref:`enable-connext750-index` describe how to use |CONNEXT| standalone
  with ROS 2, regardless of the RMW that your ROS 2 application uses.