.. _whats-new-420:

What's New in 4.2.0
===================

|rti_me| 4.2.0 is a feature release. See the 
`Connext Releases <https://www.rti.com/products/connext-releases>`_ 
page on the RTI website for more information on RTI's software release model.

The following features are new since |me| 4.1.0.

.. MICRO-9026

Reduced core library size
-------------------------

This release separates the Extensible Types (XTypes) module from the
core library, ``rti_me``, into a separate library, ``rti_me_ddsxtypes``. This
change reduces the size of ``rti_me``. The XTypes module is now
optional and can be omitted if your application does not use its functionality.

Refer to the `Migration Guide <https://community.rti.com/static/documentation/connext-micro/current/doc/mg/html/index.html>`__
(if you have internet access) for more information on how this change affects
existing |me| applications.

.. MICRO-10732

Secure RTPS communication with the Lightweight Security Plugin
--------------------------------------------------------------

This release introduces the *Lightweight Security Plugin* for |me|, a module
that enables you to secure your application's RTPS messages with pre-shared key
(PSK) encryption. The *Lightweight Security Plugin* includes a Platform
Independent Library (PIL) and a Transform Platform Support Library (PSL) for
interfacing with `OpenSSL 3.5 <https://github.com/openssl/openssl/tree/openssl-3.5.0>`__.

For more information on this feature, refer to the :ref:`section-psk` section.

.. MICRO-10733

Optimize network bandwidth usage with content filtering
-------------------------------------------------------

.. attention::

  This is an experimental feature in |me| 4.2.0. It is not guaranteed to be
  consistent or supported and should not be used in production.

  Refer to :ref:`section-experimental-features` for more information.

This release introduces content filtering to |me|, enabling *DataReaders*
to filter incoming sample data. This can reduce the network bandwidth usage in
your application, since matching *DataWriters* can be configured to only send
samples that pass the *DataReader*'s filter.

For more information on this feature, consult the
:ref:`section-content-filtering` section.

.. MICRO-9108

Improve system robustness with DomainParticipant rediscovery
------------------------------------------------------------

This release adds the ability for a *DomainParticipant* with its
``DomainParticipantQos.participant_name.name`` set to a non-empty value to be
rediscovered if it is restarted before its ``lease_duration`` expires. You can
enable this feature by setting the
``DomainParticipantQos.discovery.enable_participant_discovery_by_name`` property
to ``DDS_BOOLEAN_TRUE``.

For more information on this feature, refer to the
:ref:`section-domainparticipant-rediscovery` section.

.. MAG-185

Develop secure applications in XML with MAG
-------------------------------------------

This release allows you to enable and configure the *Lightweight Security
Plugin* while defining an application in XML format. Micro Application Generator
(MAG) will then create the necessary code for |me|.

For more details, refer to the :ref:`section-appgen-psk` section of
:ref:`section-appgen`. 

.. MAG-186

Develop applications with content filtering in XML with MAG
-----------------------------------------------------------

This release allows you to enable and configure content filtering while defining
an application in XML format. Micro Application Generator (MAG) will then create
the necessary code for |me|.

For more details, refer to the :ref:`section-appgen-content-filtering` section
of :ref:`section-appgen`.

.. MAG-193

Enable DomainParticipant rediscovery in XML with MAG
----------------------------------------------------

This release allows you to enable *DomainParticipant* rediscovery while defining
an application in XML format. Micro Application Generator (MAG) will then create
the necessary code for |me|.

For more information on this feature, see
:ref:`section-domainparticipant-rediscovery`. You can enable *DomainParticipant*
rediscovery via the ``enable_participant_discovery_by_name`` field in the
:link_connextmicro_dds_api_c_up_one:`PROPERTY <structDDS__PropertyQosPolicy.html>`
QoS policy, as described in :ref:`section-appgen-discovery-config`.

.. MAG-199

Enable endpoint discovery message queueing in XML with MAG
----------------------------------------------------------

This release allows you to enable endpoint discovery message queueing while
defining an application in XML format. Micro Application Generator (MAG) will
then create the necessary code for |me|.

This feature is included as a fix for a potential discovery issue; see
:ref:`MICRO-10044` for more information. You can enable discovery message
queueing via the ``enable_endpoint_discovery_queue`` field in the
:link_connextmicro_dds_api_c_up_one:`PROPERTY <structDDS__PropertyQosPolicy.html>`
QoS policy, as described in :ref:`section-appgen-discovery-config`.

.. THIRDPARTY-323

Third-party and open source software changes
--------------------------------------------

This release adds the following open source software as part of the
:ref:`Lightweight Security Plugin <section-psk>`:

.. list-table:: Open Source Software Additions
    :widths: 50 50
    :header-rows: 1

    * - Software
      - Version
    * - OpenSSL
      - 3.5.0

For more information, see the :ref:`section-3rd-party` section.