.. include:: /../getting_started/vars.rst

.. _section-General-731:

General Compatibility 7.3.1
***************************

This section describes compatibility issues that affect an upgrade to 7.3.1.
It describes general, wire, and other compatibility issues between *Connext*
7.3.1 and previous releases.

Unless noted otherwise, the issues in this section do not
apply to *RTI* |CONNEXT| *Micro*.

See :ref:`section-Product-Index-731` for specific issues.

See `RTI Connext Performance Benchmarks <https://community.rti.com/static/documentation/performance/benchmarks/index.html>`__
for performance details in 7.3 LTS.

Wire Compatibility
==================

RTPS Versions
-------------
For information about the RTPS versions supported for each |CONNEXT| release, 
see `Compatibility <https://community.rti.com/static/documentation/connext-dds/7.3.1/doc/manuals/connext_dds_professional/release_notes/compatibility_section.html>`__
in the *RTI Connext Core Libraries Release Notes* for 7.3 LTS. 


New requirement if you interoperate with DDS vendors that produce multiple RTPS messages in a single datagram
--------------------------------------------------------------------------------------------------------------
Release 7.3.1 fixed an issue (`CORE-14701 <https://community.rti.com/static/documentation/connext-dds/7.3.1/doc/manuals/connext_dds_professional/release_notes/whats_fixed/731/fixes_interoperability.html>`__)
related to how |CONNEXT| processes multiple RTPS messages in a single datagram.
As a result, |CONNEXT| now requires the RTPS Header Extension's message
length (``messageLength``) to be present and correctly populated in every RTPS
message that does not finish at the end of the underlying datagram. This requirement
corresponds to the
`OMG RTPS 2.5 specification <https://www.omg.org/spec/DDSI-RTPS/About-DDSI-RTPS/>`__.

.. note::
  
   Currently, no RTI software produces a datagram containing two or more RTPS
   messages. 

If your |CONNEXT| 7.3.1 or later system interacts with another DDS vendor that
produces multiple RTPS messages in a single datagram, that vendor must now
populate the RTPS Header Extension message length in order to interoperate with
|CONNEXT| 7.3.1 or later.


.. CORE-14701