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

.. _section-General-601:

General Compatibility 6.0.1
***************************

This section describes compatibility issues that affect the *Connext* suite 
in Release 6.0.1. Unless noted otherwise, the issues in this section do not 
apply to |CONNEXT| *Micro*. 


Platforms
=========

.. note::

    For information on new and removed platforms in this release, see
    :link_connext_whats_new_601:`What's New in 6.0.1 <>`. 
    See also individual products' :link_rti_community_doc_s:`Release Notes <601>`.


.. _section-General-Wire-601:

Wire Changes and Compatibility
==============================

RTPS Versions
-------------
See :numref:`section-General-RTPS` for more information about the RTPS versions 
supported for each |CONNEXT| release.

Fragmentation is now independent of sample serialized size
----------------------------------------------------------
In 6.0.1, when using a FlowController, the fragment size for a sample should be either 
(a) ``bytes_per_token`` or (b) the smallest of the ``message_size_max`` values across all  
transports installed with the |DW|, whichever is less.

In previous releases, however, if the serialized size of the sample was smaller 
than or equal to the maximum message size of the transport with which the sample 
was sent, minus some protocol overhead (512 bytes by default), |CONNEXT| chose the 
maximum message size of the transport as the fragment size, ignoring ``bytes_per_token``, 
which may be smaller.

This behavior may have led to a bursty behavior of the FlowController that resulted 
in not sending fragments every period but sending them only when enough tokens were 
accumulated to send the full sample.

This problem has been resolved. (See RTI Issue ID CORE-9287 in 
:link_connext_relwire_release_notes:`"Fixes Related to Reliability Protocol and Wire Representation" in the RTI Connext DDS Core Libraries Release Notes <>`.) 
Now when the serialized size of a sample when using a FlowController is smaller than 
or equal to the maximum message size of the transport as described above, the fragment 
size for the sample is the lesser of (a) ``bytes_per_token`` or (b) the smallest of the 
``message_size_max`` values across all transports installed with the |DW|.

If you need to go back to the old behavior, before this fix, please contact support@rti.com.


.. _section-General-Type-601:

Type System Compatibility
=========================

Wire representation of TypeObject
---------------------------------
In 6.0.0, |CONNEXT| enabled *TypeObject* compression by default to reduce
bandwidth usage when exchanging endpoint discovery data. 
See :numref:`section-General-wire_rep_typeobject`. The compressed *TypeObject* (*TypeObjectLb*) 
deserialization depended on the DDS_DomainParticipantResourceLimitsQosPolicy's 
``type_object_max_serialized_length`` to control the maximum size of the buffer that 
|CONNEXT| uses to uncompress the received compressed *TypeObject*. 

Starting in 6.0.1, this uncompression buffer is no longer controlled by the 
DDS_DomainParticipantResourceLimitsQosPolicy's ``type_object_max_serialized_length`` 
(default value: 8192 bytes). Instead, it is controlled by the 
DDS_DomainParticipantResourceLimitsQosPolicy's ``type_object_max_deserialized_length`` 
(default value: DDS_LENGTH_UNLIMITED). 

As a result, you can now configure |CONNEXT| to only receive (but not propagate) compressed 
*TypeObjects* by setting ``type_object_max_serialized_length`` to zero and keeping 
``type_object_max_deserialized_length`` set to DDS_LENGTH_UNLIMITED.


.. _section-general-java-net-xcdr2:

Incompatibility issues for Java and .Net when using XCDR2
---------------------------------------------------------
Starting in 6.0.0, |CONNEXT| supports the Extended Common Data Representation (CDR) encoding
version 2 (XCDR2), in addition to version 1 (XCDR). XCDR2 is supported in both
|CONNEXT| and |CONNEXT| *Micro*. See :numref:`section-General-Extended-CDR` 
for details.

Support for XCDR2 introduced two known issues in 6.0.0 (described in 
:numref:`section-codegen-keyhash` and :numref:`section-codegen-serialize-xcdr2`). 
Those issues are fixed in 6.0.1; however, because of those fixes, applications 
in Java or .Net in release 6.0.1 or above may not interoperate with applications in 
another language in 6.0.0, and vice-versa (applications in Java or .Net in release 
6.0.0 may not interoperate with applications in another language in 6.0.1 or above). 
For details, see :numref:`section-codegen-keyhash` 
and :numref:`section-codegen-serialize-xcdr2`.

 
Other Compatibility Issues
==========================

Large data support for Multichannel and TopicQuery has been disabled
--------------------------------------------------------------------
Due to the Known Issue described in 
:link_connext_ki_multi_release_notes:`"Multichannel and TopicQuery do not Work with Large Data in Some Cases," in the RTI Connext DDS Core Libraries Release Notes <>`, 
large data support for Multichannel and TopicQuery has been disabled in release 6.0.1. 
If you need this functionality enabled as it was in 6.0.0, please contact RTI support 
(support@rti.com).