.. include:: /substitutions.rst

Interoperability
================

|ProductName| provides interoperability between participants and utilities from different released versions of |ProductName|.
This section documents known issues and potentially misleading messages reported by |ProductName| participants in certain cases.

Duplicate Participant Names
~~~~~~~~~~~~~~~~~~~~~~~~~~~

Multiple participants with the same name connect to a single registry instance.

The |ProductName| Registry with version 4.0.7 or lower just drops the connection in this case.
The participant is not informed and eventually times out.

Scenario A
----------

- Registry-Version: 4.0.7 or lower
- First Participant: Any version
- Second Participant 4.0.7 or lower

The second participant connecting with the same name reports a connection timeout with the following message:

.. code-block:: powershell

   Timeout during connection handshake with SIL Kit Registry.

Scenario B (Mixed Versions)
---------------------------

- Registry-Version: 4.0.7 or lower
- First Participant: Any version
- Second Participant 4.0.8 or higher

The message reported by the second participant has been modified in SIL Kit 4.0.8 (when connecting to a registry of version 4.0.7 or lower):

.. code-block:: powershell

   Timeout during connection handshake with SIL Kit Registry. This might indicate that a participant with the same name ('...') has already connected to the registry.

Scenario C (Mixed Versions)
---------------------------

- Registry-Version: 4.0.8 or higher
- First Participant: Any version
- Second Participant 4.0.7 or lower

The registry transmits an error to the second participant in SIL Kit 4.0.8 via the ``ParticipantAnnouncementReply`` message with the ``status`` field set to ``Failed``.

The second participant does not report a timeout anymore, but immediately reports a misleading error message, referring to an unsupported protocol version:

.. code-block:: powershell

    SIL Kit Connection Handshake: ParticipantAnnouncementReply contains unsupported version. participant=SilKitRegistry participant-version=3.1

Scenario D
----------

- Registry-Version: 4.0.8 or higher
- First Participant: Any version
- Second Participant 4.0.8 or higher

The registry transmits an error to the second participant in SIL Kit 4.0.8 via the ``ParticipantAnnouncementReply`` message with the ``status`` field set to ``Failed``.

The second participant does not report a timeout anymore, but immediately reports an error message containing the diagnostic message reported by the registry:

.. code-block:: powershell

    SIL Kit Connection Handshake: Received failed ParticipantAnnouncementReply from 'SilKitRegistry' with protocol version 3.1 and diagnostic message: participant with name 'CanReader' is already connected