.. _transport-overview:

Transport Overview
------------------

.. toctree::
   :caption: File listing
   :name:
   :maxdepth: 1

   protobuf/authentication
   protobuf/transport
   protobuf/subscription
   protobuf/shop_requests
   protobuf/base_types
   protobuf/error

For historical prototyping reasons, the transport and RPC of writing and receiving objects to and from a :term:`Relay` is still `Protobuf <https://protobuf.dev/>`_ based.
The protocol is built in blocks:

- :ref:`ref_authentication.proto` defines how to use a :term:`KeyCard` to gain access to the stream.
- :ref:`ref_subscription.proto` defines how to receive patches, optionally filtered by some criteria.
- :ref:`ref_transport.proto` defines how events are sent and received.
- :ref:`ref_shop_requests.proto` defines a few requests specific to the :term:`shops<shop>`.