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Connect IDE to Runtime

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======================

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Connection is described by the *URI_location* in project's configuration.

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    ``Open project tree root -> Config tab -> URI_location``

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eRPC

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----

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`eRPC <https://github.com/embeddedrpc/erpc>`_ (Embedded RPC) is an open source

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Remote Procedure Call (RPC) developed by NXP. 

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In case of Beremiz, Runtime is the eRPC server and IDE is a client. Transport

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can be either TCP/IP or Serial.

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``URI_location`` for eRPC:

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^^^^^^^^^^^^^^^^^^^^^^^^^^^^

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    * ``ERPC://host[:port]`` unencrypted connection. Default port is 3000.

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        This connection is highly unsecure, and should never be used on

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        untrusted network. It is intended to be used on peer to peer connection

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        such as ethernet over USB, for initial pairing with IDE.

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    * ``ERPCS://host[:port]`` SSL-PSK encrypted connection.

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        Default port is 4000.

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    * ``LOCAL://`` starts local runtime and connect with it through TCP/IP

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        bound to Localhost using random port.

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SSL-PSK setup:

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^^^^^^^^^^^^^^

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In order to provide practical secure communication in between runtime and IDE

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TLS-PSK connection according to rfc4279.

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Server (runtime)

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""""""""""""""""

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.. highlight:: ini

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PSK ciphersuite avoids the need for public key operations and certificate

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management. It is perfect for a performance-constrained environments with

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limited CPU power as a PLC.

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`Stunnel <https://www.stunnel.org/>`_ is used to wrap unencrypted eRPC server

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into an TLS-PSK SSL socket. Hereafter is ``stunnel.conf``::

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    [ERPCPSK]

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    accept = 4000

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    connect = 127.0.0.1:3000

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    ciphers = PSK

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    sslVersion = TLSv1.2

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    PSKsecrets = psk.txt

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.. highlight:: text

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List PSK ciphers available in server's openssl::

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    openssl ciphers -s -psk -tls1_2

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Launch ``stunnel``::

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    stunnel ./stunnel.conf

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Client (IDE) 

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""""""""""""

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Compare client's available openssl PSK ciphers with Server's ciphers. At least

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a few of them should match::

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    openssl ciphers -s -psk -tls1_2

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Use unencrypted peer-to-peer connection such as network over USB 

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or simple Ethernet cable, connect an obtain PSK::

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    ERPC://hostname[:port]

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Then use Identity Management dialog in IDE to select matching ID and generate

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``ERPCS`` URI::

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    ERPCS://hostname[:port]#ID

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WAMP

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----

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`WAMP <https://wamp-proto.org/>`_ is an open standard WebSocket subprotocol that provides two application messaging 

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patterns in one unified protocol: Remote Procedure Calls + Publish & Subscribe.

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Beremiz WAMP connector implementation uses python ``autobahn`` module, from the `crossbar.io <https://github.com/crossbario>`_ project.

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Both IDE and runtime are WAMP clients that connect to ``crossbar`` server through HTTP.

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``URI_location`` for WAMP:

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	* ``WAMP://host[:port]#realm#ID`` Websocket over unencrypted HTTP transport.

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	* ``WAMPS://host[:port]#realm#ID`` Websocket over secure HTTPS transport.

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..

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    TODO : 

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        crossbar server setup with example config and minimal backend.