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Beremiz and Beremiz_service connectors 

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

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To connect a PLC, Beremiz provides 2 types of connectors :

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 * a Pyro connector

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 * a WAMP connector

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To configure the connection, you have to set the *URI_location* in your project Config tab according to this documentation. 

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The Pyro connector

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----------------------------

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Pyro is an advanced and powerful Distributed Object Technology system written entirely in Python.

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Beremiz_service spawns a Pyro server, serving a PLCObject (see runtime/PLCObject.py). Therefore, Beremiz acts as a Pyro client.

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TODO:: link to PLCObject API documentation

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URI_location :

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 * LOCAL:// is a facility that starts the PLC service locally and connect Beremiz to it via Pyro.

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   This is intended for use in development stage.

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 * PYRO://<ip:port> normal connection to a remote PLC. PLC default port is 3000.

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 * PYROS://<ip:port> SSL connection to a remote PLC, see below.

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more information about Pyro can be found on http://pythonhosted.org//Pyro/1-intro.html

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

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Setup a Pyro SSL connection

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

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Pyro v3 has a limited TLS/SSL support based on m2crypto. Pyro v4 had dropped it.

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In order to have a full and reliable SSL, we recommand to use a TLS/SSL wrapper as nginx, stub or stunnel.

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--------------------

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TLS-PSK with stunnel

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--------------------

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In this example, we setup a simple TLS-PSK connection according to rfc4279.

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This ciphersuite avoid the need for public key operations and certificate management.

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It is perfect for a performance-constrained environments with limited CPU power as a PLC.

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Needed :

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 * stunnel >= 5.09

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verify openssl support for PSK cipher::

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    openssl ciphers -v 'PSK'

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Client setup (Beremiz)

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----------------------

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You need to choose an identity for your client, here *client1*.

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generate a valid and strong key::

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    $ echo client1:$(openssl rand -base64 48) > pskclient1.txt

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write a stunnel client configuration file *stunnel-client.conf*::

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    output = stunnel-client.log

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    client = yes

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    [beremiz]

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    accept = 3002

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    connect = [PLC]:3001

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    PSKidentity = client1

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    PSKsecrets = pskclient1.txt

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start stunnel client side::

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    stunnel stunnel-client.conf

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You could now connect beremiz with classic URI_location = PYRO://127.0.0.1:3002

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--------------------

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Server setup (PLC)

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--------------------

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import the client key in a keyfile psk.txt, concatening all client key.

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write a stunnel server  configuration file *stunnel-server.conf*::

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    output = stunnel-server.log

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    [beremiz]

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    accept = 3001

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    connect = 127.0.0.1:3000

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    PSKsecrets = psk.txt

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start stunnel server side::

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    stunnel stunnel-server.conf

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more documentation on stunnel http://www.stunnel.org/docs.html

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The WAMP connector

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------------------

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WAMP 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 Autobahn and crossbar.

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URI_location :

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	* WAMP://127.0.0.1:8888#Automation#2534667845

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more information about WAMP can be found on http://wamp.ws/