doc/manual/connectors.rst
author Edouard Tisserant
Thu, 19 Apr 2018 13:02:13 +0200
changeset 1995 691d119ba20f
parent 1455 4ba27ed51e48
permissions -rw-r--r--
Removed DebugThread. Take advantage of the fact that buffering is done in runtime. No need to poll for traces more than ten per second, then use simple wxTimer for that. Also removed Debug Lock since now everything happens in wx' mainloop.
Beremiz and Beremiz_service connectors 
======================================

To connect a PLC, Beremiz provides 2 types of connectors :
 * a Pyro connector
 * a WAMP connector

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

The Pyro connector
----------------------------

Pyro is an advanced and powerful Distributed Object Technology system written entirely in Python.
Beremiz_service spawns a Pyro server, serving a PLCObject (see runtime/PLCObject.py). Therefore, Beremiz acts as a Pyro client.

TODO:: link to PLCObject API documentation

URI_location :
 * LOCAL:// is a facility that starts the PLC service locally and connect Beremiz to it via Pyro.
   This is intended for use in development stage.
 * PYRO://<ip:port> normal connection to a remote PLC. PLC default port is 3000.
 * PYROS://<ip:port> SSL connection to a remote PLC, see below.

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

===========================
Setup a Pyro SSL connection
===========================

Pyro v3 has a limited TLS/SSL support based on m2crypto. Pyro v4 had dropped it.
In order to have a full and reliable SSL, we recommand to use a TLS/SSL wrapper as nginx, stub or stunnel.

--------------------
TLS-PSK with stunnel
--------------------

In this example, we setup a simple TLS-PSK connection according to rfc4279.
This ciphersuite avoid the need for public key operations and certificate management.
It is perfect for a performance-constrained environments with limited CPU power as a PLC.


Needed :
 * stunnel >= 5.09

verify openssl support for PSK cipher::

    openssl ciphers -v 'PSK'

----------------------
Client setup (Beremiz)
----------------------

You need to choose an identity for your client, here *client1*.
generate a valid and strong key::

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

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

    output = stunnel-client.log
    client = yes
    
    [beremiz]
    accept = 3002
    connect = [PLC]:3001
    PSKidentity = client1
    PSKsecrets = pskclient1.txt

start stunnel client side::

    stunnel stunnel-client.conf

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

--------------------
Server setup (PLC)
--------------------

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

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

    output = stunnel-server.log
    
    [beremiz]
    accept = 3001
    connect = 127.0.0.1:3000
    PSKsecrets = psk.txt

start stunnel server side::

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

The WAMP connector
------------------

WAMP is an open standard WebSocket subprotocol that provides two application messaging 
patterns in one unified protocol: Remote Procedure Calls + Publish & Subscribe.

Beremiz WAMP connector implementation uses Autobahn and crossbar.

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

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