add basic opcua server

this is a very dirty adhoc approach: we basically build our own asyncua.Server.

product/ERP5/bin/zopewsgitw.py

@@ -250,11 +250,23 @@ def runwsgi():
 #
 ################################################################
 
+import math
+
+# We need asyncio support in twisted because our opcua lib is written with
+# asyncio syntax. See https://meejah.ca/blog/python3-twisted-and-asyncio
+import asyncio
+from twisted.internet import asyncioreactor
+asyncioreactor.install(asyncio.get_event_loop())
+from twisted.internet.task import react
+from twisted.internet.defer import ensureDeferred
+
 from twisted.web.wsgi import WSGIResource
 from twisted.internet import protocol, reactor, endpoints
 from twisted.web import server as twisted_server
 import urllib
 
+import asyncua
+
 from Products.ERP5Type.Log import log
 
 # I modified runwsgi() without thinking carefully.
@@ -393,6 +405,37 @@ def runwsgitw():
     class EchoFactory(protocol.Factory):
       def buildProtocol(self, addr):
         return Echo()
+    
+    class OPCUA(protocol.Protocol, asyncua.server.binary_server_asyncio.OPCUAProtocol):
+      def __init__(self, *args, **kwargs):
+        asyncua.server.binary_server_asyncio.OPCUAProtocol.__init__(self, *args, **kwargs)
+        protocol.Protocol.__init__(self)
+
+      def dataReceived(self, data):
+        log("data received")
+        log(data)
+        self.data_received(data)
+        log("PASSED data received")
+
+      def connectionMade(self):
+        log("connection made")
+        # opcua transport has 'get_extra_info':
+        # https://github.com/FreeOpcUa/opcua-asyncio/blob/ff6969d/asyncua/server/uaprocessor.py#LL32-L32C61
+        self.transport.get_extra_info = lambda *args, **kwags: "test"
+        # this also has 'close'
+        # https://github.com/FreeOpcUa/opcua-asyncio/blob/master/asyncua/server/binary_server_asyncio.py#L108
+        self.transport.close = lambda *args, **kwags: None
+        self.connection_made(self.transport)
+        log("PASSED conn made")
+
+      def connectionLost(self, ex):
+        log("connection lost")
+        self.connection_lost(ex)
+        log("PASSED conn lost")
+
+    class OPCUAFactory(protocol.Factory):
+      def buildProtocol(self, addr):
+        return OPCUA(self.iserver, [], [], [], self.limits)
 
     # Add a wsgi server, this is normal.
     endpoints.serverFromString(reactor, "tcp:%s:interface=%s" % (port, ip)).listen(twisted_server.Site(resource))
@@ -402,5 +445,40 @@ def runwsgitw():
     # to a different port.
     endpoints.serverFromString(reactor, "tcp:2261:interface=%s" % ip).listen(EchoFactory())
 
+    # Add OPCUA server
+    opcua_ip, opcua_port = ip, '2262'
+    opcua_factory = OPCUAFactory()
+    add_iserver(opcua_factory)
+    add_limits(opcua_factory)
+
+    endpoints.serverFromString(
+      reactor, f"tcp:{opcua_port}:interface={opcua_ip}").listen(opcua_factory)
+
     # Start main loop.
     reactor.run()
+
+
+def add_iserver(opcua_factory, opcua_ip, opcua_port):
+  opcua_factory.iserver = asyncua.server.internal_server.InternalServer()
+  # see https://github.com/FreeOpcUa/opcua-asyncio/blob/ff6969d2/asyncua/server/server.py#LL411C13-L411C70
+  opcua_factory.iserver.supported_tokens = (asyncua.ua.AnonymousIdentityToken,)
+
+  # adhoc creation of endpoint, only most essential parts
+  # https://github.com/FreeOpcUa/opcua-asyncio/blob/ff6969d2b7d93cc22c517cbb2f43ef98dc643a8c/asyncua/server/server.py#L434
+  edp = asyncua.ua.EndpointDescription()
+  edp.EndpointUrl = urllib.parse.urlparse(f"opc.tcp://{opcua_ip}:{opcua_port}/freeopcua/server/").geturl()
+  edp.SecurityMode = asyncua.ua.MessageSecurityMode.None_
+  edp.SecurityPolicyUri = asyncua.ua.SecurityPolicy.URI
+  opcua_factory.iserver.add_endpoint(edp)
+
+
+def add_limits(opcua_factory):
+  # Use acceptable limits
+  buffer_sz = 65535
+  max_msg_sz = 100 * 1024 * 1024  # 100mb
+  opcua_factory.limits = asyncua.common.connection.TransportLimits(
+      max_recv_buffer=buffer_sz,
+      max_send_buffer=buffer_sz,
+      max_chunk_count=math.ceil(max_msg_sz / buffer_sz),  # Round up to allow max msg size
+      max_message_size=max_msg_sz
+  )
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