Read previous state from ERP5 backend.

opcua-to-http-gw/opcua-to-http-gw.py

@@ -40,9 +40,12 @@ class ERP5Handler(asyncua.common.subscription.SubHandler):
     if self.url is not None:
       return f"%s/%s" %(self.url, ERP5_REQUEST_API)
 
-  def call(self, **data):
+  def call(self, http_method = "POST", **data):
     params = urllib.parse.quote_plus(json.dumps({k: str(v) for k, v in data.items()}))
-    self.session.post(f"{self.uri}?data={params}")
+    if http_method == "POST":
+      self.session.post(f"{self.uri}?data={params}")
+    elif http_method == "GET":
+      return self.session.get(f"{self.uri}")
 
   def datachange_notification(self, node, val, data):
     self.call(node=node, val=val, data=data)
@@ -72,6 +75,17 @@ async def main():
   if xml is not None:
     await server.import_xml(xml)
 
+
+  # read previous state as saved in ERP5 backend
+  erp5_json = erp5_handler.call(http_method="GET").json()
+  _logger.error(erp5_json)
+  for k,v in erp5_json.items():
+    # set
+    node = server.get_node(k)
+    _logger.error("Set %s = %s at %s" %(k, v, node))
+    # XXX: this leads to a change notification which calls ERP5 and endless loop!
+    #await node.write_value(v)
+
   if erp5_handler:
     subscription = await server.create_subscription(1000, erp5_handler)
     await subscription.subscribe_events()