pythonfiwarefiware-orion

Notify python orion/quantumleap subscription changes


Is there any way to get notified in python when a Quantumleap o Orion subscription fires for a changed value?


Solution

  • I've dockerized the nickjj web server, switched the bind_host to 0.0.0.0 as specified in the documentation, and exposed the port 8008:8008 in docker-compose.

    nickjj Python web server:

    from http.server import HTTPServer, BaseHTTPRequestHandler
    from sys import argv
    
    BIND_HOST = '0.0.0.0'
    PORT = 8008
    
    class SimpleHTTPRequestHandler(BaseHTTPRequestHandler):
        def do_GET(self):
            self.write_response(b'')
    
        def do_POST(self):
            content_length = int(self.headers.get('content-length', 0))
            body = self.rfile.read(content_length)
    
            self.write_response(body)
    
        def write_response(self, content):
            self.send_response(200)
            self.end_headers()
            self.wfile.write(content)
    
            print(self.headers)
            print(content.decode('utf-8'))
    
    
    if len(argv) > 1:
        arg = argv[1].split(':')
        BIND_HOST = arg[0]
        PORT = int(arg[1])
    
    print(f'Listening on http://{BIND_HOST}:{PORT}\n')
    
    httpd = HTTPServer((BIND_HOST, PORT), SimpleHTTPRequestHandler)
    httpd.serve_forever()
    

    Dockerfile to build the web server service:

    # Build the service from the base image
    FROM python:3.9.16-alpine3.17
    
    # During building, run the following commands to install dependecies
    RUN apk add --no-cache openssl-dev curl-dev
    RUN pip install --upgrade pip
    # RUN pip install pycurl crate requests
    
    # Set the work directory
    WORKDIR /webserver
    
    # Copy in the continer the following files
    COPY ./webserver ./webserver
    
    # Run this command at startup
    CMD ["python","-u","webserver", "webserver:8008"]
    

    docker-compose configuration for the web server, with curl for debug:

    webserver:
      image: webserver
      stdin_open: true # docker run -i
      tty: true        # docker run -t
      container_name: 'webserver'
      ports:
        - "8008:8008"
      networks:
        - default
    

    I've provisioned the relative subscription in Orion:

    curl -iX POST \
        'http://localhost:1026/v2/subscriptions/' \
        -H 'Content-Type: application/json' \
        -H 'fiware-service: opcua_car' \
        -H 'fiware-servicepath: /demo' \
        -d '{
      "description": "Subscriptions for Python webserver",
      "subject": {
        "entities": [
          {
            "idPattern": ".*",
            "type": "PLC"
          }
        ],
        "condition": {
          "attrs": [
            "processStatus"
          ]
        }
      },
      "notification": {
        "http": {
          "url": "http://webserver:8008/"
        },
        "attrs": [
          "processStatus"
        ],
        "metadata": [
          "dateCreated",
          "dateModified"
        ]
      },
      "throttling": 1
    }'
    

    And I finally get my subscription notifications in Python.