我正在开发一个简单的项目，其中我做了一个我放在Orion-LD上的实体列表。现在我想做一个服务器，它允许在实体属性的状态发生变化时接收通知。我选择使用Node.JS Express，但它不是强制性的。我在这里留下用于实现我的服务器的简单代码。

const express = require('express');
const request = require('request');

const app = express();
const PORT = 3000;

//Subscription on batteryLevel changes of device 9845A
app.get('/subscribe', (req, res) => {
    const data = {
        "description": "Subscription",
        "subject": {
            "entities": [
                {
                    "id": "urn:ngsi-ld:Device:9845A",
                    "type": "Device"
                }
            ],
            "condition": {
                "attrs": ["batteryLevel"]
            }
        },
        "notification": {
            "http": {
                "url": `http://localhost:${PORT}/notification`
            },
            "attrsFormat" : "keyValues"
        }
    };
      
    const options = {
        headers: {
            'Content-Type': 'application/json',
          },
        json: data
    };

    request.post('http://localhost:1026/v2/subscriptions', options, (error, response, request) => {
        console.log(response.body);
        res.end("Succesfully subscribed!");
    });
});

// Listen on notification
app.post('/notification', (req, res) => {
    console.log('Notification received:', req.body);
    res.sendStatus(200);
});

app.listen(PORT, () => {
  console.log(`Example app listening on port ${PORT}`)
});

以下是docker-compose.yaml的实现：

version: "3.9"

services:
  # Orion-LD Context Broker
  orion:
    container_name: fiware-orion
    image: fiware/orion:latest
    hostname: orion
    depends_on:
      - mongo-db
    expose:
      - "1026"
    ports:
      - "1026:1026"
    command: -dbhost mongo-db -logLevel DEBUG
    networks:
      - default
  
  # Database
  mongo-db:
    container_name: fiware-mongo
    image: mongo:4.4
    hostname: mongo-db
    expose:
      - "27017"
    ports:
      - "27017:27017"
    command: --nojournal
    volumes:
      - ./data/mongo-db:/data
    networks:
      - default
  
  # Server
  node-server:
    container_name: fiware-node
    build: .
    hostname: node-server
    depends_on:
      - orion
    expose:
      - "3000"
    ports:
      - "3000:3000"
    volumes:
      - ./data/node:/data
    networks:
      default:
        aliases:
          - iot-sensors
          - context-provider

  # RDF Store
  virtuoso:
    container_name: fiware-virtuoso
    image: openlink/virtuoso-opensource-7:latest
    ports:
      - "1111:1111"
      - "8890:8890"
    environment:
      SPARQL_UPDATE: true
      DBA_PASSWORD: dba
    volumes:
      - ./data/virtuoso:/data

networks:
  default:

这是与Node.js Express相关的Dockerfile：

FROM node:latest
WORKDIR /app
COPY server/package*.json server/server.js ./
RUN npm install
EXPOSE 3000
CMD [ "node", "server.js" ]

问题是，如果我正确订阅了一个现有的实体，它会在订阅中报告一个"status": "failed"，因此我无法收到有关状态的通知。阅读Orion LD日志，它似乎无法与我的服务器在端口3000通信，但我不知道为什么。有人能帮助我吗？