Nodejs 的微服务概念

[yaogengzhu]

示例代码
以下是使用 Seneca 构建微服务架构的示例代码，包括用户服务、商品服务、订单服务、库存服务和网关服务。

用户服务

// userService.js
const Seneca = require('seneca');

const userService = Seneca();

let users = [];

userService.add({ role: 'user', cmd: 'register' }, (msg, reply) => {
  const { username, password } = msg;
  if (!username || !password) {
    return reply(null, { error: 'Username and password are required' });
  }
  const user = { id: users.length + 1, username, password };
  users.push(user);
  reply(null, user);
});

userService.add({ role: 'user', cmd: 'login' }, (msg, reply) => {
  const { username, password } = msg;
  const user = users.find(u => u.username === username && u.password === password);
  if (!user) {
    return reply(null, { error: 'Invalid username or password' });
  }
  reply(null, { success: true, userId: user.id });
});

userService.listen({ type: 'http', port: 3001, pin: 'role:user' });

商品服务

// productService.js
const Seneca = require('seneca');

const productService = Seneca();

let products = [];

productService.add({ role: 'product', cmd: 'create' }, (msg, reply) => {
  const { name } = msg;
  if (!name) {
    return reply(null, { error: 'Product name is required' });
  }
  const product = { id: products.length + 1, name };
  products.push(product);
  reply(null, product);
});

productService.listen({ type: 'http', port: 3002, pin: 'role:product' });

订单服务

// orderService.js
const Seneca = require('seneca');

const orderService = Seneca();

let orders = [];

orderService.add({ role: 'order', cmd: 'create' }, (msg, reply) => {
  const { userId, productId } = msg;
  if (!userId || !productId) {
    return reply(null, { error: 'User ID and Product ID are required' });
  }

  orderService.act({ role: 'user', cmd: 'get', id: userId }, (err, user) => {
    if (err || !user) {
      return reply(null, { error: 'Invalid User ID' });
    }

    orderService.act({ role: 'product', cmd: 'get', id: productId }, (err, product) => {
      if (err || !product) {
        return reply(null, { error: 'Invalid Product ID' });
      }

      const order = { id: orders.length + 1, userId, productId };
      orders.push(order);
      reply(null, order);
    });
  });
});

orderService.listen({ type: 'http', port: 3003, pin: 'role:order' });

库存服务

// inventoryService.js
const Seneca = require('seneca');

const inventoryService = Seneca();

let inventory = [];

inventoryService.add({ role: 'inventory', cmd: 'update' }, (msg, reply) => {
  const { productId, quantity } = msg;
  if (!productId || quantity === undefined) {
    return reply(null, { error: 'Product ID and Quantity are required' });
  }
  const item = inventory.find(i => i.productId === productId);
  if (item) {
    item.quantity = quantity;
  } else {
    inventory.push({ productId, quantity });
  }
  reply(null, { success: true });
});

inventoryService.listen({ type: 'http', port: 3004, pin: 'role:inventory' });

网关服务

// gatewayService.js
const Seneca = require('seneca');
const express = require('express');
const bodyParser = require('body-parser');

const app = express();
app.use(bodyParser.json());

const gatewayService = Seneca();

gatewayService.client({ type: 'http', port: 3001, pin: 'role:user' });
gatewayService.client({ type: 'http', port: 3002, pin: 'role:product' });
gatewayService.client({ type: 'http', port: 3003, pin: 'role:order' });
gatewayService.client({ type: 'http', port: 3004, pin: 'role:inventory' });

app.post('/api/:role/:cmd', (req, res) => {
  const { role, cmd } = req.params;
  const msg = { role, cmd, ...req.body };
  gatewayService.act(msg, (err, result) => {
    if (err) {
      return res.status(500).json({ error: err.message });
    }
    res.json(result);
  });
});

app.listen(3000, () => {
  console.log('Gateway service listening on port 3000');
});

请求示例
以下是如何通过 HTTP 请求调用网关服务的示例。

URL: http://localhost:3000/api/user/register

1. 请求方法: POST
2. 请求体: {"username":"testuser","password":"testpass"}
3. 头部: Content-Type: application/json
4. 这个请求会被网关服务接收，并转发到用户服务的注册处理器。

URL: http://localhost:3000/api/user/login

1. 请求方法: POST
2. 请求体: {"username":"testuser","password":"testpass"}
3. 头部: Content-Type: application/json
4. 这个请求会被网关服务接收，并转发到用户服务的登录处理器。

说明
网关服务使用 Express 框架接收 HTTP 请求，并通过动态路由和模式匹配将请求转发到相应的微服务。
请求通过 HTTP POST 方法发送到网关服务的 /api/:role/:cmd 路径，网关服务接收到请求后，通过 Seneca 的 act 方法将请求转发到相应的微服务，并返回结果。
通过这种方式，可以简化网关服务的维护，并且更容易扩展。每次新增接口时，只需要在相应的微服务中添加处理器，而不需要修改网关服务。