Question

我一直在尝试使用以下代码来启动并运行基本服务器发送的事件（nodejs + express用于后端，React在前端上），但是当我尝试更新{{1时，onmessage不会触发}}通过终端。

这是流程：

启动服务器并运行。
打开浏览器，然后点击count。
在用户界面中，我可以看到通知计数为localhost:9000。
尝试通过终端中的0调用通过cURL更新通知计数，如下所示：

curl -X POST -H“内容类型：application / json” -d'{“ count”：10}'-s http：// localhost：9000 / notification

在运行服务器的终端外壳中，我看到触发了POST回调，但是/events仍然是count。

这是我尝试的代码。在主题（在浏览器的控制台中看到）和UI中提到的获取错误不会随着更新的通知计数而更新。请让我知道我做错了什么：

服务器代码（NodeJS + Express）：

反应代码

const sseHandler = (req: express.Request, res: express.Response) => {
console.log("server sent event handler triggered");
//Mandatory headers and http status to keep connection open
const headers = {
  'Content-Type': 'text/event-stream',
  'Connection': 'keep-alive',
  'Cache-Control': 'no-cache'
};

res.writeHead(200, headers);
//After client opens connection send all notifications as string
const data = `count:${notificationCount}\n\n`;
console.log(data);
res.write(data);
// Generate an id based on timestamp and save res
// object of client connection on clients list
// Later we'll iterate it and send updates to each client
// In Real world scenario, client list should be saved to the DB
const clientId = Date.now();
const newClient = {
  id: clientId,
  res,
};
clients.push(newClient);
// When client closes connection we update the clients list
// avoiding the disconnected one
req.on('close', () => {
  console.log(`${clientId} Connection closed`);
  clients = clients.filter(c => c.id !== clientId);
 });
};

// Iterate clients list and use write res object method to send latest notification count
const sendEventsToAll = (count:number) => {
  console.log("send event to all");
  clients.forEach(c => c.res.write(`count:${count}\n\n`));
};

// Middleware for POST /notification endpoint
const updateNotification = async (
  req: express.Request,
  res: express.Response,
) => {
  let currentCount= req.body.count;
  console.log("post count is: ", currentCount);
  // Send recently updated notification count as POST result
  res.json({count: currentCount});
  // Invoke iterate and send function
  return sendEventsToAll(currentCount);
}

Answer 1

我不得不停止响应正文的默认压缩，从而达到了目的。这是我放置的支票（Content-Type上的响应标头支票）：

const shouldCompress = (
  req: express.Request,
  res: express.Response
): boolean => {
// don't compress responses explicitly asking not
if (req.headers["x-no-compression"] || res.getHeader('Content-Type') === 'text/event-stream') {
  return false;
}

// use compression filter function
  return compression.filter(req, res);
};

我的nodejs + express代码使用压缩中间件，如下所示：

import compression from "compression";
...
..
.
.
.
/**
 * Express application setup
*/
const expressApp = express();

// setup compression in express
expressApp.use(compression({ filter: shouldCompress }));

此外，来自服务器的响应应具有以下字段：https://javascript.info/server-sent-events#server-response-format

服务器发送事件不起作用：:错误:: net :: ERR_INCOMPLETE_CHUNKED_ENCODING 200

1 个答案: