Node.js 获取SSE消息、角度前端、节点后端时出错
我使用SSE从节点后端向Angular应用程序发送简单消息。到目前为止,它一直在完美地工作,但今天我意识到它不再工作了,我找不到原因 以下是相关代码: 节点Node.js 获取SSE消息、角度前端、节点后端时出错,node.js,angular,server-sent-events,eventsource,Node.js,Angular,Server Sent Events,Eventsource,我使用SSE从节点后端向Angular应用程序发送简单消息。到目前为止,它一直在完美地工作,但今天我意识到它不再工作了,我找不到原因 以下是相关代码: 节点 router.get('/stream', function (req, res) { [ ... ] // Send headers for event-stream connection res.writeHead(200, { 'Content-Type': 'text/event-strea
router.get('/stream', function (req, res) {
[ ... ]
// Send headers for event-stream connection
res.writeHead(200, {
'Content-Type': 'text/event-stream',
'Cache-Control': 'no-cache',
'Connection': 'keep-alive'
});
res.write('\n');
[ ... ]
// NOTE: This line connects to a Redis server
subscriber.subscribe(channel);
// In case we encounter an error...print it out to the console
subscriber.on("error", function (err) {
logger.debug("Redis Error: " + err);
});
// When we receive a message from the Redis connection
subscriber.on("message", function (channel, message) {
logger.debug('MESSAGE RECEIVED: ' + message); // This message is printed in the log file
[ ... ]
// Note: 'msgData' is obtained by parsing the received 'message'
// Send data to the client
res.write('data: ' + msgData + "\n\n");
});
}
角度应用程序
declare var EventSource : any;
getSSEMessages(): Observable<string> {
let sseUrl = `${ConfigService.settings.appURL}/stream`;
return new Observable<string>(obs => {
const es = new EventSource(sseUrl, { withCredentials: true });
// This prints '1' (CONNECTION OPEN)
console.log('SSE Connection: ', es.readyState);
// Note: I've also tried 'es.onerror'
es.addEventListener("error", (error) => {
console.log("Error in SSE connection", error);
return false;
});
// Note: I've also tried 'es.onmessage'
es.addEventListener("message", (evt : any) => {
// Never gets in here
console.log('SSE Message', evt.data);
obs.next(evt.data);
});
return () => es.close();
});
}
正如我所说,几周来一切都很顺利。今天我看到我没有收到任何消息,我一直在努力寻找原因,但运气不好
有什么线索可以说明问题吗?最后,我找到了一个解决方案: 可能是因为更新了一些节点模块或节点本身,它添加了某种缓冲区来优化连接流量。要使应用程序再次工作,我所要做的就是在每条消息后添加一个
flush
,如下所示:
[...]
res.write('data: ' + msgData + "\n\n");
// Send the message instantly
res.flush();
[...]
干杯,使用Chrome开发工具的网络选项卡,我刚刚意识到,当我请求流路由时,会创建一个新的“eventsource”项,“Time”列显示“Pending”,与所有其他请求不同,它以毫秒为单位显示时间。这与问题有关吗?谢谢。有点像这个问题。。您不需要删除“/stream”处理程序中的事件侦听器吗?我觉得上面的代码会导致内存泄漏!我们从SSE/Redis切换到Socket.IO,所以我无法回答您的问题,抱歉!
[...]
res.write('data: ' + msgData + "\n\n");
// Send the message instantly
res.flush();
[...]