我有一个Koa Node 服务器,我正在尝试从中发送服务器发送的事件。但是,我只看到EventSource.onerror
事件到达时调用的回调。
这是我的 SSE 实现:
import * as Koa from 'koa';
import { PassThrough } from 'stream';
import { KoaServerSentEvent } from './koaServerSentEvent';
export class KoaServerSentStream {
private readonly eventStream: PassThrough;
private readonly retryInterval: number;
private eventCount: number;
readonly request: Koa.Request;
readonly response: Koa.Response;
constructor( req: Koa.Request, resp: Koa.Response ) {
this.retryInterval = 10000;
this.eventCount = 0;
this.eventStream = new PassThrough();
this.request = req;
this.response = resp;
this.configureLifecycle();
}
static buildStreamContext( ctx: Koa.Context ): KoaServerSentStream {
const stream: KoaServerSentStream = new KoaServerSentStream( ctx.request, ctx.response );
// order matters here: https://github.com/koajs/koa/issues/1120
ctx.body = stream;
ctx.type = 'text/event-stream';
///////////////////////////////////////////////////////////////
return stream;
}
private configureLifecycle(): void {
this.request.req.on( 'close', this.response.res.end );
this.request.req.on( 'finish', this.response.res.end );
this.request.req.on( 'error', this.response.res.end );
this.eventStream.write( `retry: ${this.retryInterval}` );
}
queueEvent( event: KoaServerSentEvent ): void {
const formattedData: string = ( typeof event.data === 'string' ) ? event.data : JSON.stringify( event.data );
const payload: string = `id: ${this.eventCount}\nevent: ${event.name}\ndata: ${formattedData}`;
this.eventStream.write( payload );
this.eventCount++;
}
publish(): void {
this.eventStream.write( '\n\n' );
}
}
POC 路由处理程序:
export async function handler( ctx: Koa.Context ): Promise<void> {
const stream: KoaServerSentStream = KoaServerSentStream.buildStreamContext( ctx );
setInterval( () => {
stream.queueEvent( {
name: 'greetings',
data: {
french: 'bonjour tout le monde',
english: 'hello world',
german: 'hallo welt',
spanish: 'hola mundo'
}
} );
stream.publish();
}, 2000 );
}
当我尝试在浏览器中使用这些事件时:
const events = new EventSource( 'http://localhost:3000/v1/helloWorld' );
events.onmessage = ( e ) => {
console.log( 'We received an event!', e );
};
events.onerror = ( error ) => {
console.error( 'An error occurred:', error );
console.info( 'ReadyState', events.readyState.valueOf() );
// events.close();
};
events.onopen = ( opened ) => {
console.info( 'Opened:', opened );
console.info( 'ReadyState', events.readyState.valueOf() );
};
这个的输出是
打开:事件{isTrusted:true,类型:“open”,目标:EventSource,currentTarget:EventSource,eventPhase:2,...}
就绪状态 1
发生错误:事件 {isTrusted: true, type: "error", target: EventSource, currentTarget: EventSource, eventPhase: 2, ...}
就绪状态 0
打开:事件{isTrusted:true,类型:“open”,目标:EventSource,currentTarget:EventSource,eventPhase:2,...}
就绪状态 1
发生错误:事件 {isTrusted: true, type: "error", target: EventSource, currentTarget: EventSource, eventPhase: 2, ...}
就绪状态 0
...