节点流：管道对流的引用不会更新原始流

Question

更新以更好地解释问题：我正在尝试构建一个简单的代理服务器模块，该模块将允许实施者监听和修改来自源服务器的响应。当代理收到响应时，我发出一条customResponse消息，其中包含对响应流的引用。任何收听该事件的人都应该能够管理响应并实现自定义业务逻辑。该模块应该将＆＃34; final＆＃34; 管道返回给客户端 - 否则它不会成为代理（请参阅下面的示例代码）。

1. 安装

   npm install eventemitter3 && npm install event-stream && touch index.js
   

2. index.js

   var http = require("http");
   var EE3 = require('eventemitter3');
   var es = require("event-stream");
   
   var dispatcher = new EE3();
   dispatcher.on("customResponse", function (response) {
       // Implementers would implement duplex or transform streams here
       // and modify the stream data.
       response.pipe(es.mapSync(function (data) {
           return data.toString().replace("sometext", "othertext");
       }));
   });
   
   http.createServer(function (req, res) {
       // BEGIN MODULE CODE - THIS WILL HAVE AN API AND WILL RETURN
       // THE EVENT EMITTER FOR IMPLEMENTERS TO LISTEN TO
       http.request({
           host: "localhost",
           port: 9000,
           path: "/path/to/a/file.txt"
       }, function (response) {
           // Dispatch the event, allow consumers to pipe onto response
           dispatcher.emit("customResponse", response);
   
           // Here's where the problem is - the "response" stream
           // may have been piped onto, but we don't have a reference
           // to that new stream. If the data was modified by a consumer,
           // we don't see that new data here.
           response.pipe(res);
       }).end();
       // END MODULE CODE
   }).listen(7000);