最简单的Node.js回显服务器 [英] Simplest nodejs echo server

问题描述

我熟悉nodejs中的流，并且有一个问题:

I am getting acquainted with streams in nodejs and I have a question:

我有可能是最简单的nodejs回显服务器"，即简单地通过管道将其返回到响应流的服务器，无论它通过请求流接收到什么. 它有效，但有一个警告.客户端仅在关闭提交流后才收到数据. 这是服务器代码:

I have what I think is the simplest possible nodejs "echo server" ie a server that simple pipes back to the response stream whatever it receives via the request stream. It works but with a caveat. The client only receives the data back after it closes the submitting stream. Here is the server code:

var http = require('http')
var server = http.createServer(function (req, res) {
  req.pipe(res);
});
server.listen(8000);

这是我的测试方式:

执行以下操作就可以了

term1> node server.js&

term2> echo 'hello world!'|curl --no-buffer --data-binary  @-  'http://localhost:8000'
hello world!

但是，它只能工作是因为echo在完成后会关闭其输出文件描述符，即，服务器在客户端发送完内容之前不会写任何东西:

However, it only works because echo closes its output file descriptor after being done, ie., the server will not write anything until after its client is done sending stuff:

term2>
term2> yes|curl --no-buffer --data-binary  @-  'http://localhost:8000'

(这条线永远卡住了)

我希望yes会很快填充流缓冲区，所以我会开始看到y很快恢复.不幸的是，他们从来没有这样做.

I would expect that yes will fill stream buffers pretty fast so I would start seeing y's coming back pretty fast. Unfortunately they never do.

这是预期的吗?我应该如何使用溪流/管道以达到预期的效果? 顺便说一下，我不在乎输出是否会成块返回……我知道那是流(或基础文件I/O)执行缓冲的结果.

Is this expected? How should I use the streams/pipes so as they have the desired effect? By the way I don't care whether the output would come back in chunks... I understand that that would be results of streams (or the underlying file i/o) doing their buffering magic.

谢谢您的帮助

推荐答案

好， 我想我知道我在做什么错. server.js正常工作...是curl中断了流水线. 显然，@-选项将stdin视为文件，即读取其完整内容然后提交.在读取内容时，我找不到如何使curl管道传输内容的方法.我认为这是不可行的，因为curl希望将文件的内容视为普通的HTTP帖子形式值.

Ok, I think I figured out what I was doing wrong. The server.js was working fine... it was curl that was breaking the pipeline. Apparently, the @- option treats stdin like a file ,ie reads its full content and then submits it. I couldn't find how to make curl pipe the contents as they are being read. I think its not feasible because curl wants to treat the contents of the file as a normal HTTP post form value..

无论如何，我使用一个简单的nodejs客户端修改了上面的示例，该客户端正在执行我想要的操作:

Anyway, I modified the example above using a simple nodejs client that was doing what I wanted:

term2> cat client.js
var http = require('http');
var req = http.request('http://localhost:8000', function(res) {
  res.pipe(process.stdout);
});
process.stdin.pipe(req);

term2> yes|node client.js
y
y
...

nodejs流和管道都是岩石！

nodejs streams and pipes rock!!

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