如何创建Node.js流服务器

Question

I am trying to create a server that sends out a stream of events. I have created a Readable stream that I am trying to push to in response to key presses, so that I can control the stream of events to go out to the client.

var Readable = require('stream').Readable
var rs = new Readable()

var server = http.createServer(function(req, res) {
    rs.pipe(res)
})
server.listen(8888)

keypress(process.stdin)
process.stdin.on('keypress', function (ch, key) {
    if( key && key.name === 'up' ) {
        rs.push('up key')
    }
}

When I press the up key, I get this:

events.js:85
      throw er; // Unhandled 'error' event
            ^ Error: not implemented
    at Readable._read (_stream_readable.js:464:22)
    at Readable.read (_stream_readable.js:341:10)
    at maybeReadMore_ (_stream_readable.js:449:12)
    at _stream_readable.js:439:7
    at process._tickCallback (node.js:355:11)

I don't even know what events.js is. It is not my code.

What I would hope to happen is that the string up key would be emitted out the server stream. What am I doing wrong?

Answer 1

It turns out that what I really wanted was a chunked response, which does not pre-declare the Content-Length of the response. This allows the node server to keep the connection open, writing to it periodically.

var streamResponse

var server = http.createServer(function(req, response) {
    response.setHeader('Content-Type', 'text/html; charset=UTF-8');
    response.setHeader('Transfer-Encoding', 'chunked');
    streamResponse = response
})

server.listen(44445)


setTimeout(function(){
    streamResponse.write('this is a chunk');
}, 5000)

I believe that Node uses chunked transfer by default, but the key piece is calling response.write() rather than response.send(). You can call response.end() when there is nothing more to send.

Note: I may have some confusion in here between what is Node vs what is Express. If you run into any problems, that may be a place to start.