流打开时如何保持节点应用程序运行？

Question

I'm wondering what a good solution would be to keep a Node application running until a readable stream has closed. So in a simple example such as this:

var tcpVideoStream = new TcpVideoStream(options);
var writeStream = fs.createWriteStream(options.fileName);
tcpVideoStream.pipe(writeStream);

How can keep my application running so that it continues to write the streaming data to file until the readable stream, tcpVideoStream in this case, closes? ie emits 'end' or 'close'.

Thanks!

Answer 1

Your application will not close until the data has been fully piped. Your application will only close if the readable stream remains is, such as when there is no data event listener, or you haven't called resume() on it (if it is already paused). Using pipe() is like adding a data listener.

For example, this will exit with no output.

var fs = require('fs');

var read = fs.createReadStream('./src');
var write = fs.createWriteStream('./dest');
read.pause();

read.on('data', function(chunk) {
  console.log(chunk);
});

Answer 2

You might want to look at this page. {for WriteStreams}

http://nodejs.org/docs/v0.6.18/api/stream.html#stream_stream_pipe_destination_options

Basically using {end: false} keeps the write stream open so that you can dispatch another end event.