multistream

What is multistream?

The 'multistream' npm package allows you to combine multiple streams into a single stream. This can be useful for tasks such as concatenating files, streaming data from multiple sources, or handling multiple input streams in a unified manner.

What are multistream's main functionalities?

Combining Multiple Streams

This feature allows you to combine multiple file streams into a single output stream. In this example, the contents of 'file1.txt', 'file2.txt', and 'file3.txt' are concatenated and written to 'combined.txt'.

const MultiStream = require('multistream');
const fs = require('fs');

const streams = [
  fs.createReadStream('file1.txt'),
  fs.createReadStream('file2.txt'),
  fs.createReadStream('file3.txt')
];

MultiStream(streams).pipe(fs.createWriteStream('combined.txt'));

Dynamic Stream Creation

This feature allows you to dynamically create streams based on a factory function. The factory function is called with an index and a callback, and it should call the callback with a new stream or null to indicate the end. In this example, streams for 'file1.txt', 'file2.txt', and 'file3.txt' are created dynamically and concatenated into 'combined.txt'.

const MultiStream = require('multistream');
const fs = require('fs');

const streamFactory = (i, callback) => {
  if (i > 3) return callback(null, null);
  callback(null, fs.createReadStream(`file${i}.txt`));
};

MultiStream(streamFactory).pipe(fs.createWriteStream('combined.txt'));

Other packages similar to multistream

concat-stream

The 'concat-stream' package is used to concatenate multiple streams into a single buffer or string. Unlike 'multistream', which can handle multiple streams sequentially, 'concat-stream' is more focused on collecting all data into a single output at once. It is useful for scenarios where you need the entire data set available at once rather than streaming it.

stream-combiner

The 'stream-combiner' package allows you to combine multiple streams into a single pipeline. It is similar to 'multistream' in that it can handle multiple streams, but it is more focused on creating a pipeline of streams that process data in sequence. This can be useful for tasks like transforming data through multiple stages.

merge-stream

The 'merge-stream' package allows you to merge multiple streams into a single stream. Unlike 'multistream', which concatenates streams sequentially, 'merge-stream' interleaves the data from multiple streams. This can be useful for scenarios where you need to handle data from multiple sources simultaneously.

README

multistream

A stream that emits multiple other streams one after another (streams3)

Simple, robust streams3 version of combined-stream. Allows you to combine multiple streams into a single stream. When the first stream ends, the next one starts, and so on, until all streams are consumed.

This module is used by WebTorrent, specifically create-torrent.

install

npm install multistream

usage

Use multistream like this:

var MultiStream = require('multistream')
var fs = require('fs')

var streams = [
  fs.createReadStream(__dirname + '/numbers/1.txt'),
  fs.createReadStream(__dirname + '/numbers/2.txt'),
  fs.createReadStream(__dirname + '/numbers/3.txt')
]

new MultiStream(streams).pipe(process.stdout) // => 123

You can also create an object-mode stream with MultiStream.obj(streams).

To lazily create the streams, wrap them in a function:

var streams = [
  fs.createReadStream(__dirname + '/numbers/1.txt'),
  function () { // will be executed when the stream is active
    return fs.createReadStream(__dirname + '/numbers/2.txt')
  },
  function () { // same
    return fs.createReadStream(__dirname + '/numbers/3.txt')
  }
]

new MultiStream(streams).pipe(process.stdout) // => 123

Alternatively, streams may be created by an asynchronous "factory" function:

var count = 0
function factory (cb) {
  if (count > 3) return cb(null, null)
  count++
  setTimeout(function () {
    cb(null, fs.createReadStream(__dirname + '/numbers/' + count + '.txt'))
  }, 100)
}

new MultiStream(factory).pipe(process.stdout) // => 123

contributors

• Feross Aboukhadijeh
• Mathias Buus
• Yuri Astrakhan

license

MIT. Copyright (c) Feross Aboukhadijeh.