streams 101

Michał Michalczuk

michalczukm.xyz

repository with examples

Michał Michalczuk

Senior JavaScript Developer

Ciklum / Stibo Systems

 

 

IT trainer

infoShare Academy

michalczukm.xyz

                streams 101

Michał Michalczuk

michalczukm.xyz

  • Single threaded
  • Avoid computation
     
  • Delegate to I/O
  • Write as async as possible

https://strongloop.com/strongblog/node-js-is-faster-than-java/

How does streams

fit in?

What are streams?

Is it new idea?

And what is the problem?

The problem

github.com/michalczukm/nodejs-streams-101/tree/master/1_big-files

Streams, streams everywhere

streams you know

const http = require('http');

const hostname = '127.0.0.1';
const port = 3000;

const server = http.createServer((req, res) => {
  res.statusCode = 200;
  res.setHeader('Content-Type', 'text/plain');
  res.end('Hello World\n');
});

server.listen(port, hostname, () => {
  console.log(`Server running at http://${hostname}:${port}/`);
});

streams you know

const http = require('http');

const hostname = '127.0.0.1';
const port = 3000;

const server = http.createServer((req, res) => {
  res.statusCode = 200;
  res.setHeader('Content-Type', 'text/plain');
  res.end('Hello World\n');
});

server.listen(port, hostname, () => {
  console.log(`Server running at http://${hostname}:${port}/`);
});
http.IncommingMessage
Readible Stream
http.ServerResponse
Writable Stream

streams you know

process.stdin



process.stdout
Readible Stream
Writable Stream
fs.createReadStream(...)



fs.createWriteStream(...)
Readible Stream
Writable Stream

Text

ls | wc

Output

Input

Pipe

ls | wc
process.stdin.pipe(process.stdout);

 

process.stdin.pipe(wc).pipe(process.stdout);

Readable stream

Writable stream

          .pipe(        );

https://medium.freecodecamp.org/node-js-streams-everything-you-need-to-know-c9141306be93

Streams types

Readable

Writable

Dup lex

Trans form

Streams types

Writable
Transform
const { Writable } = require('stream');
const outStream = new Writable({
  write(chunk, encoding, callback) {
    console.log(chunk.toString().toUpperCase());
    callback();
  }
});

process.stdin.pipe(outStream);

Streams types

Writable
Transform
const { Writable } = require('stream');
const outStream = new Writable({
  write(chunk, encoding, callback) {
    console.log(chunk.toString().toUpperCase());
    callback();
  }
});

process.stdin.pipe(outStream);

Streams types

Readable
Transform
const { Readable } = require('stream'); 
const inStream = new Readable();
inStream.push('first chunk\n');
inStream.push('second chunk\n');
inStream.push(null);

setTimeout(() => {
    inStream.pipe(process.stdout);
}, 2000);

Streams types

Readable
Transform
const { Readable } = require('stream'); 
const inStream = new Readable();
inStream.push('first chunk\n');
inStream.push('second chunk\n');
inStream.push(null);

setTimeout(() => {
    inStream.pipe(process.stdout);
}, 2000);

Streams types

Duplex
Transform
const { Duplex } = require('stream');

const inoutStream = new Duplex({
  write(chunk, encoding, callback) {
    console.log(chunk.toString().toUpperCase());
    callback();
  },

  read(size) {
  }
});

inoutStream.push('first chunk\n');
inoutStream.push('second chunk\n');
inoutStream.push(null);

process.stdin.pipe(inoutStream).pipe(process.stdout);

Streams types

Duplex
Transform
const { Duplex } = require('stream');

const inoutStream = new Duplex({
  write(chunk, encoding, callback) {
    console.log(chunk.toString().toUpperCase());
    callback();
  },

  read(size) {
  }
});

inoutStream.push('first chunk\n');
inoutStream.push('second chunk\n');
inoutStream.push(null);

process.stdin.pipe(inoutStream).pipe(process.stdout);

Streams types

Transform
Transform
const { Transform } = require('stream');

const upperCaseTr = new Transform({
  transform(chunk, encoding, callback) {
    this.push(chunk.toString().toUpperCase());
    callback();
  }
});

process.stdin.pipe(upperCaseTr).pipe(process.stdout);

Streams types

Transform
Transform
const { Transform } = require('stream');

const upperCaseTr = new Transform({
  transform(chunk, encoding, callback) {
    this.push(chunk.toString().toUpperCase());
    callback();
  }
});

process.stdin.pipe(upperCaseTr).pipe(process.stdout);

 

 

 

 

where to use streams?

More real-life examples

github.com/michalczukm/nodejs-streams-101

Short summary

http://highlandjs.org/

Questions time

Feedback?

Yes please

Michał Michalczuk

michalczukm.xyz

Thank you!

michalczukm

github.com/michalczukm/nodejs-streams-101

Node.js streams 101

By Michał Michalczuk

Create a presentation like this

Node.js streams 101

No matter what you are doing as front-end developer Node.js is everywhere and you won’t escape from it. On my presentation I will focus on steams - one of the basic, and often not understand, element of this environment. How they work and what benefit you will get by using them as intended.

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