Michał Michalczuk
I am fullstack software developer #dotnet #angular #typescript, IT trainer. Both fascinated and terrified by technology advancement.
streams 101
Michał Michalczuk
- Single threaded
-
Avoid computation
- Delegate to I/O
- Write as async as possible
How does streams
fit in?
What are streams?
Is it new idea?
And what is the problem?
Michał
Michalczuk
@michalczukm
Senior Software Engineer
Spartez / Atlassian
IT trainer
infoShare Academy
The problem
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}/`);
});http.IncommingMessage Readible Stream
http.ServerResponse Writable Stream
streams you know
process.stdin
process.stdoutReadible Stream
Writable Stream
fs.createReadStream(...)
fs.createWriteStream(...)Readible Stream
Writable Stream
ls | wcOutput
Input
Pipe
ls | wcprocess.stdin.pipe(process.stdout);
Readable stream
Writable stream
.pipe( );
process.stdin.pipe(wc);
Examples
Writable
Transform
const { Writable } = require('stream');
const outStream = new Writable({
write(chunk, encoding, callback) {
console.log(chunk.toString().toUpperCase());
callback();
}
});
process.stdin.pipe(outStream);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
Writable
Dup lex
Trans form
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);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?
Real-life examples
Short summary
Links
Questions time
Feedback?
Yes please
Michał Michalczuk
michalczukm.xyz
Thank you!
Node.js streams 101
By Michał Michalczuk
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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