streams

streams

Examples of reading and writing streams

Node.js

const { Readable, Writable } = require('stream')

const inStream = new Readable()

inStream.push(Buffer.from('foo'))
inStream.push(Buffer.from('bar'))
inStream.push(null) // end stream
inStream.pipe(process.stdout)

const outStream = new Writable({
  write(chunk, encoding, callback) {
    console.log('received: ' + chunk.toString('utf8'))
    callback()
  }
})

outStream.write(Buffer.from('abc'))
outStream.write(Buffer.from('xyz'))
outStream.end()

Output

foobar
received: abc
received: xyz

Go

package main

import (
    "bufio"
    "bytes"
    "fmt"
    "io"
    "os"
    "runtime"
)

func main() {
    inStream := new(bytes.Buffer)
    w := bufio.NewWriter(inStream)
    _, err := w.Write([]byte("foo"))
    if err != nil {
        panic(err)
    }
    _, err = w.Write([]byte("bar"))
    if err != nil {
        panic(err)
    }
    err = w.Flush()
    if err != nil {
        panic(err)
    }

    inStream.WriteTo(os.Stdout)
    fmt.Print("\n")

    outStream := new(bytes.Buffer)
    outStream.Write([]byte("abc\n"))
    outStream.Write([]byte("xyc\n"))
    piper, pipew := io.Pipe()

    go func() {
        sc := bufio.NewScanner(piper)
        for sc.Scan() {
            fmt.Println("received: " + sc.Text())
        }
        if err := sc.Err(); err != nil {
            panic(err)
        }

        os.Exit(0)
    }()

    go func() {
        defer pipew.Close()
        io.Copy(pipew, outStream)
    }()

    defer runtime.Goexit()
}

Output

foobar
received: abc
received: xyc