gistfile1.go

package main

import (
	"bufio"
	"compress/gzip"
	"fmt"
	"io"
	"io/ioutil"
	"log"
	"net/http"
	"os"
)

func gzipHandler(rw http.ResponseWriter, r *http.Request) {
	log.Printf("Recv'd request")
	defer r.Body.Close()
	gr, err := gzip.NewReader(r.Body)
	if err != nil {
		log.Fatal(err)
	}
	defer gr.Close()
	plaintext, err := ioutil.ReadAll(gr)
	if err != nil {
		log.Fatal(err)
	} else {
		log.Printf("Sample: %s", string(plaintext[0:100]))
	}

	rw.Write([]byte(fmt.Sprintf("Recv'd %d plaintext bytes", len(plaintext))))
}

func main() {
	http.HandleFunc("/foo", gzipHandler)
	go http.ListenAndServe(":8080", nil)

	in, err := os.Open("/usr/share/dict/words")
	if err != nil {
		log.Fatal(err)
	}
	// gzip writes to pipe, http reads from pipe
	pr, pw := io.Pipe()

	// buffer readers from file, writes to pipe
	bufin := bufio.NewReader(in)

	// gzip wraps buffer writer
	gw := gzip.NewWriter(pw)

	// Actually start reading from the file and writing to gzip
	go func() {
		log.Printf("Start writing")
		n, err := bufin.WriteTo(gw)
		if err != nil {
			log.Fatal(err)
		}
		gw.Close()
		pw.Close()
		log.Printf("Done writing: %d", n)
	}()

	req, err := http.NewRequest("POST", "http://localhost:8080/foo", pr)
	if err != nil {
		log.Fatal(err)
	}
	log.Printf("Making request")
	resp, err := http.DefaultClient.Do(req)
	if err != nil {
		log.Fatal(err)
	}
	defer resp.Body.Close()
	respBody, err := ioutil.ReadAll(resp.Body)
	if err != nil {
		log.Fatal(err)
	}

	log.Printf("Done! Received: \n%s", string(respBody))
}

explanation:

• line 61 initiates req to webserver, where POSTed data will be read from pr, the read end of the io.Pipe
• pr is a pipe connected to pw, set to read what is written to pw
• line 50: goroutine starts reading from dict plain text file and will write to gw, the gzip writer connected to pw (producing a gzip bytestream to pr to POST to /foo)
• on line 61, when the req is made, /foo will handle the req and call a readAll on its r reader arg, which is pr
• this triggers pw to write the contents of gw to pr
• in a sense this is a streaming interface