(#1554) Add support for all common compressions (write and read)

- Remove the context.Context interface and export the *context, the iris.Context now points to the pointer\nSupport compression and rate limiting in the FileServer\nBit of code organisation


Former-commit-id: ad1c61bf968059510c6be9e7f2cceec7da70ba17

_examples/compression/client-using-iris/main.go

@@ -0,0 +1,112 @@
+package main
+
+import (
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"io/ioutil"
+	"net/http"
+
+	"github.com/kataras/iris/v12/context"
+)
+
+const baseURL = "http://localhost:8080"
+
+// Available options:
+// - "gzip",
+// - "deflate",
+// - "br" (for brotli),
+// - "snappy" and
+// - "s2"
+const encoding = context.BROTLI
+
+var client = http.DefaultClient
+
+func main() {
+	fmt.Printf("Running client example on: %s\n", baseURL)
+
+	getExample()
+	postExample()
+}
+
+func getExample() {
+	endpoint := baseURL + "/"
+	req, err := http.NewRequest(http.MethodGet, endpoint, nil)
+	if err != nil {
+		panic(err)
+	}
+	// Required to receive server's compressed data.
+	req.Header.Set("Accept-Encoding", encoding)
+
+	resp, err := client.Do(req)
+	if err != nil {
+		panic(err)
+	}
+	defer resp.Body.Close()
+
+	// decompress server's compressed reply.
+	cr, err := context.NewCompressReader(resp.Body, encoding)
+	if err != nil {
+		panic(err)
+	}
+	defer cr.Close()
+
+	body, err := ioutil.ReadAll(cr)
+	if err != nil {
+		panic(err)
+	}
+
+	fmt.Printf("Received from server: %s", string(body))
+}
+
+type payload struct {
+	Username string `json:"username"`
+}
+
+func postExample() {
+	buf := new(bytes.Buffer)
+
+	// Compress client's data.
+	cw, err := context.NewCompressWriter(buf, encoding, -1)
+	if err != nil {
+		panic(err)
+	}
+
+	json.NewEncoder(cw).Encode(payload{Username: "Edward"})
+
+	// `Close` or `Flush` required before `NewRequest` call.
+	cw.Close()
+
+	endpoint := baseURL + "/"
+
+	req, err := http.NewRequest(http.MethodPost, endpoint, buf)
+	if err != nil {
+		panic(err)
+	}
+	req.Header.Set("Content-Type", "application/json")
+
+	// Required to send gzip compressed data to the server.
+	req.Header.Set("Content-Encoding", encoding)
+	// Required to receive server's compressed data.
+	req.Header.Set("Accept-Encoding", encoding)
+
+	resp, err := client.Do(req)
+	if err != nil {
+		panic(err)
+	}
+	defer resp.Body.Close()
+
+	// Decompress server's compressed reply.
+	cr, err := context.NewCompressReader(resp.Body, encoding)
+	if err != nil {
+		panic(err)
+	}
+	defer cr.Close() // Closes the request body too.
+
+	body, err := ioutil.ReadAll(cr)
+	if err != nil {
+		panic(err)
+	}
+
+	fmt.Printf("Server replied with: %s", string(body))
+}