Golang(6)Web Basic

Golang(6)Web Basic

3.1 How Go Work with Web
URL (Uniform Request Locator)
DNS (Domain Name System)
TCP ——> HTTP (80 port TCP)

Http Request
Http Request —> Request Line,Request Header,Request Body

GET /domains/example/ HTTP/1.1 //Request Line: Request Method
Host: www.iana.org //server host name
User-Agent
Accept //Client mine
Accept-Encoding //
Accept-Charset //Client Charset

Body

Http Response
HTTP/1.1 200 OK //response status Line
Server: nginx/1.0.8 //Web Server software name and version
Date: Tue,30 Oct 2012 04:14:25 GMT //sending time
Content-Type: text/html //Server side data mine
Transfer-Encoding: chunked //
Connection: keep-alive
Content-Length: 90 //length of the body

<!Document html>…. Body

4XX client errors,5XX server side errors,2XX success,3XX redirect,1XX info

Keep-Alive
After HTTP/1.1,Keep-Alive will default be true. We can reuse the TCP connection. This Keep-Alive time can be set on the server side configuration.

3.2 Construct the Web Server based on Go

The Simplest Server based on http package
package main

import (
"fmt"
"log"
"net/http"
"strings"
)

func sayhelloName(w http.ResponseWriter,r *http.Request) {
r.ParseForm() //解析参数，默认是不会解析的
fmt.Println("form: ",r.Form) //这些信息是输出到服务器端的打印信息
fmt.Println("path: ",r.URL.Path)
fmt.Println("scheme: ",r.URL.Scheme)
fmt.Println(r.Form["url_long"])
for k,v := range r.Form {
fmt.Println("key:",k)
fmt.Println("val:",strings.Join(v,""))
}
fmt.Fprintf(w,"Hello astaxie!") //这个写入到w的是输出到客户端的
}

func main() {
http.HandleFunc("/",sayhelloName) //设置访问的路由
err := http.ListenAndServe(":9090",nil) //设置监听的端口
if err != nil {
log.Fatal("ListenAndServe: ",err)
}
}

Visit the http://localhost:9090 to see the result.

3.3 Further Work to Build Web
Some Concepts from Server Side
Request,Response,Connection,Handler

How http Package Works
for {
rw,e := l.Accept()
if e != nil {
}
c,err := srv.newConn(rw)
if err != nil {
continue
}
go c.serve()
}

handler is the second parameter of ListenAndServe,if it is nil,we will use handler = DefaultServeMux

3.4 Details of http Package
There are 2 key functions in http: Conn,ServeMux

Conn and Concurrence
c,err := srv.newConn(rw)
if err != nil {
continue
}
go c.serve()

Customer ServeMux
How the old codes work

type ServeMux struct {
mu sync.RWMutex //lock
m map[string]muxEntry
hosts bool // if put the host in the mapping rules
}

type muxEntry struct {
explicit bool //match exactly
h Handler
pattern string
}

type Handler interface {
ServeHTTP(ResponseWriter,*Request)
}

When we call method HandlerFuc,it will convert the function to contains method ServHTTP

type HandlerFunc func(ResponseWriter,*Request)

func (f HandlerFunc) ServeHTTP(w ResponseWriter,r *Request) {
f(w,r)
}

Map the Rules and then Call the Handler

Customer Mapping
package main

import (
"fmt"
"net/http"
)

type MyMux struct {
}

func (p *MyMux) ServeHTTP(w http.ResponseWriter,r *http.Request) {
if r.URL.Path == "/" {
sayhelloName(w,r)
return
}
http.NotFound(w,r)
return
}

func sayhelloName(w http.ResponseWriter,r *http.Request) {
fmt.Fprintf(w,"Hello myroute!")
}

func main() {
mux := &MyMux{}
http.ListenAndServe(":9090",mux)
}

4. Forms
…snip...

References:
https://github.com/astaxie/build-web-application-with-golang/blob/master/ebook/03.0.md