An HTTP server is a program (service) that:

• listens on an address (host:port),
• accepts incoming HTTP connections/requests,
• runs a handler to process each request,
• writes an HTTP response (status + headers + body).

In Go, the standard library package `net/http` provides everything needed to build an HTTP server.

• Build REST APIs and microservices.
• Serve web pages, JSON, files, webhooks.
• Provide health checks (e.g. `/health`) for monitoring/load balancers.

• Handler: processes requests and writes responses
  • `http.Handler` (interface)
  • `http.HandlerFunc` (function adapter)
• ResponseWriter: writes status code, headers, and body.
• Request: method, URL, headers, body, context.
• ServeMux (router): maps URL paths to handlers
  • `http.DefaultServeMux` is the default global mux.
  • `http.NewServeMux()` creates a dedicated mux.

package main
 
import (
    "log"
    "net/http"
)
 
func main() {
    mux := http.NewServeMux()
 
    mux.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
        w.Write([]byte("hello"))
    })
 
    mux.HandleFunc("/health", func(w http.ResponseWriter, r *http.Request) {
        w.WriteHeader(http.StatusOK)
        w.Write([]byte("ok"))
    })
 
    log.Println("listening on :8080")
    log.Fatal(http.ListenAndServe(":8080", mux))
}

• Default mux pattern (quick demos): use `http.HandleFunc` + `ListenAndServe(…, nil)`
• Custom mux pattern (recommended): `mux := http.NewServeMux()` and pass it to server
• Middleware pattern: wrap handlers (logging, auth, recover, rate limit)

For production, prefer `http.Server{…}` with timeouts and graceful shutdown. Time-outs help protect against slow-client attacks and avoid hanging connections.

• http.Server
• http.ListenAndServe
• http.Client
• Middleware
• httptest

• server /ˈsɝːvər/: máy chủ / dịch vụ phục vụ
• service /ˈsɝːvɪs/: dịch vụ
• listen /ˈlɪsən/: lắng nghe (mở cổng nhận kết nối)
• accept /əkˈsept/: chấp nhận kết nối/nhận vào
• handler /ˈhændlər/: bộ xử lý request
• interface /ˈɪntərfeɪs/: giao diện (hợp đồng)
• adapter /əˈdæptər/: bộ chuyển/đệm để khớp kiểu
• router /ˈruːtər/: bộ định tuyến (map path → handler)
• multiplexer (mux) /ˈmʌltɪˌpleksər/: bộ chọn route theo đường dẫn
• webhook /ˈwebhʊk/: callback qua HTTP
• load balancer /ˈloʊd ˌbælənser/: cân bằng tải
• middleware /ˈmɪdəlwer/: lớp trung gian (bọc handler)
• graceful shutdown /ˈɡreɪsfəl ˈʃʌtdaʊn/: tắt êm
• timeout /ˈtaɪmaʊt/: hết thời gian chờ
• hanging /ˈhæŋɪŋ/: treo/chờ mãi