A simple web service in Go

main.go

// usage: curl -H "Content-Type: application/json" -d '{"N1":3.1, "N2":5.7}' http://localhost:8080

package main

import (
	"net/http"
	"encoding/json"

	"github.com/gorilla/mux"
	"log"
	"fmt"
)

type Result struct {
	Sum float64 `json:"sum"`
	Sub float64 `json:"sub"`
	Mul float64 `json:"mul"`
	Div float64 `json:"div"`
}

type Operation struct {
	N1 float64
	N2 float64
}

func main() {
	router := mux.NewRouter().StrictSlash(true)
	router.HandleFunc("/", Index)
	log.Fatal(http.ListenAndServe(":8080", router))
}

func Index(w http.ResponseWriter, r *http.Request) {
	decoder := json.NewDecoder(r.Body)

	var op Operation

	err := decoder.Decode(&op)

	if err != nil {
		w.WriteHeader(http.StatusBadRequest)
	} else {
		jsonResult := Result{
			Sum:op.N1 + op.N2,
			Sub:op.N1 - op.N2,
			Mul:op.N1 * op.N2,
			Div:op.N1 / op.N2,
		}

		err = json.NewEncoder(w).Encode(jsonResult)
		if (err != nil) {
			w.WriteHeader(http.StatusInternalServerError)
			fmt.Fprint(w, err.Error())
		} else {
			w.Header().Set("Content-Type", "application/json; charset=UTF-8")
			w.WriteHeader(http.StatusOK)
		}
	}
}