开源技术架构漫谈:基于Go语言快速构建RESTful API服务

摘要

  • What is a JSON API?
  • 启动一个RESTful服务
  • 抽象数据模型
  • 增加路径分发功能
  • 重构:Handlers & Router

In this post, we will not only cover how to use Go to create a RESTful JSON API, but we will also talk about good RESTful design.

部分内容删减调整,原文请查看: Making a RESTful JSON API in Go,2014Nov

Author:CORY LANOU:a full stack technologist who has specialized in start-ups for the last 17 years. I’m currently working at InfluxDB on their core data team. I also help lead and organizer several community technology meetups and do Go training.

一、What is a JSON API?

JSON API 是数据交互规范,用以定义客户端如何获取与修改资源,以及服务器如何响应对应请求。JSON API设计用来最小化请求的数量,以及客户端与服务器间传输的数据量。通过遵循共同的约定,可以提高开发效率,利用更普遍的工具,基于 JSON API 的客户端还能够充分利用缓存,以提升性能。(更多:http://jsonapi.org.cn/format/)。

示例:

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{
"links": {
"posts.author": {
"href": "http://example.com/people/{posts.author}",
"type": "people"
},
"posts.comments": {
"href": "http://example.com/comments/{posts.comments}",
"type": "comments"
}
},
"posts": [{
"id": "1",
"title": "Rails is Omakase",
"links": {
"author": "9",
"comments": [ "5", "12", "17", "20" ]
}
}]
}

启动一个RESTful服务

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$ go run main.go

$ curl http://localhost:8080
Hello,"/"
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package main

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

func main() {
http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
fmt.Fprintf(w, "Hello, %q", html.EscapeString(r.URL.Path))
})

log.Fatal(http.ListenAndServe(":8080", nil))

}

增加路径分发功能

路径又称”终点”(endpoint),表示API的具体网址。在RESTful架构中,每个网址代表一种资源(resource)。
第三方组件(Gorilla Mux package): “github.com/gorilla/mux”

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package main

import (
"fmt"
"log"
"net/http"
"github.com/gorilla/mux"
)

func main() {
router := mux.NewRouter().StrictSlash(true)
router.HandleFunc("/", Index)
router.HandleFunc("/todos", TodoIndex)
router.HandleFunc("/todos/{todoId}", TodoShow)

log.Fatal(http.ListenAndServe(":8080", router))
}

func Index(w http.ResponseWriter, r *http.Request) {
fmt.Fprintln(w, "Welcome!")
}

func TodoIndex(w http.ResponseWriter, r *http.Request) {
fmt.Fprintln(w, "Todo Index!")
}

func TodoShow(w http.ResponseWriter, r *http.Request) {
vars := mux.Vars(r)
todoId := vars["todoId"]
fmt.Fprintln(w, "Todo show:", todoId)
}

访问测试:

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$ curl http://localhost:8080/todo
404 page not found
$ curl http://localhost:8080/todos
Todo Index! ,"/todos"
$ curl http://localhost:8080/todos/{123}
TodoShow: ,"123"

抽象数据模型

创建一个数据模型“Todo”、“Routes”。在其它语言中,使用类(class)实现。
在Go语言中,没有class,必须使用结构(struct)。

Todo.go

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package main

import "time"

type Todo struct {
Id int `json:"id"`
Name string `json:"name"`
Completed bool `json:"completed"`
Due time.Time `json:"due"`
}

type Todos []Todo

Routes.go

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package main

import (
"net/http"
"github.com/gorilla/mux"
)

type Route struct {
Name string
Method string
Pattern string
HandlerFunc http.HandlerFunc
}

type Routes []Route

重构:Handlers & Router

Handlers.go

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package main

import (
"encoding/json"
"fmt"
"net/http"
"github.com/gorilla/mux"
)

func Index(w http.ResponseWriter, r *http.Request) {
fmt.Fprintln(w, "Welcome!")
}

func TodoIndex(w http.ResponseWriter, r *http.Request) {
todos := Todos{
Todo{Name: "Write presentation"},
Todo{Name: "Host meetup"},
}

if err := json.NewEncoder(w).Encode(todos); err != nil {
panic(err)
}
}

func TodoShow(w http.ResponseWriter, r *http.Request) {
vars := mux.Vars(r)
todoId := vars["todoId"]
fmt.Fprintln(w, "Todo show:", todoId)
}

Router.go

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package main

import (
"net/http"
"github.com/gorilla/mux"
)

func NewRouter() *mux.Router {
router := mux.NewRouter().StrictSlash(true)
for _, route := range routes {
var handler http.Handler
handler = route.HandlerFunc
handler = Logger(handler, route.Name)

router.
Methods(route.Method).
Path(route.Pattern).
Name(route.Name).
Handler(handler)

}
return router
}

启动入口是不是清爽很多!

Main.go

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Main.go
package main

import (
"log"
"net/http"
)

func main() {
router := NewRouter()
log.Fatal(http.ListenAndServe(":8080", router))
}

web access:http://localhost:8080/todos

Todo Index! ,”/todos”
[
{
“id”:0,
“name”:”Write sth ….”,
“completed”:false,
“due”:”0001-01-01T00:00:00
},
{
“id”:1,
“name”:”Host meetup ….”,
“completed”:false,
“due”:”0001-01-01T00:00:00Z”
}
]

增强功能:持久化

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func TodoCreate(w http.ResponseWriter, r *http.Request) {
var todo Todo
//add Todo instance
}

增强功能:日志

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2017/05/23 15:57:23 http: multiple response.WriteHeader calls
2017/05/23 15:57:23 GET /todos TodoIndex 6.945807ms
2017/05/23 16:18:40 http: multiple response.WriteHeader calls
2017/05/23 16:18:40 GET /todos TodoIndex 2.127435ms

Things We Didn’t Do

  1. 版本控制
    API版本迭代 & 跨版本资源访问。常用做法是将版本号放在URL,较为简洁,例如:https://localhost:8080/v1/
    另一种做法是将版本号放在HTTP头信息中。

  2. 授权验证:涉及到OAuth和JWT。
    (1)OAuth 2.0,OAuth2 is an authentication framework,RFC 6749
    OAuth2是一种授权框架,提供了一套详细的、可供实践的指导性解决方案。OAuth 2.0定义了四种授权方式。授权码模式(authorization code)、简化模式(implicit)、密码模式(resource owner password credentials)、客户端模式(client credentials)。

(2)JSON web tokens,JWT is an authentication protocol,RFC 7519
JWT是一种安全协议。基本思路就是用户提供用户名和密码给认证服务器,服务器验证用户提交信息信息的合法性;如果验证成功,会产生并返回一个Token(令牌),用户可以使用这个token访问服务器上受保护的资源。

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eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiIxMjM0NTY3ODkwIiwibmFtZSI6IkpvaG4gRG9lIiwiYWRtaW4iOnRydWV9.TJVA95OrM7E2cBab30RMHrHDcEfxjoYZgeFONFh7HgQ

header:定义算法(alg:ALGORITHM)和TOKEN TYPE(typ)

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{
"alg": "HS256",
"typ": "JWT"
}

Data:

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{
"sub": "1234567890",
"name": "John Doe",
"admin": true
}

  1. eTags:关于缓存、性能和用户标识和追踪。

参考文献

  1. 阮一峰:RESTful API 设计指南
  2. CORY LANOU:Making a RESTful JSON API in Go,2014Nov
  3. InfoQ:使用ETags减少Web应用带宽和负载
  4. Stackoverflow:jwt vs oauth authentication
  5. OAuth 2 VS JSON Web Tokens:How to secure an API,20160605
  6. 阮一峰:理解OAuth 2.0,201405
  7. RESTful routing in Go | Karl Seguin

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