Golang实现CoAP协议客户端与服务端通信的插件库Canopus的使用

Canopus是一个实现了RFC7252约束应用协议(CoAP)的客户端/服务器库。

简单示例

服务端代码

// 创建CoAP服务器
server := canopus.NewServer()

// 注册GET请求处理函数
server.Get("/hello", func(req canopus.Request) canopus.Response {
    // 创建确认消息
    msg := canopus.ContentMessage(req.GetMessage().GetMessageId(), canopus.MessageAcknowledgment)
    msg.SetStringPayload("Acknowledged: " + req.GetMessage().GetPayload().String())

    res := canopus.NewResponse(msg, nil)
    return res
})

// 监听5683端口
server.ListenAndServe(":5683")

客户端代码

// 连接到服务器
conn, err := canopus.Dial("localhost:5683")
if err != nil {
    panic(err.Error())
}

// 创建GET请求
req := canopus.NewRequest(canopus.MessageConfirmable, canopus.Get, canopus.GenerateMessageID()).(*canopus.CoapRequest)
req.SetStringPayload("Hello, canopus")
req.SetRequestURI("/hello")

// 发送请求
resp, err := conn.Send(req)
if err != nil {
    panic(err.Error())
}

// 打印响应
fmt.Println("Got Response:" + resp.GetMessage().GetPayload().String())

观察/通知模式示例

服务端代码

server := canopus.NewServer()
server.Get("/watch/this", func(req canopus.Request) canopus.Response {
    msg := canopus.NewMessageOfType(canopus.MessageAcknowledgment, req.GetMessage().GetMessageId(), canopus.NewPlainTextPayload("Acknowledged"))
    res := canopus.NewResponse(msg, nil)
    return res
})

// 每3秒发送一次通知
ticker := time.NewTicker(3 * time.Second)
go func() {
    for {
        select {
        case <-ticker.C:
            changeVal := strconv.Itoa(rand.Int())
            fmt.Println("[SERVER << ] Change of value -->", changeVal)
            server.NotifyChange("/watch/this", changeVal, false)
        }
    }
}()

// 观察请求回调
server.OnObserve(func(resource string, msg canopus.Message) {
    fmt.Println("[SERVER << ] Observe Requested for " + resource)
})

server.ListenAndServe(":5683")

客户端代码

conn, err := canopus.Dial("localhost:5683")

// 观察资源
tok, err := conn.ObserveResource("/watch/this")
if err != nil {
    panic(err.Error())
}

// 创建观察通道
obsChannel := make(chan canopus.ObserveMessage)
done := make(chan bool)
go conn.Observe(obsChannel)

// 处理通知
notifyCount := 0
for {
    select {
    case obsMsg, _ := <-obsChannel:
        if notifyCount == 5 {
            fmt.Println("[CLIENT >> ] Canceling observe after 5 notifications..")
            go conn.CancelObserveResource("watch/this", tok)
            go conn.StopObserve(obsChannel)
            return
        } else {
            notifyCount++
            resource := obsMsg.GetResource()
            val := obsMsg.GetValue()
            fmt.Println("[CLIENT >> ] Got Change Notification for resource and value: ", notifyCount, resource, val)
        }
    }
}

使用PSK的dTLS示例

服务端代码

server := canopus.NewServer()

server.Get("/hello", func(req canopus.Request) canopus.Response {
    msg := canopus.ContentMessage(req.GetMessage().GetMessageId(), canopus.MessageAcknowledgment)
    msg.SetStringPayload("Acknowledged: " + req.GetMessage().GetPayload().String())
    res := canopus.NewResponse(msg, nil)
    return res
})

// 设置PSK处理函数
server.HandlePSK(func(id string) []byte {
    return []byte("secretPSK")
})

// 监听DTLS端口
server.ListenAndServeDTLS(":5684")

客户端代码

// 使用DTLS连接
conn, err := canopus.DialDTLS("localhost:5684", "canopus", "secretPSK")
if err != nil {
    panic(err.Error())
}

req := canopus.NewRequest(canopus.MessageConfirmable, canopus.Get, canopus.GenerateMessageID())
req.SetStringPayload("Hello, canopus")
req.SetRequestURI("/hello")

resp, err := conn.Send(req)
if err != nil {
    panic(err.Error())
}

fmt.Println("Got Response:" + resp.GetMessage().GetPayload().String())

CoAP-CoAP代理示例

后端服务端代码

server := canopus.NewServer()

server.Get("/proxycall", func(req canopus.Request) canopus.Response {
    msg := canopus.ContentMessage(req.GetMessage().GetMessageId(), canopus.MessageAcknowledgment)
    msg.SetStringPayload("Data from :5685 -- " + req.GetMessage().GetPayload().String())
    res := canopus.NewResponse(msg, nil)
    return res
})
server.ListenAndServe(":5685")

代理服务端代码

server := canopus.NewServer()
// 启用CoAP代理
server.ProxyOverCoap(true)

server.Get("/proxycall", func(req canopus.Request) canopus.Response {
    canopus.PrintMessage(req.GetMessage())
    msg := canopus.ContentMessage(req.GetMessage().GetMessageId(), canopus.MessageAcknowledgment)
    msg.SetStringPayload("Acknowledged: " + req.GetMessage().GetPayload().String())
    res := canopus.NewResponse(msg, nil)
    return res
})
server.ListenAndServe(":5683")

客户端代码

conn, err := canopus.Dial("localhost:5683")
if err != nil {
    panic(err.Error())
}

req := canopus.NewRequest(canopus.MessageConfirmable, canopus.Get, canopus.GenerateMessageID())
// 设置代理URI
req.SetProxyURI("coap://localhost:5685/proxycall")

resp, err := conn.Send(req)
if err != nil {
    println("err", err)
}
canopus.PrintMessage(resp.GetMessage())

CoAP-HTTP代理示例

代理服务端代码

server := canopus.NewServer()
// 启用HTTP代理
server.ProxyOverHttp(true)

server.ListenAndServe(":5683")

客户端代码

conn, err := canopus.Dial("localhost:5683")
if err != nil {
    panic(err.Error())
}

req := canopus.NewRequest(canopus.MessageConfirmable, canopus.Get, canopus.GenerateMessageID())
// 设置HTTP代理URI
req.SetProxyURI("https://httpbin.org/get")

resp, err := conn.Send(req)
if err != nil {
    println("err", err)
}
canopus.PrintMessage(resp.GetMessage())