物联网协议Coap之C#基于Mozi的CoapServer实现解析

原创

夜郎King

发布于 2026-05-23 10:17:39

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文章被收录于专栏：JavaJava

前言

在之前的关于物联网协议的介绍中，我们详细介绍了如何基于Java进行Coap协议的开发，由于一些项目原因，在项目中采用的不是Java的技术栈，而是ASP.NET Core,因此需要基于C#进行Coap协议的开发与实现。Coap本身是与编程语言无关的，不仅可以用Java进行实现，当然也可以使用C#，还可以是Python、GO等多语言，感兴趣的朋友可以自行问度娘，其实每一种语言都有相应的Coap实现。以下是weixin_34026276博主分享的博客，大家可以自己熟悉的编程语言所进行的开源实现，Coap各编程语言实现传送门。非常感谢他的认真整理。

名称	开发语言	CoAP版本	客户端/服务端	实现的CoAP特征	开源协议	项目链接地址
Californium	Java	RFC 7252	Client + Server	Observe, Blockwise Transfers, DTLS	EPL+EDL	Eclipse Californium™
cantcoap	C++/C	RFC 7252	Client + Server		BSD	https://github.com/staropram/cantcoap
CoAP implementation for Go	Go	RFC 7252	Client + Server	Core + Draft Subscribe	MIT	https://github.com/dustin/go-coap
CoAP.NET	C#	RFC 7252, coap-13, coap-08, coap-03	Client + Server	Core, Observe, Blockwise Transfers	3-clause BSD	https://github.com/smeshlink/CoAP.NET
CoAPSharp	C#, .NET	RFC 7252	Client + Server	Core, Observe, Block, RD	LGPL	http://www.coapsharp.com
CoAPthon	Python	RFC 7252	Client + Server + Forward Proxy + Reverse Proxy	Observe, Multicast server discovery, CoRE Link Format parsing, Block-wise	MIT	https://github.com/Tanganelli/CoAPthon
Copper	JavaScript (Browser Plugin)	RFC 7252	Client	Observe, Blockwise Transfers	3-clause BSD	https://github.com/mkovatsc/Copperhttps://addons.mozilla.org/de/firefox/addon/copper-270430/
eCoAP	C	RFC 7252	Client + Server	Core	MIT	josé bollo / ecoap · GitLab
Erbium for Contiki	C	RFC 7252	Client + Server	Observe, Blockwise Transfers	3-clause BSD	Contiki: The Open Source Operating System for the Internet of Things (er-rest-example)
ETRI CoAP	C	RFC 7252	Client + Server	Core, Observe, Block	Commercial	http://coap.or.kr/index_en.html
iCoAP	Objective-C	RFC 7252	Client	Core, Observe, Blockwise Transfers	MIT	https://github.com/stuffrabbit/iCoAP
jCoAP	Java	RFC 7252	Client + Server	Observe, Blockwise Transfers	Apache License 2.0	https://code.google.com/p/jcoap/
libcoap	C	RFC 7252	Client + Server	Observe, Blockwise Transfers	BSD/GPL	libcoap: C-Implementation of CoAP download \| SourceForge.net
microcoap	C	RFC 7252	Client + Server		MIT	https://github.com/1248/microcoap
nCoap	Java	RFC 7252	Client + Server	Observe	BSD	https://github.com/okleine/nCoAP
node-coap	Javascript	RFC 7252	Client + Server	Core, Observe, Block	MIT	https://github.com/mcollina/node-coap
Ruby coap	Ruby	RFC 7252	Client + Server (david)	Core, Observe, Block, RD	MIT, GPL	https://github.com/nning/coap https://github.com/nning/david
Sensinode C Device Library	C	RFC 7252	Client + Server	Core, Observe, Block, RD	Commercial	Downloads - Arm Developer
Sensinode Java Device Library	Java SE	RFC 7252	Client + Server	Core, Observe, Block, RD	Commercial	Downloads - Arm Developer
Sensinode NanoService Platform	Java SE	RFC 7252	Cloud Server	Core, Observe, Block, RD	Commercial	Downloads - Arm Developer
SMCP	C	RFC 7252	Client + Server	Core, Observe, Block	MIT	https://github.com/darconeous/smcp
SwiftCoAP	Swift	RFC 7252	Client + Server	Core, Observe, Blockwise Transfers	MIT	https://github.com/stuffrabbit/SwiftCoAP
TinyOS CoapBlip	nesC/C	coap-13	Client + Server	Observe, Blockwise Transfers	BSD	http://docs.tinyos.net/tinywiki/index.php/CoAP
txThings	Python (Twisted)	RFC 7252	Client + Server	Blockwise Transfers, Observe (partial)	MIT	https://github.com/siskin/txThings/

由于对ASP.NET Core并不是很熟悉，在进行基础入门编程学习之后后，我们基于Mozi开源框架进行扩展扩展实现，这是gitee上mozi项目地址。原本的项目包含的内容比较多，我们可以在它的基础之上进行简化，改造成符合自己需求的项目。本文以CoapServer为主线，介绍CoapServer使用C#语言的定义以及后台资源管理类的定义和实现。

一、C#的Coap Server实现

本节将重点介绍CoapServer在C#中的设计与实现，由于Coap协议在Java的篇章中有所涉及，相信大家对Coap已经不再陌生，因此这里不再对Coap进行赘述。下面依然采用熟悉的OOA即面向对象分析，采用面向对象的方式进行源代码分析。

1、CoapServer相关类

在CoapServer中，在这个工程中，主要涉及的类如下：

序号	类名	说明
1	CoAPServer	CoAP的服务端
2	CoAPResource	类似于Java的中controller
3	ResourceManager	资源管理器，可以理解成IOC容器

2、主要类解析

CoapServer是服务端程序中最重要的类，其中主要定义了后端的服务，以及绑定了Coap协议，用于接收前端来自Client的请求。

从类的继承体系来说，CoapServer是CoAPPeer的子类，有必要对CoAPPeer进行一个全面的说明。

using System;
using System.Collections.Generic;
namespace Mozi.IoT
{
    /// <summary>
    /// CoAP对等端
    /// </summary>
    public class CoAPPeer
    {
        /// <summary>
        /// 最大数据包尺寸 包含所有头信息和有效荷载 Byte
        /// </summary>
        private int _maxTransferPackSize = 512;
        private int _blockSize = 128;
        private ulong _packetSendCount, _totalSendBytes, _packetReceived = 0, _totalReceivedBytes;
        protected UDPSocketIOCP _socket;
        protected int BindPort = CoAPProtocol.Port;
        /// <summary>
        /// 最小分块大小,单位Byte
        /// </summary>
        public const int MinBlockSize = 16;
        /// <summary>
        /// 最大分块大小,单位Byte
        /// </summary>
        public const int MaxBlockSize = 2048;
        /// <summary>
        /// 当前端默认采用块大小,默认值为128bytes,单位Byte
        /// </summary>
        /// <remarks>在通讯两方没有进行协商的情况下，默认采用此值作为分块大小。取值区间为{<see cref="MinBlockSize"/>~<see cref="MaxBlockSize"/>}</remarks>
        public int BlockSize { get { return _blockSize; } set { _blockSize = value; } }
        /// <summary>s
        /// 受支持的请求方法
        /// </summary>
        protected List<CoAPCode> SupportedRequest = new List<CoAPCode> { CoAPRequestMethod.Get, CoAPRequestMethod.Post, CoAPRequestMethod.Put, CoAPRequestMethod.Delete };
        /// <summary>
        /// 数据包接收事件，字节流数据包
        /// </summary>
        public PackageReceive DatagramReceived;
        /// <summary>
        /// 服务端口
        /// </summary>
        public int Port { get { return BindPort; } protected set { BindPort = value; } }
        /// <summary>
        /// 启动时间
        /// </summary>
        public DateTime StartTime { get; private set; }
        /// <summary>
        /// 服务器运行状态
        /// </summary>
        public bool Running
        {
            get; set;
        }
        /// <summary>
        /// 最大数据包尺寸 包含所有头信息和有效荷载
        /// </summary>
        internal int MaxTransferPackSize { get => _maxTransferPackSize; set => _maxTransferPackSize = value; }
        /// <summary>
        /// 累计接收到的包的数量
        /// </summary>
        public ulong PacketReceivedCount { get => _packetReceived; }
        /// <summary>
        /// 累计接收的字节数
        /// </summary>
        public ulong TotalReceivedBytes { get => _totalReceivedBytes; }
        /// <summary>
        /// 累计发出的包的数量
        /// </summary>
        public ulong PacketSendCount => _packetSendCount;
        /// <summary>                                                               
        /// 累计发出的字节数                                                                
        /// </summary>
        public ulong TotalSendBytes => _totalSendBytes; 

        public CoAPPeer()
        {
            _socket = new UDPSocketIOCP();
            _socket.AfterReceiveEnd += Socket_AfterReceiveEnd;
        }
        /// <summary>
        /// 以指定端口启动<see cref="F:Port"/>，如果不配置端口则使用默认端口
        /// </summary>
        public void Start()
        {
            Start(BindPort);
        }
        /// <summary>
        /// 启动本端服务 默认5683端口
        /// </summary>
        /// <param name="port"></param>
        public void Start(int port)
        {
            BindPort = port;
            _socket.Start(BindPort);
            StartTime = DateTime.Now;
            Running = true;
        }
        /// <summary>
        /// 端口下线
        /// </summary>
        public void Shutdown()
        {
            _socket.Shutdown();
            StartTime = DateTime.MinValue;
            Running = false;
        }
        /// <summary>
        /// 数据接收完成回调
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="args"></param>
        /// <remarks>继承类如果覆盖该事件，则可以接管数据处理</remarks>
        protected virtual void Socket_AfterReceiveEnd(object sender, DataTransferArgs args)
        {
            _packetReceived++;
            _totalReceivedBytes += args.Data != null ? (uint)args.Data.Length : 0;
            if (DatagramReceived != null)
            {
                DatagramReceived(args.IP, args.Port, args.Data);
            }
        }
    }
}

从以上的代码中可以发现，上述类也是定义了CoAP协议工作所必须要的一些属性，比如端口、协议、数据包内容等等。CoapServer的属性代码如下：

 private Cache.MessageCacheManager _cm;

/// <summary>
/// 接收到请求
/// </summary>
public MessageTransmit RequestReceived;
/// <summary>
/// 发起响应请求
/// </summary>
public MessageTransmit Responsed;
private bool _proxyPassed = false;
private uint maxBodySize=20*1024*1024;
/// <summary>
/// 服务端能处理的最大POST资源大小 单位byte
/// </summary>
public uint MaxBodySize { get => maxBodySize; set => maxBodySize = value; }
/// <summary>
/// 服务器根目录
/// </summary>
public string Root = AppDomain.CurrentDomain.BaseDirectory;

3、资源控制器定义

每一个后台都会对应一个资源控制器，这里也不例外，我们来看下C#的实现。在CoapResource中同样的定义了get、post、put、delete四种请求方法。如下图所示：

/// <summary>
    /// CoAP资源
    /// </summary>
    public abstract class CoAPResource
    {
        /// <summary>
        /// 资源总大小
        /// </summary>
        public abstract uint ResourceSize { get; }
        /// <summary>
        /// 默认分块大小128，单位Bytes 
        /// </summary>
        /// <remarks>
        /// 如果资源尺寸过大，则必须合理配置此大小。
        /// 取值范围为16-2048Bytes BlockOptionValue中Size的数据容量。参考<see cref="BlockOptionValue"/>
        /// </remarks>
        public virtual uint BlockSize { get { return 128; } }
        /// <summary>
        /// GET方法
        /// </summary>
        /// <param name="ctx"></param>
        /// <returns></returns>
        public virtual CoAPPackage OnGet(CoAPContext ctx)
        {
            ctx.Response = new CoAPPackage { MessageType = CoAPMessageType.Acknowledgement, MesssageId = ctx.Request.MesssageId, Token = ctx.Request.Token, Code = CoAPResponseCode.Forbidden };
            return ctx.Response;
        }
        /// <summary>
        /// Post方法
        /// </summary>
        /// <param name="ctx"></param>
        /// <returns></returns>
        public virtual CoAPPackage OnPost(CoAPContext ctx)
        {
            ctx.Response = new CoAPPackage { MessageType = CoAPMessageType.Acknowledgement, MesssageId = ctx.Request.MesssageId, Token = ctx.Request.Token, Code = CoAPResponseCode.Forbidden };
            return ctx.Response;
        }
        /// <summary>
        /// PUT方法
        /// </summary>
        /// <param name="ctx"></param>
        /// <returns></returns>
        public virtual CoAPPackage OnPut(CoAPContext ctx)
        {
            ctx.Response = new CoAPPackage { MessageType = CoAPMessageType.Acknowledgement, MesssageId = ctx.Request.MesssageId, Token = ctx.Request.Token, Code = CoAPResponseCode.Forbidden };
            return ctx.Response;
        }
        /// <summary>
        /// Delete方法
        /// </summary>
        /// <param name="ctx"></param>
        /// <returns></returns>
        public virtual CoAPPackage OnDelete(CoAPContext ctx)
        {
            ctx.Response = new CoAPPackage { MessageType = CoAPMessageType.Acknowledgement, MesssageId = ctx.Request.MesssageId, Token = ctx.Request.Token, Code = CoAPResponseCode.Forbidden };
            return ctx.Response;
        }
        /// <summary>
        /// 分块查找
        /// </summary>
        /// <param name="indBlock"></param>
        /// <param name="blockSize"></param>
        /// <returns></returns>
        protected virtual byte[] Seek(int indBlock, int blockSize)
        {
            return new byte[] { };
        }
        /// <summary>
        /// Block2分块协商
        /// </summary>
        /// <param name="ctx"></param>
        /// <returns></returns>
        internal virtual void HandleBlock2Query(CoAPContext ctx)
        {
            CoAPOption opt = ctx.Request.Options.Find(x => x.Option == CoAPOptionDefine.Block2);
            if (opt != null)
            {
                OptionValue opt2 = new BlockOptionValue() { Pack = opt.Value.Pack };
                //if(opt2)
            }
        }
        /// <summary>
        /// 请求服务端资源大小，响应条件为 Get Size2=0
        /// </summary>
        /// <param name="ctx">响应上下文对象</param>
        /// <returns></returns>
        internal virtual bool HandleSize2Query(CoAPContext ctx)
        {
            CoAPOption opt = ctx.Request.Options.Find(x => x.Option == CoAPOptionDefine.Size2);
            if (opt != null && int.Parse(opt.Value.ToString()) ==0 && ctx.Request.Code == CoAPRequestMethod.Get)
            {

                ctx.Response = new CoAPPackage { MessageType = CoAPMessageType.Acknowledgement, MesssageId = ctx.Request.MesssageId, Token = ctx.Request.Token, Code = CoAPResponseCode.Content };

                CoAPOption optResp = new CoAPOption() { Option = CoAPOptionDefine.Size2, Value = new UnsignedIntegerOptionValue() { Value = ResourceSize } };
                
                ctx.Response.SetOption(optResp);
                return true;
            }
            else
            {
                return false;
            }
        }
    }

4、ResourceManager管理器

每个业务接收类都对应一个Resource，而这些Resource必须要使用一个统一的容器管理起来，可以把它理解成Java对应的IOC容器，程序运行时会自动把相关资源管理起来。资源描述如下:

 public class ResourceDescriptionAttribute : Attribute
    {
        /// <summary>
        /// 命名空间
        /// </summary>
        public string Namespace { get; set; }
        /// <summary>
        /// 资源名称
        /// </summary>
        public string Name { get; set; }
        /// <summary>
        /// 文字描述
        /// </summary>
        public string Description { get; set; }
        /// <summary>
        /// 资源类型
        /// </summary>
        public string ResourceType { get; set; }
    }

资源管理器的核心管理方式也是采用反射的机制，如下：

二、CoapServer生命周期

在上面的代码中，对CoapServer的编码实现进行了介绍，下面将采用熟悉的调试方法来进行调用跟踪，在关键代码中进行深度讲解。

1、Server创建代码

创建Server的代码如下：

static void Main(string[] args)
        {
            Console.WriteLine("你好!COAP服务端已开启，等待客户端连接......");
            //////服务端
            CoAPServer cs = new CoAPServer();
            cs.RequestReceived += new MessageTransmit((host, port, pack) =>
            {
                Console.WriteLine($"From:[{host}:{port}]");
                Console.WriteLine(pack.ToString());
                Console.Title = string.Format("elapsed:{2},count:{0},pps:{3},bytes:{1}", cs.PacketReceivedCount, cs.TotalReceivedBytes,FormatSeconds(sp.ElapsedMilliseconds),pps);
            });
            cs.Start();
            Console.ReadLine();
        }