（六）分佈式通訊----MessagePack序列化

時間 2019-11-12

標籤分佈式通訊 messagepack 序列欄目系統架構简体版

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1. .Net Core的序列化方式

1.1 json.Net

經常使用的工具包，如Newtonsoft.Json，它是基於json格式的序列化和反序列化的組件html

json.net 有如下優勢：json

侵入性：能夠不添加attribute,就能進行序列化操做設計模式

靈活性：能夠靈活性配置，好比容許被序列化的成員自定義名字，屏蔽的非序列化屬性成員工具

可讀性：數據格式比較簡單, 易於讀寫性能

依賴性：能夠序列化成JObject，無需依賴對象進行序列化和泛型化。單元測試

1.2 protobuf

它是基於二進制格式的序列化和反序列化的組件測試

protobuf 有如下優勢：大數據

　性能高：序列化後體積相比Json和XML很小，適合RPC二進制傳輸
　　跨語言：支持跨平臺多語言
兼容性：消息格式升級和兼容性還不錯
速度快：序列化反序列化速度很快，快於Json的處理速度ui

1.3 messagepack

它是基於二進制格式的序列化和反序列化的組件this

messagepack有如下優勢：

　   性能高：序列化後體積相比Json和XML很小，適合RPC二進制傳輸
　　跨語言：支持跨平臺多語言
        兼容性：消息格式升級和兼容性還不錯
        速度快：序列化反序列化速度很快，快於Json的處理速度

messagepack無論是小數據量仍是大數據量都保持比較穩定的性能，本文中使用messagepack序列化方式。

2. 項目編碼及設計模式

以下是文件結構：

2.1 工廠模式

抽象接口工廠負責建立編碼器和解碼器

1.工廠

    /// <summary>
    /// 一個抽象的傳輸消息編解碼器工廠。
    /// </summary>
    public interface ITransportMessageCodecFactory
    {
        /// <summary>
        /// 獲取編碼器。
        /// </summary>
        /// <returns>編碼器實例。</returns>
        ITransportMessageEncoder GetEncoder();

        /// <summary>
        /// 獲取解碼器。
        /// </summary>
        /// <returns>解碼器實例。</returns>
        ITransportMessageDecoder GetDecoder();
    }

2.編碼器

    /// <summary>
    /// 編碼器
    /// </summary>
    public interface ITransportMessageEncoder
    {
        byte[] Encode(TransportMessage message);
    }

3.解碼器

    /// <summary>
    /// 解碼器
    /// </summary>
    public interface ITransportMessageDecoder
    {
        TransportMessage Decode(byte[] data);
    }

實現類工廠、編碼器、解碼器爲MessagePack的實現

1.工廠

　　 public sealed class MessagePackTransportMessageCodecFactory : ITransportMessageCodecFactory
    {
        #region Field
        private readonly ITransportMessageEncoder _transportMessageEncoder = new MessagePackTransportMessageEncoder();
        private readonly ITransportMessageDecoder _transportMessageDecoder = new MessagePackTransportMessageDecoder();
        #endregion Field

        #region Implementation of ITransportMessageCodecFactory

        /// <inheritdoc />
        /// <summary>
        /// 獲取編碼器 
        /// </summary>
        /// <returns></returns>
        public ITransportMessageEncoder GetEncoder()
        {
            return _transportMessageEncoder;
        }

        /// <inheritdoc />
        /// <summary>
        /// 獲取解碼器 
        /// </summary>
        /// <returns></returns>
        public ITransportMessageDecoder GetDecoder()
        {
            return _transportMessageDecoder;
        }
        #endregion Implementation of ITransportMessageCodecFactory
    }

2.編碼器

    public sealed class MessagePackTransportMessageEncoder : ITransportMessageEncoder
    {
        #region Implementation of ITransportMessageEncoder

        public byte[] Encode(TransportMessage transportMessage)
        {
            MessagePackTransportMessage messagePackTransportMessage = new MessagePackTransportMessage(transportMessage);
            return MessagePackSerializer.Serialize(messagePackTransportMessage);
        }
        
        #endregion Implementation of ITransportMessageEncoder
    }

3.解碼器

    public sealed class MessagePackTransportMessageDecoder : ITransportMessageDecoder
    {
        #region Implementation of ITransportMessageDecoder

        public TransportMessage Decode(byte[] data)
        {
            MessagePackTransportMessage messagePackTransportMessage = MessagePackSerializer.Deserialize<MessagePackTransportMessage>(data);
            return messagePackTransportMessage.GetTransportMessage();
        }

        #endregion Implementation of ITransportMessageDecoder
    }

2.2 裝飾器模式

高層的消息模型：

    public class TransportMessage
    {
        /// <summary>
        /// 消息Id。
        /// </summary>
        public string Id { get; set; }

        /// <summary>
        /// 消息內容。
        /// </summary>
        public object Content { get; set; }

        /// <summary>
        /// 內容類型。
        /// </summary>
        public string ContentType { get; set; }
    }

因爲MessagePack序列化方式具備侵入性，須要添加 MessagePackObjectAttribute 和 KeyAttribute 特性，所以須要對 TransportMessage 作裝飾：

using MessagePack;

    [MessagePackObject]
    public class MessagePackTransportMessage
    {
        private TransportMessage _transportMessage;
        public MessagePackTransportMessage(): this(new TransportMessage())
        {
        }

        public MessagePackTransportMessage(TransportMessage transportMessage)
        {
            this._transportMessage = transportMessage;
        }

        public TransportMessage GetTransportMessage()
        {
            return _transportMessage;
        }
        /// <summary>
        /// 消息Id。
        /// </summary>
        [Key(0)]
        public string Id
        {
            get { return _transportMessage.Id; }
            set { _transportMessage.Id = value; }
        }

        /// <summary>
        /// 消息內容。
        /// </summary>
        [Key(1)]
        public object Content
        {
            get { return _transportMessage.Content; }
            set { _transportMessage.Content = value; }
        }

        /// <summary>
        /// 內容類型。
        /// </summary>
        [Key(2)]
        public string ContentType
        {
            get { return _transportMessage.ContentType; }
            set { _transportMessage.ContentType = value; }
        }
    }

2.3 依賴注入

Autofac 是一個依賴注入工具包，比.net Core 原始的依賴注入擁有更完善的功能，中文官方文檔：https://autofaccn.readthedocs.io/zh/latest/index.html

using Autofac;

    public static class ContainerBuilderExtensions
    {
        /// <summary>
        /// 使用messagepack編碼解碼方式
        /// </summary>
        /// <param name="builder"></param>
        /// <returns></returns>
        public static ContainerBuilder UseMessagePackCodec(this ContainerBuilder builder)
        {
            builder.RegisterType(typeof(MessagePackTransportMessageCodecFactory)).As(typeof(ITransportMessageCodecFactory)).SingleInstance();
            return builder;
        }
    }

2.4 單元測試

端到端的測試，同時測試編碼和解碼

using MessagePack;
using Microsoft.VisualStudio.TestTools.UnitTesting;

    [TestClass]
    public class MessagePackTest
    {
        [TestMethod]
        public void TestCodec()
        {
            Person person = new Person
            {
                Name = "張宏偉",
                Age = 18
            };
            TransportMessage transportMessage = new TransportMessage
            {
                Id = "1",
                ContentType = "Person",
                Content = person
            };
            MessagePackTransportMessageCodecFactory factory = new MessagePackTransportMessageCodecFactory();
            ITransportMessageEncoder encoder = factory.GetEncoder();
            ITransportMessageDecoder decoder = factory.GetDecoder();
            byte[] vs = encoder.Encode(transportMessage);
            TransportMessage message =decoder.Decode(vs);
            Assert.AreEqual(message.Id, "1");
            Assert.AreEqual(message.ContentType, "Person");
            Assert.AreEqual(((object[])message.Content)[0].ToString(), "張宏偉" );
            Assert.AreEqual(((object[])message.Content)[1].ToString(), "18");
        }

        [MessagePackObject]
        public class Person
        {
            [Key(0)]
            public string Name { get; set; }
            [Key(1)]
            public int Age { get; set; }
        }
    }