C# Winform cilent call SignalR

一、SignalR是什么

Asp.net SignalR是微软为实现实时通信的一个类库。一般情况下，SignalR会使用JavaScript的长轮询(long polling)的方式来实现客户端和服务器通信，随着Html5中WebSockets出现，SignalR也支持WebSockets通信。另外SignalR开发的程序不仅仅限制于宿主在IIS中，也可以宿主在任何应用程序，包括控制台，客户端程序和Windows服务等，另外还支持Mono，这意味着它可以实现跨平台部署在Linux环境下。

SignalR内部有两类对象：

Http持久连接(Persisten Connection)对象：用来解决长时间连接的功能。还可以由客户端主动向服务器要求数据，而服务器端不需要实现太多细节，只需要处理PersistentConnection 内所提供的五个事件：OnConnected, OnReconnected, OnReceived, OnError 和 OnDisconnect 即可。

Hub（集线器）对象：用来解决实时(realtime)信息交换的功能，服务端可以利用URL来注册一个或多个Hub，只要连接到这个Hub，就能与所有的客户端共享发送到服务器上的信息，同时服务端可以调用客户端的脚本。

SignalR将整个信息的交换封装起来，客户端和服务器都是使用JSON来沟通的，在服务端声明的所有Hub信息，都会生成JavaScript输出到客户端，.NET则依赖Proxy来生成代理对象，而Proxy的内部则是将JSON转换成对象。

二、为什么要用SignalR

聊天室，如在线客服系统，IM系统等

消息的实时推送服务

巡更人员位置的实时推送

1. server -------- 创建一个MVC 项目,选择新建的项目，右击-->选择管理NuGet程序包-->搜索 signalr--> 安装Microsoft ASP.NET SignalR

新建启动程序 Startup.cs

在类中添加代码：

app.MapSignalR();

在集线器类ChatHub.cs中添加如下代码

using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
using System.Web;
using Microsoft.AspNet.SignalR;
using System.Threading.Tasks;
namespace ChatServer
{
    public class ChatHub : Hub
    {
        public void Hello()
        {
            //Clients.All.hello();
            //Clients.All.AddMsg();
        }


        /// <summary>
        /// 供客户端调用的服务器端代码
        /// </summary>
        /// <param name="message"></param>
        public void Send(string name,string message)
        {
            // 调用所有客户端的sendMessage方法
            Clients.All.sendMessage(name, message);
            Trace.WriteLine("调用所有客户端的sendMessage方法");

        }

        /// <summary>
        /// 客户端连接的时候调用
        /// </summary>
        /// <returns></returns>
        public override Task OnConnected()
        {
            Trace.WriteLine("客户端连接成功");
            return base.OnConnected();
        }

    }
}

2. 客户端（winform）

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Net.Http;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using Microsoft.AspNet.SignalR.Client;
namespace ChatClient
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
            Text = "Test SignalR";
            FormClosing += Form1_FormClosing;
        }

  
        public IHubProxy HubProxy { get; set; }
        const string ServerURI = "https://localhost:44306/";//ServerURI = "https://localhost:44306/signalr";
        public HubConnection Connection { get; set; }



        /// <summary>
        /// Creates and connects the hub connection and hub proxy. This method
        /// is called asynchronously 
        /// </summary>
        private async void ConnectAsync()
        {
            Connection = new HubConnection(ServerURI);
            Connection.Closed += ShowConnectionClosed;
            HubProxy = Connection.CreateHubProxy("ChatHub");
            //Handle incoming event from server: use Invoke to write to console from SignalR's thread
            HubProxy.On<string, string>("sendMessage", (name, message) =>

                   {
                       this.Invoke(
                           new Action(() =>
                           {
                               RichTextBoxConsole.AppendText(String.Format("{0}: {1}
", name, message));
                           }
                           ));
                   }
            );

            try
            {
                await Connection.Start();
            }
            catch (HttpRequestException)
            {
                Text = "Unable to connect to server: Start server before connecting clients.";
                //No connection: Don't enable Send button or show chat UI
                return;
            }

            TextBoxMessage.Focus();
            RichTextBoxConsole.AppendText("Connected to server at " + ServerURI + "
");
        }
        private void CloseConnection()
        {
            if (Connection != null)
            {
                Connection.Stop();
                Connection.Dispose();
            }
        }

        /// <summary>
        /// If the server is stopped, the connection will time out after 30 seconds (default), and the 
        /// Closed event will fire.
        /// </summary>
        private void ShowConnectionClosed()
        {
            RichTextBoxConsole.AppendText("You have been disconnected.
");
        }

        private void btnConnect_Click(object sender, EventArgs e)
        {
            RichTextBoxConsole.AppendText("Connecting to server...");
            ConnectAsync();
        }
        private void btnSend_Click(object sender, EventArgs e)
        {
            if (Connection.State == Microsoft.AspNet.SignalR.Client.ConnectionState.Disconnected)
            {
                ShowConnectionClosed();
                return;
            }
            HubProxy.Invoke("Send", "Client wgscd", TextBoxMessage.Text);
            TextBoxMessage.Text = String.Empty;
            TextBoxMessage.Focus();
        }
        private void btnDisconnect_Click(object sender, EventArgs e)
        {
            CloseConnection();
        }
        private void Form1_FormClosing(object sender, FormClosingEventArgs e)
        {
            CloseConnection();
        }

     
    }
}