Kestrel和SignalR可以配合使用吗？Yes。
实现这样一个工作场景：有一个客户端把数据源源不断低传给Hub,然后Hub推送给其它客户端，达到实时显示的效果。
文件结构如下：
源源不断提供数据的客户端：ChartExample.ConsoleApp
模型放在：ChartExample.Core
Hub所在的网站：ChartExample.Web
网站
首先是Hub:
public class SensorHub:Hub
{
public Task Broadcast(string sender, Measurement measurement)
{
return Clients
.AllExcept(new[] {Context.ConnectionId})
.InvokeAsync("BroadCast", sender, measurement);
}
}
一切的精华都在这里。提供数据源的客户端调用Hub的Broadcast方法，而Broadcast方法调用了客户端的方法。
Hub需要暴漏给外界。在Startup中定义：
public class Startup
{
public void ConfigureServices(IServiceCollection services)
{
services.AddSignalR();
services.AddCors(o => {
o.AddPolicy("Everything", p => {
p.AllowAnyHeader()
.AllowAnyMethod()
.AllowAnyOrigin();
});
});
}
// This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
public void Configure(IApplicationBuilder app, IHostingEnvironment env)
{
app.UseFileServer();
if(env.IsDevelopment())
{
app.UseDeveloperExceptionPage();
}
app.UseCors("Everything");
app.UseSignalR(routes => {
routes.MapHub<SensorHub>("sensor");
});
}
}
有关Kestrel的配置，在Prgram.cs中：
public class Program
{
public static void Main(string[] args)
{
var config = new ConfigurationBuilder()
.AddCommandLine(args)
.Build();
var host = new WebHostBuilder()
.UseConfiguration(config)
.UseSetting(WebHostDefaults.PreventHostingStartupKey, "true")
.ConfigureLogging(f =>
{
f.AddConsole();
})
.UseKestrel()
.UseContentRoot(Directory.GetCurrentDirectory())
.UseStartup<Startup>()
.Build();
host.Run();
}
}
能保证运行的组件如下：
<Project Sdk="Microsoft.NET.Sdk.Web">
<PropertyGroup>
<TargetFramework>netcoreapp2.0</TargetFramework>
</PropertyGroup>
<ItemGroup>
<PackageReference Include="Microsoft.AspNetCore.Cors" Version="2.0.1" />
<PackageReference Include="Microsoft.AspNetCore.Diagnostics" Version="2.0.1" />
<PackageReference Include="Microsoft.AspNetCore.Hosting" Version="2.0.1" />
<PackageReference Include="Microsoft.AspNetCore.Server.Kestrel" Version="2.0.1" />
<PackageReference Include="Microsoft.AspNetCore.SignalR" Version="1.0.0-alpha2-final" />
<PackageReference Include="Microsoft.AspNetCore.StaticFiles" Version="2.0.1" />
<PackageReference Include="Microsoft.Extensions.Configuration.CommandLine" Version="2.0.0" />
<PackageReference Include="Microsoft.Extensions.Logging.Console" Version="2.0.0" />
</ItemGroup>
<ItemGroup>
<ProjectReference Include="..\ChartExample.Core\ChartExample.Core.csproj" />
</ItemGroup>
</Project>
数据模型
Measurement由于需要用来传输，需要Newtonsoft.Json的辅助。
public class Measurement
{
[JsonProperty("timestamp")]
public DateTime Timestamp { get; set; }
[JsonProperty("value")]
public double Value { get; set; }
public override string ToString()
{
return $"Meaurement (Timestramp = {Timestamp}, Value = {Value})";
}
}
用到的组件：
<Project Sdk="Microsoft.NET.Sdk">
<PropertyGroup>
<TargetFramework>netcoreapp2.0</TargetFramework>
</PropertyGroup>
<ItemGroup>
<PackageReference Include="Newtonsoft.Json" Version="10.0.3" />
</ItemGroup>
</Project>
提供数据的客户端
class Program
{
private static readonly ILogger logger = CreateLogger("Program");
static void Main(string[] args)
{
var cancellationTokenSource = new CancellationTokenSource();
Task.Run(() => MainAsync(cancellationTokenSource.Token).GetAwaiter().GetResult(), cancellationTokenSource.Token);
Console.WriteLine("Press Enter to Exit ...");
Console.ReadLine();
cancellationTokenSource.Cancel();
}
private static ILogger CreateLogger(string loggerName)
{
return new LoggerFactory()
.AddConsole(LogLevel.Trace)
.CreateLogger(loggerName);
}
private static async Task MainAsync(CancellationToken cancellationToken)
{
//定义和Hub的连接
var hubConnection = new HubConnectionBuilder()
.WithUrl("http://localhost:5000/sensor")
.Build();
//开始
await hubConnection.StartAsync();
Random rnd = new Random();
double value = 0.0d;
while(!cancellationToken.IsCancellationRequested)
{
//停顿
await Task.Delay(250, cancellationToken);
//产生数据，并记录日志
value = Math.Min(Math.Max(value + (0.1 - rnd.NextDouble() / 5.0), -1), 1);
var measurement = new Measurement() { Timestamp = DateTime.UtcNow, Value = value };
if(logger.IsEnabled(LogLevel.Trace))
{
Console.WriteLine($"Broading Measurement to Clients {measurement}");
}
//发送
await hubConnection.InvokeAsync("Broadcast", "Sensor", measurement, cancellationToken);
}
await hubConnection.DisposeAsync();
}
}
用到的组件：
<Project Sdk="Microsoft.NET.Sdk">
<PropertyGroup>
<OutputType>Exe</OutputType>
<TargetFramework>netcoreapp2.0</TargetFramework>
</PropertyGroup>
<ItemGroup>
<PackageReference Include="Microsoft.AspNetCore.SignalR.Client" Version="1.0.0-alpha2-final" />
<PackageReference Include="Microsoft.Extensions.Logging" Version="2.0.0" />
</ItemGroup>
<ItemGroup>
<ProjectReference Include="..\ChartExample.Core\ChartExample.Core.csproj" />
</ItemGroup>
</Project>
客户端
var connection = new signalR.HubConnection("sensor");
//客户端响应Hub的方法
connection.on('Broadcast',
function(sender, message) {
values.push(message.value);
values.shift();
chart.update();
});
connection.start();
在近期项目中，前一段时间使用了Stream来实现实时性，现在来看，也可以换种方式，可以通过或IHostedServcie定时不间断调用Hub方法。
public class MyBackgroudService : IHostedService
{
private readonly CancellationTokenSource _cancellationTokenSource = new CancellationTokenSource();
private readonly IHubContext<MyHub> _hubContext;
public MyBackgroundService(IHubContext<MyHub> hubContext)
{
_hubContext= hubContxt;
}
public Task StartAsync()
{
_ = BackgroundTask(_cancellatioinTokenSource.CancellationToken);
}
public Task StopAsync()
{
_cancellationTokenSource.Canel();
}
private Task BackgroundTask(CancellationToken cancellationToken)
{
while(!cancellationToken.IsCancellationRequested)
{
//使用_hubContext
}
}
}
控制器中如何调用
Hub中的方法？
方式一：使用IHubContext.
private IHubContxt<SomeHub> HubContext{get;set;}
public SomeController(IHubContext<SomeHub> hubContext)
{
HubContext = hubContext;
}
await this.HubContext.Clients.All.InvokeAsync("Completed",id);
方式二：申明一个类型的Hub.
public interface ITypedHubClient
{
Task BroadcastMessage(string name, string message);
}
public class ChatHub : Hub<ITypedHubClient>
{
public void Send(string name, string message)
{
Clients.All.BroadcastMessage(name, message);
}
}
[Route("api/demo")]
public class DemoController : Controller
{
IHubContext<ChatHub, ITypedHubClient> _chatHubContext;
public DemoController(IHubContext<ChatHub, ITypedHubClient> chatHubContext)
{
_chatHubContext = chatHubContext;
}
// GET: api/values
[HttpGet]
public IEnumerable<string> Get()
{
_chatHubContext.Clients.All.BroadcastMessage("test", "test");
return new string[] { "value1", "value2" };
}
}