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从服务器获取客户端数据的信号器解决方案

taskcompletionsource asp.net-core-signalr asp.net-core-2.0 angular

1

Hayha · 技术社区 · 7 年前

我知道当调用来自服务器时,signer不能从客户端返回。在Signal的github存储库上,我要求提供一种解决方法( https://github.com/aspnet/SignalR/issues/1329 )他们建议我通过将结果从客户端发送到服务器,再发送到中心中的另一个方法来获得结果,因此使用TaskCompletionSource和一些连接元数据来捕获结果,但我一直在研究如何做到这一点

控制器服务器:

[HttpPut("send/{message}")]
public async Task<IActionResult> SendMessage(string message)
{
    if (!ModelState.IsValid) return BadRequest(ModelState.Values);

    string connectionId = Request.Headers["connectionId"];
    await _chatHubContext.Clients.Client(connectionId).InvokeAsync("send");

    // Catch the call of MessageReceived and get the chat status

    return new OkObjectResult(new EmptyJsonResult() { Result = "OK" }); 

}

集线器服务器

public class ChatHub : Hub
{
    public Task MessageReceive(bool chatStatus)
    {
        // Tell controller that message is received
    }
}

Angular 4客户端

import { Component, Inject } from '@angular/core';
import { HubConnection } from '@aspnet/signalr-client';

@Component({
  selector: 'chat',
  templateUrl: './chat.component.html',
  styleUrls: ['./chat.component.css']
})
/** chat component*/
export class ChatComponent {
  hubConnection: HubConnection;
  chatStatus = false;

  /** chat ctor */
  constructor( @Inject('BASE_URL') private originUrl: string) {
    this.hubConnection = new HubConnection(`${this.originUrl}chat`);

    setInterval(() => {
      this.chatStatus = !this.chatStatus;
    },
      5000);

    this.hubConnection
      .start()
      .then(() => {
        this.hubConnection.on('send', (message: string) => {
          if (this.chatStatus) {
            //send message
          }
          this.hubConnection
            .invoke('messageReceived', this.chatStatus);
        });
      });

  }
}

正如您在这段代码中所看到的,我不知道在控制器方法和集线器方法中要做什么,才能知道方法MessageReceive被调用了,并获得返回以将其发送回控制器请求。

1 回复 | 直到 7 年前

1

3

aaron 6 年前

“通过对连接元数据和 TaskCompletionSource 您还可以使其看起来很像返回值的方法调用。"

控制器服务器 :

注射 HttpConnectionManager .

// using Microsoft.AspNetCore.Http.Connections.Internal;

public async Task<IActionResult> SendMessage(string message)
{
    string connectionId = Request.Headers["connectionId"];

    var chatStatus = await Send(connectionId, message);

    return new OkObjectResult(new { Result = "OK", ChatStatus = chatStatus });
}

private async Task<bool> Send(string connectionId, string message)
{
    var tcs = new TaskCompletionSource<bool>();

    _connectionManager.TryGetConnection(connectionId, out HttpConnectionContext connection);

    connection.Items.Add("tcs", tcs);

    await _chatHubContext.Clients.Client(connectionId).SendAsync("send", message);

    var chatStatus = await tcs.Task;

    connection.Items.Remove("tcs");

    return chatStatus;
}

集线器服务器 :

public Task MessageReceived(bool chatStatus)
{
    Context.Items.TryGetValue("tcs", out object obj);

    var tcs = (TaskCompletionSource<bool>)obj;

    tcs.SetResult(chatStatus);

    return Task.CompletedTask;
}

Angular 4客户端 :

// No change