c# - 如何从 EasyNetQ 通知 AngularJS 应用程序

Question

所以我有以下架构:Angular SPA(单页应用程序)执行对 .NET Web API Controller 的调用，后者将消息发布到 Publisher EasyNetQ 窗口服务，后者将异步请求发送到第二个 EasyNetQ 窗口称为 Subscriber 的服务，它调用后端类生成 SSRS 报告，最后将异步响应发送回 Publisher。这是相关架构的图表:

到目前为止一切顺利，订阅者收到响应，生成报告，并将消息发送回发布者。以下是 Web API Controller 如何将报告数据消息发送给发布者:

private IHttpActionResult generateReports(int[] incidentIds)
{
    try
    {
        var incident = this.incidentRepository.GetIncident(incidentIds[0]);
        var client = this.clientService.GetClient(incident.ClientId_Fk);

        using (var messageBus = RabbitHutch.CreateBus("host=localhost"))
        {
            // Loop through all incidents
            foreach (var incidentId in incidentIds)
            {

                foreach (var format in this.formats)
                {
                    Dictionary<Dictionary<int, Client>, SSRSReportFormat> reportData = new Dictionary
                        <Dictionary<int, Client>, SSRSReportFormat>()
                        {
                            {new Dictionary<int, Client>() {{incidentId, client}}, format}
                        };

                    messageBus.Publish(new ReportData
                    {
                        clientId = client.Id,
                        incidentId = incidentId,
                        clientName = client.Name,
                        clientNetworkPath = client.NetworkPath,
                        formatDescription = EnumUtils.GetDescription(format),
                        reportFormat = format.ToString()
                    });                            
                }
            }
        }

        return this.Ok();
    }
    catch (Exception ex)
    {
        return this.InternalServerError(ex);
    }
}

这是我从发布者发送请求的方式:

public partial class CreateRequestService : ServiceBase
{
    private IBus bus = null;

    public CreateRequestService()
    {
        this.InitializeComponent();
    }

    protected override void OnStart(string[] args)
    {
        this.bus = RabbitHutch.CreateBus("host=localhost");

        this.bus.Subscribe<ReportData>("reportHandling", this.HandleReportData);
    }

    protected override void OnStop()
    {
        this.bus.Dispose();
    }

    private void HandleReportData(ReportData reportData)
    {
        int clientId = reportData.clientId;
        int incidentId = reportData.incidentId;
        string clientName = reportData.clientName;
        string clientNetworkPath = reportData.clientNetworkPath;
        string formatDescription = reportData.formatDescription;
        string reportFormat = reportData.reportFormat;

        var task = this.bus.RequestAsync<ReportData, TestResponse>(reportData);
        task.ContinueWith(response => Library.WriteErrorLog("Got response: '{0}'" + response.Result.Response, "PublisherLogFile"));

    }
}

最后，生成报告并从订阅者发回响应的代码:

public partial class RequestResponderService : ServiceBase
{
    private IBus bus = null;

    public RequestResponderService()
    {
        this.InitializeComponent();
    }

    /// <summary>
    /// Initialize the Bus to receive and respond to messages through
    /// </summary>
    /// <param name="args"></param>
    protected override void OnStart(string[] args)
    {
        // Create a group of worker objects
        var workers = new BlockingCollection<MyWorker>();
        for (int i = 0; i < 10; i++)
        {
            workers.Add(new MyWorker());
        }

        workers.CompleteAdding();

        // Initialize the bus
        this.bus = RabbitHutch.CreateBus("host=localhost");

        // Respond to the request asynchronously
        this.bus.RespondAsync<ReportData, TestResponse>(request =>
            (Task<TestResponse>) Task.Factory.StartNew(() =>
            {
                var worker = workers.Take();

                try
                {
                    return worker.Execute(request);
                }
                catch (Exception)
                {

                    throw;
                }
                finally
                {
                }
            }));
    }

    protected override void OnStop()
    {
        this.bus.Dispose();
    }        
}

class MyWorker
{
    public TestResponse Execute(ReportData request)
    {
        int clientId = request.clientId;
        int incidentId = request.incidentId;
        string clientName = request.clientName;
        string clientNetworkPath = request.clientNetworkPath;
        string formatDescription = request.formatDescription;
        string reportFormat = request.reportFormat;

        ReportQuery reportQuery = new ReportQuery();
        reportQuery.Get(incidentId, reportFormat, formatDescription, clientName, clientNetworkPath, clientId);

        return new TestResponse { Response = " ***** Report generated for client: " + clientName + ", incident Id: " + incidentId + ", and format: " + reportFormat + " ***** " };
    }
}

虽然这一切都有效，但我还需要一些方法来通知 Angular SPA 已生成报告，以便我可以为用户提供适当的反馈。这是我有点迷路的地方。 EasyNetQ 可以与 Angular 代码交互吗？此外，一旦我在 Publisher 中收到响应，我可能会在我的 Web API Controller 中调用一些方法，但仍然存在提醒 Angular 代码的问题。有什么想法吗？

Answer 1

首先请注意，您必须在某处存储有关报告状态的信息。您可以将其存储在两个地方:

• 持久存储(数据库、redis 缓存等)。
• 纪念 web api 服务(因为客户端正在与之通信的是该服务)。

当您决定存储位置时 - 如何将此信息传递给客户，同样有两种选择:

• 客户端(Angular)可以时不时地进行轮询(注意不是所谓的“长轮询”)。如果您将您的状态存储在数据库中 - 在这种情况下您可以在那里查找它。

• Angular 和您的 api 之间存在持久连接(网络套接字、长轮询也属于此处)。在这种情况下，你最好将你的状态存储在 web api 的内存中(通过将带有报告状态的兔子消息从你的服务传递到 web api，然后将其存储在内存中和/或通过持久连接直接将其转发到 Angular)。

如果您不期望不同平台(iOS、纯 Linux 等)上的客户端 - SignlarR 可以正常工作。它将根据用户浏览器的功能从 websockets 回退到长轮询再到定期轮询。