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MassTransit 消息類型不能是系統類型例外

[英]MassTransit messages types must not be System types exception

 原文  2021-10-27 12:36:17  0   2    c#/ masstransit

問題描述

我是 MassTransit 的新手，不明白我做錯了什么導致出現以下異常： Messages types must not be System types 。

以下是我的定義：

[BsonIgnoreExtraElements]
public class ArcProcess : SagaStateMachineInstance, ISagaVersion
{
    public Guid CorrelationId { get; set; }

    public string CurrentState { get; set; }

    public int Version { get; set; }

    public Guid ActivationId { get; set; }
}

public static class MessageContracts
{
    static bool _initialized;

    public static void Initialize()
    {
        if (_initialized)
            return;

        GlobalTopology.Send.UseCorrelationId<StartProcessingMessage>(x => x.ActivationId);
        GlobalTopology.Send.UseCorrelationId<ReconstructionFinishedMessage>(x => x.ActivationId);
        GlobalTopology.Send.UseCorrelationId<ProcessingFinishedMessage>(x => x.ActivationId);

        _initialized = true;
    }
}

我的 2 個消費者是：

public class StartReconstructionConsumer : IConsumer<StartProcessingMessage>
{
    readonly ILogger<StartReconstructionConsumer> _Logger;

    private readonly int _DelaySeconds = 5;

    public StartReconstructionConsumer(ILogger<StartReconstructionConsumer> logger)
    {
        _Logger = logger;
    }

    public async Task Consume(ConsumeContext<StartProcessingMessage> context)
    {
        var activationId = context.Message.ActivationId;

        _Logger.LogInformation($"Received Scan: {activationId}");

        await Task.Delay(_DelaySeconds * 1000);

        _Logger.LogInformation($"Finish Scan: {activationId}");

        await context.Publish<ReconstructionFinishedMessage>(new { ActivationId = activationId });
    }
}

public class ProcessingFinishedConsumer : IConsumer<ProcessingFinishedMessage>
{
    readonly ILogger<ProcessingFinishedConsumer> _Logger;

    public ProcessingFinishedConsumer(ILogger<ProcessingFinishedConsumer> logger)
    {
        _Logger = logger;
    }

    public async Task Consume(ConsumeContext<ProcessingFinishedMessage> context)
    {
        _Logger.LogInformation($"Finish {context.Message.ActivationId}");

        await Task.CompletedTask;
    }
}

這是 StateMachine 的定義：

public class ArcStateMachine: MassTransitStateMachine<ArcProcess>
{
    static ArcStateMachine()
    {
        MessageContracts.Initialize();
    }

    public ArcStateMachine()
    {
        InstanceState(x => x.CurrentState);

        Initially(
            When(ProcessingStartedEvent)
            .Then(context =>
            {
                Console.WriteLine(">> ProcessingStartedEvent");
                context.Instance.ActivationId = context.Data.ActivationId;
            })
            .TransitionTo(ProcessingStartedState));

        During(ProcessingStartedState,
            When(ReconstructionFinishedEvent)
            .Then(context =>
            {
                Console.WriteLine(">> ReconstructionFinishedEvent");
                context.Instance.ActivationId = context.Data.ActivationId;
            })
            .Publish(context =>
            {
                return context.Init<ProcessingFinishedMessage>(new { ActivationId = context.Data.ActivationId });
            })
            .TransitionTo(ProcessingFinishedState)
            .Finalize());
    }

    public State ProcessingStartedState { get; }
    public State ReconstructionStartedState { get; }
    public State ReconstructionFinishedState { get; }
    public State ProcessingFinishedState { get; }

    public Event<StartProcessingMessage> ProcessingStartedEvent { get; }
    public Event<ReconstructionStartedMessage> ReconstructionStartedEvent { get; }
    public Event<ReconstructionFinishedMessage> ReconstructionFinishedEvent { get; }
    public Event<ProcessingFinishedMessage> ProcessingFinishedEvent { get; }
}

MassTransit 的設置如下所示：

var rabbitHost = Configuration["RABBIT_MQ_HOST"];

        if (rabbitHost.IsNotEmpty())
        {
            services.AddMassTransit(cnf =>
            {
                var connectionString = Configuration["MONGO_DB_CONNECTION_STRING"];

                var machine = new ArcStateMachine();
                var repository = MongoDbSagaRepository<ArcProcess>.Create(connectionString,
                    "mongoRepo", "WorkflowState");

                cnf.AddConsumer(typeof(StartReconstructionConsumer));
                cnf.AddConsumer(typeof(ProcessingFinishedConsumer));

                cnf.UsingRabbitMq((context, cfg) =>
                {
                    cfg.Host(new Uri(rabbitHost), hst =>
                    {
                        hst.Username("guest");
                        hst.Password("guest");
                    });

                    cfg.ConfigureEndpoints(context);

                    cfg.ReceiveEndpoint(BusConstants.SagaQueue,
                        e => e.StateMachineSaga(machine, repository));
                });
            });

            services.AddMassTransitHostedService();

            services.AddSwaggerGen(c =>
            {
                c.SwaggerDoc("v1", new OpenApiInfo { Title = "MyApp", Version = "v1" });
            });
        }

我有幾個問題：

  1. 作為發布消息的結果，實際何時發布事件？ 即在我的示例中await _BusInstance.Bus.Publish<StartProcessingMessage>(new { ActivationId = id }); 從它被消耗的WebAPI稱為StartReconstructionConsumer但在實際狀態機開始用行動Initially(When(ProcessingStartedEvent)... ？

  2. 我的處理應該確保我已經處於ProcessingStartedState狀態，以便During(ProcessingStartedState, When(ReconstructionFinishedEvent)...正確操作。那么我如何確保我的消費者在接收到StartProcessingMessage可以發布ReconstructionFinishedMessage應該啟動During ？我是否正確構建了消息交換？

  3. 目前為await context.Publish<ReconstructionFinishedMessage>(new { ActivationId = activationId }); 我在日志中得到一個異常，指出R-FAULT rabbitmq://localhost/saga.service d4070000-7b3b-704d-0f10-08d99942c959 Nanox.GC.Shared.AppCore.Messages.ReconstructionFinishedMessage ReconCaller.Saga.ArcProcess(00:00:04.1132604)而消息中的那個 guid 實際上是MessageId 。 我在 rabbitmq 中的消息被路由到saga.service_error ，但出現異常Messages types must not be System types: System.Threading.Tasks.Task<Nanox.GC.Shared.AppCore.Messages.ProcessingFinishedMessage> (Parameter 'T') 。

看來我在這里真的很想念..

我的目的是啟動處理，由幾個消費者順序處理幾個階段。 所以在這里我嘗試構建一個簡單的 StateMachine，每當有人調用StartProcessing時它就會啟動，然后每個消費者將完成它的工作並觸發FinishedStepX ，它將提升狀態機到一個新的步驟並啟動下一個消費者直到所有處理完成和狀態機將報告ProcessingComplete 。

感謝您提前提供任何幫助

2 個解決方案

解決方案1
 1 已采納  2021-10-27 13:00:17

首先，你的總線配置有點奇怪，所以我已經清理了它：

services.AddMassTransit(cnf =>
{
    var connectionString = Configuration["MONGO_DB_CONNECTION_STRING"];

    cfg.AddSagaStateMachine<ArcStateMachine, ArcProcess>()
        .Endpoint(e => e.Name = BusConstants.SagaQueue)
        .MongoDbRepository(connectionString, r =>
        {
            r.DatabaseName = "mongoRepo";
            r.CollectionName = "WorkflowState";
        });

    cnf.AddConsumer<StartReconstructionConsumer>();
    cnf.AddConsumer<ProcessingFinishedConsumer>();

    cnf.UsingRabbitMq((context, cfg) =>
    {
        cfg.Host(new Uri(rabbitHost), hst =>
        {
            hst.Username("guest");
            hst.Password("guest");
        });

        cfg.ConfigureEndpoints(context);
    });
});

發布問題與所使用的方法有關，只有PublishAsync允許使用消息初始化程序：

During(ProcessingStartedState,
    When(ReconstructionFinishedEvent)
        .Then(context =>
        {
            Console.WriteLine(">> ReconstructionFinishedEvent");
            context.Instance.ActivationId = context.Data.ActivationId;
        })
        .PublishAsync(context =>
        {
            return context.Init<ProcessingFinishedMessage>(new { ActivationId = context.Data.ActivationId });
        })
        .TransitionTo(ProcessingFinishedState)
        .Finalize());

那應該可以解決您的問題。

解決方案2
 1  2021-10-27 14:21:38

在@Chris Patterson 的慷慨幫助下，可行的解決方案是：

定義：

[BsonIgnoreExtraElements]
public class ArcProcess : SagaStateMachineInstance, ISagaVersion
{
    public Guid CorrelationId { get; set; }

    public string CurrentState { get; set; }

    public int Version { get; set; }

    public Guid ActivationId { get; set; }
}

public interface StartProcessingMessage
{
    Guid ActivationId { get; }
}

public interface ProcessingFinishedMessage
{
    Guid ActivationId { get; }
}

public static class MessageContracts
{
    static bool _initialized;

    public static void Initialize()
    {
        if (_initialized)
            return;

        GlobalTopology.Send.UseCorrelationId<StartProcessingMessage>(x => x.ActivationId);
        GlobalTopology.Send.UseCorrelationId<ProcessingFinishedMessage>(x => x.ActivationId);

        _initialized = true;
    }
}

消費者：

public class StartProcessingConsumer : IConsumer<StartProcessingMessage>
{
    readonly ILogger<StartProcessingConsumer> _Logger;

    private readonly int _DelaySeconds = 5;

    public StartProcessingConsumer(ILogger<StartProcessingConsumer> logger)
    {
        _Logger = logger;
    }

    public async Task Consume(ConsumeContext<StartProcessingMessage> context)
    {
        var activationId = context.Message.ActivationId;

        _Logger.LogInformation($"Received Scan: {activationId}");

        await Task.Delay(_DelaySeconds * 1000);

        _Logger.LogInformation($"Finish Scan: {activationId}");

        await context.Publish<ProcessingFinishedMessage>(new { ActivationId = activationId });
    }
}

public class ProcessingFinishedConsumer : IConsumer<ProcessingFinishedMessage>
{
    readonly ILogger<ProcessingFinishedConsumer> _Logger;

    public ProcessingFinishedConsumer(ILogger<ProcessingFinishedConsumer> logger)
    {
        _Logger = logger;
    }

    public async Task Consume(ConsumeContext<ProcessingFinishedMessage> context)
    {
        _Logger.LogInformation($"Finish {context.Message.ActivationId}");

        await Task.CompletedTask;
    }
}

狀態機定義：

public class ArcStateMachine: MassTransitStateMachine<ArcProcess>
{
    static ArcStateMachine()
    {
        MessageContracts.Initialize();
    }

    public ArcStateMachine()
    {
        InstanceState(x => x.CurrentState);

        Initially(
            When(ProcessingStartedEvent)
            .Then(context =>
            {
                context.Instance.ActivationId = context.Data.ActivationId;
            })
            .TransitionTo(ProcessingStartedState));

        During(ProcessingStartedState,
            When(ProcessingFinishedEvent)
            .Then(context =>
            {
                context.Instance.ActivationId = context.Data.ActivationId;
            })
            .Finalize());
    }

    public State ProcessingStartedState { get; }
    public State ProcessingFinishedState { get; }

    public Event<StartProcessingMessage> ProcessingStartedEvent { get; }
    public Event<ProcessingFinishedMessage> ProcessingFinishedEvent { get; }
}

大眾運輸設置：

var rabbitHost = Configuration["RABBIT_MQ_HOST"];

        if (rabbitHost.IsNotEmpty())
        {
            services.AddMassTransit(cnf =>
            {
                var connectionString = Configuration["MONGO_DB_CONNECTION_STRING"];

                cnf.AddSagaStateMachine<ArcStateMachine, ArcProcess>()
                    .Endpoint(e => e.Name = BusConstants.SagaQueue)
                    .MongoDbRepository(connectionString, r =>
                    {
                        r.DatabaseName = "mongoRepo";
                        r.CollectionName = "WorkflowState";
                    });


                cnf.AddConsumer(typeof(StartProcessingConsumer));
                cnf.AddConsumer(typeof(ProcessingFinishedConsumer));

                cnf.UsingRabbitMq((context, cfg) =>
                {
                    cfg.Host(new Uri(rabbitHost), hst =>
                    {
                        hst.Username("guest");
                        hst.Password("guest");
                    });

                    cfg.ConfigureEndpoints(context);
                });
            });

            services.AddMassTransitHostedService();

            services.AddSwaggerGen(c =>
            {
                c.SwaggerDoc("v1", new OpenApiInfo { Title = "MyApp", Version = "v1" });
            });
        }

這個例子對我理解 MassTrasit 的基本原理有很大幫助。

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