Business metric collector and calculation sample using NServiceBus events and sagas

ShippingSpeedMetricCollector.cs

using System;
using System.Threading.Tasks;
using NServiceBus;

class ShippingSpeedMetricCollector
    : Saga<ShippingSpeedData>
    , IAmStartedByMessages<OrderCreated>
    , IHandleMessages<OrderCancelled>
    , IHandleMessages<OrderShipped>
{
    public Task Handle(OrderCreated message, IMessageHandlerContext context)
    {
        var createdAt = DateTimeExtensions.ToUtcDateTime(context.MessageHeaders[Headers.TimeSent]);
        Data.CreatedAt = createdAt;
        return Task.CompletedTask;
    }

    public Task Handle(OrderCancelled message, IMessageHandlerContext context)
    {
        MarkAsComplete();
        return Task.CompletedTask;
    }

    public Task Handle(OrderShipped message, IMessageHandlerContext context)
    {
        var shippedAt = DateTimeExtensions.ToUtcDateTime(context.MessageHeaders[Headers.TimeSent]);
        var duration = Data.CreatedAt - shippedAt;

        MarkAsComplete();

        return context.Send(new UpdateShippedMetric { OrderId = message.OrderId, Duration = duration });
    }

    protected override void ConfigureHowToFindSaga(SagaPropertyMapper<ShippingSpeedData> mapper)
    {
        mapper.ConfigureMapping<OrderCreated>(m => m.OrderId).ToSaga(s => s.OrderId);
        mapper.ConfigureMapping<OrderCancelled>(m => m.OrderId).ToSaga(s => s.OrderId);
        mapper.ConfigureMapping<OrderShipped>(m => m.OrderId).ToSaga(s => s.OrderId);
    }
}

class ShippingSpeedData : ContainSagaData
{
    public string OrderId { get; set; }
    public DateTime CreatedAt { get; set; }
}

class SendUpdateShippedMetricToInfluxDB : IHandleMessages<UpdateShippedMetric>
{
    public Task Handle(UpdateShippedMetric message, IMessageHandlerContext context)
    {
        // Connect to InfluxDB and add data
        return Task.CompletedTask;
    }
}

class UpdateShippedMetric : ICommand
{
    public string OrderId { get; set; }
    public TimeSpan Duration { get; set; }
}

class OrderShipped : IEvent
{
    public string OrderId { get; set; }
}

class OrderCreated : IEvent
{
    public string OrderId { get; set; }
}

class OrderCancelled : IEvent
{
    public string OrderId { get; set; }
}