Execute a routing slip

Using the routing slip executor

The IRoutingSlipExecutor is registered as a scoped service in the container and can be resolved within any active container scope. To execute a routing slip, use the Execute method on the IRoutingSlipExecutor.

Tip

MassTransit consumers, saga state machine activities, routing slip activities, scoped filters, and ASP.NET controllers are all examples of components that have a valid container scope.

The following example shows how to execute a routing slip from a service.

using System;
using System.Threading.Tasks;
using MassTransit;

public class EmailDeliveryService
{
    readonly IRoutingSlipExecutor _executor;

    public EmailDeliveryService(IRoutingSlipExecutor executor)
    {
        _executor = executor;
    }

    public async Task<Guid> DispatchEmail(string emailAddress, CancellationToken cancellationToken = default)
    {
        var trackingNumber = NewId.NextGuid();

        var builder = new RoutingSlipBuilder(trackingNumber);
        builder.AddActivity("send-email", new Uri("queue:send-email_execute?bind=false"), new {To = emailAddress, Body = "Hello World!"});
        var routingSlip = builder.Build();

        await _executor.Execute(routingSlip, cancellationToken);

        return trackingNumber;
    }
}

The service should be registered in the container using AddScoped<EmailDeliveryService> to ensure that the service has a valid container scope.

Using the bus

The routing slip can also be executed using the bus. This is useful when the routing slip is created without an available container scope. However, creating a container scope is preferred whenever possible.

await bus.Execute(routingSlip);

Caution

It should be pointed out that if the address for the first activity is invalid or cannot be reached, an exception will be thrown by the Execute method.

Once built, the routing slip is executed, which sends it to the first activity’s execute URI. To make it easy and to ensure that source information is included, an extension method on IBus is available, the usage of which is shown below.

Routing Slip Events

During routing slip execution, events are published when the routing slip completes or faults. Every event message includes the TrackingNumber as well as a Timestamp (in UTC, of course) indicating when the event occurred:

• RoutingSlipCompleted
• RoutingSlipFaulted
• RoutingSlipCompensationFailed

Additional events are published for each activity, including:

• RoutingSlipActivityCompleted
• RoutingSlipActivityFaulted
• RoutingSlipActivityCompensated
• RoutingSlipActivityCompensationFailed

By observing these events, an application can monitor and track the state of a routing slip. To maintain the current state, an Automatonymous state machine could be created. To maintain history, events could be stored in a database and then queried using the TrackingNumber of the routing slip.