Extension Seam Changes in NServiceBus Version 6

Timeout storage

IPersistTimeouts has been split into two interfaces, IPersistTimeouts and IQueryTimeouts, to separate those storage concerns. Both must be implemented to have a fully functional timeout infrastructure.

IQueryTimeouts implements the concern of polling for timeouts outside the context of a message pipeline. IPersistTimeouts implements the concern of storage and removal for timeouts which is executed inside the context of a pipeline. Depending on the design of the timeout persisters, those concerns can now be implemented independently. Furthermore, IPersistTimeouts introduced a new parameter TimeoutPersistenceOptions . This parameter allows access to the pipeline context. This enables timeout persisters to manipulate everything that exists in the context during message pipeline execution.

Outbox

IOutboxStorage introduced a new parameter OutboxStorageOptions. This parameter provides access to the pipeline context. This enables outbox storage methods to manipulate everything that exists in the context during message pipeline execution.

Queue creation

In NServiceBus version 5, the implementation of the interface ICreateQueues was called for each queue that needed to be created. In version 6, ICreateQueues has been redesigned. The implementation of the interface is called once but with all queues provided on the QueueBindings object. It is now up to the implementation of that interface to determine if the queues are created asynchronously in a sequential order or even in parallel.

// For NServiceBus version 6.x
public class FeatureThatRequiresAQueue :
    Feature
{
    protected override void Setup(FeatureConfigurationContext context)
    {
        var queueBindings = context.Settings.Get<QueueBindings>();
        queueBindings.BindReceiving("someQueue");
    }
}

class YourQueueCreator :
    ICreateQueues
{
    public async Task CreateQueueIfNecessary(QueueBindings queueBindings, string identity)
    {
        // create the queues here
    }
}

// For NServiceBus version 5.x
public class QueueRegistration :
    IWantQueueCreated
{
    public QueueRegistration(Address queueAddress)
    {
        Address = queueAddress;
    }

    public Address Address { get; }

    public bool ShouldCreateQueue()
    {
        return true;
    }
}

public class FeatureThatRequiresAQueue :
    Feature
{
    protected override void Setup(FeatureConfigurationContext context)
    {
        var container = context.Container;
        container.ConfigureComponent(
            componentFactory: () =>
            {
                return new Transports.QueueRegistration(Address.Parse("someQueue"));
            },
            dependencyLifecycle: DependencyLifecycle.InstancePerCall);
    }
}

class YourQueueCreator :
    ICreateQueues
{
    public void CreateQueueIfNecessary(Address address, string account)
    {
        // create the queues here
    }
}

See also Transport-specific queue creation.

Features

Removed FeaturesReport

FeaturesReport exposed reporting information about features of a running endpoint instance. It has been internalized. As with previous versions, the information is still available by inspecting the DisplayDiagnosticsForFeatures logger when the endpoint runs with log level DEBUG.

Feature dependencies

Feature dependencies, using the string API, are now declared using the target feature's full type name (Type.FullName) which includes the namespace. Removing the Feature suffix is no longer required.

// For NServiceBus version 6.x
public class DependentFeature :
    Feature
{
    public DependentFeature()
    {
        DependsOn("Namespace.DependencyB");
        DependsOnAtLeastOne("Namespace.DependencyC", "Namespace.DependencyD");
    }

// For NServiceBus version 5.x
public class DependentFeature :
    Feature
{
    public DependentFeature()
    {
        DependsOn("DependencyB");
        DependsOnAtLeastOne("DependencyC", "DependencyD");
    }

Satellites

ISatellite and IAdvancedSatellite interfaces are obsolete

Both the ISatellite and the IAdvancedSatellite interfaces are deprecated. The same functionality is available via the AddSatelliteReceiver method on the context passed to the features Setup method. The satellite documentation shows more detail.

Performance counters

Satellite pipelines (e.g. retries or timeouts) no longer create performance counters. Endpoints provide a single performance counter instance related to the main message processing pipeline.

To learn more about using performance counters, refer to the performance counter usage sample and the performance counters article.

Transport seam

IDequeueMessages is now obsolete and has been replaced by IPushMessages. The interfaces are equivalent so when creating a transport, implement the new interface. PushContext has been given a new property PushContext.ReceiveCancellationTokenSource, revealing the intent of cancellation for receiving the current message. The transport implementation should act accordingly, canceling the receive when the source's token is canceled.

The ConfigureTransport class was deprecated. Custom transports are now configured using the TransportDefinition class.

Corrupted messages

The core will now pass the error queue address to the transport to make it easier to handle corrupted messages. If a corrupted message is detected the transport is expected to move the message to the specified error queue.

Unit of work