Release v2.2.0

Cirreum.Runtime.Messaging 2.2.0 — Conductor Marker Rename

Cirreum.Kernel 2.0.0 renames Conductor's publish/subscribe markers — INotification →
IDomainEvent, INotificationHandler<T> → IDomainEventHandler<T>. Cirreum used "notification"
for two unrelated concepts: in-application publish/subscribe, and the human-facing state family a
client binds to in order to show a person something. IDomainEvent names the first for what it is;
"notification" now refers only to the second.

This package follows. Nothing about delivery changes: no wire-format change, no configuration
change, no behavioral change.

Why this is a minor, not a major

This package's own public surface is unchanged. Every reference to the renamed markers here is
inside an internal sealed type or in an XML doc comment — DistributedMessage,
[MessageVersion], IPublisher.PublishAsync, AddMessaging() and the batching seam are all
untouched.

The break your consumers hit belongs to Cirreum.Kernel / Cirreum.Contracts, which went major
2.0.0 to signal exactly that. You cannot take this release without those, and their majors are the
honest warning.

That said, your consumer classes do need a one-line edit each — because they name this package's
DistributedMessageReceived<T> alongside the renamed marker, that combination appears in no other
package's migration guide. It is written out below.

What you change

Only consumers, and only their interface:

// Before
public sealed class EvidenceChangedConsumer
	: INotificationHandler<DistributedMessageReceived<EvidenceInstanceChangedV1>> {

	public Task HandleAsync(
		DistributedMessageReceived<EvidenceInstanceChangedV1> notification,
		CancellationToken cancellationToken) {
		var change = notification.Message;
		var envelope = notification.Envelope;
	}
}

// After
public sealed class EvidenceChangedConsumer
	: IDomainEventHandler<DistributedMessageReceived<EvidenceInstanceChangedV1>> {

	public Task HandleAsync(
		DistributedMessageReceived<EvidenceInstanceChangedV1> domainEvent,
		CancellationToken cancellationToken) {
		var change = domainEvent.Message;
		var envelope = domainEvent.Envelope;
	}
}

Before	After
INotificationHandler<DistributedMessageReceived<T>>	IDomainEventHandler<DistributedMessageReceived<T>>
INotificationHandler<TEvent> (local reaction)	IDomainEventHandler<TEvent>
HandleAsync(notification, …)	HandleAsync(domainEvent, …)

Handlers are still auto-discovered with no registration boilerplate. The publish side —
[MessageVersion], : DistributedMessage, IPublisher.PublishAsync(msg) — is unchanged.

The two-handler distinction the README documents still holds, with the vocabulary updated:

Handler	Runs
IDomainEventHandler<TEvent>	locally, at publish — the reaction comes home in the publishing process
IDomainEventHandler<DistributedMessageReceived<TEvent>>	on receipt from the wire, in a consuming replica

Do not run a project-wide find/replace of "Notification". INotificationState and
IScopedNotificationState keep their names — they are the human-facing concept, and
preserving that separation is the entire point of the rename.

What didn't change

• The wire format, envelope, self-echo prevention, and cirreum.node stamping
• Every Cirreum:Messaging:* configuration key, including Distributed, BackgroundDelivery,
  Receiver, and Metrics
• Batching, prioritization, circuit breaking, and IBatchingPolicy
• The messaging metric names and the Cirreum.Messaging ActivitySource
• AddMessaging() and its fluent composition

Rolling upgrades are safe. A 2.1.x publisher and a 2.2.0 consumer are wire-compatible in both
directions — this release changes no bytes on the broker, so the two can run side by side during a
deployment.

Downstream package impact

Applications with distributed-message consumers need the one-line interface change per handler.
Applications that only publish need a re-pin.

See also

• CHANGELOG.md