'Pattern 4: Integration Routing' — RouteIntegrationCallAsync →
SiteEnvelope(IntegrationCallRequest) → SiteCommunicationActor integration
handler — was plumbed end to end but connected at neither end: no
producer (zero callers) and no handler (AkkaHostedService never
registered LocalHandlerType.Integration). It was an early scaffold the
architecture routed around — the brokered External→Central→Site→Central
round-trip is served by the Inbound API's routed-site-script path (the
RouteTo* verbs, driven from CommunicationServiceInstanceRouter), which is
live, tested, and shares IntegrationTimeout.
Decision (#32): delete. Removed the IntegrationCall{Request,Response}
messages, RouteIntegrationCallAsync, the SiteCommunicationActor receive
block + _integrationHandler field + LocalHandlerType.Integration, and the
four tests that covered them (2 actor, 2 message-contract, 1 dispatcher-
reject, 1 mapper-reject). KEPT IntegrationTimeout — it is the live
timeout for the RouteTo* verbs. Updated the exclusion-narrative comments
(proto/mapper/dispatcher), design §4, the components doc timeout table,
and marked the known-issue RESOLVED.
Full solution build clean (0/0); Communication 634 + Host 421 green.
Net -172/+20 across 14 files. Not in the gRPC proto (was deliberately
excluded there), so no wire-format change.
Refactor SiteCommunicationActor's central→site routing table into one
SiteCommandDispatcher — the single routing truth for the 28 migrated commands
(IntegrationCallRequest, the dead 29th, stays on the actor and out of the
dispatcher). The Akka actor and the new SiteCommandGrpcService both route through
one dispatcher instance so the two transports can never drift on where a command
goes. Server-side only: nothing central flips to gRPC yet (that is T1B.3);
ClusterClient remains the live path.
Decisions worth recording:
- Targets preserved byte-for-byte. Lifecycle/OPC UA/query/route → the Deployment
Manager singleton proxy; DeployArtifacts/EventLog/parked → their null-guarded
handlers with the exact same "handler not available" replies; the parked
handler stays NODE-LOCAL (per-node replicated-store owner), never the singleton
proxy — pinned by a dispatcher test that asserts the target is the parked probe
and NOT the dm proxy.
- Sender preservation intact. The actor's command handlers became thin
DispatchCommand delegations that still Forward (central Ask → reply routes
straight back); the existing SiteCommunicationActorTests pass unchanged, which
is the regression guard for that plumbing. UnsubscribeDebugView keeps its
fire-and-forget shape: the actor Forwards, the gRPC service Tells + returns the
synthetic UnsubscribeDebugViewAck so a unary RPC still answers.
- Ack-before-Leave on failover. The dispatcher's PrepareFailover resolves the
standby with a DRY-RUN (no leave) to build the ack, and hands back a deferred
CommitLeave; the gRPC service returns the ack, then schedules the real
Cluster.Leave — so a caller reaching the very node about to leave still gets its
ack instead of a broken stream. The actor path keeps today's coupled
resolve-and-leave (over ClusterClient the ack Tell only enqueues, so order is
immaterial). Proven at both levels: a dispatcher test asserts the ack is built
before CommitLeave runs, and a TestServer test asserts the recorded seam order
is resolve-then-leave.
- ControlPlaneAuthInterceptor gates SiteCommandService by EXTENDING
DefaultGatedPrefixes (descriptor-derived), not by adding a constructor — the
one-public-ctor invariant and its test stay green.
Tests: SiteCommandDispatcherTests (28-command routing incl. parked node-locality
and both failover paths) and SiteCommandGrpcService TestServer tests (auth,
readiness→Unavailable, one command per oneof group, failover ordering). Full
solution build 0/0; Communication.Tests 574 and Host.Tests 377 green. No active
<Protobuf> item.
Joseph Doherty