Glossary

Core Cresco terms, in one place.

Term	Meaning
Agent	A leaf node — a JVM running the Cresco host + plugins, attached as a client to a regional controller's broker. Also, the identity of any node (region_agent).
Region / Regional controller	A controller that runs its own embedded ActiveMQ broker; the agents in its region attach to it. Federates up to a global.
Global / Global controller	The top of the hierarchy; federates regions (and other globals) together. Serves clients via wsapi.
Controller mode	A node's role: STANDALONE, AGENT, REGION, REGION_GLOBAL, or GLOBAL.
Controller	The fabric-brain module present on every node (messaging, discovery, security, health, db, data plane).
Plugin	An OSGi bundle providing functionality and exposing actions (e.g. sysinfo, wsapi, stunnel, repo).
MsgEvent	The unit of the control plane — a typed, addressed, routed message. See MsgEvent.
Action	A callable operation a plugin exposes, declared with @CrescoAction; invoked by sending a MsgEvent.
Capability inventory	The fabric-wide catalog of all actions (getcapabilityinventory).
Data plane	The pub/sub streaming channel over ActiveMQ topics (agent.event / region.event / global.event).
Control plane	The addressed MsgEvent channel over ActiveMQ queues.
MsgRouter	The controller component that makes the deterministic per-hop routing decision.
Federation / Network of brokers	Broker-to-broker ActiveMQ bridges that connect regions to globals (and globals to each other).
Bridge	A duplex, demand-forwarding ActiveMQ network connector between two brokers.
QoS tier	The priority class of a message: LIVENESS > CONTROL > TELEMETRY > BULK.
Discovery	Finding a parent controller (UDP broadcast or static TCP), gated by a tier join secret.
Join secret	The pre-shared discovery_secret_{agent,region,global} a node must present to join a tier.
Service key	cresco_service_key — the shared symmetric key authenticating agent traffic; must match fabric-wide.
CrescoIdentity	A node's identity tenant/region/agent(/uid), bound into its X.509 leaf DN (CN=agent, OU=region, O=tenant).
Regional CA	A region/global controller acting as a certificate authority, signing joiners' leaves — distributed trust (O(regions)).
Tenant	An isolation domain (O= in the cert DN). Multiple tenants can share one fabric; see Multi-Tenancy.
Tenant namespacing	Qualifying destinations T.<tenant>.<raw> so isolation is enforceable by a local prefix check at every broker.
Role	An authorization role: SUPERUSER (all tenants) or TENANT (own tenant only).
Health check	A Felix HealthCheck contributing a pass/fail verdict; run centrally by CrescoHealthExecutor.
MeasurementEngine	The per-bundle Micrometer registry; metrics are aggregated mesh-wide via getmetricinventory.
LinkMetrics	Per-edge network quality (RTT/jitter/throughput/backlog) in the netlink metric group.
Cost-aware routing	Dynamic path selection over a pushed link-state view with per-hop cost, choosing the cheapest path across the federated mesh. Gated by net_cost_routing. See Dynamic Cost-Aware Routing.
RouteView / LSA	The pushed link-state advertisement (route_lsa) each node shares so peers build a topology graph and compute paths — pushed as it changes, not polled.
Source route	A pre-computed hop sequence stamped on a message (srcroute) so it follows a chosen path instead of per-hop re-selection. Gated by net_source_routing.
Coordinator	A controller elected to coordinate a scope. Multiple globals can coexist and regions can boot/run without one (global_optional). See Coordinator Decentralization.
Quorum / epoch	Coordinator elections use a majority quorum (f+1 of 2f+1) with epoch fencing, so a stale coordinator cannot act.
Failure detector	φ-accrual suspicion + SWIM indirect probing that decides when a peer is dead (failure_phi_suspect/failure_phi_dead, failure_swim_k).
Tunnel tracing	End-to-end stunnel path tracing: brokers stamp cresco_hops on marked bytes, streamed live (throughput + path) on the subscribable stunnel_trace channel. See Tunnel Path Tracing.
wsapi	The WebSocket API plugin that bridges external clients to the fabric (wss://host:8282).
clientlib / pycrescolib / cppcrescolib	The external Java, Python, and C++ / Arduino (ESP32) client SDKs.
CADL / pipeline	A described application (a graph of plugins/edges) submitted to and orchestrated by the global controller.