Integration Hub
Overview
Integration Hub is the Keymate platform's subscription-based event distribution system. It ingests platform events from upstream sources, resolves active subscriptions to determine which downstream services need to receive each event, and delivers events to subscriber endpoints via HTTP. The system is composed of four cooperating microservices: a subscription registry, an event ingestion and routing engine, an outbox delivery processor, and a dead letter topic (DLT) processor for failed deliveries.
Integration Hub follows the Transactional Outbox pattern with domain-specific event bus topics, ensuring reliable at-least-once delivery to external subscriber endpoints. Failed deliveries are automatically retried, and permanently failed events are persisted for operator inspection and manual replay.
When to Read This Section
- You want to register a downstream service to receive platform events
- You want to understand how events are routed from ingestion to subscriber delivery
- You want to learn about the subscription model and supported authentication types
- You want to operate Integration Hub — monitor deliveries, inspect DLT events, and trigger replays
Who Should Start Here
- Developer — Developers building subscriber endpoints or integrating with the subscription management API
- Architect — Architects designing event-driven integration flows and evaluating the subscription-based routing model
- Operator — Operations engineers monitoring delivery pipelines, inspecting failed events, and managing DLT replays
Key Topics
Overview
Integration Hub's architecture, the four microservices, and the end-to-end event flow.
gRPC Ingestion Surface
How platform events enter Integration Hub via gRPC and REST, and the ingestion validation flow.
Connector & Delivery Model
Outbox-based HTTP delivery to subscriber endpoints, authentication, and retry behavior.
Producer Model
How event sources publish events and how events are mapped to domain-specific outbox topics.
Consumer Model
Subscription registration, event type definitions, and delivery configuration for downstream services.
Event-Driven Distribution
Domain-based topic routing, fan-out to multiple subscribers, and the outbox topic structure.
Connector Runtime
Delivery execution lifecycle, retry strategy, dead letter processing, and operator replay API.
Representative Journeys
- I want to understand Integration Hub's overall architecture → Overview
- I want to register my service to receive events → Consumer Model
- I want to understand how events are ingested → gRPC Ingestion Surface
- I want to learn how events are routed to topics → Event-Driven Distribution
- I want to understand the delivery and retry mechanism → Connector Runtime
- I want to inspect and replay failed events → Connector Runtime
Recommended Reading Order
- Overview — Understand the four-service architecture and end-to-end flow
- Consumer Model — Learn how subscriptions and event types are registered
- gRPC Ingestion Surface — Understand how events enter the system
- Producer Model — Learn how events are mapped to domain topics
- Event-Driven Distribution — Understand topic routing and fan-out
- Connector & Delivery Model — Learn the HTTP delivery mechanism
- Connector Runtime — Understand retry, DLT processing, and operator tools
Related Sections
- Event Hub — The upstream event routing component that feeds events into Integration Hub
- Audit & Observability — Receives audit logs from all Integration Hub services
- Config Store — Centralized configuration management