Architecture Overview

Business Events connects publishers and consumers through Microsoft Fabric Real-Time Hub. This page explains how the components fit together.

High-level architecture

flowchart TB
    subgraph Publishers
        NB[Notebook]
        UDF[User Data Function]
        ES[Eventstream]
        ACT_P[Activator]
    end

    subgraph RTH[Real-Time Hub]
        BE1([Retail.Sales.VolumeAlert])
        BE2([Retail.Inventory.LowStockThreshold])
        BE3([DataOps.Pipeline.RunCompleted])
    end

    subgraph Consumers
        ACT_C[Activator\nRules Engine]
        EH[Eventhouse\nKQL Database]
    end

    NB -->|publish| BE1
    UDF -->|publish| BE2
    ES -->|publish| BE3
    ACT_P -->|publish| BE1

    BE1 -->|subscribe| ACT_C
    BE2 -->|subscribe| ACT_C
    BE1 -->|subscribe| EH
    BE3 -->|subscribe| EH

Event Schema Registry

The Event Schema Registry is a platform-level capability in Microsoft Fabric that stores and validates all schema definitions. Business Events are a special type of event schema stored in the registry, organized into Event Schema Sets.

flowchart LR
    PUB[Publisher] -->|publish event| RTH
    subgraph RTH[Real-Time Hub]
        ESR[(Event Schema Registry\nEvent Schema Set)] -->|validate| BE([Business Event])
    end
    BE -->|route| CON[Consumer]

Business Events cannot be created directly from the Event Schema Registry. They must be created from Real-Time Hub → Business Events. During creation, you can create a new Event Schema Set inline or select an existing one. The Event Schema Registry is the underlying storage; Real-Time Hub → Business Events is the entry point.

Before publishing, go to Real-Time Hub → Business Events and create your Business Event from there. You will be prompted to create or select an Event Schema Set as part of the flow.

Component roles

Publishers

Any workload that detects a meaningful condition and signals it to the rest of the platform.

Publisher	Best suited for
Notebook	Batch analysis results, data quality checks, scheduled monitoring
User Data Function	External webhook normalization, custom integrations
Eventstream	Real-time stream threshold conditions
Activator	Re-publishing derived events from existing rules

Real-Time Hub

The managed service in Microsoft Fabric Real-Time Intelligence that receives, routes, and delivers Business Events. Publishers write to it; consumers read from it. Real-Time Hub holds the schema registry for all defined Business Events.

Consumers

Workloads that subscribe to one or more Business Events and react when a matching event arrives.

Consumer	Best suited for
Activator	Triggering alerts, notifications, or downstream actions based on event conditions
Eventhouse	Persisting events for historical analysis and KQL queries

One event, multiple consumers

A single Business Event can trigger reactions in multiple consumers simultaneously. Publishers do not need to change when new consumers are added.

flowchart LR
    NB[Notebook] -->|publish| BE([Retail.Sales.VolumeAlert])
    BE --> ACT[Activator\nSend Teams alert]
    BE --> EH[Eventhouse\nLog for audit]

This fan-out pattern is one of the key architectural advantages of Business Events over direct service-to-service calls.