Broker Topology vs Mediator Topology: Decentralized vs Centralized Event Flow

Tue, 04 Aug 2026 05:22:46 +0900

Overview

Broker and mediator topology are the two core styles for structuring event-driven architectures, differing in who controls the flow of events between components. In a broker topology, events flow directly between producers and consumers through a distributed broker with no central authority, while a mediator topology routes every event through a central orchestrator that dictates the sequence of steps. The choice determines how easily the system scales versus how easily complex, stateful workflows can be managed and debugged.

Orchestration vs Choreography: Coordinating Distributed Workflows

Tue, 04 Aug 2026 05:11:21 +0900

Overview

Orchestration and choreography are two ways to coordinate multiple services in a distributed system or workflow. Orchestration relies on a central controller that explicitly directs each step, while choreography lets services independently respond to event reactions with no single component in charge. The choice shapes coupling, visibility, and how easily the workflow evolves over time.

Comparison Diagram

Comparison Table

Aspect	Orchestration	Choreography
Control flow	A central orchestrator explicitly invokes and sequences each step	Each service reacts to events independently; no component sequences the whole flow
Coupling	Services couple to the orchestrator’s contract, not to each other	Services couple to shared event schemas rather than a controller
Workflow knowledge	Orchestrator holds the full picture; services only know their own task	No single component knows the entire workflow, only its trigger and reaction
Failure handling	Retries and compensation logic live centrally in the orchestrator	Compensation is distributed, with services reacting to failure events themselves
Adding new steps	Requires modifying the orchestrator to include the new call	A new service just subscribes to existing events with no central change
Observability	Single place to trace and inspect current workflow state	Requires aggregating distributed logs and traces across services
Failure/scaling risk	Orchestrator can become a bottleneck or single point of failure	Overall flow becomes hard to see, risking uncoordinated ’event sprawl'
Typical tooling	BPMN engines, AWS Step Functions, Temporal, Camunda	Message brokers and event buses like Kafka, SNS/SQS, domain events

Key Differences

Orchestration uses a central controller; choreography relies on services reacting to events
Orchestration couples services to the controller; choreography couples them to event contracts
Extending orchestration means updating the orchestrator; extending choreography just means subscribing to events
Orchestration gives centralized visibility; choreography requires distributed tracing to see the full flow
Orchestration risks a bottleneck at the controller; choreography risks workflow sprawl across services

When to Use Each

Orchestration

Event-Driven-Architecture on IT Comparison

Broker Topology vs Mediator Topology: Decentralized vs Centralized Event Flow

Overview

Orchestration vs Choreography: Coordinating Distributed Workflows

Overview

Comparison Diagram

Comparison Table

Key Differences

When to Use Each