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System Design: Designing an Event Mesh (Pub/Sub at Global Scale)

How does an Event Mesh connect services across multiple clouds? Deep dive into Event routing, dynamic topics, and the differences between Pub/Sub and Event Mesh.

Sachin Sarawgi•April 20, 2026•2 min read•2 minute lesson
#system-design#event-mesh#pubsub#distributed-systems#event-driven#microservices
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System Design: Designing an Event Mesh

An Event Mesh is a modern evolution of Pub/Sub. While Pub/Sub manages a single topic, an Event Mesh dynamically routes events between different clouds, data centers, and on-premise environments, acting as a global nervous system for your microservices.

1. Pub/Sub vs. Event Mesh

  • Pub/Sub: Static and centralized. A producer sends to a topic, and a subscriber connects to it.
  • Event Mesh: Dynamic and decentralized. It automatically understands where data needs to go and routes it across your entire infrastructure, even if the producer and consumer are on different continents.

2. Core Requirements

  • Dynamic Routing: Events should flow regardless of where the producer or consumer is located.
  • Multi-Cloud Support: Routing between AWS, Azure, and GCP.
  • Visibility: A global dashboard to see what events are flowing where.
  • Schema Management: Enforcing message formats globally.

3. High-Level Architecture

  • Event Brokers: A cluster of brokers (Kafka/NATS/Solace) deployed in every region.
  • Global Event Router: A control plane that builds a "Mesh" of routes between brokers.
  • Broker Federation: Using techniques like MirrorMaker (for Kafka) or native clustering to bridge regions together.

4. Handling Traffic: The Hub-and-Spoke Mesh

  • The "Hub": Every region acts as a Hub.
  • The "Spoke": Regional services connect to their local Hub.
  • Cross-Region Routing: When a service in US-East sends an event to a service in EU-West, the US-East broker intelligently routes the event through the mesh to the EU-West broker.

5. Security & Governance

  • Global Policies: Define who can produce to what topic, regardless of their location.
  • Encryption: All inter-broker traffic MUST be encrypted in transit via TLS.

Summary

An Event Mesh is the ultimate expression of Event-Driven Architecture. By abstracting the location of producers and consumers away from the infrastructure, it allows you to build truly global, cloud-agnostic systems where data flows seamlessly to wherever it is needed.

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Sachin Sarawgi

Written by

Sachin Sarawgi

Engineering Manager and backend engineer with 10+ years building distributed systems across fintech, enterprise SaaS, and startups. CodeSprintPro is where I write practical guides on system design, Java, Kafka, databases, AI infrastructure, and production reliability.

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