API gateway: North-south entry point — authentication, rate limiting, routing for external consumers.
Event broker: Asynchronous publish/subscribe (Kafka, RabbitMQ). Decouples producers from consumers.
Service mesh: East-west infrastructure layer for service-to-service traffic inside a cluster.
1 / 5
Your architecture team is debating between two integration topologies.
A colleague says: "Point-to-point integrations worked when we had five systems. Now we have forty — we need a hub-and-spoke model."
What problem is the colleague describing?
The core problem with point-to-point integration is combinatorial explosion. With 5 systems: 10 connections. With 40 systems: 780 connections. Each is a custom pipeline to maintain, monitor, and modify when either system changes. A hub-and-spoke model (ESB, API gateway, or event broker as the hub) reduces this to n connections — each system connects once to the hub. The tradeoff: the hub becomes a single point of failure and a potential bottleneck.
2 / 5
An architect recommends using an API gateway as the integration layer.
Which statement best describes the role of an API gateway?
An API gateway sits at the north-south traffic boundary (external consumers → internal services) and centralises cross-cutting concerns: authentication/authorisation, rate limiting, SSL termination, request routing, protocol translation (REST↔gRPC), and logging. Examples: AWS API Gateway, Kong, Apigee, Azure API Management. Distinguish from a service mesh (east-west, internal service-to-service) and an ESB (broader orchestration, transformation, routing).
3 / 5
Complete the architecture decision from an integration review:
"For our order processing pipeline, we chose an _____ broker over synchronous REST calls — this decouples the order service from fulfilment and allows each to scale independently without blocking."
An event broker (Kafka, RabbitMQ, AWS SNS/SQS, Azure Service Bus) enables asynchronous, decoupled communication. Publishers emit events; subscribers consume them independently. The language "decouples... allows each to scale independently without blocking" is the canonical justification for choosing an event broker over synchronous REST. Note: "message broker" is also widely used and broadly acceptable — the distinction is that event brokers (like Kafka) retain event history, while traditional message brokers (like RabbitMQ) delete messages after delivery.
4 / 5
During a migration discussion, the team references an ESB (Enterprise Service Bus).
What is an ESB, and what is a common criticism of the pattern?
An ESB was the dominant enterprise integration pattern of the 2000s. It centralises routing, transformation, orchestration, and protocol translation. The classic criticism (popularised by microservices advocates) is that ESBs become "smart pipes" that accumulate business logic — violating the principle that services should be the source of truth for their own behaviour. Martin Fowler's "dumb pipes, smart endpoints" is the counter-pattern. That said, ESBs remain appropriate in many enterprise contexts where centralised governance and transformation are required.
5 / 5
Which sentence correctly uses integration architecture vocabulary in a design review?
Option B uses vocabulary correctly and quantifiably: point-to-point mesh (the problem), event broker (the solution), reduction in connections (the measured benefit), and event replay (an additional capability). This is the language of a credible integration architecture decision. Option A is a contradiction — ESB and point-to-point are alternative patterns. Option D confuses ESB (integration middleware) with service mesh (infrastructure layer for east-west traffic).