Q26-Q30

Q26. What is aggregator Design pattern?

Q27: what is the difference between orchestration and choreography in microservices architecture

Q28: 

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Q26. What is aggregator Design pattern?

Answer:

The Aggregator Design Pattern in microservices is a structural pattern used when you need to gather data from multiple microservices and present it as a unified response.

Keyconcepts:

1. The Aggregator Design Pattern usually implemented with API Gateway or BFF (Backend for Frontend) Patterns. 

2. Create a BFF or Aggregator Service using Azure Functions or Azure API App as an Aggregator Microservice. Use Azure Logic Apps (Low-code Option) as well. 

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Q27: what is the difference between orchestration and choreography in microservices architecture

Answer:

Aspect	Orchestration	Choreography
Definition	A central service (orchestrator) controls the interactions and flow between microservices.	Each microservice reacts to events and decides what to do, with no central controller.
Control Flow	Centralized — one service knows and manages the process steps.	Decentralized — each service decides its behavior based on events.
Analogy	Conductor leading an orchestra.	Dancers responding to the rhythm individually in a flash mob.
Coupling	More tightly coupled — the orchestrator needs to know all participating services.	Loosely coupled — services publish/subscribe to events without knowing each other.
Communication Pattern	Often synchronous (REST calls, workflows).	Asynchronous (event-driven: e.g., Kafka, Azure Event Grid, RabbitMQ).
Tools	Azure Durable Functions, AWS Step Functions, Netflix Conductor, Camunda.	Kafka, Azure Event Grid, NATS, RabbitMQ.
Visibility	Easier to trace and monitor (central point of control).	Harder to trace (distributed decisions and flows).

Use Orchestration When...	Use Choreography When...
Business process is complex and needs strict control.	You want highly decoupled, event-driven architecture.
You need a clear view of the flow and error handling.	Scalability and independence of services are top priority.
Easier debugging/tracking is important.	The system must evolve flexibly over time.

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