Interview Q&A

Short answer: Identify and define roles (e.g., Admin, User, Manager) within your system and the permissions each role should have.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: And behavior of each API endpoint.

Real-world example (ShopNest)

ShopNest splits Catalog, Cart, Order, and Payment into services so teams can deploy catalog changes without redeploying payments.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: RESTful endpoints with consistent, versioned URLs.

Real-world example (ShopNest)

ShopNest splits Catalog, Cart, Order, and Payment into services so teams can deploy catalog changes without redeploying payments.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: pipelines and manage deployments.

Real-world example (ShopNest)

ShopNest splits Catalog, Cart, Order, and Payment into services so teams can deploy catalog changes without redeploying payments.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: blocking operations indefinitely. Combine with retries to handle transient failures.

Real-world example (ShopNest)

If Payment is down, the Order service fails fast with a circuit breaker instead of hanging every checkout thread.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: HTTP/REST: Protocol: Uses HTTP/1.1 for communication.

Explain a bit more

Data Format: Typically uses JSON (text-based) for data exchange, which is human-readable but less efficient than binary.

Real-world example (ShopNest)

ShopNest splits Catalog, Cart, Order, and Payment into services so teams can deploy catalog changes without redeploying payments.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: The Circuit Breaker pattern is a design pattern used to prevent a system from repeatedly trying to perform an action that is likely to fail, allowing it to "break" and avoid causing more damage. It helps improve system resilience by detecting failures early and preventing cascading failures. Implementation:

Real-world example (ShopNest)

If Payment is down, the Order service fails fast with a circuit breaker instead of hanging every checkout thread.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: The Bulkhead pattern is a design pattern that isolates different parts of the system to prevent a failure in one part from affecting others. It divides a system into isolated pools, such as different threads, queues, or databases, so that a failure in one doesn't cascade and bring down other parts of the system. Implementation:

Real-world example (ShopNest)

ShopNest splits Catalog, Cart, Order, and Payment into services so teams can deploy catalog changes without redeploying payments.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: Event Sourcing and CQRS are related patterns, but they serve different purposes and are often used together: Event Sourcing: Focuses on how state changes are stored and communicated.

Explain a bit more

It stores events instead of the current state of an entity. The events can be replayed to rebuild the state, ensuring that every state change is traceable and auditable. CQRS: Separates the command (write) and query (read) operations into distinct models. In CQRS, the write model (or command) is responsible for modifying data, and the read model (or query) is optimized for querying data. This separation allows for optimizations in both reading and writing. How they relate: Event Sourcing can serve as the write model in CQRS. Events are stored as part of the write process. The read model in CQRS can be a materialized view (a denormalized representation) that is optimized for querying, which may be updated asynchronously based on the events.

Real-world example (ShopNest)

After payment succeeds, ShopNest publishes OrderPaid. Inventory and Notification services react independently—no giant distributed transaction.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: The Circuit Breaker pattern is used to detect and prevent failures from cascading through a system by stopping requests to a service that is known to be failing.

Explain a bit more

How it helps resilience: When a service starts failing, the circuit breaker trips and prevents further requests from being made to the failing service. This helps to protect the rest of the system and gives the failing service time to recover. It improves system stability by avoiding repetitive failures that would otherwise cause further damage or delays. Implementation:

Real-world example (ShopNest)

If Payment is down, the Order service fails fast with a circuit breaker instead of hanging every checkout thread.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.