A Minimalist Spring Cloud Microservice Architecture Diagram for Interview Success

Many claim that the era of cloud‑native and large‑model AI has made microservices obsolete, yet most developers have never built or selected a microservice framework in practice. Interviewers often ask how to handle microservices, so this article shares a stripped‑down architecture diagram to help candidates discuss confidently.

Component Interaction Overview

Browser queries the DNS server to discover service instance locations.

CDN delivers static assets, improving cross‑region speed.

LVS load balancer provides network‑level load distribution.

Nginx reverse proxy forwards requests to the gateway for routing and security.

The Nacos registry and configuration center supply backend services and configuration items.

Sentinel enforces rate limiting.

Redis offers caching, session management, and distributed locks.

Elasticsearch enables full‑text search, log storage, and real‑time visualization with Kibana.

1. DNS in Microservices

Each service registers its IP and port with DNS; browsers query DNS to obtain up‑to‑date instance locations, achieving automatic discovery.

DNS can apply policies (round‑robin, random) to distribute requests to LVS, enhancing concurrency and fault tolerance.

2. LVS (Linux Virtual Server)

LVS is an open‑source load‑balancer running in the Linux kernel, supporting multiple algorithms (round‑robin, weighted, etc.) and protocols (TCP, HTTP, HTTPS). It offers high availability, master‑slave redundancy, and dynamic node scaling.

3. CDN for Static Resources

CDN caches images, videos, JS, CSS, and static HTML across geographically distributed nodes, reducing latency and bandwidth consumption for high‑read static content.

4. Nginx Reverse Proxy

Reverse proxy : forwards client requests to backend services.

Load balancing : distributes traffic among service instances.

Service routing : routes based on path rules.

Static asset serving : offloads static content delivery from backend services.

When choosing between Nginx and CDN, consider performance, control, cost, and global coverage. CDN excels in speed and worldwide reach, while Nginx offers finer configuration control and lower cost.

5. Gateway

Unified entry point : hides internal service details.

Routing and forwarding : directs requests to appropriate microservice instances.

Security and authentication : integrates auth, rate limiting, and circuit breaking.

Protocol conversion : bridges different protocols.

Logging and monitoring : records request/response data for analysis.

Service aggregation : combines responses from multiple services into a single payload.

6. Nacos Registry & Configuration Center

Service registration : services register IP/port; clients discover via DNS/RPC.

Dynamic configuration : modify settings without restarting services.

Health checks & load balancing : ensure only healthy instances receive traffic.

7. Redis in Microservices

Cache service : stores frequently accessed data in memory.

Session management : shares user sessions across services.

Distributed lock : prevents race conditions on shared resources.

Message queue : supports pub/sub and asynchronous communication.

Race Condition Overview

A race condition occurs when multiple threads or processes access a shared resource without proper synchronization, leading to unpredictable results. It can also appear in networks when simultaneous access attempts conflict.

Redis Session Management Steps

Create a session in Redis when a user first accesses the application.

Store session data (user ID, login status, permissions) keyed by a unique session ID.

Set an expiration time using the EXPIRE command to auto‑expire inactive sessions.

On each request, retrieve and optionally update the session; prompt re‑login if expired.

Destroy the session by deleting its key when the user logs out or the timeout elapses.

8. Elasticsearch Full‑Text Search

Search engine : distributed real‑time full‑text queries.

Distributed storage : indexes data for fast retrieval.

Data analysis : integrates with Kibana for visual analytics.

Log and monitoring : stores logs for real‑time querying and alerting.

Scalability : horizontally scales to hundreds of nodes handling petabytes of data.

9. Redis vs. Elasticsearch

Storage & query model : Redis is key‑value, fast reads/writes; Elasticsearch uses inverted indexes for complex search.

Data structures : Redis offers strings, hashes, lists, sets; Elasticsearch focuses on document indexing.

Real‑time vs. near‑real‑time : Redis provides millisecond latency; Elasticsearch has slight delay due to indexing.

Scalability : Redis scales via sharding; Elasticsearch scales horizontally with added nodes.