sandesh-543/cdn_simulation

Purpose and Entry Points

This is a Java CDN simulation/service that exposes HTTP endpoints for cache/data access, node health, and CDN routing. The application starts from src/main/java/cdn_server/CdnSimulationApplication.java; request-facing entry points are in src/main/java/controller/CdnController.java, src/main/java/controller/DataController.java, and src/main/java/controller/HealthController.java.

HTTP/API Layer

Controllers define the external control boundary:

• CdnController likely accepts CDN content requests and delegates node selection and cache access.

• DataController provides data/object-oriented operations used by the simulation.

• HealthController exposes node or service liveness for clients, proxies, or orchestration.

Paths: src/main/java/controller/CdnController.java, src/main/java/controller/DataController.java, src/main/java/controller/HealthController.java.

Request Routing and Node Selection

src/main/java/loadbalancer/LoadBalancer.java is the routing decision point between incoming CDN requests and available simulated edge nodes. src/main/java/node/CdnNode.java represents an individual node and its state/capacity/cache-facing behavior. The key control flow is controller → load balancer → selected CDN node → cache/data result.

Caching and Object Model

Cached content is represented by src/main/java/model/CachedObject.java. src/main/java/service/CacheService.java is the application-level cache boundary: it should determine cache lookup, insertion, expiry/validity behavior, and cache-miss handling before data is returned to the caller. This isolates HTTP routing from storage semantics.

Redis Persistence/Shared Cache Boundary

Redis is the material external state service. src/main/java/service/RedisService.java encapsulates Redis operations, while src/main/java/config/RedisConfig.java owns client/template connection configuration. Redis server configuration is supplied at redis/redis.conf. The expected data path is CacheService → RedisService → Redis, allowing multiple CDN node instances to share cache state.

Deployment and Edge Infrastructure

The service is containerized by docker/Dockerfile and composed with supporting services through docker/docker-compose.yml. Nginx is configured in nginx/nginx.conf and is the likely reverse-proxy/load-distribution boundary in front of one or more application instances. scripts/start_cdn_nodes.sh operationalizes starting multiple CDN nodes, while scripts/test_load_balancing.sh exercises that topology.

Runtime Configuration and Observability

Application runtime settings are centralized in src/main/resources/application.properties; logging behavior is defined by src/main/resources/logback.xml. The primary runtime is a Maven-built Java application (pom.xml) backed by Redis and optionally fronted by Nginx/Docker Compose. Health endpoints provide the main operational signal for node availability and routing decisions.