sujaydevx/url-shortner

Purpose and Runtime

This is a Java/Gradle URL-shortening service, built as a Spring Boot application. It creates shortened URLs, resolves short codes into redirects, tracks URL usage, supports expiration, and exposes operational health/metrics. The process starts at src/main/java/com/sujay/urlshortener/UrlShortenerApplication.java; HTTP entry points are in src/main/java/com/sujay/urlshortener/controller/UrlController.java and src/main/java/com/sujay/urlshortener/controller/HomeController.java.

HTTP API and Boundary Layer

Controllers accept URL-shortening requests and redirect/statistics-facing traffic, using request/response DTOs to isolate the HTTP contract from domain persistence: src/main/java/com/sujay/urlshortener/dto/request/ShortenUrlRequest.java, src/main/java/com/sujay/urlshortener/dto/response/ShortenUrlResponse.java, and src/main/java/com/sujay/urlshortener/dto/response/UrlStatsResponse.java. Cross-origin behavior and API documentation configuration are centralized in src/main/java/com/sujay/urlshortener/Config/CorsConfig.java and src/main/java/com/sujay/urlshortener/Config/OpenApiConfig.java.

Core URL Lifecycle

UrlService is the principal business boundary: src/main/java/com/sujay/urlshortener/service/UrlService.java and src/main/java/com/sujay/urlshortener/service/impl/UrlServiceImpl.java. On creation, it derives a code through the short-code abstraction (src/main/java/com/sujay/urlshortener/shortcode/ShortCodeGenerator.java, src/main/java/com/sujay/urlshortener/shortcode/SqidsShortCodeGenerator.java), calculates expiration (src/main/java/com/sujay/urlshortener/util/ExpiryCalculator.java), and persists a Url record through src/main/java/com/sujay/urlshortener/repository/UrlRepository.java. Expiry behavior is modeled by src/main/java/com/sujay/urlshortener/enums/ExpiryOption.java.

Persistence and Cache Read Path

The durable URL model is src/main/java/com/sujay/urlshortener/entity/Url.java, backed by the repository layer. Redis is configured at src/main/java/com/sujay/urlshortener/Config/RedisConfig.java and accessed through src/main/java/com/sujay/urlshortener/cache/service/RedisCacheService.java. The expected redirect path is cache-first, with persisted lookup as the fallback; cached URL representation is src/main/java/com/sujay/urlshortener/cache/model/CachedUrl.java. This creates a clear boundary between low-latency resolution state and durable URL records.

Analytics and Background Processing

Redirect activity is accumulated via src/main/java/com/sujay/urlshortener/cache/service/AnalyticsCacheService.java, then periodically persisted by src/main/java/com/sujay/urlshortener/service/AnalyticsFlushService.java. Scheduling is separated into src/main/java/com/sujay/urlshortener/scheduler/AnalyticsFlushScheduler.java and src/main/java/com/sujay/urlshortener/scheduler/ExpiredUrlScheduler.java; the latter drives cleanup through src/main/java/com/sujay/urlshortener/service/CleanupService.java. This decouples redirect latency from analytics writes and expired-record maintenance.

Failure, Health, and Observability

Domain failures distinguish missing codes from expired URLs through src/main/java/com/sujay/urlshortener/exception/ShortUrlNotFoundException.java and src/main/java/com/sujay/urlshortener/exception/UrlExpiredException.java; src/main/java/com/sujay/urlshortener/exception/GlobalExceptionHandler.java maps them to HTTP errors. Operational endpoints/checks and cache metrics are implemented in src/main/java/com/sujay/urlshortener/health/HealthCheck.java and src/main/java/com/sujay/urlshortener/metrics/MetricsService.java.

Infrastructure and Load Characteristics

The service depends on Redis for caching and buffered analytics, with connection settings provided by application configuration classes. docker-compose.yml and prometheus/prometheus.yml indicate containerized local infrastructure and Prometheus scraping. Load scenarios target the two core traffic modes—URL creation and redirect resolution—in load-test/create-url.js and load-test/redirect.js.