Edge computing patterns: CDNs, workers, and regional processing

Edge computing moves computation closer to users, reducing latency and improving experience. What started as simple CDN caching has evolved into a rich ecosystem of edge functions, databases, and compute platforms. Understanding edge computing patterns helps you build faster, more responsive applications.

CDN caching is the original edge pattern. Static assets, API responses, and even full HTML pages can be cached at edge locations close to users. Proper cache invalidation is critical use cache tags or surrogate keys to selectively purge content when it changes.

Edge functions execute code at the CDN edge in response to HTTP requests. Platforms like Cloudflare Workers, Fastly Compute, and AWS Lambda@Edge let you run logic before the request reaches your origin. Common use cases include A/B testing, geolocation-based routing, authentication checks, and response transformation.

Regional edge caching with stale-while-revalidate provides fast responses with fresh data. Serve cached content immediately while fetching fresh content in the background. This eliminates the latency penalty of cache misses. Most CDNs support this pattern natively.

The edge database pattern uses geographically distributed databases that serve reads from local replicas. PlanetScale, Neon, and Cloudflare D1 offer serverless databases with read replicas in multiple regions. Write to a primary region and read from the nearest replica.

Edge computing works best for stateless, cache-friendly workloads. Authentication checks, content personalization, redirect logic, and API response transformation are ideal candidates. Stateful workloads that require database writes are harder to run at the edge.

Start with CDN caching before adding edge functions. Most applications benefit more from proper caching than from edge compute. Add edge functions incrementally for specific use cases where you measure a real latency improvement.

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Rizwan Saleem | https://rizwansaleem.co