Caching Strategies for Faster API Responses
Microsoft Net Framework

What is Caching?

Caching stores a copy of data in a faster storage layer (like memory) so future requests can be served quicker without hitting the database or doing expensive computation again.


๐Ÿง  Common Caching Strategies for APIs

1. In-Memory Caching (e.g. Redis, Memcached)

  • Best for: High-performance APIs with frequent reads.
  • How it works: Data is stored in RAM (like a key-value store).
  • Tools: Redis, Memcached

Example:

// Pseudo-code

if (cache.has("user:123")) {

   return cache.get("user:123");

}

const user = db.getUser(123);

cache.set("user:123", user);

return user;

2. HTTP Caching (Client-side + CDN)

  • Best for: Public APIs and static content (like images, product listings).
  • How it works: Uses HTTP headers like Cache-Control, ETag, Expires to instruct browsers/CDNs to cache.
  • Tools: CDNs (Cloudflare, Fastly), browsers

Example headers:

Cache-Control: public, max-age=3600

ETag: "abc123"

3. Database Query Result Caching

  • Best for: Repeated complex queries with infrequent changes.
  • How it works: Cache the result of the DB query in memory (like Redis) and return the cached result if it exists.

4. Application-level Caching

  • Store computed results (like filtered lists, analytics) in memory or files.
  • Useful when the logic is expensive but doesn’t change often.

5. Persistent Caching

  • Saves cached data to disk or a database so it survives app restarts.
  • Good for infrequent data changes but high read demand.

6. Stale-While-Revalidate

  • Serve stale data immediately, while fetching and updating the cache in the background.
  • Keeps responses fast while data stays reasonably fresh.

Libraries: swr in React, custom middleware in Node/Express.


7. Per-User or Per-Session Caching

  • Useful for personalized data.
  • Cache is scoped to a user or token: e.g., cache.get("user:42:dashboard")

8. Reverse Proxy Caching (e.g. Varnish, Nginx)

  • Acts as a cache layer between your app and the outside world.
  • Caches whole HTTP responses.

๐Ÿ” Cache Invalidation (Hard Part)

Caching is fast, but invalidating (updating or removing) stale data is tricky:

  • Time-based (TTL): Set expiration time.
  • Event-based: Invalidate cache on database change or API call.
  • Manual purge: Admins or developers trigger cache clear.

โœ… Best Practices

  • Use cache only where data is relatively stable.
  • Set appropriate TTL (time to live).
  • Watch out for race conditions or cache poisoning.
  • Use tools like Redis with expiry, HTTP caching, and CDNs together.

๐Ÿงช Example Stack

For a MERN app:

  • Use Redis for backend caching
  • Use node-cache or lru-cache for lightweight in-memory cache
  • Add Cloudflare/CDN caching on static/public endpoints
  • Use ETags for smart HTTP caching

 

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Update on: Dec 20 2023 05:10 PM