Caching stores a copy of a requested resource locally so that future requests can be served from the local copy rather than refetching from the remote server. This improves performance by reducing bandwidth usage and server load. Caches can be both public and shared, or private. The cache behavior is controlled by response headers like Cache-Control, Expires, and ETag, and request headers like If-Modified-Since that allow conditional requests only if the resource has changed. Caching is useful for static resources but not dynamic data that changes frequently. Cache-busting forces clients to discard cached copies and retrieve the latest version.

1. Brief of Caching
Caching mechanism in HTTP and REST
Presented by Rafiul Islam

2. What and Why Caching
• Caching is a technique to storing a copy of a given
resource
• To re-use the resource instead of re-load
• Increase the performance of both server and client
side
• Low bandwidth
• Make server available for other operation

3. How it works
Requesting while no cache available

4. How it works
Caching while reading response

5. How it works
Reusing the cache next time

6. Types of cache
• Public / Shared
• Private

7. Cache controlling
Cache mechanism can be controlled by using
• Response headers
– Cache-Control
– Expires
– Last-Modified
– ETag
• Request headers
– If-Modified-Since
– If-Unmodified-Since
– If-Match
– If-None-Match

8. Cache-Control header
Cache-Control header attributes
– public/private
– max-age
– no-cache
– must-revalidate
– no-store
– httponly

9. Caching Use-Case
Expires header

10. Caching Use-Case
Expires, Last-Modified and Cache-Control header (Conditional)

11. Caching Use-Case
Expires, ETag and Cache-Control header (Condition)

12. Caching Use-Case
Renew Stale Cache

13. Scenarios
Why and when we should and shouldn’t use cache
• Application level (A single user)
• Cache dynamic data : makes no sense
• Cache static data : Good
• Network level (1000 requests/sec)
• Cache dynamic data : Effective
• Cache static data : OK

14. Cache Busting
How to enforce a client to remove cache and
use recent updated data?
Disadvantage?

15. Thank You