Caching is a very know word for any programmer or IT person, but very few of us have the concrete knowledge of Caching. We often use cache in our system or application in conscious or sub-conscious mind. I got a change to deep dive into HTTP and REST during my internship period in Cefalo. This slide was prepared for my presentation on HTTP caching. By making this presentation I gained the actual concept of caching, when, where and why we can use this mechanism.

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