basic introduction of HTTP Caching.

1. HTTP caching
HTTP caching
HTTP Caching

2. What is Caching?

3. WHY HTTP CACHING?
▸ Decrease latency
▸ Decrease server response times
▸ Decrease the costs of origin servers
▸ Decrease the costs of data transfer

4. Types of web caches
● Browser Cache
● Proxy Cache

5. Browser Cache

6. Proxy Cache

7. Caching Benefits
● Decreased network costs
● Improved responsiveness
● Increased performance on the same hardware
● Availability of content during network interruptions

8. Controlling caching
● No caching (Cache-control : no-store )
● Cache but revalidate (Cache-control : no-store )
● Private and public caches
• (Cache-control : private
• Cache-control : public)
● Expiration(Cache-control : max-age=31536000 )
● Validation(Cache-control : must-revalidate )

9. Controlling caching(cont.)
● The pragma header:
● Cache validation : When a cached document's expiration time has been
reached, it is either validated or fetched again. Validation can only occur if the
server provided either a strong validator or a weak validator.
Pragma is an HTTP/1.0 header. Pragma: no-cache is like Cache-Control: no-cache in that it
forces caches to submit the request to the origin server for validation, before releasing a
cached copy. However, Pragma is not specified for HTTP responses and is therefore not a
reliable replacement for the general HTTP/1.1 Cache-Control header.

10. Controlling caching(cont.)
● Etags: The Etag response header is an opaque-to-the-useragent value that
can be used as a strong validator. That means that a HTTP user-agent, such
as the browser, does not know what this string represents and can't predict
what its value would be.
● Last-Modified: The Last-Modified response header can be used as
a weak validator. It is considered weak because it only has 1-second
resolution. If the Last-Modified header is present in a response, then
the client can issue an If-Modified-Since request header to validate
the cached document.

11. Conclusion
● Taking the time to ensure that your site has proper caching policies in place
can have a significant impact on your site.
● Caching allows you to cut down on the bandwidth costs associated with
serving the same content repeatedly.
● Your server will also be able to handle a greater amount of traffic with the
same hardware.

12. THANKS