A technique that stores a copy of a frequently accessed resource and serves it back when requested.

1. HTTP Caching

2. Md. Rakib Trofder
Trainee Software Engineer
Cefalo Bangladesh Ltd.
Presented By

3. HTTP Caching
A technique that stores a copy of a frequently
accessed resource and serves it back when
requested.

4. Why Caching?
Reduce redundant data transfer
Reuse content
Increase application performance
Reduces the load on
the database.

5. What Can be Cached?
Cache-friendly Content Careful in Caching Content

6. What Can be Cached? (cont.)
Image files
Html files
Css files
Javascript files

7. When the data that is being requested
by an application is found in the cache
and data is still fresh.
When the data that is being requested by an
application isn’t found in the cache or data is not
fresh.
Cache Hit Cache Miss

8. Figure 1 : Processing a fresh cache hit
Client
Cache
Server
1. Receive HTTP
request message
2. Parse message 3. In cache?
4.Is fresh?
New headers Server headers
Body Body
5.Create
response
headers
6. Send Response

9. Figure 2 : Processing a cache miss
Client
Cache
Server
1. Receive HTTP request
message
2. Parse
message
3. In cache?
5. Send
Response
NEW headers
Body
4.Create
response
headers

10. Figure 3 : Processing a cache miss when cache is stale
Client
Cache
1. Receive HTTP
request message
2. Parse message
3. In cache?
4.Is fresh?
Server headers
Body
6. Send
Response
Server
NEW headers
Body
5.Create
response
headers

11. Types of caches in general view point
Private Cache Public Cache

12. Private Cache
A private cache is only used by one client, only for the IP it was created for.
User: rakib3004
Private Cache
Cached only for
User: rakib3004

13. Public Cache
Public cache is used by more than one client. Any public content that don’t need any
authentication or personalized info, that is stored in public cache
Client 1
Public
Cache
Client 2
Cached for both
Client 1 & Client 2

14. Some Common Approaches for Caching
Read Through
Cache Aside
Read Strategies
Write Back
Write Through
Write Strategies

15. Cache Aside
The application first checks the cache. If the data is not found in cache it queries the database to
read the data, returns it to the client and stores the data in cache.
Application
Cache
Database
Faster in read heavy applications
Data is not much frequently updated
Use TTL for remain consistent
between cache and database

16. Read Through
The application first checks the cache. If the data is not found in cache it queries the
database to read the data, populates the cache and returns it to the application.
Application Cache Database
Cache and database data always
remain consistent
Cache sits in-line with the
database.
The application treats cache as
the main data store
2. Cache Hit

17. Write Through
Data is first written to the cache and then to the database. The cache sits in-line with the
database and writes always go through the cache to the main database.
Cache maintains consistency
with the main database.
Implements in write heavy
applications
Application
Cache
Database
Heavy load on database due to
redundant write operation
1. {color: teal }
3.{color: dodger-blue}
5.{color: dark-turquoise}
7.{color: brown}
2. {color: teal }
4.{color: dodger-blue}
6.{color: dark-turquoise}
8.{color: brown}

18. Write Back
Here, the application writes data to the cache which stores the data and acknowledges to
the application immediately. A modified cache block is written back to the database, just
before it is replaced.
Reduces write operations in
write heavy applications
Asynchronous between cache
and database
Writes to the database with a
delay Application Cache Database
1. {color: teal }
3.{color: dodger-blue}
2.{color: dark-turquoise}
4.{color: brown}
5.{color: brown}

19. Some Caching Types in Web Development
Application Caching
Web Caching Data Caching
Distributed Caching

20. Web Caching is 2 types. They are: Browser Caching & Proxy Caching
Web Caching
Browser
Cache
Server
request
Response (content is
not cached or stale)
request
Response
(content is
cached and
fresh
Browser Caching helps individual users to quickly navigate pages they have recently visited.
A temporary storage area in memory or on disk
Instruct the user’s browser to cache certain files.

21. Web Caching (cont.)
Proxy Server
Cache
Server
Client
Proxy Caching allows cached information to be shared across larger groups of users.
Proxy Cache provides content to be delivered
to customers faster.
Proxy Cache data does not change frequently

22. Application Caching
Application caching cache database queries, HTML fragments, or the output of heavy
computations. It can drastically reduce your website load time and reduce server overhead.
Application
Cache
Database
Client
Decreased network costs
Access content without internet

23. Data Caching
It stores the data in local memory on the server and helps avoid extra trips to the database
for retrieving data that has not changed.
Client Data Cache Database
Reduces turnover time of database
queries
Implements in Database Driven Applications
Backup for any cache failure

24. Distributed Caching
Distributed cache is made up of a cluster of machines only serving up memory. Web servers
pull and store from distributed server’s memory.
Client Server
Distributed Cache
Used in high volume applications like
google, microsoft, amazon
Increase scalability
Application acceleration

25. 1. caching-techniques-one-should-know
2. system-design-blog/what-is-caching-
3. four-major-caching-types-and-their-differences
4. choosing-between-public-cache-private-cache-and-esi
5. cache-aside-vs-read-through-cache
6. Web Caching
7. HTTP_cookie
8. first-party-cookies-vs-third-party-cookies/
9. how-to-prepare-for-the-cookieless-era
10. digging-into-the-privacy-sandbox
11. Federated_Learning_of_Cohorts
12. google-kills-off-floc-replaces-it-with-topics
13. turtledove-explained
14. privacy-sandbox/fledge
References