Discuss the basics of HTTP Caching according to HTTP 1.1 and how CacheCow library can implement these requirements for the server and the client.

1. HTTP Caching 101
and a bit of CacheCow
Ali Kheyrollahi

2. What you need for the Journey

3. Let’s hear from Roy
“The problem with
SOAP is that it tries to
escape from the Web
interface. It deliberately
attempts to suck…”

4. Caching – weuseinASP.NET
• Output caching
• HttpContext.Cache
• Memcached
• CacheCow.Server
• CacheCow.Client
• …

5. Output caching
• A web server feature
• How to enable?
• User-mode vs. kernel-mode
• DEMO 1 -> netsh http show
cachestate
• DEMO 2 -> perfmon

6. HttpContext.Cache and
Memcached
Key-Value store for storing anything you like

7. HTTP Caching
• Server sets cache directives
• Clients or intermediaries store
• Technically every response by default
is cacheable unless directives say
otherwise – although …
• What do we cache?
We cache resources

8. How to identify a resource?
URL
http://www.example.com/this/that ?a=b&c=d
And any other header defined by
Vary header sent by server

9. Cache-Control - 1
private
public
Server
Man-in the
middle
Client
Server
Man-in the
middle
Client
✓

10. Cache-Control - 2
no-store no-cache

11. Cacheability – Lifecycleof resource
Fresh Stale Invalid

12. Fresh
Cache-Control: max-age=3600
Expires: Tue, 11 Nov 2014 22:26:14 GMT
1
2

13. Stale
Cache-Control: max-age=3600
Expires: Mon, 11 Nov 2013 22:26:14 GMT
1
2

14. Validation
1
S T A L E
2 Cache-Control: no-cache
3 Cache-Control: must-revalidate
+ stale

15. Validation – against ???
Last-Modified: Mon, 11 Nov 2013 22:26:14 GMT
1
ETag: “1edec-3e3073913b100”
2
“Resource Cache
State”
Server

16. Demo

17. Give-away!
Connection:keep-alive
Content-Length:43
Content-Type:image/gif
Date:Fri, 15 Nov 2013 09:12:12 GMT
Expires: -1
Can a proxy (man-in-the-middle)
cache this resource? And why?

18. … there is moar …eee…eeeeeeehhhhh!!!!!!

19. CacheCow !!

20. CacheCow
Looks after caching so you don’t have to
Has client and server components
(You need client if your client is .NET)
1
2
3 You can choose from (or build) from a
range of soft or persistent storages
4 Remember “cache state” gets stored on server
while “resources” (or responses) themselves get
stored on the client

21. CacheCow.Server
1
2

22. CacheCow.Server (setting cache
control)
NOT SURE I WANNA DO
THAT!

23. CacheCow.Server (attribute-based)
1
2

24. CacheCow.Server (storage)
• In-memory (default)
• Memcached
• Memcached 1.2
• MongoDB
• RavenDB
• SQL Server
• Build your own (implement an interface)

25. CacheCow.Client
Turns HttpClient’s caching from zero
to hero – like a browser
Request does not even touch the network
If you have a fresh cache of the resource
1
2
3 Does all that conditional validation on
GET and PUT so you don’t have to
4 You can choose from (or build) from a
range of soft or persistent storages

26. CacheCow.Client (setup)
1
2

27. WHO CAN GUESS THE RESPONSE???
CacheCow.Client (example)

28. CacheCow.Server (storage)
• In-memory (default)
• Memcached
• Memcached 1.2
• Redis
• File
• SQL Server
• Build your own (implement an interface)

29. Questions??