HTTP Caching 101 and a bit of CacheCow Ali Kheyrollahi

What you need for the Journey

Let’s hear from Roy

“The problem with SOAP is that it tries to escape from the Web interface. It deliberately attempts to suck…”

Caching – we use in ASP.NET

• Output caching

• HttpContext.Cache

• Memcached

• CacheCow.Server

• CacheCow.Client

• …

Output caching

• A web server feature

• How to enable?

• User-mode vs. kernel-mode

•DEMO 1 -> netsh http show cachestate

•DEMO 2 -> perfmon

HttpContext.Cache and Memcached

Key-Value store for storing anything you like

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

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

Cache-Control - 1

private

public

Server Man-in the

middle Client

Server Man-in the

middle Client

✓

Cache-Control - 2

no-store no-cache

Cacheability – Lifecycle of resource

Fresh Stale Invalid

Fresh

Cache-Control: max-age=3600

Expires: Tue, 11 Nov 2014 22:26:14 GMT

1

2

Stale

Cache-Control: max-age=3600

Expires: Mon, 11 Nov 2013 22:26:14 GMT

1

2

Validation

1

S T A L E

2 Cache-Control: no-cache

3 Cache-Control: must-revalidate

+ stale

Validation – against ???

Last-Modified: Mon, 11 Nov 2013 22:26:14 GMT

1

ETag: “1edec-3e3073913b100”

2

“Resource Cache

State”

Server

Demo

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?

… there is moar … eee…eeeeeeehhhhh!!!!!!

CacheCow !!

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

CacheCow.Server

1

2

CacheCow.Server (setting cache

control)

NOT SURE I WANNA DO THAT!

CacheCow.Server (attribute-based)

1

2

CacheCow.Server (storage)

• In-memory (default)

• Memcached

• Memcached 1.2

• MongoDB

• RavenDB

• SQL Server

• Build your own (implement an interface)

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

CacheCow.Client (setup)

1

2

WHO CAN GUESS THE RESPONSE???

CacheCow.Client (example)

CacheCow.Server (storage)

• In-memory (default)

• Memcached

• Memcached 1.2

• Redis

• File

• SQL Server

• Build your own (implement an interface)

Questions??