= Caching in a Multilanguage Environment by Benjamin Krause

== Benjamin Krause
Of omdb.org

== Caching in Rails

 * Page Caching
 * Action Caching
 * Fragment Caching

Great, but DHH expects a website to be in English only

=== Page Caching

The webserver handles everything about that page
No routing, filters, controller or rendering

Webserver gets the request - if the file exists in the location, it will just serve it, otherwise it will route it through to Rails

=== Fragment caching

Parts of a page is cached and used in the render phase

== Problems with caching in Rails

 * No support for caching in different languages
 * No support to expire all language-caches at once
 * No support for language-negotation

== Conent Negotation
- let the user decide, what he wants to see
- consists of format negotiation and ...

=== Format negoatiation

HTTP "Accept" Header
	Accept:
	
Rails supports format negotiation
Rails allows you to request a format explicitly

=== Language negoation

HTTP "Accept-Language" Header

Rails ignors the HTTP Header

== Lets fix that - extending Rails
- everything here is available as a plugin and as a patch

=== Language Routes

map.resources :movies

Format /2062.html.de # .de added!

Implemented by extending with another route with .:format.:lang

Added default_language and accepts_languages


== Multilanguage View caching

=== Page caching
just add caches_page directive
- it will store just the html page

Need to add language to cache_page's url_for call

== Apache
- how to use Apache's content negotiations

We need to add the %{LA-U} Rewrite condition
- Can be used for look-aheads which perform intial negoation

Override with cookie SetEnvIf Cookie "language=(..)" prefer-language=$1

=== Fragment caching

<% cache  do %>
	..
<% end %>

Places the content into MemCache

Has created their own MemCache implementation, which uses one MemCache for each language

expire_fragment now also supports the :lang parameter


== Testing
- how to test the views

You can set the accept header in a functional test
- language has been added

assert_cached_page do
 ...
end

assert_no_cached_page do
	...
end

assert_cached_fragment( params )
 ...
end

== Plugins

svn.omdb-beta.org/plugins/mlr # Multilanguage Routing
svn.omdb-beta.org/plugins/mlcache # Multilanguage Caching

blog.omdb-beta.org