Wodan

Wodan is a reverse proxy module for the Apache web browser. It caches web content for better performance. A typical setup would be somewhat like this:



The web clients don't know anything about the reverse proxy. They get content just like they would directly from a web server. But the web server gets a lot less work to do.

When to use wodan

• The web server uses a content management system that requires a lot of cpu power to generate live pages, but the pages don't change too often.
• To hide the web servers from the internet.

When not to use wodan, or when to think twice about using it

• The web site has a user login/authentication system. Or rather, do not use it if the biggest part of your site is hidden behind a login system. If you have a much visited set of pages and a part behind a login system, you can still use mod_wodan to cache the public part.
• The web site site has very dynamic content. In this case, mod_wodan will not gain you much in terms of server load. You can still cache things like graphics and css files though, so there still might be some gain.

In general, it all depends on the cachability of your content.

Why use wodan and not mod_proxy?

mod_proxy has excellent proxying, so if you only need proxying, you should use mod_proxy instead ofwodan. But caching is a problem with mod_proxy, it wasn't build for reverseproxy caching. Problem with the caching system of mod_proxy is that it is based on the standard HTTP headers and that's not always what you want with reverseproxy caching. The proxy part of wodan's code is based on mod_proxy.

Why use wodan and not squid?

Squid has better caching than mod_proxy, but the problem with squid is like mod_proxy that it wasn't build for reverseproxying. It also uses the standard http headers. We have used squid (and are still using actually) for reverseproxying by changing some of its code, but it isn't as nice as apache. Besides because squids source isn't as nice apache, things like usertracking are more difficult to implement.