From: Rob Biedenharn <Rob@...>
Date: 2008-01-24T22:23:35+09:00
Subject: Re: Creating a canonicalized url


On Jan 24, 2008, at 7:14 AM, Dan Cuddeford wrote:

> Hello there guys,
>
> I'm trying to track down an easy way to canonicalize a URL from with
> ruby. I've been looking around for this but all I can find are some
> procedure hacks sure as  # canonicalize the url
>    if ($url -notmatch "^[a-z]+://") { $url = "http://$url" }
>
> which isn't going to take into account everything according to RFC  
> 2396
>
>    *   Remove all leading and trailing dots
>    * Replace consecutive dots with a single dot.
>    * If the hostname can be parsed as an IP address, it should be
> normalized to 4 dot-separated decimal values. The client should handle
> any legal IP address encoding, including octal, hex, and fewer than 4
> components.
>    * Lowercase the whole string.
>
>
> #  The sequences "/../" and "/./" in the path should be resolved, by
> replacing "/./" with "/", and removing "/../" along with the preceding
> path component.
> # Runs of consecutive slashes should be replaced with a single slash
> character.
>
> So is there a method out there for this?

I'd start looking at URI, in particular, URI#parse.

$ fri URI#parse
------------------------------------------------------------- URI::parse
      URI::parse(uri)
------------------------------------------------------------------------
      Synopsis
        URI::parse(uri_str)

      Args
      +uri_str+: String with URI.

      Description
      Creates one of the URI's subclasses instance from the string.

      Raises
      URI::InvalidURIError

        Raised if URI given is not a correct one.

      Usage
        require 'uri'

        uri = URI.parse("http://www.ruby-lang.org/")
        p uri
        # => #<URI::HTTP:0x202281be URL:http://www.ruby-lang.org/>
        p uri.scheme
        # => "http"
        p uri.host
        # => "www.ruby-lang.org"

As for the "Lowercase the whole string" part, only the domain is  
required to be case-insensitive.  It is possible for the underlying  
web server to ignore case when finding a path, but the URI is not  
necessarily a reference to the same resource if the case is altered.

-Rob

Rob Biedenharn		http://agileconsultingllc.com
Rob@AgileConsultingLLC.com