Zovirl Industries

The Beginning

Out of the box, Blosxom comes with two URL styles for stories and one for categories. URLs for stories can be date-based (http://example.com/2003/12/26#duck.html) or category-based (http://example.com/photography/nature/duck.html). Categories get only category-based URLs (http://example.com/photography/nature/index.html).

After reading several articles on URL design, I decided I wanted something different than what Blosxom gave me. Especially influential were Jakob Nielsen’s URL as UI and Tim Berners-Lee’s Cool URIs don’t change. Tanya Rabourn has also posted a nice list of articles on URI design. After reading those articles, I decided I wanted to have URIs which I could keep forever, without breaking them.

The Plan

The URI format I decided to use is similar to Blosxom’s category-based format, except every URI is extensionless and begins with the creation date of that URI: http://example.com/2003/12/26/photography/nature/duck.

Advantages of this format:

• By starting each URI with a date, I should be able to reorganize my site without breaking links. Old URIs can be pointed to the new locations with 301 redirects
• There is no extension so I can change the default format of the document without changing the URI.
• The URI doesn’t expose any of the technology used to serve the site, so I can change the technology without breaking old links

Disadvantages of this format:

• Since a story will have a different date than the category it is in, URIs aren’t hackable. I don’t know of a way to solve this
• The dates make the URL rather long. This can be solved by including only the year: http://example.com/2003/photography/nature/duck.
• Some items are better without dates. http://example.com/2003/resume looks fine now but in 5 years that “2003″ will look bad. This can be solved by updating the URI every year and using 301 redirects to keep the old URIs working

The Implementation

While reading all the articles I saw a lot of material on how to design URIs and very little material on how to implement them. Getting Blosxom to use my new URI format ended up being more work than I expected. There were two main problems to solve: Blosxom had to generate the new URLs when it served content, and Blosxom had to recognize the new URLs when a client requested something.

I wrote the cooluri2 plugin to make Blosxom recognize the new URLs. The plugin is more complicated than I would like but it works.

Getting Blosxom to generate the new URLs took several plugins. The main one is permalink, which provides permalinks for stories and can be used by other plugins when they need a URL generated. Some files, like binary files and directories, can’t contain metadates and since the new scheme needs dates for everything, I wrote the metadate plugin. It lets metadates reside in an external file, so I can use metadates for all my categories. Finally, I patched the absolute plugin so I can easily reference other stories/files/categories.

Finally, when it comes time to reorganize my site I can do it freely. If I want to change a document’s URI (by moving it or changing the date on it) the old URI can be replaced with a 301 redirect to the new URI.

The Results

The new URI format requires several plugins but adds very little overhead when I’m just writing articles. The only extra thing I have to remember is to update my external metadate file when I add new directories or non-story files (if I forget then the modification time of the file is used, so nothing terrible happens, but I prefer to use metadates since last-modification times are fragile). By including only the year and not the full date in the URI there is very little cruft added. Overall I’m pleased with the results.

This plugin makes Blosxom recognize date-based, extensionless URIs (aka Cool URIs) for both stories and categories. If you are using the static_file plugin, Cool URIs will be recognized for static files also. The main motivation for this URI format is that links never have to break…ever. Goodbye 404 errors! You can read Tim Berners-Lee’s essay for more details on why Cool URIs are cool.

The idea for this plugin was based on the cooluri plugin written by Rob Hague, which makes Blosxom recognize extensionless URIs. Along with Blosxom’s built-in ability to recognize date-based URIs for stories, cooluri did almost what I wanted. It didn’t handle date-based URIs for categories however.

I wrote cooluri2 to do both. Now categories, stories, and static-files all can be referenced by cool URIs, like this:
http://example.com/2003/12/03/category
http://example.com/2003/12/14/category/story

Days and months can be left off if you prefer a shorter URI:
http://example.com/2003/12/category
http://example.com/2003/12/category/story
http://example.com/2003/category
http://example.com/2003/category/story

The date part of the URI is the creation date for that document. Note that stories may have different creation dates then the categories they are in, so you may end up with URIs like this:
http://example.com/2003/10/23/category
http://example.com/2003/12/14/category/story

If you use the cooluri2 plugin, you might want to read about how I converted my site to use Cool URIs.

Download cooluri2 0.0.1

Documentation is available here.