Kristjan Jansen

Here's some shared experiences I've gained when creating my Drupal site and using its meta system. Actually, its kinda a second installment of series – first part was posted to Drupal-devel mailing list

Here's what I've done:

1. Creating vocabulary

Or in Drupal-speak: creating collection of metatags.

Because my site is about travelling, I had to tie every content item (node) with a geographic location(s). In other words: I had to build up a controlled vocabulary of geographic locations an apply index terms to each node (is it correct, jibbajabbaboy?)

The biggest problem with geographic hierarchies is that you can't use tree-like stucture. The relations with geographic places are far more complex.

For example: Gibraltar – will I found it under category “Spain” (by geogr.location) or under “Great Britain” (political)? Canary Islands – under “Afica”, “Europe”, or “Spain” ?

When definining relations, the primary criteria I used was how Average Joe usually looks for countries. When he mind-maps Canaries to Africa – its ok with me. But just in case I add index terms “Europe” and “Spain” as well.
Anyways, using Drupal 3.0 metatags building such vocabulary is trivial. I defined the collection “Destination” and started adding tags.

 Name: “Africa – Botswana” Attributes: “Africa, Botswana” Collection: “Destination” 

The full list is here: http://trip.ee/module.php?…
As you problaly notice, there's some tags (destinations) twice. This is correct, in there are many cases when some term happens to fall into several categories (in real world: destination crosses the country borders). Examples:

 Africa – Maroc – Sahara Africa – Tunisia – Sahara 

or

 Europe – Austria – Alps Europe – France – Alps Europe – Germany – Alps Europe – Switzerland – Alps Europe – Italy – Alps 

The power of meta.module Ok, time to test out some tags.
Clicking on “Etna” tab (volcano in Italy)…What? Why I see endless list of Vietnam stories?
It seems Drupal is pretty loose when getting nodes from database by attribute. Instead

attributes LIKE ‘%“.$meta.”%’

its should be far more stict.I patched node_attributes_save() to save all attributes separated with commas and always use whitespace in start: " attribute, attribute,". New query looks as follows:

attributes LIKE ‘% “.$meta.”,%’

I'm sure this patch can be implemented much cleaner way, help me out here :)

2. Assigning attributes to nodes

I've been through a laborious 4-month tagging process and the conclusion is clear – first you must retreive from source as much metadata as possible, using machine processing, and then have complete the tagging manually (reviewing and adding data)

Read about the pains of process from my drupal-devel posting

3. Presenting attributes to user

The only place where Drupal show attributes is in $theme->node(), by function node_index().

Function does something really simple – maps every attribute to a link

<a href=index.php?meta=attribute>attribute</a>

.
First, it should be more flexible than that. Presenting attributes to user is a matter of UI, it should not directly derived from storing mechanism. It should take account the metatag name, not just the attributes. Also, someone would like to display an icon (a la Slashdot's topic images) instead of plain link etc. Configurability needed
Second – why map it to index.php? index.php is just a placeholder, instead it should be mapped to some module as parameter $meta:

 <a href=module.php?mod=some_module&meta=attribute>attribute</a> 

While ago I suggested collection handlers – basically this means you can say for each attribute where to map it (what module should accept it as a parameter).
For example, if I have defined metatag collection “Destination” and have a special module destinations.module for displaying destinations, node_index() should map attribute “Spain” to a

<a href=module.php?mod=destinations&meta=Spain>Spain</a>

Time has passed and now I'm sure there are be a better options (passing global variables is just ugly).

All this is getting to complicated in my head. I've been thinking is use the similar system to user roles and permissions – every module can define a new set of features (a la “user permissions”), what can be later assigned to metatags as “roles” – a new UI for a attribute link, mapping to Dublin Core, assigning to a template etc.

More ideas regarding meta attributes:

• Metatag-based templates: I'm not in the state to come up with a proposal, but there were ideas hanging around how to assign templates to certain metatag.
  Something ala Manila metatag plugin: http://zelotes.ent.iastate.edu/…/managetypes http://zelotes.ent.iastate.edu/…/storyReader$229
  “Metatags is the glue that ties everything together” – that was the slogan we used back then :)
• Dublin Core support: This goes together with improved newsfeed import-export. When RSS 1.0 (not yet supported in export) goes in/out from Drupal, it shoud carry DC tags and these should be auto-mapped to/from Drupal metadata.
• Distributed conrolled vocabularies (categories):
  Here's my favourite subject :)

  Currently we use XML-RPC cloud to gather together a dynamic list of Drupal sites http://www.drupal.org/node.php?id=3, but there's far more opportunities.

  I'd like to see a distributed controlled vocabulary where every Drupal site can suggest (and retreive) some index terms to/from central server via XML-RPC. Sever can then compile a master list of terms and generate something like SuperOpenDirectory. This has been already suggested by Moshe: http://mail.zind.net/…/002379.html

  There has been some similar work in RSS camp, namely Syndic8 project. http://www.syndic8.com/services.php (See functions like SetFeedCategory, GetCategory* …)
  RSS categorization is under discussion in Syndic8 mailinglist: http://groups.yahoo.com/…/message/678 http://groups.yahoo.com/…message/2658

• Localization: Although studied some papers, I still haven't found research about localization efforts (jibbajabba – help :). There should be an option to map index terms from one language to another. It's ok to use English-based controlled vocabularies in export-import (flowing content), but for localized sites there should be an option to display index terms in local language.