A sorely needed module for Drupal ... some functions exist but others do not.

Feb 16 2009: new authoritative upgrade guide from Drupal.

There are a good series of articles on the subject from becircle.com. This could be the start of something big ... if I'm not careful.

I must say that preliminary results have been a mixed bag. It's probably something I'm doing, but in any case, upgrading a medium-sized site with half-a-dozen modules to Drupal 6 is far from a trivial undertaking at this point of time. That may change in the coming months - I hope so.

Update: Jan 16 2009 - Current development release ( rules-6.x-1.x-dev ).
Update: Sept 29 2008 - Current production release ( 6.x-1.0-beta3 )

Wolfgang Ziegler ( a.k.a. fago ) has started a project derived from the workflow-ng module to create a Drupal rules nodule implementing inference engine functionality, tightly coupled to the Workflow-NG module. One presumes that the rules engine will implement forward/backward chaining and be pluggable into the workflow engine.

The game's a foot.

From the Workflow-NG project page, a list of Drupal 5 modules that integrate with Workflow-NG ( other than Workflow ):

It's getting serious. Things are moving resolutely forward toward Drupal 6 and 7.

The seems to be some confusion about the difference between 'rule engines' and 'semantic web' applications.  See related link to "Semantic Web Inferencing versus Rule Engines"

Potential RDF use cases for Drupal - an excellent article about RDF in Drupal 6 - 7.

The Drupal RDF module uses the recently-rewritten ARC2 RDF Library if available but apparently does not require it.

Also a link to CCK-related modules.

From the drupal.org post, Semantic Search - Faceted Search and Semantic Web:

From the project page:

Node linking and Metadata

The Relationship Manager module is intended to allow free-form links between nodes, recording not just that one page relates to another, but HOW it relates. ... The core module is made available to be extended by other modules that wish to make use of the generalized relationship management functions. Several examples of simple modules that leverage this power are provided as optional plugins.

The major plugins are:

Revised: Sept 20 2007

After a great burst of initial activity with the NINA project and then with Dan Morrison driving the Relationship Manager project, there was good momentum to semantic web projects for Drupal. But the efforts seem to have gone into something like a hiatus during the the last year or so.

Drupal has been good to me, no question about it.

I had planned to roll up my sleeves and do some PHP coding to make it work the way I wanted. But, between the Drupal core, Links and a few other modules, it pretty much does what I need already ( with maybe some more meta-data for the links ). So instead of coding PHP, I devote my time to creating content, which was the point of the exercise in the first place. It's worked very well for my purposes.

According to the Drupal web site,

From the jQuery site: "jQuery is a fast, concise, JavaScript Library that simplifies how you traverse HTML documents, handle events, perform animations, and add Ajax interactions to your web pages".

jQuery is also the base Javascript library in Drupal.

Also see the Weblink to PQuery.

More on Drupal Performance Tuning and Optimization for large web sites.

One of the main Drupal articles on Server Tuning Considerations.

Drupal's Performance and Scalability forum. 

 An interesting article: Drupal Performance Tuning and Optimization for large web sites.

Relationship Module ( CVS Repository )

Discussion about relationships and set theory