Registered 2008-07-24 by Zearin

Most technical specifications online fulfill their purpose…but in general they're very long, very dry, and communicate with precision but not clarity. Most specifications can be grasped with a well-presented diagram.

The Schema Collective aims to provide as many as many XML schemas and diagrams as possible, for as many standards as possible, in the most human-friendly way possible.

Each standard in The Schema Collective is to receive its own set of entity-relationship diagrams. Each diagram's goal is to communicate part or all of its standard's spec in such a way as to make its information understandable at a glance (which I like to call “glanceable” 8-D ).

Entity-relationship diagrams have two especially nice qualities:

(1) They can be created as UML Class diagrams, simply by leaving out the methods. (UML likes to call these “operations”.) Technically, this might mean that it's not “really” an ER diagram. But the only differences are cosmetic.
(2) They present—in very understandable terms—RDF models for each standard.

The FIRST ITEM allows a wide choice of free tools to create the diagrams.

I've chosen to use ArgoUML, because it's cross platform, supports graphical export to PNG, and can generate skeleton code in multiple languages from a diagram…but, mostly because I'm familiar with it. :)

I recommend using ArgoUML for diagram work. But if you prefer to use another tool, ArgoUML can export diagrams as XMI, which can be imported into your program of choice. XMI is an open standard designed specifically for representing UML as XML with the goal of allowing this very type of exchange between programming tools.

The SECOND ITEM helps demystify the idea the RDF is horrendously complex. In fact, RDF is a great example of how a specification can make a simple idea seem ridiculously more complex than it actually is. RDF *expressed as XML* can get trickier. But it becomes much less intimidating once it's realized that all that XML can be expressed as a simple ER diagram.

LAST (but not least), the final goal of The Schema Collective is to use those diagrams to provide an XML schema for every standard. There are several types of schema languages for XML. Of all of these, Relax-NG Compact (or “RNC”) schemas are preferred, because they are the most human-friendly, and are easily transformable to the other schema languages. This allows humans to work on a schema in the most human-friendly way, while providing for software that favors another language via the transformations.

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