RDF to describe XML::Edifact Namespaces: RDF to describe XML::EDIFACT namespaces

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## 2. RDF to describe XML::EDIFACT namespaces

XML::Edifact has several default namespaces. Those are called edifact, trsd, trcd, tred, uncl, anxs, anxc, anxe, unsl and unknown. The edifact namespace is intended to cover the overall message, while the four character namespaces are extracted from their UN/EDIFACT batch directory counterparts.

But XML document type definitions are badly suited to constrain Edifact messages. While any valid UN/EDIFACT message will produce a valid XML::Edifact message, it would be possible to hack a valid XML::Edifact message, where the conforming UN/EDIFACT is not even well formed!

Once a UN/EDIFACT message is parsed, translated to XML and stored in a DOM, it may have elements in the unknown namespace, most likely to come from unknown codes. As those elements from the unknown namespace are not defined in the edifact document type definition, a validating parser would trigger further checks. The parser now has to query a resource description framework to find a resolution for the unknown namespace. The Document now has migrated in namespace. Now it's not an edifact:message, but perhaps an editeur or etis:message or even a kraehe:message, if we agree on private extensions. Even if a resolution cant be found the document would migrate in namespace becoming an unknown:message as unknown:message's can have unknown elements.

Further checks using the RDF are now necessary. The current document has a generic type and is just a sequential collection of translated UN/EDIFACT segments. The parser may check those segments using the RDF files provided for each namespace, when designing new messages. Most important are checks in the top level RDF the document type will migrate from the generic edifact:message to edifact:invoic or edifact:orders, the structure of segment groups will be patched into the DOM on that time.

A last check using trading partner and document type as index on a RDF will round up for trade partner constrains. Now the message can be further processed.

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