XML Schema

A Worldwide Web Consortium (W3C) recommendation, XML Schema soon gained quite a bit of popularity as an Extensible Markup Language (XML) Schema language. Coupled with the Xs3P style sheet, for example, the schema has become a highly understandable way to communicate XML processes for humans (developers), akin to high-level scripting languages of the past. This, of course, is only an added benefit of the nature of this recommended schema. The original objective was validation and standardization, something achieved quite effectively as a result not only of the generally useful nature of the schema but also the great support it received and a name who’s ambiguity allows easy neglecting of other schema for XML. Material produced using this schema takes the suffix of (.xsd), differentiating it from several other schema which may not invalidate material with different suffixes.

A schema as powerful and extensive as the XML Schema however could not have been designed arbitrarily on the spot. Rather, documentation humbly accepts how much the schema owes to previous efforts that fell short of the success it reached. For example, there was a significant influence on the schema from such predecessors as SOX, XDR, and XML-data. In designing the present schema, the best features of previous schema were integrated while the pitfalls associated with them were ignored, leading to a final product of greater comparable efficiency and use.

In spite of this popularity which doesn’t seem on the verge of ebbing or abating any time in the near future, the schema isn’t without it’s naysayers and criticisms. For example, XML Schema lacks an ordered set of datatypes, giving users rather non-intuitive material with which to work. On top of which, though the schema does present human readable code, this isn’t done without a significant deal of difficulty. Some of the most well-cited critics of the recommended schema have proposed a number of alternatives which resolve these issues, such as RELAX NG. Only time will tell whether the XML Schema can maintain predominance, however, present forecasts are for clear sailing ahead for this schema – leading even more developers to make this choice.

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RELAX NG, an alternative to XML Schema

Though XML Schema, the forerunner in XML schema (no pun intended), has gained quite a bit of popularity over time, it isn’t without it’s critics. And these very same critics, besides producing both constructive, and not so constructive, criticism, have also been regular proponents of a number of alternatives to XML Schema. One of the most well-known and oft-cited criticisms of the presently well-established schema was James Clark, an XML expert at the forefront of the open source software movement, who instead proposed that users adopt RELAX NG. The criticisms of XML Schema were extensive, however, were not meant as criticisms simply of the schema, but of an ignorance of alternatives.

Amongst the criticisms originally levied by Clark, there were those of the schema itself and those of proponents and bodies recommending it (such as the Wordlwide Web Consortium). In the second category, for example, Clark had noted that the proponents had an undeveloped understanding of XML schema and couldn’t tell the difference between two unique schema and two schema who’s relationship was more linear and co-dependent (such as RELAX NG’s evolution from Document Schema Definition Language(s) [DSDL]). Another criticism of this nature was of the proposal by XML Schema proponents that it should adapted as it is already widely used. Clark argued that this was counterproductive as the objective of schema is not populism but of providing a beneficial product – one that actually made it easier for the users to identify legal documents for the relevant applications, which he argued, XML Schema had not provided.

The alternative Clark suggested, RELAX NG, has quite a bit going for it. It’s open and democratic development background as being OASIS is just one aspect of this. Open development of schema has assured countless times that instead of producing bloated products with a heavy bias towards major sponsors, an industry useful project would be produced. The ease with which it is learned and understood being yet another. The list goes on, and it’s quite clear to see that where populism ends and efficiency begins, the industry will find far more beneficial products.

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