Technical Standards

Because developers are using XML for so many different purposes and XML can accommodate significant complexity, there are understandable difficulties covering all the potential cases of XML document processing. Therefore, there are several standards that add rigor to the XML processing model. These standards ensure that XML documents remain portable, interchangeable, and unambiguous. These are some of the more important ones.

• XML Infoset. The original XML specification focused primarily on defining how to process content from the document perspective. There was no means to construct an abstract model of document information. This made it very difficult to perform operations like determining if two documents contain the same logical information. If they order elements differently, contain different whitespace, or use alternative syntax for empty elements, the document representations are different. Infoset acts much like a data dictionary for documents, cataloging only the logical information they contain, so that processing software can operate on them at a more abstract level.

• XML Include. Developers commonly want to partition their code into different files for programming convenience. XInclude enables developers to include an external XML file in another. While technically a new feature, all of the issues with delivering it lie in the details of internal processing and treatment of content from the external file.

• XML Fragment Interchange. The issues of processing content from an external source become even more difficult if the content is only a fragment of a complete file. While conceptually straightforward, treating such fragments appropriately requires a significant amount of work on the processing model. Therefore, it is really more of a technical issue than a feature issue.