Project pxml2ods

Converts an XML document with a simplified schema into an ODS spreadsheet document. It will work in concert with other projects to convert scraped web pages into an easily-imported spreadsheet.

Project Purpose

This project exists to serve as a prototype for a C-language version with the same basic utility. It will provide

• A testing place for XSL transformation of the data document
• A testing place for building an ODS document
• A place to discuss design decisions that will be carried over to the C version
• A repository for online references that help develop the application

Design Elements

ODS File Format

This file format is much more complicated than a CSV (comma-separated-values) document that might also serve the same purpose, but its advantage is that the separation between rows and columns is unambiguous. Unlike CSV files, an ODS file can define non-string data-types for more accurate and usable data transfer.

Advantages of the ODS file format

• The ODS file format is directly-readable (need not be imported) by Microsoft Excel as well as most other open-source spreadsheet programs.
• It is much easier to produce that other well-supported spreadsheet formats. The data is stored as an XML document, with other XML and text documents, in a zipped file.

XML Source Format

The XML document that is the source for the ODS file must conform to some simple rules. The rules are a greatly-simplified version of the XML document created by the Schema Server component.

• The document must include a schema element as a child of the document element, and the table rows must be elements that are also direct children of the document element.

• The schema must include a row-name attribute, the value of which is the name of the row elements.

• The schema must contain a collection of field elements containing a name attribute that corresponds to an attribute of the row elements.

• The spreadsheet columns will consist of the field elements of the schema, in document order.

<?xml version=1.0?>
<list>
   <schema row-name="row">
      <field name="id" />
      <field name="fname" />
      <field name="lname" />
   </schema>
   <row id="1" fname="Tom" lname="Swift" />
   <row id="2" fname="Phyllis" lname="Newton" />
</list>

XSL Transformation

Using libxml2 to parse HTML pages makes even very-badly formatted HTML usable as well-formatted XML. XSL is the ideal tool for converting XML to other forms because it is a mature design with good conversion tools available.

References

• OpenDocument technical specification