Datasheet

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Chapter 1: First Steps with XSLT

Try It Out The Saxon CLI

Enter the following code on the command line and execute it:

java net.sf.saxon.Transform -s:xsl_stylesheet.xml -xsl:local.xsl

-o:xsl_stylesheet.html

The options in the example have the following meanings:

-s:filename

: The source XML ﬁle

-xsl:filename

: The XSL stylesheet to use

-o:filename

: The output ﬁlename

The remaining Saxon CLI options are extensive and quite powerful. If you are interested in pursuing the

CLI approach, you should review the Saxon documentation at your leisure before using them.

Transforming XML Data to XML

The next example illustrates how simple it can be to transform content from one XML format to another.

A common transform problem is that two similar schemas will use different names for identical content

values. Another problem is that in one case an attribute is used for a value, while another uses an element

for the same purpose.

The next stylesheet uses two common metadata vocabularies that express information in roughly the

same manner. One is the Atom 1.0 format, increasingly used for blogs and news feeds; the other is RSS

1.0, which uses a combination of the Dublin Core Metadata Initiative vocabulary and RDF/XML.

There is also a version 2.0 ‘‘branch’’ of RSS. Although it is often assumed that RSS 2.0 supersedes

RSS 1.0, it doesn’t; and the versions are incompatible in several ways. RSS 2.0 is also in widespread

use, but we won’t be using it in this chapter. If you want to explore the structure of RSS 2.0, go to

http://cyber.law.harvard.edu/rss/rss.html

Of course, you wouldn’t bother serializing either of these feeds to XML if the data were in a SQL database

or an RDF triple store. However, if you are aggregating the data from feed URLs, or you have been

provided with source data in XML, you won’t have much choice.

Atom and RSS Elements

The next two tables compare the feed elements and entry elements in the Atom 1.0 schema with the

equivalents in RDF Site Summary (RSS) 1.0. The pros and cons of the different ways to describe metadata

can be a contentious issue, but just now we need not be concerned with the details.

The following table lists the top-level elements that deﬁne the properties of the Atom feed in the

<feed>

and RSS 1.0

elements. The matches are quite weak at this level, perhaps reﬂecting the history