Formatting an XML Document

To format planets.xml into planets.pdf, we can use the XSL-FO formatting objects that are introduced in Chapter 12. For example, heres how we might display the name of the first planet, Mercury, using XSL-FO formatting objects such as flow and block :

 <fo:page-sequence master-name="page">      <fo:flow flow-name="xsl-region-body">  <fo:block font-family="sans-serif" line-height="48pt"              font-size="36pt" font-weight="bold">              Mercury          </fo:block>          .          .          .

However, writing an entire document using the XSL formatting objects is not an easy task for any but short documents. W3C foresaw that difficulty, and thats one of the main reasons they introduced the transformation language, XSLT. In particular, you can write a stylesheet and use XSLT to transform an XML document so that it uses the XSL formatting objects.

In practice, using stylesheets is almost invariably the way such transformations are done, and its the way well do things in Chapters 11 and 12. All you have to do is supply an XSLT stylesheet that can be used to convert your document to use formatting objects. In this way, an XSLT processor can do all the work for you, transforming a document from a form youre comfortable working with to formatting object form, which you can then feed to a program that can handle formatting objects and display the formatted result.

To make all this self-evident, heres an example using the XML document weve already seen in this chapter, planets.xml:

 <?xml version="1.0"?>  <PLANETS>      <PLANET>          <NAME>Mercury</NAME>          <MASS UNITS="(Earth = 1)">.0553</MASS>          <DAY UNITS="days">58.65</DAY>          <RADIUS UNITS="miles">1516</RADIUS>          <DENSITY UNITS="(Earth = 1)">.983</DENSITY>          <DISTANCE UNITS="million miles">43.4</DISTANCE><!--At perihelion-->      </PLANET>      <PLANET>          <NAME>Venus</NAME>          <MASS UNITS="(Earth = 1)">.815</MASS>          <DAY UNITS="days">116.75</DAY>          <RADIUS UNITS="miles">3716</RADIUS>          <DENSITY UNITS="(Earth = 1)">.943</DENSITY>          <DISTANCE UNITS="million miles">66.8</DISTANCE><!--At perihelion-->      </PLANET>      <PLANET>          <NAME>Earth</NAME>          <MASS UNITS="(Earth = 1)">1</MASS>          <DAY UNITS="days">1</DAY>          <RADIUS UNITS="miles">2107</RADIUS>          <DENSITY UNITS="(Earth = 1)">1</DENSITY>          <DISTANCE UNITS="million miles">128.4</DISTANCE><!--At perihelion-->      </PLANET>  </PLANETS>

In this example, Ill use an XSLT stylesheetwhich youll see how to create in Chapter 11to transform planets.xml so that it uses formatting objects. Then Ill use the FOP processor to turn the new document into a PDF file. Ill also take a look at the formatted document as it appears in Adobe Acrobat.