XML in a Nutshell, 3rd Edition

Arcs

Paths between resources are called arcs, and they are represented by arc elements; that is, elements of arbitrary type that have an xlink:type attribute with the value arc. Each arc element should have an xlink:from attribute and an xlink:to attribute. The xlink:from attribute identifies the source of the link. The xlink:to attribute identifies the target of the link. These attributes do not contain URIs as you might expect. Rather they contain a name matching the value of the xlink:label attribute of one of the locator elements in the extended link.

Example 10-1 shows an extended link that contains the first three novels in the Wizard of Oz series: The Wonderful Wizard of Oz, The Marvelous Land of Oz, and Ozma of Oz. Arcs connect the first book in the series to the second and the second to the third, and then back again. In this example, the root series element is the extended link element, each novel element is a locator element, and the next and previous elements are arc elements.

Example 10-1. An extended link with three locators and four arcs

<series xlink:type="extended" xmlns:xlink="http://www.w3.org/1999/xlink"> <author>L. Frank Baum</author> <!-- locator elements --> <novel xlink:type="locator" xlink:label="oz1" xlink:href="ftp://archive.org/pub/etext/etext93/wizoz10.txt"> <title>The Wonderful Wizard of Oz</title> <year>1900</year> </novel> <novel xlink:type="locator" xlink:label="oz2" xlink:href="ftp://archive.org/pub/etext/etext93/ozland10.txt"> <title>The Marvelous ...