12、Web Data Query: Node, Link Objects, and Predicates

Web Data Query: Node, Link Objects, and Predicates

1. Node and Link Objects

1.1 Label Usage

In dealing with node and link objects, typically one of two types of labels is employed. Node labels hold an advantage as it’s straightforward to convert edge labels to node labels. This is done by creating a node to represent the edge and transferring the label to it. As a result, the model can be applied to edge - labeled trees as well.

1.2 XPath

The World Wide Web Consortium has recommended XPath as a language for operating on the logical structure of XML documents. It models XML as a tree of nodes at a higher level than the DOM but doesn’t describe the abstract logical structure.

1.3 Open Hypermedia System

Open h