XPath at a Glance
XPath 1.0 is a W3C recommendation available for your perusal from the W3C web site (http://www.w3.org/TR/xpath). XPath allows for the retrieval of portions of an XML document via XPath expressions. The specification defines a concrete syntax for expressions and offers a well-defined meaning for the expressions when interpreted. When an XPath expression is processed with a DOM, the nodes that match the expression are returned to the caller. XPath expressions target a specific node, or groups of nodes, within an XML document. The result is one of four types:
A collection of nodes
A Boolean value
A floating-point number
A string
In XPath, the term context refers to the location in the document where the XPath expression is being applied. You may start from the document element (the root element) or from any descendent element. XPath may inform you of the current context node (representing the current location in the document). A pair of integers may represent context position and context size. There may also be variable bindings in the context, available functions, and a namespace relevant to the current position.
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