As you know, we will be discussing XPath during our next seminar. XPath is a language for exploring XML documents. XQuery and XSLT both make use of XPath. You'll need a good understanding of XPath to make effective use of XQuery.

Here's the input document we'll be using as a reference at our next meeting.

As you see, it's basically a bare bones TEI document. So how can XPath help us to explore the nodes and atomic values in this document? Let's try a few examples:

• Write an expression to select the teiHeader.

  /TEI/teiHeader
  

• Write an expression to select the title of this TEI document.

  /TEI/teiHeader/fileDesc/titleStmt/title/text()
  

• Write an expression to select all p elements in the document.

  //p
  

• Write an expression to select all p elements that have a body element as an ancestor.

  //body/p
  

• Write an expression to select the third p element that is a child of the body element.

  //body/p[3]
  

• Write an expression to select only the text node of the same p element.

  //body/p[3]/text()
  

• Write an expression to select only the first and second p child elements of the body element.

  //body/p[position() = (1, 2)]
  

• Write an expression to select the value of the when attribute of the date element.

  //date/@when
  

• Write an expression to select the parent of any p element with an n attribute.

  //*[p[@n]]
  

• Write an expression to select only those text nodes that are children of elements with n attributes.

  //*[@n]/text()
  

We'll go through all these exercises in class. We'll also learn how to use oXygen to assist with writing and testing our XPath expressions.

See you next week!