Lecture 9: Trees and XML

Slides : Recording

From the strict rectangles of structured data to the more generous triangles of semistructured data. This morning’s lecture gave an overview of what kind of data is seen as “semistructured”; the idea of trees as a mathematical model of data; the particular form of trees in the XPath data model; and their textual representation in XML — the Extensible Markup Language.

XML also has a large number of domain-specific variants. These are all valid XML, and use standardised sets of element types to give a custom language for representing data relevant to a particular field: from musical scores to financial trading.

Links: Slides for Lecture 9; Recording of Lecture 9

Homework

1. Read This

• XML Essentials from the World Wide Web Consortium (W3C).

  Link: XML Essentials — What is XML? What is XML used for?

• Sections 2.1–2.5 from Chapter 2 of Møller and Schwartzbach. I have sent a scanned PDF of this chapter to all students by email; there will also be printed copies outside the ITO in Appleton Tower; and you can find the whole book in the Library HUB.

2. Do This

• Find an SVG file and open it in a text editor to study its XML content.

• Find a Microsoft Office .docx file and look at the XML content in that. This format (OOXML) is in fact a zipped archive of XML files, so you will need to unzip it first. Depending on your platform, this may require renaming the .docx extension as .zip

  Link: Wikipedia on Microsoft’s OOXML format

References

To learn more about XML, try any of the following.

• Read more of An Introduction to XML and Web Technologies, the book in today’s homework reading. There are copies available right now in the Main Library HUB.

• Work through the MusicXML tutorial.

• Browse the full XML specification.

• Have at look at some documents in the Financial Products Markup Language: such as a composite basket equity swap or a European swaption straddle. The full site has dozens of such examples.

  (In case you were wondering: a swaption is an option to undertake a swap in the future; and a straddle is a combination of contracts that returns a profit if a certain security changes price in either direction.)