This is last in a series of related posts on Fun Tech Stuff going under the hood with XML and its uses in learning technologies: Learning Management Systems, SCORM, Tin Can, Metadata, and XML, as well as examples of XML in SCORM and XML in eBooks.
Most ebooks, including the Kindle (with minor proprietary variations), are based on the open, XML-based EPUB standard. And what does an EPUB ebook look like on the inside? Believe it or not, it is essentially a zip file. And if you unzip it, you will find a folder with a whole set of other files and folders filled with XML files, XHTML files (a stricter version of HTML), image files, and maybe even sound and video files. All these files are stitched together—you guessed it—through the magic of XML, doing it’s semantic job of providing meaning and context to all that surround it.
One of the key files in an ebook is the content.opf file. It tells the ebook reader (e.g., your iPad or Kindle) what the book is, and how to navigate through it.
Let’s take a peek inside.
1. Yay! The file starts with a line that identifies it as an xml file.
2. The next line defines it as a package file, as defined by the Open Packaging Format bit of the EPUB standard.
3. Next comes the metatada section. Notice the “dc:”? That refers to the Dublin Core metadata standard discussed in our previous Metadata post.
4. Next comes the manifest, with its list of all the files that make up the ebook.
5. Finally comes the spine, which tells your ereader the order in which the content should be presented.
And those are just a few of the ways in which XML helps people and computers work more closely together to improve the meaning and the context of information.