Content and SystemsToday’s goalsThe Digital Library ContentContent - requirementsDescribing the contentMetadataXMLXML rulesElement namingElements and attributesRepeating elementsUsing XML - an exampleProcessing the XML dataDocument Type DefinitionPowerPoint PresentationXML exerciseAnother exampleSlide 18VocabularyVocabulary exampleDublin CoreDublin Core elements see: http://dublincore.org/documents/dces/A DSpace exampleIEEE - LOMComputing systemsThis sessionContent and Systems Week 3Today’s goals•Obtaining, describing, indexing content–XML–Metadata•Preparing for the installation of Dspace–Computers available–User names and passwords–AccessThe Digital Library Content•Essential elements for a digital library–Users–Content–ServicesContent - requirements•Store–Organize–Describe•Find•DeliverDescribing the content•How to describe content–Metadata•Machine readable description of anything•What description–Machine readable requires standard descriptive elements•Dublin Core (http://dublincore.org/)–International standard–“a standard for cross-domain information resource description.”–15 descriptive elements•Other metadata schemes–IEEE-LOMMetadata•What does metadata look like?•Metadata is data about data–Information about a resource, encoded in the resource or associated with the resource.•The language of metadata: XML–eXtensible Markup LanguageXML•XML is a markup language•XML describes features•There is no standard XML•Use XML to create a resource type•Separately develop software to interact with the data described by the XML codes.Source: tutorial at w3school.comXML rules•Easy rules, but very strict•First line is the version and character set used: –<?xml version="1.0" encoding="ISO-8859-1"?> •The rest is user defined tags•Every tag has an opening and a closingElement naming•XML elements must follow these naming rules:–Names can contain letters, numbers, and other characters–Names must not start with a number or punctuation character–Names must not start with the letters xml (or XML or Xml ..)–Names cannot contain spacesElements and attributes•Use elements to describe data•Use attributes to present information that is not part of the data–For example, the file type or some other information that would be useful in processing the data, but is not part of the data.Repeating elements•Naming an element means it appears exactly once.•Name+ means it appears one or more times•Name* means it appears 0 or more times.•Name? Means it appears 0 or one time.Using XML - an exampleDefine the fields of a recipe collection:<?xml version="1.0" encoding="ISO-8859-1"?><recipe><recipe-title> </recipe-title><ingredient-list> <ingredient> <ingredient-amount> </ingredient-amount> <ingredient-name> </ingredient-name> </ingredient></ingredient-list><directions></directions></recipe>ISO 8859 is a character set. See http://www.bbsinc.com/iso8859.htmlProcessing the XML data•How do we know what to do with the information in an XML file?–Document Type Definition (DTD)•Put in the same file as the data -- immediate reference•Put a reference to an external description•Provides the definition of the legitimate content for each elementDocument Type Definition•<?xml version="1.0" encoding="ISO-8859-1"?>•<!DOCTYPE recipe [•<!ELEMENT recipe (recipe-title, ingredient-list, directions)>•<!ELEMENT recipe-title (#PCDATA)>•<!ELEMENT ingredient-list (ingredient)*>•<!ELEMENT ingredient (ingredient-amount, ingredient-name)>•<!ELEMENT ingredient-amount (#PCDATA)>•<!ELEMENT ingredient-name (#PCDATA)>•<!ELEMENT directions (#PCDATA)> ]>Repeat 0 or more times<?xml version="1.0" encoding="ISO-8859-1"?><!DOCTYPE recipe SYSTEM “recipe.dtd”><recipe><recipe-title> Meringue cookies</recipe-title><ingredient-list> <ingredient> <ingredient-amount>3 </ingredient-amount> <ingredient-name> egg whites</ingredient-name> </ingredient> <ingredient> <ingredient-amount> 1 cup</ingredient-amount> <ingredient-name> sugar</ingredient-name> </ingredient> <ingredient> <ingredient-amount>1 teaspoon </ingredient-amount> <ingredient-name> vanilla</ingredient-name> </ingredient> <ingredient> <ingredient-amount>2 cups </ingredient-amount> <ingredient-name>mini chocolate chips </ingredient-name> </ingredient></ingredient-list><directions>Beat the egg whites until stiff. Stir in sugar, then vanilla. Gently fold in chocolate chips. Place in warm oven at 200 degrees for an hour. Alternatively, place in an oven at 350 degrees. Turn oven off and leave overnight. </directions> </recipe>Not the way that I want to see a recipe in a magazine!What could we do with a large collection of such entries?How would we get the information entered into a collection?External reference to DTDXML exercise•Design an XML schema for an application of your choice. Keep it simple.•Examples -- address book, TV program listing, DVD collection, …Another example•A paper with content encoded with XML: http://tecfaseed.unige.ch/staf18/modules/ePBL/uploads/proj3/paper81.xml•First few lines:•<?xml version="1.0" encoding="ISO-8859-1"?>•<?xml-stylesheet href="ePBLpaper11.css" type="text/css"?>•<?xml-stylesheet href="ePBLpaper11.xsl" type="text/xsl"?>•<!DOCTYPE paper SYSTEM "ePBLpaper11.dtd">•<paper id="proj3">• <info>• <title>Standards E-learning and their possible support for a rich pedagogic approach in a• 'Integrated Learning' context</title>• <authors>• <author>•<firstname>Rodolophe</firstname>•<familyname>Borer</familyname>•<homepageurl>http://tecfa.unige.ch/perso/staf/borer/</homepageurl>•<email/>• </author>• </authors>"ePBLpaper11.dtd” shown on next slide<?xml version="1.0" encoding="ISO-8859-1" ?><!-- _________ _____________________ --><!-- ePBL-project DTD for student project management & specification --><!-- Copyright: (2004) [email protected] --><!-- http://tecfa.unige.ch/~paraskev/ --><!-- Daniel K. Schneider --><!-- http://tecfa.unige.ch/tecfa-people/schneider.html--><!-- Created: 13/11/2002 (based on EVA_pm grammar) --><!-- Updated: 07/05/2004 --><!-- VERSIONS --><!-- v1.1 Adaptations to use with Morphon xml editor and addition of IDs--><!-- ____________________ --><!-- _ ENTITY DECLARATIONS ______