W E N D Y H A G E N M A I E R & C A R I S H U R D F A L L 2 0 1 1

Introduction to XML

The Machine is Us/ing Us

What is XML?

•  stands for “eXtensible Markup Language” •  is a language for documents containing structured information

•  structured information – contains both content (words, pictures, etc.) and some indication of what role that content plays • XML vs. HTML: XML was designed to transport and store data. HTML was designed to display data.

Tags?! What are those?

<?xml version= “1.0”?> <example> <quote type=“movie”>The dude abides.</quote> </example>

More info

<?xml version= “1.0”?> <example> <quote>The dude abides.</quote> </example>

F. I. L. O. First In Last Out

We’ve got the M, Let’s return to the X

X stands for “extensible” in XML – remember?

•  Extensible means there is NO predefined tag set •  XML is pretty general, in that it allows users to define their

own tags and the relationships between them

DTDs Make Rules for Tags

•  Without rules, your document and tags will be worthless to others •  Rules are set with a DTD

DTD = Document Type Definition

Your DTD defines all kinds of things! •  what tags can be nested inside of other tags •  what kind of information can be stored inside certain tags

Sample DTD #1

<?xml version =“1.0” encoding=“US-ASCII”?>…our XML declaration statement

<!DOCTYPE customerorder [ <!ELEMENT Customer (Name, Email)> <!ELEMENT Name (#PCDATA)> <!ELEMENT Email (#PCDATA)> <!ELEMENT Physical Address (street, unit#*,

city, state, zipcode)> <!ELEMENT street (#PCDATA)> <!ELEMENT unit# (#PCDATA)> <!ELEMENT city (#PCDATA)> <!ELEMENT state (#PCDATA)> <!ELEMENT zipcode (#PCDATA)> <!ELEMENT Shipment (ShipDate, ShipMode)> <!ELEMENT ShipDate (#PCDATA)> <!ELEMENT ShipMode (#PCDATA)> ]>

Parent and Child Elements ¡  Child elements are the only ones that can be

nested inside of Parent elements ¡  An example of DTD’s rule making abilities!

Parent = Customer ¡  Children =

÷  Name ÷  Email

Sample DTD #2 <!DOCTYPE TVSCHEDULE [ <!ELEMENT TVSCHEDULE (CHANNEL+)> <!ELEMENT CHANNEL (BANNER,DAY+)> <!ELEMENT BANNER (#PCDATA)> <!ELEMENT DAY (DATE,(HOLIDAY | PROGRAMSLOT+)+)> <!ELEMENT HOLIDAY (#PCDATA)> <!ELEMENT DATE (#PCDATA)> <!ELEMENT PROGRAMSLOT (TIME,TITLE,DESCRIPTION?)> <!ELEMENT TIME (#PCDATA)> <!ELEMENT TITLE (#PCDATA)> <!ELEMENT DESCRIPTION (#PCDATA)> <!ATTLIST TVSCHEDULE NAME CDATA #REQUIRED> <!ATTLIST CHANNEL CHAN CDATA #REQUIRED> <!ATTLIST PROGRAMSLOT VTR CDATA #IMPLIED> <!ATTLIST TITLE RATING CDATA #IMPLIED> <!ATTLIST TITLE LANGUAGE CDATA #IMPLIED> ]>

Element Type Declarations

Element Type Declaration Definition

EMPTY No content allowed

ANY Any content allowed

a,b Specific order (a, followed by b)

X|Y Either/or (X or Y)

a,b,(X|Y) Groups (a, then b, then X or Y)

* Zero or more elements allowed

+ One or more elements allowed

? Zero or one element allowed

One and only one allowed

#PCDATA Parsed character data

Sample DTD #2 (again) <!DOCTYPE TVSCHEDULE [ <!ELEMENT TVSCHEDULE (CHANNEL+)> <!ELEMENT CHANNEL (BANNER,DAY+)> <!ELEMENT BANNER (#PCDATA)> <!ELEMENT DAY (DATE,(HOLIDAY | PROGRAMSLOT+)+)> <!ELEMENT HOLIDAY (#PCDATA)> <!ELEMENT DATE (#PCDATA)> <!ELEMENT PROGRAMSLOT (TIME,TITLE,DESCRIPTION?)> <!ELEMENT TIME (#PCDATA)> <!ELEMENT TITLE (#PCDATA)> <!ELEMENT DESCRIPTION (#PCDATA)> <!ATTLIST TVSCHEDULE NAME CDATA #REQUIRED> <!ATTLIST CHANNEL CHAN CDATA #REQUIRED> <!ATTLIST PROGRAMSLOT VTR CDATA #IMPLIED> <!ATTLIST TITLE RATING CDATA #IMPLIED> <!ATTLIST TITLE LANGUAGE CDATA #IMPLIED> ]>

Attribute List

<example> <quote type=“movie”>The dude abides.</quote> </example>

<!ELEMENT quote (#PCDATA)> <!ATTLIST quote type CDATA #REQUIRED>

Attribute example in XML:

Attribute example defined in DTD:

http : / / t inyurl .com/3r5o9y2

Now let’s try doing it!

1.  Download two files to your desktop

2.  Save them in a new folder called “xml_practice”

3.  Open them in Oxygen

XSD versus DTD

Applying XML

EAD! •  stands for Encoded Archival Description •  is a XSD (but all the rules are already made for you!) •  started in 1993 as part of The Berkeley Project at the Univ. of California – Berkeley •  based on commonalities between finding aids sent in by archivists around the world •  The prototype of EAD was released on February 26,1996! •  Today the official EAD standards are maintained by The Library of Congress and the Society of American Archivists. •  If you’re in Archival Enterprise I and have any questions about the EAD assignment, feel free to come to the lab and ask us questions!

http://www.loc.gov/ead/ http://www.archivists.org/saagroups/ead/

Applying XML (cont’d)

There are hundreds, but just to name a few…

•  XHTML http://www.w3.org/TR/xhtml1/ •  CML http://www.xml-cml.org/ •  WML http://www.openmobilealliance.org/Technical/wapindex.aspx •  ThML http://www.ccel.org/ThML/ •  WebML http://webml.org/webml/page1.do •  LegalXML http://www.legalxml.org/committees/index.shtml •  Text Encoding Initiative (TEI): http://www.tei-c.org/index.xml

Resources

•  http://www.w3.org/XML/ •  http://www.w3schools.com/xml/default.asp •  http://www.w3schools.com/dtd/default.asp •  http://www.tizag.com/xmlTutorial/ •  http://www.loc.gov/ead/ •  http://www.archivists.org/saagroups/ead/ •  XML syntax validator:

http://www.w3schools.com/xml/xml_validator.asp •  More about ATTLIST:

http://www.w3schools.com/dtd/dtd_attributes.asp