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XMLAn Overview
Roger DebrecenyUniversity of Hawai`i
Skip WhiteUniversity of Delaware
XBRL Workshop, August 2006
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XMLThe eXtensible Markup Language
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Markup languages
What is a markup language? Markup languages “markup” text (data) so
that one string of text can be distinguished from another!
What does the following mean? 141 68 7.5
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XML
Markup language Could be anything – space, comma, tab , … Need agreement on the markup!
eXtensible Able to “extend” Need agreement on the markup rules!
<weight> 141 </weight> <height> 68 </height> <shoeSize> 7.5 </shoeSize>
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HTML
HyperText Markup Language An agreed-on language for creating Web pages A fixed set of tags as markup
<head> <title> My Web Page </title> </head> <body> <center> Hello – Welcome to my Web page!
</center> </body>
Tells a browser how to display things!
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XML - markup for documents
The markup rules & syntax that all “well-formed” XML documents must follow: One and only one root element All elements must be properly nested All non-empty elements must have the same
beginning and ending tag names (case-sensitive)
Elements can contain data items or other elements (mixed is considered bad form)
All elements can contain attributes
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XML Elements
The basic unit of all XML documents is the “element” A root element
Is the master element … the overall “container” Its name tells what the document is all about
Simple elements contain data values and do not have attributes <IdNumber> 12345 </IdNumber>
Complex elements have attributes and/or other elements nested within <Weight units=“OZS”>12.00</Weight> <InventoryItem>
<IdNumber>12345</IdNumber> <Weight units=“OZS”>12.00</Weight> </InventoryItem>
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XML document (part 1) <SalesOrder>
<CustomerInformation> <CustomerNumber>12345</CustomerNumber> <Address type=“shipping” sameAs=“billing”>
<FirstName>Skip</FirstName> <LastName>White</LastName> <StreetAddress1> 1234 Main Street
</StreetAddress1> <StreetAddress2></StreetAddress2> <City> Newark </City> <State> DE </State> <ZipCode> 19716 </ZipCode> <Country> USA </Country> </Address>
<Address type=“billing” sameAs=“shipping”/> </CustomerInformation>
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XML document (part 2) <OrderInformation>
<OrderNumber>111</OrderNumber> <OrderDate>2006-08-02</OrderDate> <CreditCard type="VISA"> <CardHolderName> Skip
White</CardHolderName> <CardNumber>
1234567891011213</CardNumber> <ExpirationDate>
2009-05</ExpirationDate> </CreditCard> <Item> <ItemId>srh123</ItemId> <ItemDescription> Specialized RH
Mountain Bike </ItemDescription> <Size units="in">19</Size> <QuantityOrdered> 1</QuantityOrdered> <SalePrice units="USD">
550.00</SalePrice> </Item> </OrderInformation>
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XML documents What can we say about XML documents?
XML documents are made up of tags (markup) that add meaning/context to data items A pair or tags and its content is known as an element
XML elements can contain attributes within the beginning tag – attributes add meaning! The XML attribute format is: attributeName=“value”
XML documents are structured in a strict hierarchy
Well-formed XML documents can be processed by an XML processor
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XML Documents
Why are XML documents so popular for storing and transforming information on networks? Easy to create & understand Contain data with meaning & context
Processing data as information Very efficient for computers to process A standardized and non-proprietary
language
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XML Fundamentals
XML documents are hierarchical Structured as tree-like hierarchies
XML documents are self-describing Each piece of data (information) has
descriptive information associated with it XML is directly usable over the Internet
Designed for storing & delivering information XML does not currently replace HTML
XML describes the content while in most cases HTML is used to tell a browser how to display it
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Information in XML Documents
So … What do you have when you have information in XML documents? You have information that can be
understood by humans as well as ANY COMPUTER APPLICATION!!!
XML is being referred to as the Rosetta Stone of networked computing! The transfer of information between computer
applications and between computers and humans will become much more intelligible and automatic
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XML specifications
XML is a set of rules and syntax for creating XML documents and specifications (stds.) that extend the capabilities of XML XML documents are used to store and transfer
structured data over computer networks XML specifications extend the basic rules of XML
to create languages & vocabularies to be used to: Define the contents & structure of XML documents Process XML documents Create languages to support XML document processing
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XML Specifications XML Schema language
To define the allowable contents & structure of XML documents & to create additional XML specs.
XML Namespaces (xmlns) A collection of element names & attributes for
a particular purpose - like business reporting & they help to avoid naming collisions!
XML Linking Language (XLink) Attributes to be used to define sophisticated
links between networked resources XBRL – a special purpose XML vocabulary!
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XML namespaces
The naming collision problem: What if within your company, you have an
accounting department & a shipping department and they each want to use the XML element name “status” to mean things uniquely relevant to them? In accounting, status is used to mean billed or
not! In shipping, status is used to mean shipped or
not!
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XML namespaces
The solution Create a separate namespace for each
department & within each namespace, define the element name “status”
myCompany.com/xml/accounting Preferred namespace prefix: acct <status> billed (notBilled) </status>
myCompany.com/xml/shipping Preferred namespace prefix: ship <status> shipped (notShipped) </status>
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XML namespaces in XML docs.(a sales order status report) <SalesOrderStatus xmlns:acct=“http://myCompany.com/xml/accounting” xmlns:ship=“http://myCompany.com/xml/shipping”>
<OrderNumber> 12345 </OrderNumber> <OrderDate> 2006-08-02</OrderDate> <ship:Status> shipped </ship:Status> <acct:Status> notBilled </acct:Status> </SalesOrderStatus>
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XML Namespaces
XML namespaces Contain a collection of elements & attributes for a
particular purpose In XML documents:
Namespaces must be declared using the xmlns attribute (usually declared in the root element) xmlns:prefix=“http: namespace URI”
After declaration, a namespace prefix can be appended to an element or an attribute – designates that it was defined in a particular namespace (for a particular purpose) <us-gaap-ci:CurrentAssets>10000</us-gaap-
ci:CurrentAssets>
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XLink language
The XML XLink language A link is an explicit relationship between any
addressable resources – information or services The XLink specification defines a set of
attributes that can be used with any XML element to create explicit relationships
Simple links (commonly seen on Web pages) are unidirectional from a source to a target doc.
Extended links are two-way and multidirectional and can describe relationships
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Xlink language XLink is used heavily in the XBRL
specification (& in XBRL documents) To link a taxonomy to an XBRL instance
document <link:schemaRef xlink:type=“simple”
xlink:href=“us-gaap-ci-2005-02-28.xsd”/> <us-gaap-ci:CurrentAssets>10000</us-gaap-
ci:CurrentAssets> To define relationships between facts
reported in an XBRL instance document To create “linkbases” to provide additional
information about accounting concepts in instance documents
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Summary – Introduction to XML
XML is a set of rules and syntax for creating XML documents and specifications (stds.) that extend the capabilities of XML XML documents are used to hold and transfer
structured data over computer networks XML specifications extend the basic rules of
XML to create languages & vocabularies XML Namespaces XML XLink language XML Schema language XBRL – a special purpose XML vocabulary
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Reference material
W3C Schools – XML tutorial: http://www.w3schools.com/xml/default.asp
W3C Schools – HTML tutorial: http://www.w3schools.com/html/default.asp
HTMLHelp.com – HTML references & tutorials: http://www.htmlhelp.com/
