XML reading notes

Reading Question -How prevalent have XML schema become and will they replace the traditional XML format?

muddiest point - As we contemplate moving toward a standard metadata schema for all groups will that require something like Dublin Core to continue adding elements and will that make it far less simplistic if it were to grow to include groups such as archives. Does interoperability matter as much with EAD since it is the accepted standard within the archival community and so all sharing of metadata will all be done in EAD?

Reading Notes:

XML is designed to make it easier to interchange structured documents over the Internet. Defines how structured URLs can be used to identify components of XML data streams.

XML elements ensure that document creators put information in its appropriate place which is the Document Type Definition.

Allows users to:
-bring multiple files together to form compound documents.
-identify where illustrations are to be incorporated into text files and the format used to encode each illustration.
-provide processing control information to supporting programs such as doc. validators and browsers.
-add editorial comments to a file.

Core XML technologies:
-unicode defines strict rules for text format as well as the DTD validation language
-XML is a simplification of SGML and includes adjustments that make it better suited to the web environment.

XML Catalogs - defines a format for instructions on how an XML processor resolves XML entity identifiers into actual documents

URIs - uniform resource identifiers. an extensions of URLs

XML Namespaces - provides a mechanism for universal naming of elements and attributes in XML

XML Schema:
-defines elements that can be in a doc.
-what attributes can be in a doc.
-which elements are child elements
-the order of child elements
-the # of child elements
-whether and element is empty or can define text
-defines data types for elements and attributes
-defines default and fixed values for elements and attributes

XML Schema are the successor to DTDs because:
-They are extensible to future additions
-richer and more powerful than DTDs
-Schemas are written in XML
-support data types
-support namespaces

Schema support data types:
-easier to describe allowable document content, correctness of data, data from a database, restrictions on data. Also easier to define data formats and convert data between different elements.

-even well formed XML documents still contain errors but most of these will be found by validator in XML schema.

Simple Element - an XML element that can only contain text w/o other elements or attributes allowed.

attribute - string, decimal, interger, boolean, date, time
restrictions - used to define acceptable values for XML elements or attributes.

Complex Elements:
-Empty Elements
-elements that contain only other elements
-contain only text
contain both elements and text.

Indicators:
order indicators - used to define the order of element
-all
-choice - specifies that one child element or another can occur
-sequence - child elements must occur in a specific order

Occurance Indicators:
maxOccurs
minOccurs

Group Indicators - elements are defined with a group decleration
group names
attributGroupe name

Any Element - enables an XML doc. w/ elements not included in a schema

String data type- used for values that contain character strings. can contain characters, live feels, carriage returns and tab characters

Misc. Data Types - boolean, base64Binare etc.