Topic: XML schemas

topics > computer science > data > Group: data type

type checking

database schema
hypertext subsets, webs, and contexts
schemas for hypertext
semi-structured text
semistructured messages for automated processing
translation of data
XML data type


An XML document may define a schema the restricts the elements, attributes, and sequences. The schema defines the data type of the document. A document is validated if it conforms to its schema.

When defining a schema, information may be encoded as attributes or as textual elements. Attributes must be simple, single-valued, and unordered. Attributes serve the same role as columns of a relational database.

Schemas are important for transformations. Transformations can be guaranteed for validated documents. Schemas help to insure that a transformation is complete. (cbb 7/06)

Subtopic: XML schema up

Quote: XML should be understandable and useable without a universal schema [»boswA10_2005]
Quote: an XML schema is a shared secret that ties clients and servers together
Quote: RELAX NG specifies a class of XML documents as labeled-trees [»vandE_2004]

Subtopic: XML type up

Quote: XML types are composed of atomic types and element types; sequence, choice, multiple occurrence; optional element name and type name [»simeJ1_2003]
Quote: an untyped XML value is a sequence of untyped elements and strings; e.g., XML before validation [»simeJ1_2003]
Quote: an XML value is a sequence of zero or more elements and atomic values, strings or integers; an element has a name, optional type, and value [»simeJ1_2003]

Subtopic: XML processing up

Quote: to combine XML processing components reliably, it is essential to verify their inputs and outputs; most components do not accept arbitrary XML documents [»vandE_2004]

Subtopic: XML validation up

Quote: a validated element must match its type, since validation yields sensible values; consequence of pure named typing [»simeJ1_2003]
Quote: instead of matching, an XML value validates against a type; either produces an internal value or it fails; e.g., element ints of type intsType { 1, 2, 3 } [»simeJ1_2003]

Subtopic: path consistency up

Quote: path consistency -- the valid trees for a node only depend on the path to the node; allows a subtree to move to the same location in another tree [»fostJN8_2005]

Subtopic: XML synchronization up

Quote: Harmony synchronizes tree-structured data formats using their schema; handles conflicts [»fostJN8_2005]
Quote: a syncronizer should be safe, maximal, and schema preserving; do not back out changes; do not make up content; do not propagate conflicts [»fostJN8_2005]

Subtopic: formalizing XML schema up

Quote: formalization of XML Schema used for XQuery and XPath specifications; one of the first
Quote: formalization of XML Schema using tree grammars; named types and structural types; matching and validation [»simeJ1_2003]
Quote: XML cannot distinguish integers from strings; XML Schema requires all type extensions before validation [»simeJ1_2003]

Subtopic: translation up

Quote: translate between partially shared object types: automatic adoption, type translation, translation to supertype

Related Topics up

Group: type checking   (12 topics, 392 quotes)

Topic: database schema (29 items)
Topic: hypertext subsets, webs, and contexts (12 items)
Topic: schemas for hypertext (7 items)
Topic: semi-structured text (17 items)
Topic: semistructured messages for automated processing (22 items)
Topic: translation of data (26 items)
Topic: XML data type
(22 items)

Updated barberCB 6/05
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