Introduction the course and XML

1
Introduction the course and XML

• Shiyong Lu

2
Course Info

• CSC8710 Seminar on Database Management 
• Time 600-720PM TuTh
• Place State Hall 213
• Webpage http//www.cs.wayne.edu/csc8710

3
What is this course about?

• Reading XML papers
• Doing XML projects
• Conducting XML research (writing research papers
  on XML)

4
Reading XML papers

• Each student will present one paper selected from
  the list of papers covering the following
• Using RDBMS to store and query XML
• Publishing relational data as XML
• XML constraints
• XML integration
• Query and searching XML data
• XML algebra, XPath, type checking, etc.

5
Doing XML projects

• As a warming up of the final research project,
  two small programming projects will be given.
• They are simple, but good practice of XML
  programming
• Detailed specifications will be given

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Conducting XML research

• Each group selects one project with a
  consultation from the instructor
• Team work, each group of two students
• Work closely with your partner and the instructor
• To promote progress, a series of assignments will
  be given. They will not be graded, but will
  affect the instructors impression of your
  progress.

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Goal of the course

• Have an broad knowledge of XML literature
• improved presentation skill
• Have a deep knowledge and experience on the
  specific research topic
• Ready to do XML research

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Course Info

• Prerequisites
• CSC6710 and CSC7710 Or with the permission of the
  instructor. 
• Instructor
• Shiyong Lu (shiyong_at_cs.wayne.edu )
• Office 430 State Hall 
• Telephone [phone]
• Office hours Tu, Th 400-500PM or by
  appointment.

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Prerequisites

• CSC6710 and CSC7710 Or with the permission of the
  instructor. 

10
Course load and grading

• (0 )  a series of assignments will be given,
  although they will not be graded.
• (30 ) Two programming projects (15 pts each)
• (15 ) Lecture presentation
• (15 ) Final project demonstration
• (40 ) Final professional publication-quality
  research paper.
• The grade will be given on a group basis (of two
  students) except for the individual lecture
  presentation.

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Late work penalty

• You can have one late assignment submission up to
  one week without any penalty. Please indicate on
  the cover page of your submission when you use
  your late excuse. If late excuse is not used, a
  penalty of 2 per day will be assessed up to one
  week. No credits will be given for works handed
  in one week after the due date. The late excuse
  cannot be used for the final project. 

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Academic Honesty

• Copying an assignment from another student in
  this class or obtaining a solution from some
  other source will lead to an automatic failure
  for this course and to a disciplinary action.
  Allowing another student to copy one's work will
  be treated as an act of academic dishonesty,
  leading to the same penalty as copying. get a
  failure).

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What is XML?

• Example
• lt?xml version1.0
• ltemailgt
• ltfromgtsmith_at_cs.wayne.edult/fromgt
• lttogt shiyong_at_cs.wayne.edu lt/togt
• ltsubjectgtWhat is XMLlt/subjectgt
• ltbodygt
• Can tell you me what XML is all about?
  
• lt/bodygt
• lt/emailgt

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What is XML (cont)

• XML eXtensible Markup Language
• No fixed collection of markup tags (meta
  language)
• Semi-structured self-descrbing
• Separate syntax from semantics
• The standard for representing and exchanging
  information on the WWW

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HTML example

• lth1gtRhubarb Cobblerlt/h1gt lth2gtMaggie.Herrick_at_b
  bs.mhv.netlt/h2gt
• lth3gtWed, 14 Jun 95lt/h3gt
• Rhubarb Cobbler made with bananas as the
  main sweetener. It was delicious. Basicly it was
• lttablegt
• lttrgtlttdgt 2 1/2 cups lttdgt diced rhubarb
  lttrgtlttdgt 2 tablespoons lttdgt sugar lttrgtlttdgt 2 lttdgt
  fairly ripe bananas lttrgtlttdgt 1/4 teaspoon lttdgt
  cinnamon lttrgtlttdgt dash of lttdgt nutmeg lt/tablegt
  Combine all and use as cobbler, pie, or crisp.
  Related recipes lta href"GardenQuiche"gtGarden
  Quichelt/agt

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A corresponding XML doc

• ltrecipe id"117" category"dessert"gt
• lttitlegtRhubarb Cobblerlt/titlegt ltauthorgtltemailgtMagg
  ie.Herrick_at_bbs.mhv.netlt/emailgtlt/authorgt
  ltdategtWed, 14 Jun 95lt/dategt
• ltdescriptiongt Rhubarb Cobbler made with
  bananas as the main sweetener. It was delicious.
  lt/descriptiongt ltingredientsgt ltitemgtltamountgt2 1/2
  cupslt/amountgtlttypegtdiced rhubarblt/typegtlt/itemgt
  ltitemgtltamountgt2 tablespoonslt/amountgtlttypegtsugarlt/t
  ypegtlt/itemgt ltitemgtltamountgt2lt/amountgtlttypegtfairly
  ripe bananaslt/typegtlt/itemgt ltitemgtltamountgt1/4
  teaspoonlt/amountgtlttypegtcinnamonlt/typegtlt/itemgt
  ltitemgtltamountgtdash oflt/amountgtlttypegtnutmeglt/typegtlt
  /itemgt lt/ingredientsgt ltpreparationgt Combine all
  and use as cobbler, pie, or crisp. lt/preparationgt
  ltrelated url"GardenQuiche"gtGarden
  Quichelt/relatedgt lt/recipegt

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HTML vs XML

• the markup tags are chosen purely for logical
  structure this is just one choice of markup
  detail level
• we need to define which XML documents we regard
  as "recipe collections" (XML Schema)
• we need a stylesheet to define browser
  presentation semantics (XSL)
• we need to express queries in a general way
  (XQuery)

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A conceptual view of XML

• Character data (XML content)
• XML elements
• XML attributes

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A concrete view of XML
Markup tags denote elements   ...ltfoo
attr"val" ...gt...lt/foogt...               
                         
          a matching element end
tag                        the
contents of the element          an
attribute with name attr and value val, values
enclosed by ' or "     an element start tag
with name foo There is a short-hand notation for
empty elements ...ltfoo attr"val".../gt...
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A concrete view of XML (cont)

• An XML document must be well-formed
• start and end tags must match
• element tags must be properly nested
• some more subtle syntactical requirements

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A concrete view of XML (cont)

• XML is case sensitive!
• Special characters can be escaped using Unicode
  character references
• 60 and lt both yield lt
• 38 and amp both yield
• lt!-- comment --gt
• lt!DOCTYPE ...gt document type declaration
  (described later...)

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XML application examples

• XHTML, W3C's XMLization of HTML 4.0.
• CML, Chemical Markup Language
• WML, Wireless Markup Language for WAP services
• ThML, Theological Markup Language
• Much more

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Why XML

• It is hot () (both in industry and academic)!
• Syntax itself is not enough, but tools and
  languages to process XML
• For database people, how to manage XML data
  (storage, update, query, and exchange, and
  transformation, etc)

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XML techniques

• common extensions to the core XML specificationa
  namespace mechanism, document inclusion, etc.
• schemas grammars to define classes of documents
• linking between documentsa generalization of
  HTML anchors and links
• addressing parts of read-only documentsflexible
  and robust pointers into documents
• transformationconversion from one document class
  to another
• queryingextraction of information, generalizing
  relational databases

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XML namespaces

• ltwidget type"gadget"gt  lthead size"medium"/gt 
  ltbiggtltsubwidget ref"gizmo"/gtlt/biggt  ltinfogt   
  ltheadgt      lttitlegtDescription of
  gadgetlt/titlegt    lt/headgt    ltbodygt     
  lth1gtGadgetlt/h1gt      A gadget contains a big
  gizmo    lt/bodygt  lt/infogt
• Problem the meaning of head and big depends on
  the context!

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XML namespaces (cont)

• Simple solution qualify names with URIs
  (Universal Resource Identifiers)
  lthttp//www.w3.org/TR/xhtml1headgt
    \                         
  / \  /   
  ------------------------------------     
   qualifying URI      
  local name
• Do not be confused by the use of URIs for
  namespaces
• they are not supposed to point to anything
• it is simply the cheapest way of getting unique
  names
• we rely on existing organizations that control
  domain names

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XML namespaces (cont)

• lt... xmlnsfoo"http//www.w3.org/TR/xhtml1"gt 
  ...  ltfooheadgt...lt/fooheadgt  ...lt/...gt

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XML namespaces (cont)

• xmlnsprefix"URI" declares a namespace with a
  prefix and a URI
• the scope of declaration is lexical, the element
  containing the declaration and all descendants
  can be overridden by nested declaration
• both element and attribute names can be qualified
  with namespaces
• the name of the prefix is irrelevant
  -applications should use only the URI

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XML name spaces (cont)

• ltwidget xmlns"http//www.widget.org"       
  xmlnsxhtml"http//www.w3.org/TR/xhtml1"       
  type"gadget"gt  lthead size"medium"/gt 
  ltbiggtltsubwidget ref"gizmo"/gtlt/biggt  ltinfogt   
  ltxhtmlheadgt      ltxhtmltitlegtDescription of
  gadgetlt/xhtmltitlegt    lt/xhtmlheadgt   
  ltxhtmlbodygt      ltxhtmlh1gtGadgetlt/xhtmlh1gt 
      A gadget contains a big gizmo   
  lt/xhtmlbodygt  lt/infogtlt/widgetgt

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XML schemas

• A schema is a definition of the syntax of an
  XML-based language (i.e. a class of XML
  documents).
• A schema language is a formal language for
  expressing schemas. (DTD, XML Schema)

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DTD Document Type Defintion

• lt!DOCTYPE root-element doctype-declaration...
• lt!ELEMENT element-name content-modelgt, content
  model , ,, , , ?
• lt!ATTLIST element-name attr-name attr-type
  attr-default ...gt

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Element Type Declaration

• elementdecl     'lt!ELEMENT' Name
  contentspec 'gt'   
• contentspec     'EMPTY' 'ANY' Mixed
  Children
• No element type may be declared more than once

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Element Type Declaration Example

• lt!ELEMENT br EMPTYgt
• lt!ELEMENT p (PCDATAemph) gt
• lt!ELEMENT name.para content.para gt
• lt!ELEMENT container ANYgt

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Empty Elements

• EmptyElemTag     'lt' Name (Attribute) '/gt
• Example
• ltIMG align"left" src"http//www.w3.org/Icons/WWW
  /w3c_home" /gt
• ltbr/gt
• Question is ltagtlt/agt an empty element?

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DTD (cont)

• lt!ATTLIST element-name attr-name attr-type
  attr-default ...gtdeclares which attributes are
  allowed or required in which elements attribute
  types
• CDATA any value is allowed (the default)
• (value...) enumeration of allowed values
• ID, IDREF, IDREFS ID attribute values must be
  unique (contain "element identity"), IDREF
  attribute values must match some ID (reference to
  an element)
• ENTITY, ENTITIES, NMTOKEN, NMTOKENS, NOTATION
  just forget these... (consider them deprecated)
• attribute defaults
• REQUIRED the attribute must be explicitly
  provided
• IMPLIED attribute is optional, no default
  provided
• "value" if not explicitly provided, this value
  inserted by default
• FIXED "value" as above, but only this value is
  allowed

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Attribute-list declaration example

• lt!ATTLIST termdef
• id ID REQUIRED
• name CDATA IMPLIEDgt
• lt!ATTLIST list
• type (bulletsorderedglos
  sary) "ordered"gt
• lt!ATTLIST form
• method CDATA FIXED "POST"gt

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A DTD example

• lt!ELEMENT collection (description,recipe)gt
• lt!ELEMENT description ANYgt
• lt!ELEMENT recipe (title,ingredient,preparation,co
  mment?,nutrition)gt
• lt!ELEMENT title (PCDATA)gt
• lt!ELEMENT ingredient (ingredient,preparation)?gt
• lt!ATTLIST ingredient name CDATA REQUIRED amount
  CDATA IMPLIED unit CDATA IMPLIEDgt
• lt!ELEMENT preparation (step)gt
• lt!ELEMENT step (PCDATA)gt
• lt!ELEMENT comment (PCDATA)gt
• lt!ELEMENT nutrition EMPTYgt
• lt!ATTLIST nutrition protein CDATA REQUIRED
  carbohydrates CDATA REQUIRED fat CDATA REQUIRED
  calories CDATA REQUIRED alcohol CDATA IMPLIEDgt

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XML Schema language requirement

• more expressive than XML DTDs
• expressed in XML
• self-describing
• simple enough to be implemented with modest
  design and runtime resources
• Structures and data types

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XML doc and schema examples

• ltcard xmlns"http//businesscard.org"gt
  ltnamegtJohn Doelt/namegt
• lttitlegtCEO, Widget Inc.lt/titlegt
• ltemailgtjohn.doe_at_widget.comlt/emailgt
• ltphonegt(202) 456-1414lt/phonegt
• ltlogo url"widget.gif"/gt
• lt/cardgt

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XML doc and schema examples (business_card.xsd,
cont)

• ltschema xmlns"http//www.w3.org/2001/XMLSchema"
  xmlnsb"http//businesscard.org"
  targetNamespace"http//businesscard.org"gt
• ltelement name"card" type"bcard_type"/gt
  ltelement name"name" type"string"/gt
• ltelement name"title" type"string"/gt ltelement
  name"email" type"string"/gt
• ltelement name"phone" type"string"/gt ltelement
  name"logo" type"blogo_type"/gt
• ltcomplexType name"card_type"gt
• ltsequencegt ltelement ref"bname"/gt
• ltelement ref"btitle"/gt
• ltelement ref"bemail"/gt
• ltelement ref"bphone" minOccurs"0"/gt
• ltelement ref"blogo" minOccurs"0"/gt
• lt/sequencegt
• lt/complexTypegt
• ltcomplexType name"logo_type"gt
• ltattribute name"url" type"anyURI"/gt
  lt/complexTypegt lt/schemagt

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Overview of XML Schema

• a (global) element declaration associates an
  element name with a type
• a complex type definition defines requirements
  for attributes, sub-elements, and character data
  in elements of that type
• attribute declarations describe which attributes
  that may or must appear
• element references describe which sub-elements
  that may or must appear, how many, and in which
  order
• a simple type definition defines a set of strings
  to be used as attribute values or character data