More xml chpt 6 DTD

1
More xml chpt 6 DTD

• Document Type Definition

2
DTD document type definition

• A DTD is defined using EBNF (extended BNF) and
  can be used to specify allowable elements and
  attributes for an XML document.
• There is a move away from DTD currently, toward
  Schema. Schema documents have XML (not BNF)
  syntax.
• Some parsers can check an XML document against
  its DTD and determine if it is valid. These are
  called validating parsers. A document which is
  syntactically correct but does not correspond to
  its DTD is well-formed. Non-validating parsers
  cant check documents against their DTD and can
  thus only determine if the document is
  well-formed.

3
Document Type Declaration

• ltDOCTYPE.gt in an XML document prolog is used to
  specify DTD appearing within or outside the
  document. These are referred to as the internal
  or external subset.
• ltDOCTYPE thingy
• lt!ELEMENT thingy (PCDATA)gt
• gt
• Declares a dtd called thingy with one element in
  the internal subset.
• PCDATA refers to parseable character data
  meaning reserved characters lt,gt and within the
  PCDATA will be treated as markup. The
  parentheses contain the content specification for
  the element.

4
MS XML validator

• We can check an xml document for adherence to an
  external DTD using MS XML validator. Heres the
  xml
• lt?xml version "1.0"?gt
• lt!-- Fig. 6.1 intro.xml --gt
• lt!-- Using an external subset --gt
• lt!DOCTYPE myMessage SYSTEM "intro.dtd"gt
• ltmyMessagegt
• ltmessagegtWelcome to XML!lt/messagegt
• lt/myMessagegt
• And heres the DTD
• lt!-- Fig. 6.2 intro.dtd --gt
• lt!-- External declarations --gt
• lt!ELEMENT myMessage ( message )gt
• lt!ELEMENT message ( PCDATA )gt

5
MS Validating parser can validate against schema
or dtd
6
Invalid xml

• In the next slide we use the MS XML validator to
  check an xml (appearing below) like intro.xml but
  missing the message element
• lt?xml version "1.0"?gt
• lt!-- Fig. 6.3 intro-invalid.xml --gt
• lt!-- Simple introduction to XML markup --gt
• lt!DOCTYPE myMessage SYSTEM "intro.dtd"gt
• lt!-- Root element missing child element message
  --gt
• ltmyMessagegt
• lt/myMessagegt

7
If xml doc does not match dtd/schema
8
Sequences, pipes and occurrences

• The comma can be used to indicate a sequence in
  which elements must appear.
• lt!ELEMENT class (prof, student)gt
• Indicates the order and number of elements making
  up a class one prof and one student, in that
  order. Content may specify any number of
  elements.
• lt!ELEMENT sidedish (coleslawchips)gt
• Indicates just one of the choices must be
  selected.
• , , and ? Indicate frequency of element
  occurrences.
• means 1 or more occurences, means 0 or more
  occurences, ? Means 0 or 1 occurrence.
• lt!ELEMENT class (prof, student)gt
• Might be appropriate for a class DTD meaning just
  one professor and one or more students.

9
example

• lt!ELEMENT donuts (jelly?,lemon,((crèmesugar)gl
  azed))gt
• Specifies donuts consists of 0 or 1 jelly, 0 or
  more lemon, 1 or more of crème or sugar, or a
  glazed. A legal markup for this would be
• ltdonutsgt
• ltjellygtgrapelt/jellygt
• ltlemongtsourlt/lemongt
• ltlemongtreal sourlt/lemongt
• ltglazedgtchocolatelt/glazedgt
• lt/donutsgt

10
The dtd and xml

• Pastry.dtd
• lt!ELEMENT jelly (PCDATA)gt
• lt!ELEMENT glazed (PCDATA)gt
• lt!ELEMENT lemon (PCDATA)gt
• lt!ELEMENT creme (PCDATA)gt
• lt!ELEMENT sugar (PCDATA)gt
• lt!ELEMENT donuts (jelly?,lemon,((cremesugar)gl
  azed))gt
• Pastry.xml
• lt?xml version "1.0"?gt
• lt!-- pastry.xml --gt
• lt!-- Using an external subset --gt
• lt!DOCTYPE donuts SYSTEM "pastry.dtd"gt
• ltdonutsgt
• ltjellygtgrapelt/jellygt
• ltlemongtsourlt/lemongt
• ltlemongtreal sourlt/lemongt
• ltglazedgtchocolatelt/glazedgt
• lt/donutsgt

11
In validator files are in myexamples directory
12
Pastry.xml in xml validator
13
content specification

• An element may contain one or more child elements
  as content.
• Content specification types describe non-element
  content.
• Theses consist of ANY, EMPTY and mixed content.
• Empty elements do not contain character data or
  child elements. An empty element specification
  like
• lt!ELEMENT nest EMPTYgt could be marked up as
• ltnest/gt. Recall the shorthand /gt may be used for
  an empty element closetag.
• , and cant be used with mixed content
  elements containing only PCDATA. If mixed
  content may contain PCDATA, then this must be
  listed first.
• An element of type ANY may contain any content
  including PCDATA, or combinations of elements and
  PCDATA. They may also be empty.

14
Mixed content

• ltELEMENT mymessage (PCDATAmessage)gt
• Declares mymessage to have mixed content. PCDATA
  must be listed first in mixed content. means
  mymessage may contain nothing or any number of
  occurences of PCDATA and message elements. This
  would be legal markup
• ltmymessagegthere is an example of the dtd above
• ltmessagegtthis is a messagelt/messagegt
• ltmessagegtand anotherlt/messagegt
• lt/mymessagegt

15
Internal dtd

• An xml document is standalone if it does not
  reference an external subset.
• lt?xml version "1.0" standalone "yes"?gt
• lt!-- Fig. 6.5 mixed.xml --gt
• lt!-- Mixed content type elements --gt
• lt!DOCTYPE format
• lt!ELEMENT format ( PCDATA bold italic )gt
• lt!ELEMENT bold ( PCDATA )gt
• lt!ELEMENT italic ( PCDATA )gt
• gt
• ltformatgt
• This is a simple formatted sentence.
• ltboldgtI have tried bold.lt/boldgt
• ltitalicgtI have tried italic.lt/italicgt
• Now what?
• lt/formatgt

16
In ms xml validator
17
Element group

• lt!ELEMENT courselist (department, (coursenumber,
  coursedescription))gt
• Above, a courselist contains a single department
  followed by any number of coursenumber,
  coursedescription pairs.
• What does the following mean?
• lt!ELEMENT course (coursenumber, (sectionnumber,
  instructor, roomnumber))gt

18
Attribute specification

• An attribute specification specifies an attribute
  list for an element via ATTLIST declaration
• lt!ELEMENT x EMPTYgt
• ltATTLIST x y CDATA REQUIREDgt
• Here, y is a required attribute of element x. y
  may contain any char data (except lt,gt, , and
  ).
• CDATA in an attribute declaration has different
  meaning than a CDATA section in an XML document
  where gt (end tag) may not appear.

19
Using attributes

• lt?xml version "1.0"?gt
• lt!-- Fig. 6.7 intro2.xml --gt
• lt!-- Declaring attributes --gt
• lt!DOCTYPE myMessage
• lt!ELEMENT myMessage ( message )gt
• lt!ELEMENT message ( PCDATA )gt
• lt!ATTLIST message id CDATA REQUIREDgt
• gt
• ltmyMessagegt
• ltmessage id "445"gt
• Welcome to XML!
• lt/messagegt
• lt/myMessagegt

20
Document with attributes in MS validator
21
Attribute defaults

• Page authors can specify default values for
  attributes.
• The keywords are IMPLIED, REQUIRED and FIXED.
  
• An implied attribute, if missing, can be replaced
  by any value the application using the document
  wishes.
• A required attribute must appear or the document
  is not valid.
• A fixed attribute must have the specific value
  provided.
• ltmessagegtnumberlt/messagegt does not conform to
  lt!ATTLIST message number CDATA REQUIREDgt
• lt!ATTLIST address zip FIXED 13820gt specifies
  that zip can only have value 13820 and an
  application processing an XML document with
  address element missing attribute zip would be
  passed this default zip value.

22
Attributes

• Attribute types may be CDATA (Strings), tokenized
  or enumerated.
• Strings have no constraints beyond prohibiting
  lt,gt,,,and . Entity references must be used
  for these.
• Tokenization imposes constraints on attribute
  values such as which characters are permitted in
  an attribute name.
• An enumerated attribute has a restricted value
  range It can only take on one of the values
  listed in the attribute declaration.

23
tokenized attribute

• 4 tokenized types exist
• ID
• IDREF
• ENTITY
• NMTOKEN
• ID uniquely identifies an element.
• IDREF attributes point to elements with ID
  attribute.
• A validating parser verifies that each ID
  attribute type referenced by an IDREF is in the
  document.
• Using the same value for multiple ID attributes
  is an error.
• Declaring attributes of type ID to be FIXED is
  an error.

24
Using ID and IDREF attributes

• lt?xml version "1.0"?gt
• lt!-- IDExample.xml Example for ID
  and IDREF values of attributes --gt
• lt!DOCTYPE bookstore
• lt!ELEMENT bookstore ( shipping, book )gt
• lt!ELEMENT shipping ( duration )gt
• lt!ATTLIST shipping shipID ID REQUIREDgt
• lt!ELEMENT book ( PCDATA )gt
• lt!ATTLIST book shippedBy IDREF IMPLIEDgt
• lt!ELEMENT duration ( PCDATA )gtgt
• ltbookstoregt
• ltshipping shipID "s1"gt
• ltdurationgt2 to 4 dayslt/durationgt
• lt/shippinggt
• ltshipping shipID "s2"gt
• ltdurationgt1 daylt/durationgt
• lt/shippinggt
• ltbook shippedBy "s2"gt
• Java How to Program 3rd edition.
• lt/bookgt

25
In MS Validator

• Use URL http//employees.oneonta.edu/higgindm/int
  ernet20programming/validate_js.htm
• with file examples\ch06\IDExample.xml

26
ID example
27
id example internal subset

• lt?xml version "1.0"?gt
• lt!-- Fig. 6.8 IDExample.xml
  --gt
• lt!-- Example for ID and IDREF values of
  attributes --gt
• lt!DOCTYPE bookstore
• lt!ELEMENT bookstore ( shipping, book )gt
• lt!ELEMENT shipping ( duration )gt
• lt!ATTLIST shipping shipID ID REQUIREDgt
• lt!ELEMENT book ( PCDATA )gt
• lt!ATTLIST book shippedBy IDREF IMPLIEDgt
• lt!ELEMENT duration ( PCDATA )gt
• gt

28
Idexample.xml continued

• ltbookstoregt
• ltshipping shipID "s1"gt
• ltdurationgt2 to 4 dayslt/durationgt
• lt/shippinggt
• ltshipping shipID "s2"gt
• ltdurationgt1 daylt/durationgt
• lt/shippinggt
• ltbook shippedBy "s2"gt
• Java How to Program 3rd edition.
• lt/bookgt
• ltbook shippedBy "s2"gt
• C How to Program 3rd edition.
• lt/bookgt
• ltbook shippedBy "s1"gt
• C How to Program 3rd edition.
• lt/bookgt
• lt/bookstoregt

29
remarks

• It is an error not to begin a type attribute IDs
  value with a letter, underscore or colon.
• Providing more than one ID attribute type for an
  element is an error.
• Referencing a value as an ID is not defined is an
  error.

30
IDExample2.xml (note s3 shippedBy value)

• ltbookstoregt
• ltshipping shipID "s1"gt
• ltdurationgt2 to 4 dayslt/durationgt
• lt/shippinggt
• ltshipping shipID "s2"gt
• ltdurationgt1 daylt/durationgt
• lt/shippinggt
• ltbook shippedBy "s2"gt
• Java How to Program 3rd edition.
• lt/bookgt
• ltbook shippedBy "s2"gt
• C How to Program 3rd edition.
• lt/bookgt
• ltbook shippedBy "s3"gt
• C How to Program 3rd edition.
• lt/bookgt
• lt/bookstoregt

31
IDExample2.xml in Validator
32
Entities

• As we saw in chapter 5 entity references in an
  xml document are replaced by the entity values
  found in the dtd.
• We saw this for lang.xml and lang.dtd where assoc
  and text entities were replaced with Arabic
  script.
• Here is another example. Entity city is replaced.

33
entityexample.xml

• lt?xml version "1.0"?gt
• lt!-- Fig. 6.10 entityExample.xml --gt
• lt!-- ENTITY and ENTITY attribute types --gt
• lt!DOCTYPE database
• lt!NOTATION html SYSTEM "iexplorer"gt
• lt!ENTITY city SYSTEM "tour.html" NDATA htmlgt
• lt!ELEMENT database ( company )gt
• lt!ELEMENT company ( name )gt
• lt!ATTLIST company tour ENTITY REQUIREDgt
• lt!ELEMENT name ( PCDATA )gt
• gt
• ltdatabasegt
• ltcompany tour "city"gt
• ltnamegtDeitel amp Associates, Inc.lt/namegt
• lt/companygt
• lt/databasegt

34
entityexample.xml
35
entityexample.xml

• Here line 7 ltNOTATIO indicates that an
  application may wish to run IE and load tour.html
  to handle unparsed entities.
• line 8 declares an entity named city which refers
  to the external document tour.html.
• NDATA in this line indicates that the content of
  this entity is not xml and supplies the name of
  the notation (html) for this entity.

36
ENTITIES

• ENTITIES keyword can be used in a dtd to indicate
  that an attribute has mutliple entities for its
  value.
• lt!ATTLIST directory file ENTITIES REQUIREDgt
• Specifies that file must contain multiple
  entities. Conforming markup is
• ltdirectory file animations graphics tablesgt
• animations, graphics and tables are entities
  declared in a dtd.
• NMTOKEN type is more restrictive, containing
  letters, digits, periods, underscores, hyphens
  and colons.
• lt!ATTLIST mathdept phonenum NMTOKEN REQUIREDgt
  might have conforming markup
• ltmathdept phonenum 607-436-3708gt
• ltmathdept phonenum 607 436 3708gt does not
  conform because spaces are not allowed.
• NMTOKENS attribute type would allow multiple
  string tokens separated by blanks.

37
Enumerated attribute types

• Enumerated attribute type declares a list of
  possible values. Attributes must be assigned a
  value from this list in order to conform to the
  dtd. Enumerated values are separated with pipe
  ()
• lt!ATTLIST person gender (MF) Fgt allows a
  person to have gender M or F with default F.
• lt!ATTLIST person gender (MF) IMPLIEDgt does not
  supply a default and would permit an application
  to process a person with no gender in whatever
  way it liked.

38
Enumerated attribute types

• NOTATION is also an enumerated attribute type.
• lt!ATTLIST CSCI116 language NOTATION (JavaC) Cgt
• Specifies that language must be assigned a value,
  Java or C with C as the default. The notation
  for C might be specified as
• lt!NOTATION C System http//....htmlgt

39
conditional.xml

• Conditional sections provide the flexibility of
  including or excluding declarations.
• These enable us to check xml documents against
  different sets of dtd requirements.
• Keywords INCLUDE and IGNORE specify included and
  excluded declarations
• lt!INCLUDE
• lt!ELEMENT name (PCDATA)gt
• gt
• Directs the parser to include the declaration of
  element name.
• Conditionals may also be used with entities.

40
Conditional.dtd

• lt!-- conditional.dtd --gt
• lt!-- DTD for conditional section example --gt
• lt!ENTITY reject "IGNORE"gt
• lt!ENTITY accept "INCLUDE"gt
• lt! accept
• lt!ELEMENT message ( approved, signature )gt
• gt
• lt! reject
• lt!ELEMENT message ( approved, reason,
  signature )gt
• gt
• lt!ELEMENT approved EMPTYgt
• lt!ATTLIST approved flag ( true false ) "false"gt
• lt!ELEMENT reason ( PCDATA )gt
• lt!ELEMENT signature ( PCDATA )gt

41
Conditional.xml

• lt?xml version "1.0" standalone "no"?gt
• lt!-- conditional.xml --gt
• lt!-- Using conditional sections --gt
• lt!DOCTYPE message SYSTEM "conditional.dtd"gt
• ltmessagegt
• ltapproved flag "true"/gt
• ltsignaturegtChairmanlt/signaturegt
• lt/messagegt

42
discussion

• Entities accept and reject have values IGNORE
  and INCLUDE.
• The percent symbol indicates that they are
  parameter entities and may only be used inside
  the dtd in which they are declared. They may only
  appear in the external subset.
• Thus the author may create entities specific to
  the dtd not xml document.

43
conditional.xml
44
conditional.xml

• lt?xml version "1.0" standalone "no"?gt
• lt!-- Fig. 6.13 conditional.xml --gt
• lt!-- Using conditional sections --gt
• lt!DOCTYPE message SYSTEM "conditional.dtd"gt
• ltmessagegt
• ltapproved flag "true"/gt
• ltsignaturegtChairmanlt/signaturegt
• lt/messagegt

45
conditional.dtd

• lt!-- DTD for conditional section example --gt
• lt!ENTITY reject "IGNORE"gt
• lt!ENTITY accept "INCLUDE"gt
• lt! accept
• lt!ELEMENT message ( approved, signature )gt
• gt
• lt! reject
• lt!ELEMENT message ( approved, reason,
  signature )gt
• gt
• lt!ELEMENT approved EMPTYgt
• lt!ATTLIST approved flag ( true false ) "false"gt
• lt!ELEMENT reason ( PCDATA )gt
• lt!ELEMENT signature ( PCDATA )gt

46
Whitespace

• Whitespace is preserved or normalized depending
  on the context in which it appears.
• A text example (whitespace.xml) uses a java
  program (Tree.java from chapt 9) to demonstrate
  when whitespace is preserved or normalized.
• File can be got from classdir\examples\ch09\tree.j
  ava

47
running Tree.java on whitespace.xml... java src
in notes

• C\Java\j2sdk1.4.1_01\bingtjava Tree yes
  whitespace.xml
• URL fileC/Java/j2sdk1.4.1_01/bin/whitespace.xml
  
• document root
• - element whitespace
• - ignorable
• - ignorable
• - ignorable
• - element hasCDATA
• - attribute cdata " simple cdata "
• - ignorable
• - ignorable
• - ignorable
• - element hasID
• - attribute id "i20"
• - ignorable
• - ignorable
• - ignorable
• - element hasNMTOKEN
• - attribute nmtoken "hello"

48
Java tree output continued

• - element hasEnumeration
• - attribute enumeration "true"
• - ignorable
• - ignorable
• - ignorable
• - element hasMixed
• - text "
• "
• - text " This is text."
• - text "
• "
• - text " "
• - element hasCDATA
• - attribute cdata " simple cdata"
• - text "
• "
• - text " This is some additional
  text."
• - text "
• "

49
whitespace.xml dtd and content

• lt?xml version "1.0"?gt
• lt!-- whitespace.xml --gt
• lt!-- Demonstrating whitespace parsing --gt
• lt!DOCTYPE whitespace
• lt!ELEMENT whitespace ( hasCDATA,
• hasID, hasNMTOKEN, hasEnumeration, hasMixed
  )gt
• lt!ELEMENT hasCDATA EMPTYgt
• lt!ATTLIST hasCDATA cdata CDATA REQUIREDgt
• lt!ELEMENT hasID EMPTYgt
• lt!ATTLIST hasID id ID REQUIREDgt
• lt!ELEMENT hasNMTOKEN EMPTYgt
• lt!ATTLIST hasNMTOKEN nmtoken NMTOKEN
  REQUIREDgt
• lt!ELEMENT hasEnumeration EMPTYgt

50
whitespace.xml continued

• ltwhitespacegt
• lthasCDATA cdata " simple cdata "/gt
• lthasID id " i20"/gt
• lthasNMTOKEN nmtoken " hello"/gt
• lthasEnumeration enumeration " true"/gt
• lthasMixedgt
• This is text.
• lthasCDATA cdata " simple cdata"/gt
• This is some additional text.
• lt/hasMixedgt
• lt/whitespacegt

51
Tree.java slide 1

• import java.io.
• import org.xml.sax. // for HandlerBase class
• import javax.xml.parsers.SAXParserFactory
• import javax.xml.parsers.ParserConfigurationExcept
  ion
• import javax.xml.parsers.SAXParser
• public class Tree extends HandlerBase
• private int indent 0 // indentation
  counter
• // returns the spaces needed for indenting
• private String spacer( int count )
• String temp ""
• for ( int i 0 i lt count i )
• temp " "
• return temp
• // method called before parsing
• // it provides the document location
• public void setDocumentLocator( Locator loc )
• System.out.println( "URL "
  loc.getSystemId() )

52
Tree.java slide 2

• // method called at the beginning of a document
• public void startDocument() throws
  SAXException
• System.out.println( " document root "
  )
• // method called at the end of the document
• public void endDocument() throws SAXException
• System.out.println( " document end "
  )
• // method called at the start tag of an
  element
• public void startElement( String name,
• AttributeList attributes ) throws
  SAXException
• System.out.println( spacer( indent )
  
• "- element " name
  " ")
• if ( attributes ! null )
• for ( int i 0 i lt attributes.getLength
  () i )
• System.out.println( spacer( indent )
  
• "- attribute "
  attributes.getName( i )
• " \"" attributes.getValue( i )
  "\"" )

53
Tree.java slide 3

• // method called at the end tag of an element
• public void endElement( String name ) throws
  SAXException
• indent--
• // method called when a processing instruction
  is found
• public void processingInstruction( String
  target,
• String value ) throws SAXException
• System.out.println( spacer( indent )
• "- proc-inst " target " \""
  value "\"" )
• // method called when characters are found
• public void characters( char buffer, int
  offset,
• int length ) throws SAXException
• if ( length gt 0 )
• String temp new String( buffer,
  offset, length )
• System.out.println( spacer( indent )
• "- text \""
  temp "\"" )
• // method called when ignorable whitespace is
  found
• public void ignorableWhitespace( char
  buffer,

54
Tree slide 4

• // method called on a non-fatal (validation)
  error
• public void error( SAXParseException spe )
• throws SAXParseException
• // treat non-fatal errors as fatal errors
• throw spe
• // method called on a parsing warning
• public void warning( SAXParseException spe )
• throws SAXParseException
• System.err.println( "Warning "
  spe.getMessage() )

55
Tree.java slide 5

• // main method
• public static void main( String args )
• boolean validate false
• if ( args.length ! 2 )
• System.err.println( "Usage java Tree
  validate "
• "filename\n" )
• System.err.println( "Options" )
• System.err.println( " validate
  yesno "
• "DTD validation" )
• System.exit( 1 )
• if ( args 0 .equals( "yes" ) )
• validate true
• SAXParserFactory saxFactory
• SAXParserFactory.newInstance()
• saxFactory.setValidating( validate )
• try
• SAXParser saxParser saxFactory.newSAXPa
  rser()
• saxParser.parse( new File( args 1 ),
  new Tree() )
• catch ( SAXParseException spe )
  System.err.println( "Parse Error "
  spe.getMessage() )

56
Day planner example continued
57
planner.xml

• lt?xml version "1.0"?gt
• lt!-- planner.xml Day Planner XML document --gt
• lt!DOCTYPE planner SYSTEM "planner.dtd"gt
• ltplannergt
• ltyear value "2000"gt
• ltdate month "7" day "15"gt
• ltnote time "1430"gtDoctor's
  appointmentlt/notegt
• ltnote time "1620"gtPhysics class at
  BH291Clt/notegt
• lt/dategt
• ltdate month "7" day "4"gt
• ltnotegtIndependence Daylt/notegt
• lt/dategt
• ltdate month "7" day "20"gt
• ltnote time "0900"gtGeneral Meeting in
  room 32-Alt/notegt
• lt/dategt
• ltdate month "7" day "20"gt
• ltnote time "1900"gtParty at
  Joe'slt/notegt
• lt/dategt
• ltdate month "7" day "20"gt

58
planner.dtd

• lt!-- DTD for day planner --gt
• lt!ELEMENT planner ( year )gt
• lt!ELEMENT year ( date )gt
• lt!ATTLIST year value CDATA REQUIREDgt
• lt!ELEMENT date ( note )gt
• lt!ATTLIST date month CDATA REQUIREDgt
• lt!ATTLIST date day CDATA REQUIREDgt
• lt!ELEMENT note ( PCDATA )gt
• lt!ATTLIST note time CDATA IMPLIEDgt

59
HW this section

• Make a dtd and a conforming xml file. Make your
  example non-trivial but feel free to copy and
  modify examples given in class or your text.
  Check your work in the MS Validator. That means,
  elements should have attributes, etc.
• You may also need to download the Xerces parser
  (youll need it at some point this semester) and
  install it as per the documentation that
  accompanies it.
• Save tree.java to your java directory. Make sure
  it compiles and runs. See step 4 below.
• For step 3, you will need to download JAXP from
  http//java.sun.com/xml/download.html