XML. extensible Markup Language. ... and its usefulness for linguists

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1 XML extensible Markup Language... and its usefulness for linguists Thomas Mayer Fachbereich Sprachwissenschaft, Universität Konstanz Seminar Computerlinguistik II (Miriam Butt) 23. Juli 2004

2 0.Outline Thomas Mayer XML 1

3 0.Outline Preliminaries Thomas Mayer XML 1

4 0.Outline Preliminaries Introduction to XML Thomas Mayer XML 1

5 0.Outline Preliminaries Introduction to XML Using XML for grammar writing (with XLE) Thomas Mayer XML 1

6 1.Preliminaries At least two types of applications can be distinguished Thomas Mayer XML 2

7 1.Preliminaries At least two types of applications can be distinguished Document-centric applications (e.g. Information Retrieval) mainly text documents with little structure (chapters, sections,... ) Thomas Mayer XML 2

8 1.Preliminaries At least two types of applications can be distinguished Document-centric applications (e.g. Information Retrieval) mainly text documents with little structure (chapters, sections,... ) Data-centric applications ( traditional database applications) very regular data; sometimes, however, we might want some flexibility Thomas Mayer XML 2

9 XML was designed to satisfy the needs of both worlds Thomas Mayer XML 3

10 XML was designed to satisfy the needs of both worlds It was designed to be simple, generic and extensible Thomas Mayer XML 3

11 XML was designed to satisfy the needs of both worlds It was designed to be simple, generic and extensible XML documents are pure ASCII files = Humans can read them Thomas Mayer XML 3

12 2.Introduction to XML Thomas Mayer XML 4

13 2.Introduction to XML 1. XML a new HTML? Thomas Mayer XML 4

14 2.Introduction to XML 1. XML a new HTML? 2. The structure of an XML document Thomas Mayer XML 4

15 2.Introduction to XML 1. XML a new HTML? 2. The structure of an XML document 3. XML data query and retrieval Thomas Mayer XML 4

16 2.1XML a new HTML?... definitely not! HTML (HyperText Markup Language) is for displaying web contents on the browser HTML is a subset of XML (HTML XML SGML) XML could be used to determine the layout of a web page, but it is much more powerful Thomas Mayer XML 5

17 2.2The structure of an XML document head <?xml version="1.0"? encoding="iso "?>... body <note> <to>tove</to> <from>jani</from> <subject>reminder</subject> <message>take a break!</message> </note> Thomas Mayer XML 6

18 The basic element of an XML document is a tag Thomas Mayer XML 7

19 The basic element of an XML document is a tag A tag usually consists of a start tag (e.g. <foo>) and its corresponding end tag (e.g. </foo>) Thomas Mayer XML 7

20 The basic element of an XML document is a tag A tag usually consists of a start tag (e.g. <foo>) and its corresponding end tag (e.g. </foo>) Exception: empty elements (e.g. <foo />) Thomas Mayer XML 7

21 The basic element of an XML document is a tag A tag usually consists of a start tag (e.g. <foo>) and its corresponding end tag (e.g. </foo>) Exception: empty elements (e.g. <foo />) Elements can have attributes, i.e. pairs of attributes and values separated by an equation sign: Thomas Mayer XML 7

22 <foo attribute="value"> Thomas Mayer XML 8

23 <foo attribute="value"> Element names may contain the following characters: letters (capital and small), numbers, underscores ( ), hyphens ( - ), dots (. ) and colons ( : ). Thomas Mayer XML 8

24 However, there are special elements... Thomas Mayer XML 9

25 However, there are special elements... Processing Instructions (PIs): information for programs that work on the XML document <?xml-stylesheet href="headlines.css" type="te Thomas Mayer XML 9

26 However, there are special elements... Processing Instructions (PIs): information for programs that work on the XML document <?xml-stylesheet href="headlines.css" type="te Special elements starting with! : Thomas Mayer XML 9

27 However, there are special elements... Processing Instructions (PIs): information for programs that work on the XML document <?xml-stylesheet href="headlines.css" type="te Special elements starting with! : <!DOCTYPE...> Thomas Mayer XML 9

28 However, there are special elements... Processing Instructions (PIs): information for programs that work on the XML document <?xml-stylesheet href="headlines.css" type="te Special elements starting with! : <!DOCTYPE...> <![CDATA[...]]> Thomas Mayer XML 9

29 However, there are special elements... Processing Instructions (PIs): information for programs that work on the XML document <?xml-stylesheet href="headlines.css" type="te Special elements starting with! : <!DOCTYPE...> <![CDATA[...]]> <! > comments as in HTML Thomas Mayer XML 9

30 The building blocks of XML documents Elements Tags Attributes PCDATA CDATA Processing Instructions Thomas Mayer XML 10

31 Comments Entities Thomas Mayer XML 11

32 PCDATA sections Thomas Mayer XML 12

33 PCDATA sections character strings between a start and an end tag <foo>... whatever... </foo> Thomas Mayer XML 12

34 PCDATA sections character strings between a start and an end tag <foo>... whatever... </foo> Escape sequences for special characters <, >, ", They begin with an ampersand and end with a semi-colon (e.g. < for <) Thomas Mayer XML 12

35 PCDATA sections character strings between a start and an end tag <foo>... whatever... </foo> Escape sequences for special characters <, >, ", They begin with an ampersand and end with a semi-colon (e.g. < for <) Thomas Mayer XML 12

36 You can define your own entities in the same way (e.g. &myentity;) Thomas Mayer XML 13

37 Well-formed vs. valid XML documents Thomas Mayer XML 14

38 Well-formed vs. valid XML documents An XML document is well-formed if it observes the rules of the XML specification (i.e. the restrictions on element names, proper nesting, etc.) Thomas Mayer XML 14

39 Well-formed vs. valid XML documents An XML document is well-formed if it observes the rules of the XML specification (i.e. the restrictions on element names, proper nesting, etc.) An XML document is valid if it is wellformed and conforms to its Document Type Definition (DTD) (either inline in the XML document or as an external reference), which specifies some rules Thomas Mayer XML 14

40 regarding the nesting of certain elements, etc. Thomas Mayer XML 15

41 regarding the nesting of certain elements, etc. What does a DTD look like? Thomas Mayer XML 15

42 Document Type Definition (DTD) Thomas Mayer XML 16

43 Document Type Definition (DTD) Internal DTD: <?xml version="1.0" encoding="iso "?> <!DOCTYPE note [... ]> Thomas Mayer XML 16

44 Document Type Definition (DTD) Internal DTD: <?xml version="1.0" encoding="iso "?> <!DOCTYPE note [... ]> External DTD: <?xml version="1.0" encoding="iso "?> Thomas Mayer XML 16

45 <!DOCTYPE note SYSTEM "note.dtd">... Thomas Mayer XML 17

46 An example DTD ("note.dtd"): <?xml version="1.0"?> <!ELEMENT note (to,from,subject,message)> <!ELEMENT to(#pcdata)> <!ELEMENT from (#PCDATA)> <!ELEMENT subject (#PCDATA)> <!ELEMENT message (#PCDATA)> Thomas Mayer XML 18

47 2.3XML related standards Thomas Mayer XML 19

48 2.3XML related standards XPath Thomas Mayer XML 19

49 2.3XML related standards XPath XQuery Thomas Mayer XML 19

50 2.3XML related standards XPath XQuery XSLT Thomas Mayer XML 19

51 XPath Thomas Mayer XML 20

52 XPath Querying XML data essentially means to identify (or address) nodes, and to test further properties of these nodes. Thomas Mayer XML 20

53 XPath Querying XML data essentially means to identify (or address) nodes, and to test further properties of these nodes. There are certain relationships between nodes (axes) Thomas Mayer XML 20

54 XPath Querying XML data essentially means to identify (or address) nodes, and to test further properties of these nodes. There are certain relationships between nodes (axes) Given the relationships preceding/following and ancestor/descendant each node Thomas Mayer XML 20

55 partitions the whole XML document into four disjoint regions: Thomas Mayer XML 21

56 Thomas Mayer XML 22

57 The syntax of XPath Thomas Mayer XML 23

58 The syntax of XPath The path expression is the core construct of XPath Thomas Mayer XML 23

59 The syntax of XPath The path expression is the core construct of XPath Each path consists of one or more steps, syntactically separated by /. s 0 /s 1 /... /s n Thomas Mayer XML 23

60 The syntax of XPath The path expression is the core construct of XPath Each path consists of one or more steps, syntactically separated by /. s 0 /s 1 /... /s n The entire XPath expression will always return a sequence of nodes (duplicate free and in document order) Thomas Mayer XML 23

61 XQuery Thomas Mayer XML 24

62 XQuery XQuery is a standard means to query XML databases Thomas Mayer XML 24

63 XQuery XQuery is a standard means to query XML databases It extends XPath by adding some powerful new operators and an elaborate type system Thomas Mayer XML 24

64 XSLT Thomas Mayer XML 25

65 XSLT XSL (extensible Stylesheet Language) consists of two important components: Thomas Mayer XML 25

66 XSLT XSL (extensible Stylesheet Language) consists of two important components: one for formatting XML data Thomas Mayer XML 25

67 XSLT XSL (extensible Stylesheet Language) consists of two important components: one for formatting XML data one for transforming XML data into other XML data Thomas Mayer XML 25

68 XSLT XSL (extensible Stylesheet Language) consists of two important components: one for formatting XML data one for transforming XML data into other XML data The second component is often abbreviated to XSLT (XSL Transformation) Thomas Mayer XML 25

69 3.Grammar writing with XML XML can be used for... Thomas Mayer XML 26

70 3.Grammar writing with XML XML can be used for... documenting grammars Thomas Mayer XML 26

71 3.Grammar writing with XML XML can be used for... documenting grammars annotating corpora Thomas Mayer XML 26

72 3.Grammar writing with XML XML can be used for... documenting grammars annotating corpora encoding grammars Thomas Mayer XML 26

73 3.Grammar writing with XML XML can be used for... documenting grammars annotating corpora encoding grammars... Thomas Mayer XML 26

74 3.1Documenting grammars Idea: The source grammar (XLE) is annotated with XML tags for documentation purposes. Together with a source documentation you can extract the information from the grammar and build a complete (output) documentation for the grammar. Thomas Mayer XML 27

75 Thomas Mayer XML 28

76 3.2Annotating corpora We already discussed that... Thomas Mayer XML 29

77 3.3Encoding grammars A rule such as NP --> D: ^=!; N: ^=!; can be encoded as... Thomas Mayer XML 30

78 <rule> <mother>np</mother> <daughters> <daughter> <c_struc>d</c_struc> <f_struc>^=!</f_struc> </daughter> <daughter> <c_struc>n</c_struc> <f_struc>^=!</f_struc> </daughter> </daughters> </rule> Thomas Mayer XML 31

79 Several output files could be generated Thomas Mayer XML 32

80 Several output files could be generated grammar code Thomas Mayer XML 32

81 Several output files could be generated grammar code pdf-file with tree structure Thomas Mayer XML 32

82 Several output files could be generated grammar code pdf-file with tree structure html-file with links to the rules Thomas Mayer XML 32

83 Have a nice term break!

M359 Block5 - Lecture12 Eng/ Waleed Omar

M359 Block5 - Lecture12 Eng/ Waleed Omar Documents and markup languages The term XML stands for extensible Markup Language. Used to label the different parts of documents. Labeling helps in: Displaying the documents in a formatted way Querying