XML (4) Extensible Markup Language

Transcription

1 XML (4) Extensible Markup Language Acknowledgements and copyrights: these slides are a result of combination of notes and slides with contributions from: Michael Kiffer, Arthur Bernstein, Philip Lewis, Hanspeter Mφssenbφck, Hanspeter Mφssenbφck, Wolfgang Beer, Dietrich Birngruber, Albrecht Wφss, Mark Sapossnek, Bill Andreopoulos, Divakaran Liginlal, Anestis Toptsis, Addison Wesley, Microsoft AA. They serve for teaching purposes only and only for the students that are registered in CSE4413 and should not be published as a book or in any form of commercial product, unless written permission is obtained from each of the above listed names and/or organizations. 1

2 The Simple Type: <simpletype> The Simplest Type Declaration: <xsd:simpletype name = FirstName type = xsd:string /> Based on a built in primitive datatype Cannot contain sub-elements or attributes Can declare constraining properties ( facets ) minlength, maxlength, Length, etc May be used as base type of a complextype (see later). 2

3 Enumerated types (in simpletype) Used to constrain the set of possible values for a simple type. Example: <xsd:element name= students > <xsd:simpletype name= 4413Winter2006 > <xsd:restriction base= xsd:string > <xsd:enumeration value= cs /> <xsd:enumeration value= cs /> <xsd:enumeration value= cs /> <xsd:enumeration value= cs /> </xsd:restriction> <xsd:simpletype> </xsd:element> Example: <student> cs </student> is not allowed <student> cs </student> is OK. 3

4 Enumeration: another Example <xsd:simpletype name= Canada-Flag-Colors"> <xsd:restriction base="xsd:string"> <xsd:enumeration value="red"/> <xsd:enumeration value="white"/> </xsd:restriction> </xsd:simpletype> This creates a new type called Canada-Flag-Colors. An element declared to be of this type must have either the value red, or white. 4

5 Patterned types (in simpletype) Allow you to use a regular expression to establish a pattern that the type value should follow. Example: <xsd:element name= pizza > <xsd:simpletype> <xsd:restriction base= xsd:string > <xsd:pattern value= (medium large)-(thin deep)- (sausage_)?(pepperoni_)?(mushrooms_)?(anchovies_)?(redonion_)?/> <xsd:restriction> </xsd:simpletype> <xsd:element> Usage: <pizza> medium-deep-pepperoni_redonion </pizza> 5

6 Operations in regular expressions for patterned types X? at most one X X+ -- at least one X X* -- any number of X (XY) group X and Y trogether X Y X or Y [XYZ] one of X, Y, Z. X{n} n number of Xs in a row. X(n,m} at least n Xs, but no more than m Xs.. any character \d any digit \D any non-digit \s any white space \S any non-white space 6

7 Another Example of Creating a New Datatype by using patterns <xsd:simpletype name="telephonenumber"> <xsd:restriction base="xsd:string"> <xsd:length value="8"/> <xsd:pattern value="\d{3}-\d{4}"/> </xsd:restriction> </xsd:simpletype> The string must follow the pattern: ddd-dddd, where 'd' represents a 'digit'. This creates a new datatype called 'TelephoneNumber'. Elements of this type can hold string values The string length must be exactly 8 characters long 7

8 List (in simpletype) xsd:list is used to create a list type, which is useful any time you need to allow for a list of information. Example: <xsd:element name= alist > <xsd:simpletype name= myintlist > <xsd:list itemtype= integer /> <xsd:length value= 12 /> </xsd:list> </simpletype> </xsd:element> Allows to create a list of 12 integers, separated by white space. <alist> </alist> 8

9 The Complex Type: <complextype> Used to define a new complex type May be based on simple or existing complextypes May declare elements or element references: <element name=... type =... /> <element ref=... /> May declare attributes or reference attribute groups <attribute name=... type=... /> <attributegroup ref =... /> 9

10 Example: Defining a complextype <xsd:complextype name= Customer > <xsd:sequence> <xsd:element name= Person type= Name /> <xsd:element name= Address type= Address /> </xsd:sequence > </complextype> Name of the type for future referencing <xsd:complextype name= Address > <xsd:sequence > <xsd:element name= Street type= string /> <xsd:element name= City type= string /> Type Address, defined and used <xsd:element name= State type= State_Region /> <xsd:element name= PostalCode type= string /> <xsd:element name= Country type= string /> </sequence> </xsd:complextype> Type State_Region used needs to be defined as well. 10

11 Complex types One of the most useful features of complex type definitions is the use of the sequence reserved word. A sequence is a list of child elements that must appear in a particular order. Ex: <xsd:element name= employee > <xsd:complextype> <xsd:sequence> <xsd:element name= name type= xsd:string /> <xsd:element name= birthday type= xsd:date /> <xsd:element name= age type= xsd:positiveinteger /> <xsd:element name= salary type= xsd:float /> </xsd:sequence> </xsd:complextype> </xsd:element> 11

12 Sequence (complextype ) Usage: <employee> <name> Joe Q. Public </name> <birthday> </birthday> <age>30</age> <salary> </salary> </employee> 12

13 Compositors: Sequences, Sets, Compositors: alternatives sequence, all, choice are required when element has at least 1 child element (= complex content) sequence -- have already seen all can specify sets of elements choice can specify alternative types 13

14 Choice (complextype ) The choice reserved word allows you to list several child elements (and/or sequences!) with only one of them allowed for use in any given element. Example: <xsd:element name= id > <xsd:complextype> <xsd:choice> <xsd:element name= sin type= xsd:string > <xsd:sequence> <xsd:element name= name type= xsd:string > <xsd:element name= address type= xsd:string > <xsd:element name= birthdate type= xsd:date > </xsd:sequence> <xsd:element name= driverslicence type= xsd:string > </xsd:choice> <xsd:complextype> <xsd:element> Define an id to be either the sin, or the (name and address and birthdate), or the driverslicence. 14

15 Choice (complextype ) 2.. Assume addresses can have P.O.Box or street name/number: <xsd:complextype name= addresstype > <xsd:sequence> <xsd:choice> <xsd:element name= POBox type= string /> <xsd:sequence> <xsd:element name= Name type= string /> <xsd:element name= Number type= string /> </xsd:sequence> </xsd:choice> <xsd:element name= City type= string /> </xsd:sequence> </xsd:complextype> This or that 15

16 Sets (compextype ) Use for when the order of components in addresses is unimportant: <xsd:complextype name= addresstype > <xsd:all> <xsd:element name= StreetName type= string /> <xsd:element name= StreetNumber type= string /> <xsd:element name= City type= string /> </xsd:all> </xsd:complextype> Problem: all comes with a host of awkward restrictions. For instance, cannot occur inside a sequence; only sets of elements, not bags. 16

17 Declaring Attributes Declared using <attribute> tag Value pairs Can only be assigned to <complextype> types May be grouped into an attribute group more later! Based on a <simpletype>, by reference or explicitly <attribute name = age type= integer /> <!-- OR --> <xsd:attribute name = age > <xsd:simpletype> <xsd:restriction base= integer > <maxlength = 3 /> </xsd:restriction> </xsd:simpletype> </xsd:attribute> 17

18 Declaring Attribute Groups 1/2 Way to group related attributes together Promotes logical organization Must be unique within an XML Schema Referenced from complextype definitions 18

19 Declaring Attribute Groups 2/2 <!-- Define the unique group: --> <xsd:attributegroup name = CreditCardInfo > <xsd:attribute name = CardNumber type = integer use = required /> <xsd:attribute name = ExpirationDate type = date use = required /> <xsd:attribute name = CardHolder type = FullName use = required /> </xsd:attributegroup> Complex type FullName defined elsewhere <!-- Then you can reference it from a complextype: --> <xsd:complextype name = CreditInformation > <xsd:attributegroup ref = CreditCardInfo /> </xsd:complextype> 19

20 <xsd:element name="book"> <xsd:complextype> <xsd:sequence> </xsd:sequence> <xsd:attribute ref="category" use="required"/> </xsd:complextype> </xsd:element> <xsd:attribute name="category"> <xsd:simpletype> <xsd:restriction base="xsd:string"> <xsd:enumeration value="autobiography"/> <xsd:enumeration value="fiction"/> <xsd:enumeration value="non-fiction"/> </xsd:restriction> </xsd:simpletype> </xsd:attribute> Attribute declaration. Use the "use" attribute here. Attribute type declaration. Must NOT have a "use" ("use" only makes sense in the context of an element) Another example: declare an element with attribute and declare the attribute as well. 20

21 Inlining Attributes An alternative way of expressing the last example - the attributes are inlined within the Book declaration rather than being separately defined. 21

22 <xsd:element name="book" maxoccurs="unbounded"> <xsd:complextype> <xsd:sequence> <xsd:element name="title" type="xsd:string"/> <xsd:element name="author" type="xsd:string" maxoccurs="unbounded"/> </xsd:sequence> <xsd:attribute name="category" use="required"> <xsd:simpletype> <xsd:restriction base="xsd:string"> <xsd:enumeration value="autobiography"/> <xsd:enumeration value="non-fiction"/> <xsd:enumeration value="fiction"/> </xsd:restriction> </xsd:simpletype> </xsd:attribute> <xsd:attribute name="instock" type="xsd:boolean" default="false"/> <xsd:attribute name="reviewer" type="xsd:string" default=" "/> </xsd:complextype> </xsd:element> 22

23 <xsd:complextype> or <xsd:simpletype>? When do you use the complextype element and when do you use the simpletype element? Use the complextype element when you want to define child elements and/or attributes of an element Use the simpletype element when you want to create a new type that is a refinement of a built-in type (string, date, year, etc) 23

24 Declaring elements :: Structure of <xsd:element> <xsd:element maxoccurs=int maximum number of occurrences minoccurs=int minimum number of occurrences name=string name of the element ref=qname refer to an existing element (QName is a namespace qualified name) type=qname a simple type or a custom type identifier > (simpletype or complextype)? optional type specs </xsd:element> 24

25 Declaring Elements <xsd:element name="name" type="type" minoccurs="int maxoccurs="int"/> <xsd:element name="name" minoccurs="int" maxoccurs="int"> <xsd:complextype> </xsd:complextype> </xsd:element> <xsd:element name="name" minoccurs="int" maxoccurs="int"> <xsd:simpletype> <xsd:restriction base="type"> </xsd:restriction> </xsd:simpletype> </xsd:element> 25

26 minoccurs and maxoccurs If not specified minoccurs is "1" If not specified maxoccurs is "1" <xsd:element ref="title" minoccurs="1" maxoccurs="1"/> Equivalent! <xsd:element ref="title"/> 26

27 Structure of complextype Nameless (anonymous) <xsd:complextype mixed=boolean allow both elements and attribute children name=ncname name for this complextype (Qname without prefix and colon) > <choice> or <sequence> of following elements (optional) <attribute> or <attributegroup> - specify attributes </xsd:complextype > OR, named <xsd:complextype name= thetypename mixed=boolean allow both elements and attribute children name=ncname name for this complextype > <choice> or <sequence> of following elements (optional) <attribute> or <attributegroup> - specify attributes </xsd:complextype > 27

28 Example 1. Declare an element called Book 2. This element has a sequence of one or more Chapter elements <Book> <Chapter number= 1 pages = 35 /> <Chapter number= 2 pages= 71 /> </Book> The XSD: <xsd:element name= Book"> <xsd:complextype> <xsd:sequence> <xsd:element name= Chapter > </xsd:element> </xsd:sequence> </xsd:complextype> </xsd:element> ( the DTD!) <!ELEMENT Book (Chapter)+> 28

29 Example 1. To complete the definition of element Book, we need to define an element called Chapter 2. This element has two attributes: 1. number, an integer, and 2. pages, an integer. The XSD <xsd:element name= Chapter" type= ItemType /> <xsd:complextype name= ItemType > <xsd:attribute name= number" type="xsd:integer" use="required"/> <xsd:attribute name= pages" type= xsd:integer" use="required"/> </xsd:complextype> (the DTD!) <!ELEMENT Chapter EMPTY> <!ATTLIST Chapter name CDATA #REQUIRED price CDATA #REQUIRED> 29

30 The completed XSD definition <xsd:element name= Book"> <xsd:complextype> <xsd:sequence> <xsd:element name= Chapter > </xsd:element> </xsd:sequence> </xsd:complextype> </xsd:element> Used here Defined here <xsd:element name= Chapter" type= ItemType /> <xsd:complextype name= ItemType > Used here <xsd:attribute name= number" type="xsd:integer" use="required"/> <xsd:attribute name= pages" type= xsd:integer" use="required"/> </xsd:complextype> Defined here 30

31 Example: Element Containing a User- Defined Simple Type (cont.) Here's an alternative method for declaring elevation: <xs:element name="elevation"> <xs:simpletype> <xs:restriction base="xs:integer"> <xs:mininclusive value="-1290"/> <xs:maxinclusive value="29035"/> </xs:restriction> </xs:simpletype> </xs:element> The simpletype definition is defined inline, it is an anonymous simpletype definition. The disadvantage of this approach is that this simpletype may not be reused by other elements. 31

32 Comparing Approaches to Defining an element <xsd:element name= Menu" type= MenuType"/> <xsd:complextype name= MenuType"> <xsd:sequence> <xsd:element name= Item" type= ItemType /> </xsd:sequence> </xsd:complextype> Element Menu is of type MenuType is equivalent to: Element Menu has the complextype definition inlined in the element declaration. <xsd:element name= Menu"> <xsd:complextype> <xsd:sequence> <xsd:element name= Item" type= ItemType /> <xsd:element name="c" /> </xsd:sequence> </xsd:complextype> </xsd:element> 32

33 Example of using Types <xsd:complextype name="itemtype"> <xsd:attribute name="name" type="xsd:string" use="required"/> <xsd:attribute name="price" type="xsd:string" use="required"/> </xsd:complextype> <xsd:complextype name="menutype"> <xsd:sequence> <xsd:element name="item" type="itemtype" maxoccurs="unbounded"/> </xsd:sequence> </xsd:complextype> <xsd:element name="restaurant"> <xsd:complextype> <xsd:sequence> <xsd:element name="menu" type="menutype"/> </xsd:sequence> <xsd:attribute name="name" type="xsd:string" use="required"/> <xsd:attribute name="location" type="xsd:string" use="required"/> </xsd:complextype> </xsd:element> </xsd:schema> Declare a type called ItemType Declare a type called MenuType containing the element <Item> Declare the root element <Restaurant> Declare the element <Menu> 33

34 Example of using ref <xsd:element name= Restaurant"> Refer to <Menu> Declaration <xsd:complextype> <xsd:sequence> <xsd:element ref= Menu" minoccurs="1" maxoccurs= 1"/> </xsd:sequence>.attributes for Restaurant. Declare the element <Menu> </xsd:complextype> </xsd:element> <xsd:element name= Menu"> <xsd:complextype> <xsd:sequence> <xsd:element name= Item" minoccurs="1 maxoccurs= unbounded"/> </xsd:sequence>.. Attributes for Item.. </xsd:complextype> </xsd:element> </xsd:schema> Declare the root element <Restaurant> Declare the element <Item> 34

35 Exercise Write a XML document that conforms to previous schema (with root element Restaurant). Note, you will need to complete the schema definition for the missing attributes (make your own choices). 35

36 type attribute or complextype Child Element, but not Both! An element declaration can have a type attribute, or a complextype child element, but it cannot have both a type attribute and a complextype child element. <xsd:element name= Menu" type= MenuType"> <xsd:complextype> </xsd:complextype> </xsd:element> 36

37 Element Containing a User- Defined Simple Type Example. Create a schema element declaration for an elevation element. Declare the elevation element to be an integer with a range to <elevation>5240</elevation> Here's one way of declaring the elevation element: <xsd:simpletype name="earthsurfaceelevation"> <xsd:restriction base="xsd:integer"> <xsd:mininclusive value="-1290"/> <xsd:maxinclusive value="29035"/> </xsd:restriction> </xsd:simpletype> <xsd:element name="elevation" type="earthsurfaceelevation"/> 37

38 Element Containing a User-Defined Simple Type inlined (with anonymous simple type definition) Here's an alternative method for declaring elevation: <xsd:element name="elevation"> <xsd:simpletype> <xsd:restriction base="xsd:integer"> <xsd:mininclusive value="-1290"/> <xsd:maxinclusive value="29035"/> </xsd:restriction> </xsd:simpletype> </xsd:element> The simpletype definition is defined inline, it is an anonymous simpletype definition. The disadvantage of this approach is that this simpletype may not be reused by other elements. 38

39 Schema Document and Namespaces <schema xmlns= targetnamespace= > </schema> Uses standard XML syntax. namespace for keywords used in a schema document (not an instance document), e.g., schema, targetnamespace, etc. targetnamespace names the namespace defined by the above schema. Every XML document that is an instance of this schema should then specify and have as default namespace the one specified by this schema (i.e., 39

40 Playing with Visual Studio.NET Visual Studio.NET supports XML and XSD (and DTD). 40

41 A XML schema (stored in a file with the extension.xsd, e.g. Books.xsd.) <xsd:schema xmlns:xsd=" xmlns="schema.xsd" elementformdefault="qualified" targetnamespace="schema.xsd"> <xsd:element name="bookstore" type="bookstoretype" /> <xsd:complextype name="bookstoretype"> <xsd:sequence maxoccurs="unbounded"> <xsd:element name="book" type="booktype" /> </xsd:sequence> </xsd:complextype> <xsd:complextype name="booktype"> <xsd:sequence> <xsd:element name="title" type="xsd:string" /> <xsd:element name="author" type="authorname" /> <xsd:element name="price" type="xsd:decimal" /> </xsd:sequence> <xsd:attribute name="genre" type="xsd:string" /> <xsd:attribute name="publicationdate" type="xsd:string" /> <xsd:attribute name="isbn" type="xsd:string" /> </xsd:complextype> <xsd:complextype name="authorname"> <xsd:sequence> <xsd:element name="first-name" type="xsd:string" /> <xsd:element name="last-name" type="xsd:string" /> </xsd:sequence> </xsd:complextype> </xsd:schema> 41

42 If open the.xsd file with visual studio.net and right-click.. Select View Schema 42

43 Generated diagram by selecting View Schema (previous slide). 43

44 A corresponding XML document (Books.xml) <?xml version="1.0"?> <!-- This file represents a fragment of a book store inventory database --> <bookstore xmlns=" <book genre="autobiography"> <title>the Autobiography of Benjamin Franklin</title> <author> <first-name>benjamin</first-name> <last-name>franklin</last-name> </author> <price>8.99</price> </book> <book genre="novel"> <title>the Confidence Man</title> <author> <first-name>herman</first-name> <last-name>melville</last-name> </author> <price>11.99</price> </book> <book genre="philosophy"> <title>the Gorgias</title> <author> <name>plato</name> </author> <price>9.99</price> </book> </bookstore> 44

45 Can open it with visual studio.net right-click.. Select View Data 45

46 And you will get a Data View of the XML document! 46

47 .. In the same XML document right-click.. Select Create Schema 47

48 And you will get a XSD generated by vs.net that corresponds to the XML document! The schema can be edited by right-click here also. Allows editing the schema 48

49 Also can use the Toolbox to edit the schema 49

50 XSD validation XSV (XML Schema Validator). Standalone command-line validator. <oxygen/> XML editor and XSD (and DTD) validator 50