Sistemi ICT per il Business Networking

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1 Corso di Laurea Specialistica Ingegneria Gestionale Sistemi ICT per il Business Networking XML Schema Docente: Vito Morreale 1

2 Motivation People are dissatisfied with DTDs It's a different syntax You write your XML (instance) document using one syntax and the DTD using another syntax --> bad, inconsistent Limited datatype capability You cannot, for example, say "I want the <elevation> element to hold an integer with a range of 0 to 12,000" Desire a set of datatypes compatible with those found in databases DTD supports 10 datatypes; XML Schemas supports 41+ datatypes

3 Highlights of XML Schemas XML Schemas are a tremendous advancement over DTDs: Enhanced datatypes 41+ versus 10 Can create your own datatypes Written in the same syntax as instance documents Object-oriented Can extend or restrict a type (derive new type definitions on the basis of old ones) Can express sets, i.e. can define the child elements to occur in any order

4 BookCatalogue.dtd <!-- A book catalogue contains zero or more books --> <!ELEMENT BookCatalogue (Book)*> <!ELEMENT Book (Title, Author, Date, ISBN, Publisher)> <!ELEMENT Title (#PCDATA)> <!ELEMENT Author (#PCDATA)> <!ELEMENT Date (#PCDATA)> <!ELEMENT ISBN (#PCDATA)> <!ELEMENT Publisher (#PCDATA)>

5 <?xml version="1.0"?> <schema xmlns=" targetnamespace=" elementformdefault="qualified" xmlns:cat=" <element name="bookcatalogue"> <complextype> <sequence> <annotation> <documentation>a book catalogue contains zero or more books</documentation> </annotation> <element ref="cat:book" minoccurs="0" maxoccurs="unbounded"/> </sequence> </element> <element name="book"> <complextype> <sequence> <element ref="cat:title" minoccurs="1" maxoccurs="1"/> <element ref="cat:author" minoccurs="1" maxoccurs="1"/> <element ref="cat:date" minoccurs="1" maxoccurs="1"/> <element ref="cat:isbn" minoccurs="1" maxoccurs="1"/> <element ref="cat:publisher" minoccurs="1" maxoccurs="1"/> </sequence> </element> <element name="title" type="string"/> <element name="author" type="string"/> <element name="date" type="string"/> <element name="isbn" type="string"/> <element name="publisher" type="string"/> </schema> (explanations on succeeding pages) xsd = Xml-Schema Definition

6 <?xml version="1.0"?> <schema xmlns=" targetnamespace=" aces/bookcatalogue" elementformdefault="qualified" All XML schemas have "schema" as the root element. xmlns:cat=" e"> </schema>

7 complextype element annotation documentation sequence schema This (default) namespace declaration says that all these elements come from the XMLSchema namespace <?xml version="1.0"?> <schema xmlns=" > </schema>

8 <?xml version="1.0"?> <schema xmlns=" targetnamespace= " elementformdefault="qualified" xmlns:cat=" </schema> The elements declared in this schema (BookCatalogue, Book, Title, Author, Date, ISBN, Publisher) are to be in this Namespace. Instance documents Instance documents will use the elements from this namespace.

9 Publishing Namespace BookCatalogue Author Book Title Publisher ISBN Date

10 <?xml version="1.0"?> <schema xmlns=" targetnamespace= " elementformdefault="qualified" xmlns:cat=" </schema> Says that in instance documents all the elements from the publishing namespace must be qualified with a namespace qualifier

11 <?xml version="1.0"?> <schema > <element name="bookcatalogue"> <complextype> <sequence> <annotation> <documentation> A book catalogue contains zero or more books </documentation> </annotation> </sequence> </element> </schema> The annotation/documentation elements are optional. Their content is intended for human consumption, i.e. it's a comment

12 Summary of Declaring Elements (two ways to do it) 1 <element name="name name" type="type type" minoccurs="int int" " maxoccurs="int int"/> A simple type (e.g., string) or the name of a complextype A nonnegative number A nonnegative number or "unbounded" 2 <element name="name name" " minoccurs="int int" " maxoccurs="int int"> <complextype> </element>

13 <?xml version="1.0"?> <schema > <element name="bookcatalogue"> <complextype> <sequence> <element name="book" minoccurs="0" maxoccurs="unbounded"> <complextype> <sequence> <element name="title" type="string" minoccurs="1" maxoccurs="1"/> <element name="author" type="string" minoccurs="1" maxoccurs="1"/> <element name="date" type="string" minoccurs="1" maxoccurs="1"/> <element name="isbn" type="string" minoccurs="1" maxoccurs="1"/> <element name="publisher" type="string" minoccurs="1" maxoccurs="1"/> </sequence> </element> </sequence> </element> </schema>

14 Named type <?xml version="1.0"?> <schema > <complextype name="cardcatalogueentry"> <sequence> <element name="title" type="string" minoccurs="1" maxoccurs="1"/> <element name="author" type="string" minoccurs="1" maxoccurs="1"/> <element name="date" type="string" minoccurs="1" maxoccurs="1"/> <element name="isbn" type="string" minoccurs="1" maxoccurs="1"/> <element name="publisher" type="string" minoccurs="1" maxoccurs="1"/> </sequence> </schema>

15 <element name="a" type= tns:foo"/> <complextype name="foo"> <sequence> <element name="b" /> <element name="c" /> </sequence> Element A references the complextype foo. is equivalent to <element name="a"> <complextype> <sequence> <element name="b" /> <element name="c" /> </sequence> </element> Element A has the complextype definition inlined in the element declaration.

16 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. <element name="a" type="foo"> <complextype> </element>

17 Problem Defining the Date element to be of type string is unsatisfactory We would like to constrain the allowable content that Date can have Modify the BookCatalogue schema to restrict the content of the Date element to just date values (actually, year values) <?xml version="1.0"?> <schema > <element name="bookcatalogue"> <complextype> <sequence> <element name="book" minoccurs="0" maxoccurs="unbounded"> <complextype> <sequence> <element name="date" type="string" minoccurs="1" maxoccurs="1"/> <element name="isbn" type="string" minoccurs="1" maxoccurs="1"/> <element name="publisher" type="string" minoccurs="1" maxoccurs="1"/> </sequence> </element> </sequence> </element> </schema> Similarly, constrain the content of the ISBN element to content of this form: ddddd-ddddd- ddddd or d-ddd-ddddd-d or d-dd-dddddd-d, where 'd' stands for 'digit'

18 The date Datatype A built-in datatype Elements must follow this form: CCYY-MM-DD range for CC is: range for YY is: range for MM is: range for DD is: if month is if month is 2 and the year is a leap year if month is 4, 6, 9, or if month is 1, 3, 5, 7, 8, 10, or 12 Example: represents May 31, 1999

19 A built-in datatype The year Datatype Elements declared to be of type year must follow this form: CCYY range for CC is: range for YY is: Example: 1999 indicates the year 1999

20 <simpletype name="isbntype"> <restriction base="string"> <pattern value="\d{5}-\d{5}-\d{5}"/> <pattern value="\d{1}-\d{3}-\d{5}-\d{1}"/> <pattern value="\d{1}-\d{2}-\d{6}-\d{1}"/> </restriction> </simpletype> Elements declared of this type must conform to one of the following patterns: - First Pattern: 5 digits followed by a dash followed by 5 digits followed by another dash followed by 5 more digits, or - Second Pattern: 1 digit followed by a dash followed by 3 digits followed by another dash followed by 5 digits followed by another dash followed by 1 more digit, or - Third Pattern: 1 digit followed by a dash followed by 2 digits followed by another dash followed by 6 digits followed by another dash followed by 1 more digit

21 <complextype> or <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, integer, etc)

22 Creating your own Datatypes A new datatype can be defined from an existing datatype (called the "base" type) by specifying values for one or more of the optional facets for the base type Example. The string primitive datatype has six optional facets: pattern enumeration length minlength maxlength whitespace (legal values: preserve, replace, collapse)

23 Example of Creating a New Datatype by Specifying Facet Values <simpletype name="telephonenumber TelephoneNumber"> <restriction base="string"> <length value="8"/> <pattern value="\d{3}-\d{4}"/> </restriction> </simpletype> This creates a new datatype called 'TelephoneNumber'. Elements of this type can hold string values, but the string length must be exactly 8 characters long and the string must follow the pattern: ddd-dddd, where 'd' represents a 'digit'. (Obviously, in this example the regular expression makes the length facet redundant.)

24 Another Example <simpletype name="us-flag-colors"> <restriction base="string"> <enumeration value="red"/> <enumeration value="white"/> <enumeration value="blue"/> </restriction> </simpletype> This creates a new type called US-Flag-Colors. An element declared to be of this type must have either the value red, or white, or blue.

25 General Form of Creating a New Datatype <simpletype name= "name"> <restriction base= "source"> <facet value= "value"/> <facet value= "value"/> </restriction> </simpletype> Facets: - length - minlength - maxlength - pattern - enumeration - mininclusive - maxinclusive - minexclusive - maxexclusive... Sources: - string - boolean - float - double - decimal - timeduration - recurringduration - urireference...

26 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: <simpletype name="earthsurfaceelevation"> <restriction base="integer"> <mininclusive value="-1290"/> <maxinclusive value="29028"/> </restriction> </simpletype> <element name="elevation" type="a:earthsurfaceelevation"/>

27 Element Containing a User-Defined Simple Type (cont.) Here's an alternative method for declaring elevation: <element name="elevation elevation"> <simpletype> <restriction base="integer"> <mininclusive value="-1290"/> <maxinclusive value="29028"/> </restriction> </simpletype> </element>

28 Derived Types We can do a form of subclassing complextype definitions. We call this "derived types" derive by extension: extend the parent complextype with more elements derive by restriction: constrain the parent complextype by constraining some of the elements to have a more restricted range of values, or a more restricted number of occurrences

29 <?xml version="1.0"?> <schema > <complextype name="publication"> <sequence> <element name="title" type="string" minoccurs="1" maxoccurs="unbounded"/> <element name="author" type="string" minoccurs="1" maxoccurs="unbounded"/> <element name="date" type="year" minoccurs="1" maxoccurs="1"/> </sequence> <complextype name="book"> <complexcontent> <extension base= tns:publication" > <sequence> <element name="isbn" type="string" minoccurs="1" maxoccurs="1"/> <element name="publisher" type="string" minoccurs="1" maxoccurs="1"/> </sequence> </extension> </complexcontent>

30 Derive by Restriction <complextype name="publication"> <sequence> <element name="title" type="string" minoccurs="1" maxoccurs="unbounded"/> <element name="author" type="string" minoccurs="1" maxoccurs="unbounded "/> <element name="date" type="year" minoccurs="1" maxoccurs="1" /> </sequence> <complextype name= "SingleAuthorPublication"> <complexcontent> <restriction base= tns:publication"> <sequence> <element name="title" type="string" minoccurs="1" maxoccurs="unbounded"/> <element name="author" type="string" minoccurs="1" maxoccurs="1"/> <element name="date" type="year" minoccurs="1" maxoccurs="1"/> </sequence> </restriction> </complexcontent>

31 In a schema: Terminology: Declaration vs Definition You declare elements and attributes. Schema components that are declared are used in an XML instance document. You define components that are used just within the schema document(s) Declarations: - element declarations - attribute declarations Definitions: - type definitions - attribute group definitions - model group definitions

32 Terminology: Global versus Local Global element declarations, global type definitions: These are element declarations/type definitions that are immediate children of <schema> Local element declarations, local type definitions: These are element declarations/type definitions that are nested within other elements/types.

33 <?xml version="1.0"?> <schema > Local type definition <complextype name="publication"> <sequence> Local element declarations <element name="title" type="string" minoccurs="1" /> Global element declaration </sequence> Global type definition <complextype name="book"> <complexcontent> <extension base="cat:publication"> <sequence> <element name="isbn" type="string" minoccurs="1" maxoccurs="1"/> <element name="publisher" type="string" minoccurs="1" maxoccurs="1"/> </sequence> </extension> </complexcontent> <element name="bookcatalogue"> <complextype> <sequence> <element name="book" minoccurs="0" maxoccurs="unbounded" type="cat:book"/> </sequence> </element> </schema>

34 Attributes <!ELEMENT BookCatalogue (Book)*> <!ELEMENT Book (Title, Author+, Date, ISBN, Publisher)> <!ATTLIST Book Category (autobiography non-fiction fiction) #REQUIRED InStock (true false) "false" Reviewer CDATA ""> <!ELEMENT Title (#PCDATA)> <!ELEMENT Author (#PCDATA)> <!ELEMENT Date (#PCDATA)> <!ELEMENT ISBN (#PCDATA)> <!ELEMENT Publisher (#PCDATA)> <!ELEMENT Month (#PCDATA)> <!ELEMENT Year (#PCDATA)>

35 Attributes <?xml version="1.0"?> <schema "> <element name="book"> <complextype> <sequence> <element ref="title" minoccurs="1" maxoccurs="1"/> <element ref="author" minoccurs="1" maxoccurs="unbounded"/> <element ref="date" minoccurs="1" maxoccurs="1"/> <element ref="isbn" minoccurs="1" maxoccurs="1"/> <element ref="publisher" minoccurs="1" maxoccurs="1"/> </sequence> <attributegroup ref= cat:bookattributes"/> </element>

36 Attributes <attributegroup name="bookattributes"> <attribute name="category" use="required"> <simpletype> <restriction base="string"> <enumeration value="autobiography"/> <enumeration value="non-fiction"/> <enumeration value="fiction"/> </restriction> </simpletype> </attribute> <attribute name="instock" type="boolean" use="default" value="false"/> <attribute name="reviewer" type="string" use="default" value=""/> </attributegroup> </schema>

37 Summary of Declaring Attributes 1 <attribute name="name" type="simple-type" use="how-its-used" value="value"/> string integer boolean... required default fixed optional prohibited This attribute is only used with use="default" and use="fixed" 2 <attribute name="name" use="how-its-used" value="value"> <simpletype> <restriction base="simple-type"> <facet value="value"/> </restriction> </simpletype> </attribute>

38 <element name="book"> <complextype> <sequence> <element name="title" type="string" minoccurs="1" maxoccurs="1"/> <element name="author" type="string" minoccurs="1" maxoccurs="unbounded"/> <element name="date"type="string" minoccurs="1" maxoccurs="1"/> <element name="isbn" type="string" minoccurs="1" maxoccurs="1"/> <element name="publisher" type="string" minoccurs="1" maxoccurs="1"/> </sequence> <attribute name="category" use="required"> <simpletype> <restriction base="string"> <enumeration value="autobiography"/> <enumeration value="non-fiction"/> <enumeration value="fiction"/> </restriction> </simpletype> </attribute> <attribute name="instock" type="boolean" use="default" value="false"/> <attribute name="reviewer" type="string" use="default" value=""/> </element>

39 Notes about Attributes The attribute declarations always come after the element declarations. The attributes are always with respect to the element that they are defined (nested) within. "bar and boo are attributes of foo" <element name="foo"> <complextype> <sequence> </sequence> <attribute name="bar" /> <attribute name="boo" /> </element>

40 These attributes apply to the element they are nested within (Book) That is, Book has three attributes - Category, InStock, and Reviewer. <element name="book"> <complextype> <sequence> <element name="title" type="string" minoccurs="1" maxoccurs="1"/> <element name="author" type="string" minoccurs="1" maxoccurs="unbounded"/> <element name="date" type="string" minoccurs="1" maxoccurs="1"/> <element name="isbn" type="string" minoccurs="1" maxoccurs="1"/> <element name="publisher" type="string" minoccurs="1" maxoccurs="1"/> </sequence> <attribute name="category" use="required"> <simpletype> <restriction base="string"> <enumeration value="autobiography"/> <enumeration value="non-fiction"/> <enumeration value="fiction"/> </restriction> </simpletype> </attribute> <attribute name="instock" type="boolean" use="default" value="false"/> <attribute name="reviewer" type="string" use="default" value=""/> </element>

41 Expressing Alternates DTD: <!ELEMENT transportation (train plane automobile)> XML Schema: <?xml version="1.0"?> <schema xmlns=" targetnamespace=" elementformdefault="qualified"> <element name="transportation"> <complextype> <choice> <element name="train" type="string" minoccurs="1" maxoccurs="1"/> <element name="plane" type="string" minoccurs="1" maxoccurs="1"/> <element name="automobile" type="string" minoccurs="1" maxoccurs="1"/> </choice> </element> </schema>

42 Expressing Any Order Problem: create an element, Book, which contains Author, Title, Date, ISBN, and Publisher, in any order (Note: this cannot be done with DTDs). <?xml version="1.0"?> <schema > <element name="bookcatalogue"> <complextype> <sequence> <element name="book" minoccurs="0" maxoccurs="unbounded"> <complextype> <all> <element name="title" type="string" minoccurs="1" maxoccurs="1"/> XML <element name="author" type="string" minoccurs="1" maxoccurs="1"/> Schema: <element name="date" type="string" minoccurs="1" maxoccurs="1"/> <element name="isbn" type="string" minoccurs="1" maxoccurs="1"/> <element name="publisher" type="string" minoccurs="1" maxoccurs="1"/> </all> </element> </sequence> </element> </schema> <all> means that Book must contain all five child elements, but they may occur in any order.

43 Constraints on using <all> Elements declared within <all> must have a maxoccurs value of "1" (minoccurs can be either "0" or "1")

44 Assembling an Instance Document from Multiple Schema Documents An instance document may have elements from multiple schemas. Validation can apply to the entire XML instance document, or to a single element.

45 <?xml version="1.0"?> <Library xmlns:b=" xmlns:e=" xmlns:xsi=" xsi:schemalocation= " BookCatalogue.xsd </Library> Employee.xsd"> Validating against two schemas

46 <?xml version="1.0"?> <camera xmlns=" xmlns:nikon=" xmlns:olympus=" xmlns:pentax=" xmlns:xsi=" xsi:schemalocation= " Camera.xsd Nikon.xsd Olympus.xsd Pentax.xsd"> <body> <nikon:description>ergonomically designed casing for easy handling</nikon:description> </body> <lens> <olympus:zoom>300mm</olympus:zoom> <olympus:f-stop>1.2</olympus:f-stop> </lens> <manual_adapter> <pentax:speed>1/10,000 sec to 100 sec</pentax:speed> </manual_adapter> </camera> The Camera instance uses elements from the Nikon, Olympus, and Pentax namespaces. Camera.xml (see example 15)

47 anyattribute The <anyattribute> allows any attributes <element name="free-form"> <complextype> <anyattribute/> </element> The free-form element can have any attribute. <free-form comment="this is great"/>

48 Materiale didattico

49 Ulteriori Informazioni Dove reperire ulteriori informazioni su XML W3C (World Wide Web Consortium)