1. XML Language Family Detailed Examples Most information contained in these slide comes from: http://www.w3.org, http://www.zvon.org/ These slides are intended to be used as a tutorial on XML and related technologies Slide author: Jürgen Mangler (juergen.mangler@univie.ac.at) This section contains examples on: XML Schema

2. The purpose of XML Schema is to deploy a standard mechanism to describe and evaluate the datatype of the content of an element. XML examples: 12 correct eT also correct The XML Parser can not distiguish the content of an Element. This is where XML Schema comes in: <name xsi:noNamespaceSchemaLocation="correct_0.xsd" xmlns="" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"> Jürgen Mangler

3. If we use the attribute " noNamespaceSchemaLocation ", we tell the document that the schema belongs to an element from the null namespace. Valid document: <name xsi:noNamespaceSchemaLocation="correct_0.xsd" xmlns="" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"> Jürgen Mangler correct_0.xsd:

4. If we use the attribute "schemaLocation", we tell the document that the schema belongs to an element from some particular namespace. In the schema definition, you have to use the "targetNamespace" attribute, which defines the element's namespace. Valid document: <f:anElement xsi:schemaLocation="http://foo correct_0.xsd" xmlns:f="http://foo" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"> This Element contains some cdata. correct_0.xsd: <xsd:schema targetNamespace="http://foo" xmlns:xsd="http://www.w3.org/2001/XMLSchema">

5. If we want the root element to be named "AAA", from null namespace and containing text only. correct_0.xsd: Valid document: xxx yyy

6. If we want the root element to be named "AAA", from null namespace, containing text and an element "BBB", we will need to set the attribute "mixed" to "true" - to allow mixed content. xxx yyy ZZZ aaa

7. We want the root element to be named "AAA", from null namespace, containing one "BBB" and one "CCC" element. Their order is not important.

8. We want the root element to be named "AAA", from null namespace, containing a mixture of any number (even zero), of "BBB" and "CCC" elements. We need to use the 'trick' below - we use a "sequence" element with "minOccurs" attribute set to 0 and "maxOccurs" set to "unbounded". The attribute "minOccurs" of the "element" elements has to be 0 too. Give a valid document!

9. We want the root element to be named "AAA", from null namespace, containing a mixture of any number (even zero) of "BBB" and "CCC" elements. You need to use the trick below - use "sequence" element with "minOccurs" attribute set to 0 and "maxOccurs" set to "unbounded", and the attribute "minOccurs" of the "element" elements must be set to 0 too. 111 YYY 222 333 ZZZ A valid solution!

10. We want the root element to be named "AAA", from null namespace, containing either "BBB" or "CCC" elements (but not both) - the "choice" element. Other valid solutions? aaa

11. In XML Schema, the datatype is referenced by the QName. The namespace must be mapped to the prefix. 25

12. Restricting simpleType is relatively easy. Here we will require the value of the element "root" to be integer and less than 25. 25 Valid? Use to force element > 0. You can also combine min/max in !

13. If we want the element "root" to be either a string "N/A" or a string "#REF!", we will use N/A Other solutions?

14. If we want the element "root" to be either an integer or a string "N/A", we will make a union from an "integer" type and "string" type.

15. Below we define a group of common attributes, which will be reused. The root element is named "root", it must contain the "aaa" element, and this element must have attributes "x" and "y". Give a valid document!

16. Below we define a group of common attributes, which will be reused. The root element is named "root", it must contain the "aaa" and "bbb" elements, and these elements must have attributes "x" and "y". Valid document from the previous Schema!

17. We want the "root" element to have an attribute "xyz", which contains a list of three integers. We will define a general list (element "list") of integers and then restrict it (element "restriction") to have a length (element "length") of exactly three items. Documents on next page …

18. Valid! Not valid! Why? Use the same method for lists in the content of elem. We want the "root" element to have an attribute "xyz", which contains a list of three integers. We will define a general list (element "list") of integers and then restrict it (element "restriction") to have a length (element "length") of exactly three items.

19. The element "A" has to contain a string which is exactly three characters long. We will define our custom type for the string named "myString" and will require the element "A" to be of that type. abc

20. The element "A" must contain an email address. We will define our custom type, which will at least approximately check the validity of the address. We will use the "pattern" element, to restrict the string using regular expressions. kung@foo.org

21. Regular Expressions - the meaning of: [^@]+@[^.]+\..+ [abc]…Characters Class (character can be a, b or c) [^abc]…Negative Character Class (everything except a,b,c) *…Match 0 or more times +…Match 1 or more times ?…Match 1 or 0 times {n}…Match exactly n times {n,}…Match at least n times {n,m}…Match at least n but not more than m times.…match any character \w …Match a "word" character (alphanumeric plus "_") \W …Match a non-word character \d …Match a digit character \D …Match a non-digit character \.…Escape a character with a special Meaning (., +, *, ?, …) [^@]+…match any character that is not a @ 1 or more times @…match exactly a @ [^.]+…match any character that is not a. 1 or more times \.…match exactly a..+…match any character 1 or more times

22. One of the big problems of XML ist the type ID. An attribute of type ID must be unique for the whole file. XML Schema solves this problem: ID's can be vaild for a certain child axis only. Document on next page …

23. One of the big problems of XML ist the type ID. An attribute of type ID must be unique for the whole file. XML Schema solves this problem: ID's can be vaild for a certain child axis only.

24. The "keyref" lets you specify, that an attribute/element refers to some node (which must be defined as "key" or "unique"). The "key" element requires the elements "a" under the "root" element to contain the existing and unique value of an "id" attribute. Replace with: Document on next page … Add to in myList:

25. The "keyref" lets you specify, that an attribute/element refers to some node (which must be defined as "key" or "unique"). The "key" element requires the elements "a" under the "root" element to contain the existing and unique value of an "id" attribute.

26. To define attributes AND childs for a certain element you have to use simpleContent. shake

27. simpleType: Wenn ich den Inhalt eines Elements als xsd:string, xsd:integer, xsd:double,... definieren will complexType Wenn ich Attribute definieren will Wenn ich andere Elemente als Inhalt definieren will (mit sequence, choice, all) Wenn ich Attribute und Elemente mischen will (xsd:attribute unterhalt von sequence, choice, all simpleContent innerhalb von complexType Wenn ich den Inhalt eines Elements als Datentyp definieren und zusätzlich Attribute haben will Wann nehm ich simple-, wann complexType