ITEC 4020A:Internet Client Server Systems

Professor: Marin LitoiuLecture 9&10 Web Service-XML

© Marin Litoiu, York University, Canada

Web Services-Content

Introduction to XML DTDs and XML Schema Web Services, SOAP, WSDL, VoiceXML

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Unit 1. Introduction to XML

Learning Objectives Understand how XML is different from HTML Understand the basic things that make up XML

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<XML> What is XML? </XML>

XML - EXtensible Markup LanguageIt is a meta-markup language

Let’s create our own tagsEx:<name>John</name>

It is a standard for data structuring and interchangeIt is surrounded by TLAs: XSL, DTD, SAX, DOM…

and FRLAs: XSLT, VXML, SOAP…Descends from SGML

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XML is a Meta-Language

(from w3c site)

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XML is about Structured Data

Unstructured data-natural language description: ”A company has a personnel and the personnel has one or more persons. Persons have name, address, etc…” Structured data: a tree

personnel

person

name

title given family

address

streetMr. John Higgins

zipM3C1H7

person

Wall St.

company

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Why not HTML?

HTML tags are concerned with rendering XML is concerned with the semantic of information XML is a meta-language, HTML can be seen as an instance of it (XHTML) HTML is one of the presentation formats for XML languages

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Simple HTML document(1 of 2)

<p>

<b>Helm Brown</b>

<br>

Moon Light

<br>

Toronto

</p>

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Simple HTML document (2 of 2)

An HTML browser knows how to render

A human can understand each line, can a computer or application?

How easy is to search for a piece of data?

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Simple XML (PML?)

<?xml version ="1.0"?><person> <name> < title> Mr.</title> < given> Helm </given> <family> Brown </family> </name> <address> <street> Moon Light </street> <zip> M3C1H7 <zip> </address></person>

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Tags, Elements, CDATA

<?xml version ="1.0"?><person> <name> < title> Mr.</title> < given> Helm </given> <family> Brown </family> </name> <address> <street> Moon Light </street> <zip> M3C1H7 <zip> </address></person>

Start tag

Element

End tag

CDATA

Markup

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XML Document as a Tree

person

name

title family given

address

street

Mr. Helm Brown

zip

M3C1H7Moon Light

parent

children

CDATA

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XML Attributes

Attributes are properties of the elementPairs of (name, value), within the elementValues are between quotation marks

<person isManager="true“ emplType=‘regular’>

<name>

….

</name>

</person>

Attributes

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Well Formed Documents

An XML document is well formed if obeys a set of rules1. Tags cannot be inferred; they must be explicit. All starting

tags must have corresponding ending tags. All ending tags must have corresponding starting tags

2. Empty tags need a Slash ( /) before the closing Greater Than (>) character: <person isManager=‘true’/>

3. All attribute values must be enclosed in either single or double quotation marks

4. Tags must nest correctly: <a><b></b></a>5. Tags are case sensitive and must match each other in

every implementation

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Namespaces in XML

Distinguish between elements and attributes from different XMLs

Qualified name = prefix:localPrefix is the NamespaceLocal identifies the particular element

1.xmlns:cmp=http://www.XML.org/company

xmlns:lb=http://www.XML.org/library2. <cmp:TITLE>Ms</cmp:TITLE>… <lb:TITLE>As You Like It</lb:TITLE>

Qualified name

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More in XML Documents

Empty elements: no children <ex x=“1”/> Comments <!-- No Comment --> Processing Instructions <? xml version=“1.0” ?> Entities <&lt..&gt..&quot..> Further readings

http://www.w3.org

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XML for Presentation

XMLdoc Presen-

tation

Voice XML

WML

HTML, PDF,PS

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XML for Communication

Appli-cation

A

Appli-cation

A

Appli-cation

1

Appli-cation

1

Appli-cation

B

Appli-cation

B

Appli-cation

2

Appli-cation

2

Transfor-mation

1

Transfor-mation

1

Transfor-mation

2

Transfor-mation

2

XML 1 XML 2

XML

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XML for Web Services

APPA

API

APPBA

PI

XML getAPI()

XML getAPI()

XML RPC (SOAP)

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2

3

3

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Summary

We learned: XML is a vehicle for representing structured data XML allows you to create your own language (data format) An XML document contains start tags, end tags, elements and attributes,

CDATA Elements: parent, children, root element, document element

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Exercise (10 min.)

Write an XML document for the course you are attending: title: XML and Related Technologies description: basics of XML and related technologies instructor

Name: Marin Litoiu Affiliation: CAS

Participants Participant:

name: John Trevis job: software programmer

Participant Name: Big Boss Job: manager

…..……. View the document with IExplorer

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Quiz(1)

Which statement(s) is(are) false?:

1. XML makes data interchange easy

2. XML is a standard

3. XML is a meta-language

4. An well-formed XML document has nested tags and is a tree

5. An empty element has no attributes True or false?

1. XML is a protocol, like HTTP, IIOP and RMI

2. You can have rendering tags in XML documents

3. Attributes for Elements are like parts to whole

4. XML isolates the presentation from content

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Quiz(2)

XML is not a language and has not recognized tags. Rather, it is a meta-language that allows you to define your own language1. True2. False

Which of the following is not a rule for creating well-formed documents in XML?1. All start tags must have corresponding ending tags2. Empty tags need a Slash (/) before the closing Greater Than (>) character.3. All attribute values must be enclosed in brackets4. Tags must nest correctly5. Tags are case sensitive and must match each other in every implementation.

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Unit 2. DTDs

Learning Objectives What is DTD Why we need DTD How to write a DTD

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Document Type Definition(DTD)

DTD defines the grammar for XML docs Tag names How elements can be nested If the elements may, must appear How often the elements appear Attributes of the elements Default values for the attributes All valid values for the attributes

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Valid documents

The XML document contains information about its dtd

Exemple:<?xml version ="1.0" encoding= “US-ASCII” standalone="no"?><!DOCTYPE person SYSTEM “person.dtd">

A valid XML document follows the syntax defined in its dtd

An XML parser will check the validity of the XML document against its dtd

Any XML editor has an XML parser Eclipse has an XML Editor

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XML Documents and DTD

author.dtd

author1.xml author3.xmlauthor2.xml

author.class One editor

One parser

Many XMLs

……..

One DTD

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Simple person.dtd

<?xml version="1.0" encoding="UTF-8"?><!ELEMENT person (name, address)><!ATTLIST person isManager (true|false) 'false'><!ATTLIST person emplType CDATA #IMPLIED><!ELEMENT address (street,city*,state*, zip)><!ELEMENT name (title?,given, family)><!ELEMENT title (#PCDATA)><!ELEMENT family (#PCDATA)><!ELEMENT given (#PCDATA)><!ELEMENT street (#PCDATA)><!ELEMENT zip (#PCDATA)>

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Element definition

<!ELEMENT person (name, address)>

<!ELEMENT address (street, city*, state*, zip)>

<!ELEMENT name (title?, given, family)>

<!ELEMENT title (#PCDATA)>

<!ELEMENT given (#PCDATA)>

…….

Element name Children Element declaration

Element Type

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Attributes in DTD

DTD<!ELEMENT person (name,address)><!ATTLIST person isManager (true|false) 'false'><!ATTLIST person emplType CDATA #IMPLIED>

XML<person isManager=“false”>

El. name

Attr. name

Attr type

Default value

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Empty Elements

No children, no start or end tag

DTD

<!ELEMENT apple EMPTY>

<!ATTLIST apple color CDATA #REQUIRED>XML

<apple color=“red”/>

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Attributes Types

CDATA “Eglinton East”NMTOKEN (name token): <name>ID: unique Id within a documentIDREF: a reference to an IDIDREFS: many IDREFENUMERATION: (a|b|c|d)ENTITY: reference to an external unparsed entityENTITIES: many ENTITY

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ID and IDREF

DTD: <!ATTLIST employee id #ID>

<!ATTLIST employee manager #IDREF>

XML: <employee name=“john” id=“056”>

<employee name=“bob” manager=“056”>

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Default values for attributes

#REQUIRED - a value MUST be provided #IMPLIED – optional value [#FIXED] “value”, if no value is provided, the “value” should be used

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Child Element Occurrences

“A man has zero or one wives, zero or more children and speaks one or more languages”<!ELEMENT man (child*, wife?, languages+)>

? zero or one times* zero or more times+ one or more times, sequence| or- choice

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Summary of Unit 2

We learned: DTD is the grammar for XML documents DTD defines: elements (parents and children), attributes, default and allowed

values DTDs are agreed upon by a community Valid XML documents obey the structure of DTD

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Exercise 1

Write an XML Document for person.dtd from slide 28 Validate the document with Internet Explorer make sure you specify the SYSTEM dtd

You can use an XML Editor For example, Eclipse has editors for XML, DTD and XML Schema.

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Quiz

Which statement(s) is(are) false1. DTD is a grammar for XML documents

2. IDREF is an attribute type and it means a reference to an attribute called “ID”

3. <!ELEMENT x (y+)> defines an element x with zero or more children elements y

4. <!ATTLIST y z (1|2) ‘2’> defines an attribute z for the element y. z can have 1 or 2 characteristics, preferably 2.

5. <!-- x=1--> is a valid comment

6. <!EMPTY bag> defines an empty element bag

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Unit 3. XML Schema

Learning Objectives Why we need XML Schema How to write an XML Schema When to use XML Schema

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XML Schema

DTD has few predefined types DTD syntax is different from XML syntax DTD cannot express certain constraints: “c occurs 3 to 5

times” XML Schema to the rescue

Describes and constrains the content of XML Defines simple data types and ways to derive new simple or

complex types Link: www.w3.org/XML/Schema Namespace: xmlns:xsd='http://www.w3.org/20001/XMLSchema'

XML Schema structure

Schema element: the top level element ( as per XML definition) Element—defines the elements that will show up in your XML doc Simple type elements: simple elements derived from predefined elements in XML

schema Complex type elements: complex data types ( sequence, union..)

Example

<?xml version="1.0" encoding="UTF-8"?>

<xsd:schema xmlns:xsd='http://www.w3.org/2001/XMLSchema'>

<xsd:element .............</xsd:element>

<xsd:element..............</xsd:element>

…………………..

<xsd:simpleType.........</xsd:simpleType>

<complexType.............</xsd:complextype>

</xsd:schema>© Marin Litoiu, York University, Canada

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XML Schema uses XML Syntax

DTD

<!ELEMENT family (#PCDATA)>

<!ELEMENT given (#PCDATA)>

XML Schema

<xsd:element name="family“ type="xsd:string"/>

<xsd:element name="given" type=‘xsd:string’/>

XML attributes

??? XMLElements

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All Built in Types

Simple types(1)

http://www.w3.org/TR/xmlschema-0/#ref18

Simple Type Examples (delimited by commas) Notes

string This is a string

normalizedString This is a string NL and CR are converted to spaces

token This is a string Trailing and leading spaces are removed

integer ...-1, 0, 1, ...  integer is ·derived· from decimal by fixing the value of ·fractionDigits· to be 0and disallowing the trailing decimal point. 

positiveInteger 1, 2, ...

negativeInteger ... -2, -1

nonNegativeInteger 0, 1, 2, ...

nonPositiveInteger ... -2, -1, 0

long-9223372036854775808, ... -1, 0, 1, ... 9223372036854775807

unsignedLong 0, 1, ... 18446744073709551615

int-2147483648, ... -1, 0, 1, ... 2147483647

int is ·derived· from long by setting the value of ·maxInclusive· to be 2147483647 and ·minInclusive· to be -2147483648. 

unsignedInt 0, 1, ...4294967295

short -32768, ... -1, 0, 1, ... 32767

unsignedShort 0, 1, ... 65535

byte -128, ...-1, 0, 1, ... 127

unsignedByte 0, 1, ... 255

Simple types(2)

http://www.w3.org/TR/xmlschema-0/#ref18

decimal -1.23, 0, 123.4, 1000.00

float-INF, -1E4, -0, 0, 12.78E-2, 12, INF, NaN

equivalent to single-precision 32-bit floating point, NaN is "not a number", INF-inifinite

double-INF, -1E4, -0, 0, 12.78E-2, 12, INF, NaN

equivalent to double-precision 64-bit floating point

boolean true, false, 1, 0

duration P1Y2M3DT10H30M12.3S1 year, 2 months, 3 days, 10 hours, 30 minutes, and 12.3 seconds

dateTime 1999-05-31T13:20:00.000-05:00May 31st 1999 at 1.20pm Eastern Standard Time which is 5 hours behind Co-Ordinated Universal Time

date 1999-05-31

time 13:20:00.000, 13:20:00.000-05:00

gYear 1999 1999, g stands for Gregorian calendar

gYearMonth 1999-02the month of February 1999, regardless of the number of days,

gMonth --05 May, regardless of year, day

gMonthDay --05-31 every May 31st

gDay ---31 the 31st day

Examples

XML Schema

<element name=‘firstname' type=“string"/>

<element name='birthdate' type="date"/>

<element name='age' type="positiveInteger"/>

<element name=‘vacation' type=“gMonthYear"/>

XML Document

<firstname> John </firstname>

<birthdate > 2001-01-01 </birthdate>

<age> 9 </age>

<vacation> 2011-01</vacation>

© Marin Litoiu, York University, Canada

Questions

How do I specify this structure of the XML elements?

<employeeName>

<family> John</family>

<given> Smith </given>

</employeeName> See next slide…

© Marin Litoiu, York University, Canada

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Complex Types in XML Schema: Sequence

Create once, use many times as a template High reusability, easy maintainability1. Types<xsd:complexType name="nameType"> <sequence> <xsd:element name="family" type="xsd:string"/> <xsd:element name="given" type="xsd:string"/> </sequence></xsd:complexType>---------------------------2. Elements<xsd:element name=“employeeName” type=“nameType” /><xsd:element name=“customerName” type=“nameType” />-----------------------------------

3. This how they will look in XML documents<employeeName> <family> John</family> <given> Smith </given> </employeeName>

<customerName> <family> Bill</family> <given> Gates </given> </customerName>

Is like “, “ in dtd

Validating XMLs and XML schemas

Schema, in a file named name.xsd<?xml version="1.0" encoding="UTF-8"?>

<schema xmlns="http://www.w3.org/2001/XMLSchema"

targetNamespace="http://www.example.org/Quiz"

xmlns:tns="http://www.example.org/Quiz"

elementFormDefault="qualified">

<complexType name="nameType">

<sequence>

<element name="family" type="string"/>

<element name="given" type="string"/>

</sequence>

</complexType>

<element name="employeeName" type="nameType" />

</schema>

XML file: references the file name.xsd

<?xml version="1.0" encoding="UTF-8"?>

<employeeName xmlns="http://www.example.org/Quiz"

xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

xsi:schemaLocation="http://www.example.org/Quiz name.xsd ">

<family>Bill</family>

<given>Gates</given>

</employeeName> © Marin Litoiu, York University, Canada

Quiz (10 min)

1. Write a valid xml document for this xml schema<?xml version="1.0" encoding="UTF-8"?>

<schema xmlns="http://www.w3.org/2001/XMLSchema"

targetNamespace="http://www.example.org/Quiz"

xmlns:tns="http://www.example.org/Quiz"

elementFormDefault="qualified">

<complexType name="meetingType">

<sequence>

<element name="meetingName" type="string" />

<element name="meetingDay" type="gDay" />

<element name="meetingYear" type="gYear" />

<element name="meetingMonth" type="gMonth" />

<element name="meetingNoAttendees" type="integer" />

<element name="meetingCost" type="decimal" />

</sequence>

</complexType>

<element name="meeting" type="tns:meetingType"/>

</schema>

2. Write a simplified version of this XML schema (condense the types)

3. Write an XML document for the new schema

© Marin Litoiu, York University, Canada

Complex Types: Choice

<xsd:complexType name="PurchaseOrderType">

<xsd:sequence>

<xsd:choice>

<xsd:element name=“USAddress“ type=“xsd:string”/>

<xsd:element name=“CAAddress" type=“xsd:string"/>

</xsd:choice>

<xsd:element name="items" type="Items"/>

</xsd:sequence>

…..<xsd:element name=‘computerOrder’ type=‘PurchaseOrderType’/>

<xsd:element name=‘computerOrder’ type=‘PurchaseOrderType’/>

Only one of those: USAddress or CAAddress will show up in an instance XML document

The address is followed by the items (items type is Items)

© Marin Litoiu, York University, Canada

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Anonymous Types

Anonymous type does not have name, it is a private child of the element it types

<xsd:element name="person“ type=“personType”> <xsd:element name="person"> <xsd:complexType> <xsd:sequence> <xsd:element name="name" type="nameType"/> <xsd:element name="address" type="addressType"/> </xsd:sequence> </xsd:complexType></xsd:element>

Anonymous

type

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Attributes

Attributes have name, value, type They are children of the element <xsd:element name="person"> <xsd:complexType> ………. <xsd:attribute name="id" type="xsd:ID"/> <xsd:attribute name="isManager" type="xsd:boolean"/> <xsd:attribute name="hiringDate" type="xsd:date"/> </xsd:complexType></xsd:element>

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Occurrence Constraints

Occurrence Constraints for Children ElementsminOccurs, maxOccurs

Ex: <xsd:element name=“languages” type=“positiveInteger”, minOccurs=“1”, maxOccurs=“100”/ >

Constraints for Attributes use, value

Ex: <xsd: attribute name="country" type=“xsd:string" use=“required" value="US"/>

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Derived Types-Pattern

“Phone number has an optional country code, an area code of tree digits, a hyphen, and 7 digits”

Use pattern<xsd:attribute name="phone">

<xsd:simpleType>

<xsd:restriction base="xsd:string">

<xsd:pattern value="(\d{2}-)?\d{3}-[0-9]{7}"/>

</xsd:restriction>

</xsd:simpleType>

</xsd:attribute>

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Derived Types-Interval

“age is an integer greater that 10, less than 121”<xsd:element name=“age">

<xsd:simpleType>

<xsd:restriction base="xsd:positiveInteger">

<xsd:maxExclusive value="121"/>

<xsd:minExclusive value=“10"/>

</xsd:restriction>

</xsd:simpleType>

</xsd:element>

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Derived Types- Enumeration

Enumerations are simple types<xsd:attribute name="emplType" default='regular'>

<xsd:simpleType>

<xsd:restriction base="xsd:string">

<xsd:enumeration value='regular'/>

<xsd:enumeration value='contractor'/>

<xsd:enumeration value='suplemental'/>

</xsd:restriction>

</xsd:simpleType>

Derived types: Extension

<complexType name="Address">

<sequence>

<element name="name" type="string"/>

<element name="street" type="string"/>

<element name="city" type="string"/>

</sequence>

</complexType>

<complexType name="USAddress">

<complexContent>

<extension base="ipo:Address">

<sequence>

<element name="state" type="ipo:USState"/>

<element name="zip" type="positiveInteger"/>

</sequence>

</extension>

</complexContent>

</complexType>

http://www.w3.org/TR/xmlschema-0/#po.xsd

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DTD or XML Schema

For reach type documents, with many types and constrains, use XML schemas

Use DTD when Want a compact representation Not interested in semantic of the grammar, just in structure

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Summary

We learned: XML Schema is a replacement for DTD

Has a syntax similar to XML

Allows the user to Specialize by extension and restriction basic simple types Define his/her own complex types

Exercise (10 min).

1. For the po.xsd schema from http://www.w3.org/TR/xmlschema-0/#po.xsd, write a sample xml document ( should be different from the one on web site)

http://www.w3.org/TR/xmlschema-0/#po.xsd

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Quiz

True of false?

1. XML schemas are more compact that DTDs

2. To define complex types, one should use <complexType> tag

3. Declaration <xsd:attribute name=“y” type=“z”/> is incorrect because is does not specify the name of the element y belongs to

4. “restriction” is a specialization mechanism in XML schema that constrains a “base” type

5. The user can only create complex types but cannot create simple types

6. “enumeration” is a simple type