structuring xml using dtd and schema ching-long yeh, phd, 葉慶隆 department of computer science...

Structuring XML Using Structuring XML Using DTD and SchemaDTD and Schema

Ching-Long Yeh, PhD, 葉慶隆Department of Computer Science and EngineeringTatung UniversityTaipei 104, TaiwanEmail: [email protected]: http://www.cse.ttu.edu.tw/~chingyeh

Structuring XML 2

ContentContent

• XML Document Basics• DTD Syntax Review• An Introduction to XML Schema• Types of Interaction with Document• DTD in Electronic Business• Conclusion

XML Document BasicsXML Document Basics

Structuring XML 4

Structure, Content, and FormatStructure, Content, and Format

• Central to XML is the concept that documents have structure, content, and format.

• These three ingredients combine to form a document.

• They interrelate in subtle ways, and you can easily confuse them as you work with your documents.

Structuring XML 5

What is Structure?What is Structure?

• The structure defines how the document is laid out and in what order elements are assembled

• For example, a bicycle assembly manual might consist of of the following section in this order: – an introduction that described the document and

lists the manufacturer’s address,

– assembly instructions,

– a part list,

– instruction for order replacement parts,

– troubleshooting advice, and

– index.

Structuring XML 6

What is Content?What is Content?

• Content is the actual data within a

document.

• The words and illustrations that make up a bicycle assembly manual are its contents.

Structuring XML 7

What is Format?What is Format?

• Format consists of how the words, sentences, and paragraphs are visually presented and distinguished from one another within a document.

• Boldface for title, italics for special terms, and blank lines between sections are examples of document formats.

• People often confuse format with structure.

Structuring XML 8

Why Structure, Content, and Format Why Structure, Content, and Format Are Important in XML?Are Important in XML?

• XML defines the structure and separate the content from the delivery-specific format.

• Through this approach, the actual document — its content and structure — becomes mobile.

Structuring XML 9

Indicating Structure Through Visual Indicating Structure Through Visual CuesCues

PRODUCT ADVISORYNumber: 146Type: PartsDate: 8/15/95

Subject: Revised Replacement Parts ...

Model 501 User Replaceable PartsThe parts list identified in the AnyCorp Mod

el 501 ...New Parts List 1. 345-234 (Filter, cooling fan)2. 148-745 (Fuse, power: 1.5amp)3 ...

Product AdvisoryNumber: 146Type: PartsDate: 8/15/95Revised:Subject: Revised

Replacement ...Model 501 User-Replaceable

PartsThe parts list identified in

the ...

New Parts List1. 345-234 (Filter, cooling

fan)2. 148-745 (Fuse, power:

1.5amp)3. ...

Structuring XML 10

Defining Structures in XMLDefining Structures in XML

• The structure of a document its type is defined by a document type definition, or DTD.

• The DTD lays out the rules for a document through the use of elements, attributes, and entities.

Structuring XML 11

Defining Structures in XMLDefining Structures in XML<!DOCTYPE advisory [<!ENTITY % parael “para|blist|nlist|graphic”><!ELEMENT advisory (idinfo,subject,subsec+)><!ELEMENT idinfo (advnbr,type,dateiss,daterev,product)><!ELEMENT subject (#PCDATA)><!ATTLIST subject safty (y|n) “n”><!ELEMENT subsec (title,(%parael;)?)> <!ELEMENT advnbr (#PCDATA)><!ELEMENT type (#PCDATA)><!ELEMENT dateiss (#PCDATA)><!ELEMENT daterev (#PCDATA)><!ELEMENT product (#PCDATA)><!ELEMENT title (#PCDATA)><!ELEMENT para (#PCDATA)><!ELEMENT blist (item+) -(nlist)><!ELEMENT nlist (item+)><!ELEMENT item (para|blist|nlist|graphic|#PCDATA)+><!ELEMENT graphic EMPTY><!ATTLIST graphic filename CDATA #REQUIRED artno CDATA #IMPLIED> ]>

Structuring XML 12

Using Structures in XMLUsing Structures in XML<?xml version=“1.0”><!DOCTYPE ADVISORY SYSTEM "advisory.dtd"><ADVISORY><IDINFO><ADVNBR>Number: 146</ADVNBR><TYPE>Type: 146</TYPE><DATEISS>Date: 8/15/95</DATEISS><DATEREV>Revised: 9/29/95</DATEREV><PRODUCT>Model 501 Nebulation</PRODUCT></IDINFO><SUBJECT>Subject: Revised Replacement Parts List (AnyCorp Model 501)</S

UBJECT><SUBSEC><TITLE>Model 501 User-Replaceable Parts</TITLE><PARA>The parts list identified in the AnyCorp Model 501 User's Mainten

ance Guide has been superseded, effective immediately. User-Replaceable parts are identified in the revised part list below. Parts orders which reference items o12n the previous list (dated 2/5/94) will be honored up to 3/14/96.Customers are advised to order from this revised list in order that they may achieve higher reliability at a lower unit cost. Questions on this subject should be directed to the Central Spares Organization.</PARA></SUBSEC>

<SUBSEC><TITLE>New Parts List</TITLE><BLIST><ITEM>345-234(Filler, coolingfan)</ITEM> <ITEM>148-745(Fuse, power, 1.5amp)</ITEM> <ITEM>345-712(Lamp, Indicator)</ITEM> <ITEM>2346-92(Disk, cleaning)</ITEM> <ITEM>347-622(Swabs, cleaning)</ITEM></BLIST></SUBSEC></ADVISORY>

Structuring XML 13

Well-Formed and Valid DocumentsWell-Formed and Valid Documents

• XML has two different notions of “correct.”

• Valid documents– Declaring conformance to a DTD in a document type

declaration – “Using the right words in the right place”– Type-valid

• Well-formed documents– Markup is intelligible.– “Getting the pronunciation right”– Non-type-valid

Structuring XML 14

Example Example — Table— Table

Structuring XML 15


Structuring XML 16


Structuring XML 17

Example Example — Database Publishing— Database Publishing

Structuring XML 18

Example: A DTD for B2B ECExample: A DTD for B2B EC

• RosettaNet PIP 3 A2 Price And Availability Query Version 1.2 Available at http://www.rosettanet.org

DTD Syntax ReviewDTD Syntax Review

Structuring XML 20

DTD SyntaxDTD Syntax

• Seven major headings:– document type declarations– element types– attributes– entities– notations– conditional sections– processing instructions

Structuring XML 21

Document Type DeclarationDocument Type Declaration

• A document type declaration defines constraints on the logical structure and to support the use of predefined storage units.

• The XML document type declaration contains or points to markup declarations that provide a grammar for a class of documents.

Structuring XML 22


<?xml version “1.0”?><!DOCTYPE label[ <!ELEMENT label (name,street,city,state,country,code)> <!ELEMENT name (#PCDATA)> <!ELEMENT street (#PCDATA)> <!ELEMENT city (#PCDATA)> <!ELEMENT state (#PCDATA)> <!ELEMENT country (#PCDATA)> <!ELEMENT code (#PCDATA)> ]><label><name>Rock N. Robyn</name> <street>Jay Bird Street</street> <city>Baltimore</city> <State>MD</state> <country>USA</country> <code>43214</code></label>

Structuring XML 23


<?xml version “1.0”?><!DOCTYPE LABEL SYSTEM http://www.sgmlsource.com/dtds/label.dtd><LABEL>. . .</LABEL>

Structuring XML 24

Elements Type DeclarationElements Type Declaration

• Elements provide the basic logical structure for XML documents.

Element Type Declaration[45] elementdecl ::= '<!ELEMENT' S Name S contentspec S? '>' [46] contentspec ::= 'EMPTY' | 'ANY' | Mixed | children

Element-content Models[47] children ::= (choice | seq) ('?' | '*' | '+')?[48] cp ::= (Name | choice | seq) ('?' | '*' | '+')?[49] choice ::= '(' S? cp ( S? '|' S? cp )* S? ')[50] seq ::= '(' S? cp ( S? ',' S? cp )* S? ')'

Structuring XML 25

Elements Type DeclarationElements Type Declaration

<!ELEMENT spec (front, body, back?)><!ELEMENT div1 (head, (p | list | note)*, div2*)><!ELEMENT dictionary-body (%div.mix; | %dict.mix;)*><!ELEMENT p (#PCDATA|a|ul|b|i|em)*><!ELEMENT b (#PCDATA)>

Structuring XML 26

AttributesAttributes

• Attributes provide meta-data for elements, such as a security level, a revision status, or a unique identifier.

• Use an attribute list declaration to declare attributes for an element<!ATTLIST sample id ID #IMPLIED n CDATA #REQUIRED status (draft|final) “final”>

attribute name attribute type default value

Structuring XML 27

EntitiesEntities

• There are two types of entities:– general entities: apply within the top-level

and its attribute values.– parameter entities: apply within the internal

and external DTD subsets.

Structuring XML 28

Entities: General EntitiesEntities: General Entities

<!ENTITY xml “Extensible Markup Language”>

<para>The &xml; is derived from ISO 8879, an International Standard<index label=&xml;> <para>

<para>The Extensible Markup Language is derived from ISO 8879, an International Standard<index label=“Extensible Markup Language”> <para>

Structuring XML 29

Entities: Parameter EntityEntities: Parameter Entity

<!ENTITY %inline “#PCDATA|emphasis|link”>

<!ELEMENT para (%inline;)*

<!ELEMENT para (#PCDATA|emphasis|link)*>

Structuring XML 30

NotationsNotations

• Notations are used to include non-XML contents ─ like graphics, sounds, video , or source-code listing ─ in XML documents.

• While the XML parser knows nothing about the specific notations, it can pass them on to the processing software to let it know what kinds of data to handle.

<!NOTATION TeX PUBLIC “+//ISBN 0-201-13448-9::Knuth//NOTATION The TeXbook//EN”>

Structuring XML 31

Conditional SectionsConditional Sections

• In the external DTD subsets and external parameter entities, XML allows conditional sections that the parser can include or ignore, depending on the value of the keywords at the start.

<![IGNORE [ <!ELEMENT para (#PCDATA)>]]>

<!ENTITY %include-para “IGNORE”><![%include-para;[ <!ELEMENT para (#PCDATA)>]]>

<!DOCTYPE book SYSTEM “book.dtd”[ <!ENTITY %include-para “INCLUDE”>]>

overriding a parameter entity

Structuring XML 32

Processing InstructionsProcessing Instructions

• XML parser will pass PIs on to your application, but will be up to you to do something useful with them.

<?IS10744:arch name=“abc”>

Introduction to XML SchemaIntroduction to XML Schema

Structuring XML 34

IntroductionIntroduction

• The new XML Schema system aims at providing a rich grammatical structure for XML documents that overcomes the limitations of the DTD.

Structuring XML 35

What is a Schema?What is a Schema?

• A schema is a model for describing the structure of information.

• In the context of XML, a schema describes a model for a whole class of documents.

• A schema might also be viewed as an agreement on a common vocabulary for a particular application that involves exchanging documents.

Structuring XML 36


• In schemas, models are described in terms of constraints.

• Two kinds of constraints that you can give:– content model constraints describe the order and sequen

ce of elements and – datatype constraints describe valid units of data.

Structuring XML 37


• For example, a schema might describe a valid <address> with the content model constraint that – it consists of a <name> element, followed by – one or more <street> elements, followed by – exactly one <city>, <state>, and <zip> element.– The content of a <zip> might have a further datatype cons

traint that it consist of either a sequence of exactly five digits or a sequence of five digits, followed by a hyphen, followed by a sequence of exactly four digits. No other text is a valid ZIP code.

<address> <name>Namron H. Slaw</name> <street>256 Eight Bit Lane</street> <city>East Yahoo</city> <state>MA</state> <state>CT</state> <zip>blue</zip></address>

invalid

Structuring XML 38

Limitations of DTDLimitations of DTD

• XML inherited DTDs from SGML. • DTDs can be used to define content models and, to

a limited extent, the datatypes of attributes, but they have a number of obvious limitations:– different (non-XML) syntax– no support for namespaces– extremely limited datatyping– a complex and fragile extension mechanism based on littl

e more than string substitution (no explicit relationship)

Structuring XML 39

Features of SchemaFeatures of Schema

• Richer datatypes – booleans, numbers, dates and times, URIs, integers, deci

mal numbers, real numbers, intervals of time, etc.• User defined types• Attribute grouping• Refinable archetypes• Namespace support

Structuring XML 40

ValidityValidity

• Reasons why need to validate documents: – EC: received is exactly what you expect.– B2B: validating before inserting into your database. – XML document for control purpose

• Content model validity tests whether the order and nesting of tags is correct.

• Datatype validity is the ability to test whether specific units of information are of the correct type and fall within the specified legal values.

Structuring XML 41

Illustrations of XML SchemaIllustrations of XML Schema

An XML document fragment<InvoiceNo>123456789</InvoiceNo><ProductID>J123456</ProductID>

DTD fragment describing the above elements <!ELEMENT InvoiceNo (#PCDATA)><!ELEMENT ProductID (#PCDATA)>

XML Schema fragment describing the above elements<element name='InvoiceNo' type='positive-integer'/><element name='ProductID' type='ProductCode'/><simpleType name='ProductCode' base='string'> <pattern value='[A-Z]{1}d{6}'/></simpleType>

Structuring XML 42

Using Namespaces in XML SchemaUsing Namespaces in XML Schema

• One person may be processing documents from many other parties and the different parties may want to represent their data elements differently.

• Moreover, in a single document, they may need to separately refer to elements with the same name that are created by different parties.

• How can you distinguish between such different definitions with the same name?

• XML Schema allows the concept of namespaces to distinguish the definitions.

Structuring XML 43

Using Namespaces in XML Using Namespaces in XML SchemaSchema

• A given XML Schema defines a set of new names. The names defined in a schema are said to belong to its target namespace.

• Definitions and declarations in a schema can refer to names that may belong to other namespaces. We refer to those namespaces as source namespaces.

• Each schema has one target namespace and possibly many source namespaces.

• In fact, every name in a given schema belongs to some namespace.

• The names for the namespaces can be fairly long, but they can be abbreviated with the syntax of xmlns declaration in the XML Schema document.

Structuring XML 44


• Target and source namespaces

<xsd:schema targetNamespace='http://www.SampleStore.com/Account' xmlns:xsd='http://www.w3.org/1999/XMLSchema' xmlns:ACC='http://www.SampleStore.com/Account'><xsd:element name='InvoiceNo' type='xsd:positive-integer'/><xsd:element name='ProductID' type='ACC:ProductCode'/><xsd:simpleType name='ProductCode' base='xsd:string'> <xsd:pattern value='[A-Z]{1}d{6}'/></xsd:simpleType>

Structuring XML 45


Multiple source namespaces, importing a namespace



<schema targetNamespace='http://www.SampleStore.com/Account'

xmlns='http://www.w3.org/1999/XMLSchema'

xmlns:ACC= 'http://www.SampleStore.com/Account'

xmlns:PART='http://www.PartnerStore.com/PartsCatalog'>

<import namespace='http://www.PartnerStore.com/PartsCatalog'

schemaLocation=

'http://www.ProductStandards.org/repository/alpha.xsd'/>

<element name='InvoiceNo' type='positive-integer'/>

<element name='ProductID' type='ACC:ProductCode'/>

<simpleType name='ProductCode' base='string'>

<pattern value='[A-Z]{1}d{6}'/>

</simpleType>

<element name='stickyGlue' type='PART:SuperGlueType'/>

Structuring XML 46

Defining ElementsDefining Elements

• To define an element is to define its name and content model.

• In XML Schema, the content model of an element is defined by its type.

• Then, the instance elements in an XML document can have only values that fit the types defined in its schema.

Structuring XML 47


• A type can be simple or complex. • A simple type cannot contain elements or

attributes in its value.• A complex type can create the effect of

embedding elements in other elements or it can associate attributes with an element.

• The XML Schema spec also includes predefined simple types

• A derived simple type constrains the values of its base type.

Structuring XML 48


• Simple, non-nested elements have a simple type– An element that does not contain attributes or o

ther elements can be defined to be of a simple type, predefined or user-defined, such as string, integer, decimal, time, ProductCode, etc.

<element name='age' type='integer'/><element name='price' type='decimal'/>

Structuring XML 49


• Elements with attributes must have a complex type– If you want to add an attribute, you must define price as a compl

ex type. – We have defined what is called an anonymous type, where no expl

icit name is given to the complex type. In other words, the name attribute of the complexType element is not defined.

<element name='price'> <complexType base='decimal' derivedBy='extension'> <attribute name='currency' type='string'/> </complexType></element>

Structuring XML 50


• Elements that embed other elements must have a complex type

<Book> <Title>Cool XML<Title> <Author>Cool Guy</Author></Book>

<!ELEMENT Book (Title, Author)><!ELEMENT Title (#PCDATA)><!ELEMENT Author (#PCDATA)>

<element name='Book' type='BookType'/><complexType name='BookType'> <element name='Title' type='string'/> <element name='Author' type='string'/></complexType>

XML Document

XML DTD

XML Schema

Structuring XML 51


• A complex type defined with global simple types

<element name='Title' type='string'/><element name='Author' type='string'/><element name='Book' type='BookType'/><complexType name='BookType'> <element ref='Title'/> <element ref='Author'/></complexType>

Structuring XML 52


• Hiding BookType as a local type

<element name='Title' type='string'/><element name='Author' type='string'/><element name='Book'> <complexType> <element ref='Title'/> <element ref='Author'/> </complexType></element>

Structuring XML 53


• Expressing sophisticated constraints on elements– XML Schema offers greater flexibility than DTD for express

ing constraints on the content model of elements. – At the simplest level, as in DTD, you can associate attribut

es with an element declaration and indicate that a sequence of one only (1), zero or more (*), or one or more (+) elements from a given set of elements can occur in it.

– You can express additional constraints in XML Schema using, for example, minOccurs and maxOccurs attributes of element element and using choice, group, and all elements.

Structuring XML 54

<xsd:schema xmlns:xsd="http://www.w3.org/2000/08/XMLSchema"> <xsd:annotation> <xsd:documentation> Purchase order schema for Example.com. Copyright 2000 Example.com. All rights reserved. </xsd:documentation> </xsd:annotation> <xsd:element name="purchaseOrder" type="PurchaseOrderType"/> <xsd:element name="comment" type="xsd:string"/> <xsd:complexType name="PurchaseOrderType"> <xsd:sequence> <xsd:element name="shipTo" type="USAddress"/> <xsd:element name="billTo" type="USAddress"/> <xsd:element ref="comment" minOccurs="0"/> <xsd:element name="items" type="Items"/> </xsd:sequence> <xsd:attribute name="orderDate" type="xsd:date"/> </xsd:complexType> <xsd:complexType name="USAddress"> <xsd:sequence> <xsd:element name="name" type="xsd:string"/> <xsd:element name="street" type="xsd:string"/> <xsd:element name="city" type="xsd:string"/> <xsd:element name="state" type="xsd:string"/> <xsd:element name="zip" type="xsd:decimal"/> </xsd:sequence> <xsd:attribute name="country" type="xsd:NMTOKEN" use="fixed" value="US"/> </xsd:complexType>

The Purchase Order Schema (1)

Structuring XML 55

<xsd:complexType name="Items"> <xsd:sequence> <xsd:element name="item" minOccurs="0" maxOccurs="unbounded"> <xsd:complexType> <xsd:sequence> <xsd:element name="productName" type="xsd:string"/> <xsd:element name="quantity"> <xsd:simpleType> <xsd:restriction base="xsd:positiveInteger"> <xsd:maxExclusive value="100"/> </xsd:restriction> </xsd:simpleType> </xsd:element> <xsd:element name="USPrice" type="xsd:decimal"/> <xsd:element ref="comment" minOccurs="0"/> <xsd:element name="shipDate" type="xsd:date" minOccurs="0"/> </xsd:sequence> <xsd:attribute name="partNum" type="SKU"/> </xsd:complexType> </xsd:element> </xsd:sequence> </xsd:complexType>  <xsd:simpleType name="SKU"> <xsd:restriction base="xsd:string"> <xsd:pattern value="\d{3}-[A-Z]{2}"/> </xsd:restriction> </xsd:simpleType> </xsd:schema>

The Purchase Order Schema (2)

Structuring XML 56

Simple Types Simple Types

<xsd:simpleType name="myInteger"> <xsd:restriction base="xsd:integer"> <xsd:minInclusive value="10000"/> <xsd:maxInclusive value="99999"/> </xsd:restriction> </xsd:simpleType>

<xsd:simpleType name="SKU"> <xsd:restriction base="xsd:string"> <xsd:pattern value="\d{3}-[A-Z]{2}"/> </xsd:restriction> </xsd:simpleType>

Structuring XML 57

<xsd:simpleType name="USState"> <xsd:restriction base="xsd:string"> <xsd:enumeration value="AK"/> <xsd:enumeration value="AL"/> <xsd:enumeration value="AR"/>  </xsd:restriction> </xsd:simpleType>


<xsd:simpleType name="listOfMyIntType"> <xsd:list itemType="myInteger"/> </xsd:simpleType>

<listOfMyInt>20003 15037 95977 95945</listOfMyInt>

Structuring XML 58


<xsd:simpleType name="USStateList"> <xsd:list itemType="USState"/> </xsd:simpleType>

<xsd:simpleType name="SixUSStates"> <xsd:restriction base="USStateList"> <xsd:length value="6"/> </xsd:restriction> </xsd:simpleType>

<sixStates>PA NY CA NY LA AK</sixStates>

sixStates is declared to be a SixUSStates element.

Types of Interaction with Types of Interaction with DocumentDocument

Structuring XML 60

Types of Interaction with Types of Interaction with DocumentsDocuments

• Most documents stored in XML forms are created for the purpose of conveying information or keeping track of information.

• Types of interactions people have with documents:– creation and modification– management, storage, and archiving– utilization.

Structuring XML 61

Printing

Import

Exchange

Searching andviewing

Creation

Types of Interaction with Types of Interaction with DocumentDocument

Workstation

UpdateWorkstation

Review/validation

Workstation

Conversion/transformation

Workstation

Document classificationDocument assemblyDocument archivalDocument storage

Useful databaseinformation

Document creationand modification

Document managementand storage

Document utilization

Workstation

Laser printer

Building alternatedocuments

Online searchingviewing,

exchange, export

Extraction,analysis

DTD in Electronic BusinessDTD in Electronic Business

Structuring XML 63

RosettaNet: An EB StandardRosettaNet: An EB Standard

• RosettaNet is a consortium of major information technology (IT), electronic components (EC) and semiconductor manufacturing (SM) companies working to create and implement industry-wide EB process standards. – Perfect real-time information. – Efficient e-business processes. – Dynamic trading-partner relationships. – New business opportunities.

Structuring XML 64

Alphabet

Grammar

Dialog

Words

XML

Framework

Dictionary

Sound Internet

Business Process

Telephone Rose

ttaN

et

Telephone

DIALOG PIP

eBusiness Process

Ecom Application

human-to-humanhuman-to-humanbusiness exchangebusiness exchange

Partner-to-Partner Partner-to-Partner eBusiness exchangeeBusiness exchange

Business Process

RosettaNet FocusRosettaNet Focus

Structuring XML 65

ConclusionConclusion

• Schemas greatly improves over DTDs. • Certain kinds of applications can be made

more interoperable by XML Schema. • DTDs are well understood and they do offer a

good way to describe the structure of an document for interchange.

• It will take some time before XML Schema are as well understood.

structuring xml using dtd and schema ching-long yeh, phd, 葉 慶 隆 department of computer science...

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structuring xml using dtd and schema ching-long yeh, phd, 葉慶隆 department of computer science...