XML Grammars

Internet Technologies 1

XML Grammars

95-733 Internet Technologies


XML Grammars: Three Major Uses

1. Validation

2. Code Generation

3. Communication


XML Validation

Sources for this lecture:

“Data on the Web” Abiteboul, Buneman and Suciu “XML in a Nutshell” Harold and Means “The XML Companion” Bradley

The validation examples were originally tested with an older parserand so the specific outputs may differ from those shown.


XML Validation

A batch validating process involves comparing the DTD against a complete document instance and producing a report containing any errors or warnings.

Consider batch validation to be analogous to program compilation, with similar errors detected.

Interactive validation involves constant comparison of the DTDagainst a document as it is being created.


XML Validation

The benefits of validating documents against a DTD include:

• Programmers can write extraction and manipulation filters without fear of their software ever processing unexpected input.

• Using an XML-aware word processor, authors and editors can be guided and constrained to produce conforming documents. Consider how Netbeans allows you to edit web.xml files.


XML Validation Examples

XML elements may contain further, embedded elements, andthe entire document must be enclosed by a single documentelement.

These are recursive hierarchical structures.

A Document Type Definition (DTD) contains rules for each element allowed within a specific class of documents.


Things the DTD does not do:

• Specify the document root.• Specify the number of instances of each kind of element. (Or, it’s rather hard to do.)• Describe the character data inside an element (the precise syntax).•DTD’s don’t naturally handle namespaces.• The XML schema language is much more recent and improves on DTD’s. We have “programmer level” type specifications.• To see a real DTD, view source on http://www.silmaril.ie/software/rss2.dtd


We’ll run this program against several xml fileswith DTD’s. We’ll study thecode soon.

// Validate.java using Xerces

import java.io.*;

import org.xml.sax.ErrorHandler;import org.xml.sax.SAXException;import org.xml.sax.SAXParseException;import org.xml.sax.XMLReader;import org.xml.sax.InputSource;import org.xml.sax.helpers.XMLReaderFactory;import org.xml.sax.helpers.DefaultHandler;

This slide shows the importedclasses.


public class Validate { public static boolean valid = true;

public static void main (String argv []) { if (argv.length != 1) { System.err.println ("Usage: java Validate filename.xml"); System.exit (1); }

Here we check if the commandline is correct.


try { // get a parser XMLReader reader = XMLReaderFactory.createXMLReader( "org.apache.xerces.parsers.SAXParser");

// request validation reader.setFeature("http://xml.org/sax/features/validation", true);

// associate an InputSource object with the file name InputSource inputSource = new InputSource(argv[0]);

// go ahead and parse reader.parse(inputSource); }


catch(org.xml.sax.SAXException e) { System.out.println("Error in parsing " + e); valid = false; } catch(java.io.IOException e) { System.out.println("Error in I/O " + e); System.exit(0); } System.out.println("Valid Document is " + valid); }}

// Catch any errors or fatal errors here.// The parser will handle simple warnings.


<?xml version="1.0" encoding="UTF-8"?><!DOCTYPE FixedFloatSwap SYSTEM "FixedFloatSwap.dtd"><FixedFloatSwap> <Notional>100</Notional> <Fixed_Rate>5</Fixed_Rate> <NumYears>3</NumYears> <NumPayments>6</NumPayments></FixedFloatSwap>

<?xml version="1.0" encoding="utf-8"?><!ELEMENT FixedFloatSwap (Notional, Fixed_Rate, NumYears, NumPayments ) ><!ELEMENT Notional (#PCDATA) ><!ELEMENT Fixed_Rate (#PCDATA) ><!ELEMENT NumYears (#PCDATA) ><!ELEMENT NumPayments (#PCDATA) >

XML Document

DTD

Valid document is true


<?xml version="1.0" encoding="UTF-8"?><!DOCTYPE FixedFloatSwap SYSTEM "http://localhost:8001/dtd/FixedFloatSwap.dtd"><FixedFloatSwap> <Notional>100</Notional> <Fixed_Rate>5</Fixed_Rate> <NumYears>3</NumYears> <NumPayments>6</NumPayments></FixedFloatSwap>


XML Document

DTD on the Web?VERY NICE



<?xml version="1.0" encoding="UTF-8"?><!DOCTYPE FixedFloatSwap [

<!ELEMENT FixedFloatSwap (Notional, Fixed_Rate, NumYears, NumPayments ) > <!ELEMENT Notional (#PCDATA) > <!ELEMENT Fixed_Rate (#PCDATA) > <!ELEMENT NumYears (#PCDATA) > <!ELEMENT NumPayments (#PCDATA) >]>

<FixedFloatSwap> <Notional>100</Notional> <Fixed_Rate>5</Fixed_Rate> <NumYears>3</NumYears> <NumPayments>6</NumPayments></FixedFloatSwap>

XML Document withan internal subset



<?xml version="1.0" encoding="UTF-8"?><!DOCTYPE FixedFloatSwap SYSTEM "FixedFloatSwap.dtd"><FixedFloatSwap> <Notional>100</Notional> <Fixed_Rate>5</Fixed_Rate> <NumYears>3</NumYears> <NumPayments>6</NumPayments></FixedFloatSwap>

<?xml version="1.0" encoding="utf-8"?><!ELEMENT FixedFloatSwap (Notional, Fixed_Rate, NumPayments ) ><!ELEMENT Notional (#PCDATA) ><!ELEMENT Fixed_Rate (#PCDATA) ><!ELEMENT NumPayments (#PCDATA) >

XML Document

DTD

Valid document is false


<?xml version="1.0" encoding="UTF-8"?><!DOCTYPE Swaps SYSTEM "FixedFloatSwap.dtd"><Swaps> <FixedFloatSwap> <Notional>100</Notional> <Fixed_Rate>5</Fixed_Rate> <NumYears>3</NumYears> <NumPayments>6</NumPayments> </FixedFloatSwap>

<FixedFloatSwap> <Notional>100</Notional> <Fixed_Rate>5</Fixed_Rate> <NumYears>3</NumYears> <NumPayments>6</NumPayments> </FixedFloatSwap></Swaps>

XML Document


<?xml version="1.0" encoding="utf-8"?><!ELEMENT Swaps (FixedFloatSwap+) ><!ELEMENT FixedFloatSwap (Notional, Fixed_Rate, NumYears, NumPayments ) ><!ELEMENT Notional (#PCDATA) ><!ELEMENT Fixed_Rate (#PCDATA) ><!ELEMENT NumYears (#PCDATA) ><!ELEMENT NumPayments (#PCDATA) >

DTD

C:\McCarthy\www\examples\sax>java Validate FixedFloatSwap.xml

Quantity Indicators ? 0 or 1 time + 1 or more times * 0 or more times



Is this a valid document?

<?xml version="1.0"?><!DOCTYPE person [ <!ELEMENT person (name+, profession*)> <!ELEMENT profession (#PCDATA)> <!ELEMENT name (#PCDATA)>]>

<person> <name>Alan Turing</name> <profession>computer scientist</profession> <profession>cryptographer</profession></person>

Sure!


The locations where document text data is allowed are indicated by the keyword ‘PCDATA’ (Parsed Character Data).

<?xml version="1.0" encoding="UTF-8"?><!DOCTYPE FixedFloatSwap SYSTEM "FixedFloatSwap.dtd">

<FixedFloatSwap> <Notional>100</Notional> <Fixed_Rate>5</Fixed_Rate> <NumYears> <StartYear>2000</StartYear> <EndYear>2002</EndYear> </NumYears> <NumPayments>6</NumPayments>

</FixedFloatSwap>

XML Document



C:\McCarthy\www\46-928\examples\sax>java Validate FixedFloatSwap.xmlorg.xml.sax.SAXParseException: Element "NumYears" does not allow "StartYear" --(#PCDATA)org.xml.sax.SAXParseException: Element type "StartYear" is not declared.org.xml.sax.SAXParseException: Element "NumYears" does not allow "EndYear" -- (#PCDATA)org.xml.sax.SAXParseException: Element type "EndYear" is not declared.Valid document is false

Output

DTD


There are strict rules which must be applied when an element is allowed to contain both text and child elements.

The PCDATA keyword must be the first token in the group, and the group must be a choice group (using “|” not “,”).

The group must be optional and repeatable.

This is known as a mixed content model.

Mixed Content


<?xml version="1.0" encoding="utf-8"?><!ELEMENT Mixed (emph) ><!ELEMENT emph (#PCDATA | sub | super)* ><!ELEMENT sub (#PCDATA)><!ELEMENT super (#PCDATA)>

DTD

<?xml version="1.0" encoding="UTF-8"?><!DOCTYPE Mixed SYSTEM "Mixed.dtd"><Mixed> <emph>H2O is water.</emph></Mixed>

XML Document

Valid document istrue


Is this a valid document?<?xml version="1.0"?><!DOCTYPE page [ <!ELEMENT page (paragraph+)> <!ELEMENT paragraph ( #PCDATA | profession | bold)*> <!ELEMENT profession (#PCDATA)> <!ELEMENT bold (#PCDATA)>]><page> <paragraph> Alan Turing broke codes during <bold>World War II</bold>. He very precisely defined the notion of "algorithm". And so he had several professions: <profession>computer scientist</profession> <profession>cryptographer</profession> And <profession>mathematician</profession> </paragraph></page>

Sure!


How about this one?

java Validate mixed.xmlorg.xml.sax.SAXParseException:The content of element type "page" must match "(paragraph)+".Valid document is false

<?xml version="1.0"?><!DOCTYPE page [ <!ELEMENT page (paragraph+)> <!ELEMENT paragraph ( #PCDATA | profession | bold)*> <!ELEMENT profession (#PCDATA)> <!ELEMENT bold (#PCDATA)>]><page> The following is a paragraph marked up in XML. <paragraph> Alan Turing broke codes during <bold>World War II</bold>. He very precisely defined the notion of "algorithm". And so he had several professions: <profession>computer scientist</profession> <profession>cryptographer</profession> And <profession>mathemetician </profession> </paragraph></page>


<?xml version="1.0" encoding="UTF-8"?><!DOCTYPE FixedFloatSwap SYSTEM "FixedFloatSwap.dtd"> <FixedFloatSwap> <Notional>100</Notional> <Fixed_Rate>5</Fixed_Rate> <NumYears>3</NumYears> <NumPayments>6</NumPayments> <Note> <![CDATA[This is text that will not be parsed for markup]]> </Note> </FixedFloatSwap>

<?xml version="1.0" encoding="utf-8"?><!ELEMENT FixedFloatSwap ( Notional, Fixed_Rate, NumYears, NumPayments, Note ) ><!ELEMENT Notional (#PCDATA)><!ELEMENT Fixed_Rate (#PCDATA) ><!ELEMENT NumYears (#PCDATA) ><!ELEMENT NumPayments (#PCDATA) ><!ELEMENT Note (#PCDATA) >

XML Document

DTD

CDATA Section


Recursion<?xml version="1.0"?><!DOCTYPE tree [ <!ELEMENT tree (node)> <!ELEMENT node (leaf | (node,node))>

<!ELEMENT leaf (#PCDATA)>]>

<tree> <node> <leaf>A DTD is a context-free grammar</leaf> </node></tree>

java Validate recursive1.xmlValid document is true


How about this one?<?xml version="1.0"?><!DOCTYPE tree [ <!ELEMENT tree (node)> <!ELEMENT node (leaf | (node,node))>

<!ELEMENT leaf (#PCDATA)>]><tree> <node> <leaf>Alan Turing would like this</leaf> </node> <node> <leaf>Alan Turing would like this</leaf> </node></tree>

java Validate recursive1.xmlorg.xml.sax.SAXParseException:The content of element type"tree" must match "(node)".Valid document is false


Relational Databases and XML

Consider the relational database r1(a,b,c), r2(c,d)

r1: a b c r2: c d a1 b1 c1 c2 d2 a2 b2 c2 c3 d3 c4 d4

How can we represent this database with an XML DTD?


Relations<?xml version="1.0"?><!DOCTYPE db [ <!ELEMENT db (r1*, r2*)> <!ELEMENT r1 (a,b,c)> <!ELEMENT r2 (c,d)> <!ELEMENT a (#PCDATA)> <!ELEMENT b (#PCDATA)> <!ELEMENT c (#PCDATA)> <!ELEMENT d (#PCDATA)> ]>

<db> <r1><a> a1 </a> b1 <c> c1 </c> </r1> <r1><a> a1 </a> b1 <c> c1 </c> </r1> <r2><c> c2 </c> <d> d2 </d> </r2> <r2><c> c3 </c> <d> d3 </d> </r2> <r2><c> c4 </c> <d> d4 </d> </r2></db>

java Validate Db.xmlValid document is true

There is a small problem….


Relations<?xml version="1.0"?><!DOCTYPE db [ <!ELEMENT db (r1|r2)* > <!ELEMENT r1 ((a,b,c) | (a,c,b) | (b,a,c) | (b,c,a) | (c,a,b) | (c,b,a))> <!ELEMENT r2 ((c,d) | (d,c))> <!ELEMENT a (#PCDATA)> <!ELEMENT b (#PCDATA)> <!ELEMENT c (#PCDATA)> <!ELEMENT d (#PCDATA)> ]><db> <r1><a> a1 </a> b1 <c> c1 </c> </r1> <r1><a> a1 </a> b1 <c> c1 </c> </r1> <r2><c> c2 </c> <d> d2 </d> </r2> <r2><c> c3 </c> <d> d3 </d> </r2> <r2><c> c4 </c> <d> d4 </d> </r2></db>

The order of the relationsshould not count and neithershould the order ofcolumns within rows.


AttributesAn attribute is associated with a particular element by the DTDand is assigned an attribute type.

The attribute type can restrict the range of values it can hold.

Example attribute types include :

CDATA indicates a simple string of characters NMTOKEN indicates a word or token A named token group such as (left | center | right) ID an element id that holds a unique value (among other element ID’s in the document) IDREF attributes refer to an ID


<?xml version="1.0" encoding="utf-8"?><!ELEMENT FixedFloatSwap (Notional, Fixed_Rate, NumYears, NumPayments ) ><!ELEMENT Notional (#PCDATA) ><!ELEMENT Fixed_Rate (#PCDATA) ><!ELEMENT NumYears (#PCDATA) ><!ELEMENT NumPayments (#PCDATA) ><!ATTLIST Notional currency (Dollars | Pounds) #REQUIRED>

DTD

<?xml version="1.0" encoding="UTF-8"?><!DOCTYPE FixedFloatSwap SYSTEM "FixedFloatSwap.dtd"> <FixedFloatSwap> <Notional>100</Notional> <Fixed_Rate>5</Fixed_Rate> <NumYears>3</NumYears> <NumPayments>6</NumPayments> </FixedFloatSwap>

XML Document

C:\McCarthy\www\46-928\examples\sax>java Validate FixedFloatSwap.xmlorg.xml.sax.SAXParseException: Attribute value for "currency" is #REQUIRED.

Valid document is false


<?xml version="1.0" encoding="utf-8"?><!ELEMENT FixedFloatSwap (Notional, Fixed_Rate, NumYears, NumPayments ) ><!ELEMENT Notional (#PCDATA) ><!ELEMENT Fixed_Rate (#PCDATA) ><!ELEMENT NumYears (#PCDATA) ><!ELEMENT NumPayments (#PCDATA) ><!ATTLIST Notional currency (Dollars | Pounds) #REQUIRED>

DTD

<?xml version="1.0" encoding="UTF-8"?><!DOCTYPE FixedFloatSwap SYSTEM "FixedFloatSwap.dtd"> <FixedFloatSwap> <Notional currency = “Pounds”>100</Notional> <Fixed_Rate>5</Fixed_Rate> <NumYears>3</NumYears> <NumPayments>6</NumPayments> </FixedFloatSwap>

XML Document



DTD

<?xml version="1.0" encoding="UTF-8"?><!DOCTYPE FixedFloatSwap SYSTEM "FixedFloatSwap.dtd"> <FixedFloatSwap> <Notional currency = “Pounds”>100</Notional> <Fixed_Rate>5</Fixed_Rate> <NumYears>3</NumYears> <NumPayments>6</NumPayments> </FixedFloatSwap>

XML Document

Valid document is true#IMPLIED means optional

<?xml version="1.0" encoding="utf-8"?><!ELEMENT FixedFloatSwap (Notional, Fixed_Rate, NumYears, NumPayments ) ><!ELEMENT Notional (#PCDATA) ><!ELEMENT Fixed_Rate (#PCDATA) ><!ELEMENT NumYears (#PCDATA) ><!ELEMENT NumPayments (#PCDATA) ><!ATTLIST Notional currency (Dollars | Pounds) #REQUIRED><!ATTLIST FixedFloatSwap note CDATA #IMPLIED>


DTD

<?xml version="1.0" encoding="UTF-8"?><!DOCTYPE FixedFloatSwap SYSTEM "FixedFloatSwap.dtd"> <FixedFloatSwap note = “For your eyes only”> <Notional currency = “Pounds”>100</Notional> <Fixed_Rate>5</Fixed_Rate> <NumYears>3</NumYears> <NumPayments>6</NumPayments> </FixedFloatSwap>

XML Document


<?xml version="1.0" encoding="utf-8"?><!ELEMENT FixedFloatSwap (Notional, Fixed_Rate, NumYears, NumPayments ) ><!ELEMENT Notional (#PCDATA) ><!ELEMENT Fixed_Rate (#PCDATA) ><!ELEMENT NumYears (#PCDATA) ><!ELEMENT NumPayments (#PCDATA) ><!ATTLIST Notional currency (Dollars | Pounds) #REQUIRED><!ATTLIST FixedFloatSwap note CDATA #IMPLIED>


ID and IDREF Attributes

We can represent complex relationships within an XML document using ID and IDREF attributes.


An Undirected Graph

u v w

x y z

edgevertex


A Directed Graph

uw

v

y x


Math 100 Geom100

Calc100 Calc200 Calc300

Philo45CS1 CS2

This is called a DAG (Directed Acyclic Graph)


<?xml version="1.0"?>

<!DOCTYPE Course_Descriptions SYSTEM "course_descriptions.dtd">

<Course_Descriptions>

<Course>

<Course-ID id = "Math100" />

<Title>Algebra I</Title>

<Description> Students in this course study

introductory algebra.

</Description>

<Prerequisites/>

</Course>

This course has an ID

But no prerequisites


<Course>

<Course-ID id = "Geom100" />

<Title>Geometry I</Title>

<Description> Students in this course study how to

prove several theorems in geometry.

</Description>

<Prerequisites/>

</Course>

The DTD will forcethis to be unique.


<Course>

<Course-ID id="Calc100" />

<Title>Calculus I</Title>

<Description> Students in this course study the derivative.

</Description>

<Prerequisites pre="Math100 Geom100" />

</Course>

<Course>

These are references toID’s. (IDREFS)


<Course-ID id = "Calc200" />

<Title>Calculus II</Title>

<Description> Students in this course study the integral.

</Description>

<Prerequisites pre="Calc100" />

</Course>

The DTD requires that this namebe a unique id defined within thisdocument. Otherwise, the documentis invalid.


<Course>

<Course-ID id = "Calc300" />

<Title>Calculus II</Title>

<Description> Students in this course study the derivative

and the integral (in 3-space).

</Description>


</Course>

Prerequisites is an EMPTYelement. It’s used only for itsattributes.


<Course>

<Course-ID id = "CS1" />

<Title>Introduction to Computer Science I</Title>

<Description> In this course we study Turing machines.

</Description>


</Course>

<Course>

IDREF ID

A One-to-one link


<Course-ID id = "CS2" />

<Title>Introduction to Computer Science II</Title>

<Description> In this course we study basic data structures.

</Description>

<Prerequisites pre="Calc200 CS1"/>

</Course>

<Course>

IDREFS

ID

ID

One-to-many links


<Course-ID id = "Philo45" />

<Title>Ethical Implications of Information Technology</Title>

<Description> TBA

</Description>

<Prerequisites/>

</Course>

</Course_Descriptions>



 <!ELEMENT Course_Descriptions (Course)+> <!ELEMENT Course (Course-ID,Title,Description,Prerequisites)> <!ELEMENT Course-ID EMPTY> <!ELEMENT Title (#PCDATA)> <!ELEMENT Description (#PCDATA)> <!ELEMENT Prerequisites EMPTY>

<!ATTLIST Course-ID id ID #REQUIRED>

<!ATTLIST Prerequisites pre IDREFS #IMPLIED>

The Course_Descriptions.dtd


General Entities &

General entities are used to place text into the XML document.

They may be declared in the DTD and referenced in the document.

They may also be declared in the DTD as residing in a file. Theymay then be referenced in the document.


<?xml version="1.0" encoding="UTF-8"?><!DOCTYPE FixedFloatSwap SYSTEM "FixedFloatSwap.dtd" [ <!ENTITY bankname "Mellon National Bank and Trust" > ]> <FixedFloatSwap> <Bank>&bankname;</Bank> <Notional>100</Notional> <Fixed_Rate>5</Fixed_Rate> <NumYears>3</NumYears> <NumPayments>6</NumPayments> </FixedFloatSwap>

<?xml version="1.0" encoding="utf-8"?><!ELEMENT FixedFloatSwap (Bank,Notional, Fixed_Rate, NumYears, NumPayments ) ><!ELEMENT Bank (#PCDATA) ><!ELEMENT Notional (#PCDATA) ><!ELEMENT Fixed_Rate (#PCDATA) ><!ELEMENT NumYears (#PCDATA) ><!ELEMENT NumPayments (#PCDATA) >

DTD

Document usinga General Entity

Validate is true


<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="1.0">

<xsl:template match = "Bank"> <WML> <CARD> <xsl:apply-templates/> </CARD> </WML> </xsl:template>

<xsl:template match = "Notional | Fixed_Rate | NumYears | NumPayments"> </xsl:template> </xsl:stylesheet>

XSLT Program

The general entity is replaced before xslt sees it.


C:\McCarthy\www\46-928\examples\sax>java -Dcom.jclark.xsl.sax.parser=com.jclark.xml.sax.CommentDriver com.jclark.xsl.sax.Driver FixedFloatSwap.xml FixedFloatSwap.xsl FixedFloatSwap.wml

C:\McCarthy\www\46-928\examples\sax>type FixedFloatSwap.wml

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

<WML><CARD>Mellon National Bank and Trust</CARD></WML>

XSLT OUTPUT


<?xml version="1.0" encoding="UTF-8"?><!DOCTYPE FixedFloatSwap SYSTEM "FixedFloatSwap.dtd" [

<!ENTITY bankname SYSTEM "JustAFile.dat" >

]> <FixedFloatSwap> <Bank>&bankname;</Bank> <Notional>100</Notional> <Fixed_Rate>5</Fixed_Rate> <NumYears>3</NumYears> <NumPayments>6</NumPayments> </FixedFloatSwap>

An external text entity


Mellon Bank And Trust CorporationPittsburgh PA

XSLT Output

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

<WML><CARD>Mellon Bank And Trust CorporationPittsburgh PA</CARD></WML>

JustAFile.dat


Parameter Entities %

While general entities are used to place text into the XML documentparameter entities are used to modify the DTD.

We want to build modular DTD’s so that we can create new DTD’susing existing ones.

We’ll look at slide from www.fpml.org and the see some examples.

http://www.fpml.org/


FpML is a Complete Description of the Trade

Pool of modular componentsgrouped into separate namespaces

Date ScheduleProduct

Rate

Adjustable PeriodNotional

Party

Trade

Trade ID

Product

Rate

Adjustable Period

Notional

Party

Vanilla SwapVanilla Fixed Float SwapCancellableSwaptionFX SpotFX OutrightFX SwapForward Rate Agreement...

MoneyDate


<?xml version="1.0" encoding="utf-8"?><!ELEMENT FixedFloatSwap (Notional, Fixed_Rate, NumYears, NumPayments ) ><!ENTITY % parsedCharacterData "(#PCDATA)"><!ELEMENT Notional %parsedCharacterData; ><!ELEMENT Fixed_Rate (#PCDATA) ><!ELEMENT NumYears (#PCDATA) ><!ELEMENT NumPayments (#PCDATA) >

XML Document

DTD

Internal Parameter Entities

<?xml version="1.0" encoding="UTF-8"?><!DOCTYPE FixedFloatSwap SYSTEM "FixedFloatSwap.dtd"> <FixedFloatSwap> <Notional>100</Notional> <Fixed_Rate>5</Fixed_Rate> <NumYears>3</NumYears> <NumPayments>6</NumPayments> </FixedFloatSwap>


External Parameter Entities and DTD Components

<?xml version="1.0" encoding = "UTF-8"?><!DOCTYPE ORDER SYSTEM "order.dtd"><ORDER SOURCE ="web" CUSTOMERTYPE="consumer" CURRENCY="USD"> <addresses> <address ADDTYPE="billship"> <firstname>Kevin</firstname> <lastname>Dick</lastname> <street ORDER="1">123 Anywhere Lane</street> <street ORDER="2">Apt 1b</street> <city>Palo Alto</city> <state>CA</state> <postal>94303</postal> <country>USA</country> </address>

Order.xml


<address ADDTYPE="bill"> <firstname>Kevin</firstname> <lastname>Dick</lastname> <street ORDER="1">123 Not The Same Lane</street> <street ORDER="2">Work Place</street> <city>Palo Alto</city> <state>CA</state> <postal>94300</postal> <country>USA</country> </address> </addresses>

An order may have more than oneaddress.


<lineitems> <lineitem ID="line1"> <product CAT="MBoard">440BX Motherboard</product> <quantity>1</quantity> <unitprice>200</unitprice> </lineitem> <lineitem ID="line2"> <product CAT = "RAM">128 MB PC-100 DIMM</product> <quantity>2</quantity> <unitprice>175</unitprice> </lineitem> <lineitem ID="line3"> <product CAT="CDROM">40x CD-ROM</product> <quantity>1</quantity> <unitprice>50</unitprice> </lineitem> </lineitems>

Several productsmay be purchased.


<payment> <card CARDTYPE="VISA"> <cardholder>Kevin S. Dick</cardholder> <cardnumber>11111-22222-33333</cardnumber> <expiration>01/01</expiration> </card> </payment></ORDER>

The payment is witha Visa card.

We want this document to be validated.


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





<!ELEMENT ORDER (addresses, lineitems, payment)> <!ATTLIST ORDER SOURCE (web | phone | retail) #REQUIRED CUSTOMERTYPE (consumer | business) "consumer" CURRENCY CDATA "USD">

Define an order based on other elements.


<!ENTITY % anAddress SYSTEM "address.dtd" >%anAddress;

<!ELEMENT addresses (address+)>

<!ENTITY % aLineItem SYSTEM "lineitem.dtd" >%aLineItem;

<!ELEMENT lineitems (lineitem+)>

<!ENTITY % aPayment SYSTEM "payment.dtd" >%aPayment;

External parameterentity declaration %

External parameter entity reference %


address.dtd<!ELEMENT address (firstname, middlename?, lastname, street+, city, state,postal,country)>

<!ELEMENT firstname (#PCDATA)><!ELEMENT middlename (#PCDATA)><!ELEMENT lastname (#PCDATA)><!ELEMENT street (#PCDATA)><!ELEMENT city (#PCDATA)><!ELEMENT state (#PCDATA)><!ELEMENT postal (#PCDATA)><!ELEMENT country (#PCDATA)><!ATTLIST address ADDTYPE (bill | ship | billship) "billship"><!ATTLIST street ORDER CDATA #IMPLIED>


lineitem.dtd<!ELEMENT lineitem (product,quantity,unitprice)><!ATTLIST lineitem ID ID #REQUIRED>

<!ELEMENT product (#PCDATA)><!ATTLIST product CAT (CDROM|MBoard|RAM) #REQUIRED>

<!ELEMENT quantity (#PCDATA)><!ELEMENT unitprice (#PCDATA)>


<!ELEMENT payment (card | PO)><!ELEMENT card (cardholder, cardnumber, expiration)><!ELEMENT cardholder (#PCDATA)><!ELEMENT cardnumber (#PCDATA)><!ELEMENT expiration (#PCDATA)><!ELEMENT PO (number,authorization*)><!ELEMENT number (#PCDATA)><!ELEMENT authorization (#PCDATA)>

<!ATTLIST card CARDTYPE (VISA|MasterCard|Amex) #REQUIRED>

payment.dtd


XML Schemas Improve on DTD’s

• XML Schema is the official name• XSDL (XML Schema Definition Language) is the language used to create schema definitions• XML Syntax• Can be used to more tightly constrain a document instance• Supports namespaces• Permits type derivation• Harder than DTD’s


Other Grammars Include

• RELAX • TREX (James Clark - Tree Regular Expressions

for XML)• RELAX NG (RELAX and TREX combined to

Relax Next Generation)• Schematron (“Rule based” rather than “grammar

based” see www.ascc.net/xml/schematron) Based on XSLT and XPath

http://www.ascc.net/xml/schematron


XSDL - A Simple Purchase Order

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

<purchaseOrder orderDate="07.23.2001" xmlns="http://www.cds-r-us.com" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.cds-r-us.com po.xsd">


<recipient country="USA"> <name>Dennis Scannel</name> <street>175 Perry Lea Side Road</street> <city>Waterbury</city> <state>VT</state> <postalCode>15216</postalCode> </recipient>

<order> <cd artist="Brooks Williams" title="Little Lion" /> <cd artist="David Wilcox" title="What you whispered" /> </order>

</purchaseOrder>


Purchase Order XSDL

<?xml version="1.0" encoding="utf-8"?> <xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns="http://www.cds-r-us.com" targetNamespace="http://www.cds-r-us.com" >


<xs:element name="purchaseOrder">

<xs:complexType> <xs:sequence> <xs:element ref="recipient" /> <xs:element ref="order" /> </xs:sequence> <xs:attribute name="orderDate" type="xs:string" /> </xs:complexType>

</xs:element>


<xs:element name = "recipient">

<xs:complexType> <xs:sequence> <xs:element ref="name" /> <xs:element ref="street" /> <xs:element ref="city" /> <xs:element ref="state" /> <xs:element ref="postalCode" /> </xs:sequence> <xs:attribute name="country" type="xs:string" /> </xs:complexType>

</xs:element>


<xs:element name = "name" type="xs:string" /> <xs:element name = "street" type="xs:string" /> <xs:element name = "city" type="xs:string" /> <xs:element name = "state" type="xs:string" /> <xs:element name = "postalCode" type="xs:short" />

<xs:element name = "order"> <xs:complexType> <xs:sequence> <xs:element ref="cd" maxOccurs="unbounded"/> </xs:sequence> </xs:complexType> </xs:element>


<xs:element name="cd"> <xs:complexType> <xs:attribute name="artist" type="xs:string" /> <xs:attribute name="title" type="xs:string" /> </xs:complexType> </xs:element>

</xs:schema>


Validate.java// Validate.java using Xerces

import java.io.*;

import org.xml.sax.ErrorHandler;import org.xml.sax.SAXException;import org.xml.sax.SAXParseException;import org.xml.sax.XMLReader;import org.xml.sax.InputSource;import org.xml.sax.helpers.XMLReaderFactory;import org.xml.sax.helpers.DefaultHandler;import java.io.*;


import javax.xml.parsers.SAXParser;

import javax.xml.parsers.SAXParserFactory;

import org.xml.sax.helpers.DefaultHandler;

import org.xml.sax.SAXException;

import org.xml.sax.InputSource;

import org.xml.sax.SAXParseException;


public class Validate extends DefaultHandler { public static boolean valid = true;

public void error(SAXParseException exception) { System.out.println("Received notification of a recoverable error." + exception); valid = false; }

public void fatalError(SAXParseException exception) { System.out.println("Received notification of a non-recoverable error."+

exception); valid = false; } public void warning(SAXParseException exception) { System.out.println("Received notification of a warning."+ exception); }


public static void main (String argv []) { if (argv.length != 1) { System.err.println ("Usage: java Validate filename.xml"); System.exit (1); } try { // get a parser XMLReader reader = XMLReaderFactory.createXMLReader( "org.apache.xerces.parsers.SAXParser"); // request validation reader.setFeature("http://xml.org/sax/features/validation",true); reader.setFeature( "http://apache.org/xml/features/validation/schema",true); reader.setErrorHandler(new Validate()); // associate an InputSource object with the file name InputSource inputSource = new InputSource(argv[0]);

// go ahead and parse reader.parse(inputSource);


} catch(org.xml.sax.SAXException e) { System.out.println("Error in parsing " + e); valid = false; } catch(java.io.IOException e) { System.out.println("Error in I/O " + e); System.exit(0); } System.out.println("Valid Document is " + valid); }}


XML Document<?xml version="1.0" encoding="utf-8"?><itemList xmlns:xsi='http://www.w3.org/2001/XMLSchema-instance' xsi:noNamespaceSchemaLocation="itemList.xsd"> <item> <name>pen</name> <quantity>5</quantity> </item> <item> <name>eraser</name> <quantity>7</quantity> </item> <item> <name>stapler</name> <quantity>2</quantity> </item></itemList>


XSDL Grammar itemList.xsd

<?xml version="1.0" encoding="utf-8"?><xsd:schema xmlns:xsd='http://www.w3.org/2001/XMLSchema'>

<xsd:element name="itemList"> <xsd:complexType> <xsd:sequence> <xsd:element ref="item" minOccurs="0" maxOccurs="3"/> </xsd:sequence> </xsd:complexType> </xsd:element>


<xsd:element name="item">

<xsd:complexType>

<xsd:sequence>

<xsd:element ref="name"/>

<xsd:element ref="quantity"/>

</xsd:sequence>

</xsd:complexType>

</xsd:element>

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

<xsd:element name="quantity" type="xsd:short"/>

</xsd:schema>


D:..95-733\examples\XSDL\testing>ant run

Buildfile: build.xml

run:

Running Validate.java on itemList-xsd.xml

Valid Document is true


Another Example

<?xml version="1.0" encoding="UTF-8"?> <myns:purchaseOrder orderDate="07.23.2001" xmlns:myns="http://www.cds-r-us.com" xmlns:xsi= "http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation= "http://www.cds-r-us.com po.xsd">


<myns:recipient country="USA">

<myns:name>Dennis Scannel</myns:name>

<myns:street>175 Perry Lea Side Road</myns:street>

<myns:city>Waterbury</myns:city>

<myns:state>VT</myns:state>

<myns:postalCode>05675A</myns:postalCode>

</myns:recipient>

Note that there is a problem with this document.


<myns:order>

<myns:cd artist="Brooks Williams" title="Little Lion" />

<myns:cd artist="David Wilcox" title="What you whispered" />

</myns:order>

</myns:purchaseOrder>


XSDL Grammar po.xsd

<?xml version="1.0" encoding="utf-8"?> <xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns="http://www.cds-r-us.com" targetNamespace="http://www.cds-r-us.com" > <xs:element name="purchaseOrder"> <xs:complexType> <xs:sequence> <xs:element ref="recipient" /> <xs:element ref="order" /> </xs:sequence> <xs:attribute name="orderDate" type="xs:string" /> </xs:complexType> </xs:element>


<xs:element name = "recipient"> <xs:complexType> <xs:sequence> <xs:element ref="name" /> <xs:element ref="street" /> <xs:element ref="city" /> <xs:element ref="state" /> <xs:element ref="postalCode" /> </xs:sequence> <xs:attribute name="country" type="xs:string" /> </xs:complexType> </xs:element>


<xs:element name = "name" type="xs:string" /> <xs:element name = "street" type="xs:string" /> <xs:element name = "city" type="xs:string" /> <xs:element name = "state" type="xs:string" /> <xs:element name = "postalCode" type="xs:short" />

<xs:element name = "order"> <xs:complexType> <xs:sequence> <xs:element ref="cd" maxOccurs="unbounded"/> </xs:sequence> </xs:complexType> </xs:element>


<xs:element name="cd">

<xs:complexType>

<xs:attribute name="artist"

type="xs:string" />

<xs:attribute name="title" type="xs:string" />

</xs:complexType>

</xs:element>

</xs:schema>


Running Validate

D:..\examples\XSDL\testing>ant runBuildfile: build.xml

run: Running Validate.java on po.xml Received notification of a recoverable

error.org.xml.sax.SAXParseException: cvc-datatype-valid.1.2.1: '05675A' is not a valid 'integer' value.

Received notification of a recoverable

error.org.xml.sax.SAXParseException: cvc-type.3.1.3: The value '05675A' of element 'myns:postalCode' is not valid.

Valid Document is false


Fix the error and run again

D:\..\XSDL\testing>ant run

Buildfile: build.xml

run:

Running Validate.java on po.xml

Valid Document is true


Introduce a Namespace Error

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



<myns:purchaseOrder orderDate="07.23.2001"

xmlns:myns="http://www.cds-r-us.edu"

xmlns:xsi=

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

xsi:schemaLocation="http://www.cds-r-us.com

po.xsd"

>


<myns:recipient country="USA"> <myns:name>Dennis Scannel</myns:name> <myns:street> 175 Perry Lea Side Road </myns:street> <myns:city>Waterbury</myns:city> <myns:state>VT</myns:state> <myns:postalCode>05675</myns:postalCode> </myns:recipient>


<myns:order>

<myns:cd artist="Brooks Williams" title="Little Lion" />

<myns:cd artist="David Wilcox" title="What you whispered" />

</myns:order>

</myns:purchaseOrder>


And run validate

run: Running Validate.java on po.xml

Received notification of a recoverable

error.org.xml.sax.SAXParseException: cvc-elt.1:

Cannot find the declaration of element 'myns:purchaseOrder'.

Valid Document is false


Code Generation

• Run JAXB against the .xsd file

• Code generated will present an API allowing us to process that style of

document


itemList.xsd again

<?xml version="1.0" encoding="utf-8"?><xsd:schema xmlns:xsd='http://www.w3.org/2001/XMLSchema'>

<xsd:element name="itemList"> <xsd:complexType> <xsd:sequence> <xsd:element ref="item" minOccurs="0" maxOccurs="3"/> </xsd:sequence> </xsd:complexType> </xsd:element>


<xsd:element name="item"> <xsd:complexType> <xsd:sequence> <xsd:element ref="name"/> <xsd:element ref="quantity"/> </xsd:sequence> </xsd:complexType></xsd:element>

<xsd:element name="name" type="xsd:string"/> <xsd:element name="quantity" type="xsd:short"/></xsd:schema>


Run xjc

D:..XSDL\testing>xjc itemList.xsd

D:\McCarthy\www\95-733\examples\XSDL\testing>java -jar D:\jwsdp-1.1\jaxb-1.0\lib

\jaxb-xjc.jar itemList.xsd

parsing a schema...compiling a schema...generated\impl\ItemImpl.javagenerated\impl\ItemListImpl.javagenerated\impl\ItemListTypeImpl.javagenerated\impl\ItemTypeImpl.javagenerated\impl\NameImpl.java


generated\impl\QuantityImpl.javagenerated\Item.javagenerated\ItemList.javagenerated\ItemListType.javagenerated\ItemType.javagenerated\Name.javagenerated\ObjectFactory.javagenerated\Quantity.javagenerated\bgm.sergenerated\jaxb.properties

Write Java Code That uses NEW the api


The build script used for these examples


<project basedir="." default="compile"> <path id="classpath"> <fileset dir="D:/jwsdp-1.1/saaj-1.1.1/lib" includes="*.jar"/> <fileset dir="D:/jwsdp-1.1/jaxb-1.0/lib" includes="*.jar"/> <fileset dir="d:/jwsdp-1.1/common/lib" includes="*.jar"/>


<fileset dir="D:/jwsdp-1.1/jaxm-1.1.1/lib" includes="*.jar"/> <fileset dir="D:/jwsdp-1.1/bin" includes="*.jar" /> <fileset dir="D:/jwsdp-1.1/jaxp-1.2.2/lib" includes="*.jar"/> <fileset dir="D:/jwsdp-1.1/jaxp-1.2.2/lib/endorsed" includes="*.jar"/> <fileset dir="D:/jwsdp-1.1/jwsdp-shared/lib" includes="*.jar"/> <fileset dir="D:/jwsdp-1.1/jaxr-1.0_03/lib" includes="*.jar"/> <fileset dir="D:/jwsdp-1.1/jakarta-ant-1.5.1/lib" includes="*.jar"/> <fileset dir="D:/j2sdk1.4.1_01/lib" includes="*.jar"/>

<pathelement location="."/> </path>


 <target name="compile">  <echo message="Compiling the java source files..."/> <javac srcdir="." destdir="." debug="on"> <classpath refid="classpath" /> </javac> </target>

<target name="run"> <echo message="Running Validate.java on po.xml"/> <java classname="Validate" fork="fasle"> <arg value="po.xml"/> <classpath refid="classpath" /> </java> </target></project>

Documents

XML Grammars