XML Grammars
95-733 Internet Technologies
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XML Grammars: Three Major Uses
1. Validation
2. Code Generation
3. Communication
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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 parser
and so the specific outputs may differ from those shown.
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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 DTD
against a document as it is being created.
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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.
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XML Validation Examples
XML elements may contain further, embedded elements, and
the entire document must be enclosed by a single document
element.
These are recursive hierarchical structures.
A Document Type Definition (DTD) contains rules for each
element allowed within a specific class of documents.
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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
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// Validate.java using Xerces
import java.io.*;
We’ll run this program
against several xml files
with DTD’s. We’ll study the
code soon.
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 imported
classes.
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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 command
line is correct.
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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);
}
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// Catch any errors or fatal errors here.
// The parser will handle simple warnings.
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);
}
}
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<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE FixedFloatSwap SYSTEM "FixedFloatSwap.dtd">
<FixedFloatSwap>
XML Document
<Notional>100</Notional>
<Fixed_Rate>5</Fixed_Rate>
<NumYears>3</NumYears>
<NumPayments>6</NumPayments>
</FixedFloatSwap>
DTD
<?xml version="1.0" encoding="utf-8"?>
<!ELEMENT FixedFloatSwap (Notional, Fixed_Rate, NumYears, NumPayments ) >
<!ELEMENT Notional (#PCDATA) >
<!ELEMENT Fixed_Rate (#PCDATA) >
<!ELEMENT NumYears (#PCDATA) >
Valid document is true
<!ELEMENT NumPayments (#PCDATA) >
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<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE FixedFloatSwap SYSTEM "http://localhost:8001/dtd/FixedFloatSwap.dt
<FixedFloatSwap>
XML Document
<Notional>100</Notional>
<Fixed_Rate>5</Fixed_Rate>
<NumYears>3</NumYears>
<NumPayments>6</NumPayments>
</FixedFloatSwap>
DTD on the Web?
VERY NICE
<?xml version="1.0" encoding="utf-8"?>
<!ELEMENT FixedFloatSwap (Notional, Fixed_Rate, NumYears, NumPayments ) >
<!ELEMENT Notional (#PCDATA) >
<!ELEMENT Fixed_Rate (#PCDATA) >
<!ELEMENT NumYears (#PCDATA) >
Valid document is true
<!ELEMENT NumPayments (#PCDATA) >
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<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE FixedFloatSwap [
XML Document with
an internal subset
<!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>
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Valid document is true
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<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE FixedFloatSwap SYSTEM "FixedFloatSwap.dtd">
<FixedFloatSwap>
XML Document
<Notional>100</Notional>
<Fixed_Rate>5</Fixed_Rate>
<NumYears>3</NumYears>
<NumPayments>6</NumPayments>
</FixedFloatSwap>
DTD
<?xml version="1.0" encoding="utf-8"?>
<!ELEMENT FixedFloatSwap (Notional, Fixed_Rate, NumPayments ) >
<!ELEMENT Notional (#PCDATA) >
<!ELEMENT Fixed_Rate (#PCDATA) >
<!ELEMENT NumPayments (#PCDATA) >
Valid document is false
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<?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>
XML Document
<FixedFloatSwap>
<Notional>100</Notional>
<Fixed_Rate>5</Fixed_Rate>
<NumYears>3</NumYears>
<NumPayments>6</NumPayments>
</FixedFloatSwap>
</Swaps>
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<?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
Valid document is true
Quantity Indicators
?
0 or 1 time
+ 1 or more times
* 0 or more times
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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>
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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>
XML Document
<Notional>100</Notional>
<Fixed_Rate>5</Fixed_Rate>
<NumYears>
<StartYear>2000</StartYear>
<EndYear>2002</EndYear>
</NumYears>
<NumPayments>6</NumPayments>
</FixedFloatSwap>
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DTD
<?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) >
Output
C:\McCarthy\www\46-928\examples\sax>java Validate FixedFloatSwap.xml
org.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
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Mixed Content
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.
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<?xml version="1.0" encoding="utf-8"?>
<!ELEMENT Mixed (emph) >
<!ELEMENT emph (#PCDATA | sub | super)* >
<!ELEMENT sub (#PCDATA)>
<!ELEMENT super (#PCDATA)>
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE Mixed SYSTEM "Mixed.dtd">
<Mixed>
<emph>H₂O is water.</emph>
</Mixed>
DTD
XML Document
Valid document is
true
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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>
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</page>
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How
about
this
one?
<?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>
java Validate mixed.xml
<profession>cryptographer</profession>
org.xml.sax.SAXParseException:
And
The content of element type "page"
<profession>mathemetician </profession>
must match "(paragraph)+".
</paragraph>
Valid document is false
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</page>
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE FixedFloatSwap SYSTEM "FixedFloatSwap.dtd">
<FixedFloatSwap>
<Notional>100</Notional>
XML Document
<Fixed_Rate>5</Fixed_Rate>
<NumYears>3</NumYears>
<NumPayments>6</NumPayments>
<Note>
<![CDATA[This is text that <b>will not be
CDATA Section
parsed for markup]]>
</Note>
</FixedFloatSwap>
DTD
<?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)
>
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<!ELEMENT Note (#PCDATA) >
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Recursion
<?xml version="1.0"?>
<!DOCTYPE tree [
<!ELEMENT tree (node)>
<!ELEMENT node (leaf | (node,node))>
<!ELEMENT leaf (#PCDATA)>
]>
java Validate recursive1.xml
<tree>
Valid document is true
<node>
<leaf>A DTD is a context-free grammar</leaf>
</node>
</tree>
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How
about
this
one?
<?xml version="1.0"?>
<!DOCTYPE tree [
<!ELEMENT tree (node)>
<!ELEMENT node (leaf | (node,node))>
<!ELEMENT leaf (#PCDATA)>
java Validate recursive1.xml
org.xml.sax.SAXParseException:
]>
The content of element type
<tree>
"tree" must match "(node)".
<node>
Valid document is false
<leaf>Alan Turing would like this</leaf>
</node>
<node>
<leaf>Alan Turing would like this</leaf>
</node>
</tree>
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Relational Databases and XML
Consider the relational database r1(a,b,c), r2(c,d)
r1: a b
a1 b1
a2 b2
c
c1
c2
r2: c
c2
c3
c4
d
d2
d3
d4
How can we represent this database with an XML DTD?
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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)>
]>
java Validate Db.xml
Valid document is true
<db>
<r1><a> a1 </a> <b> b1 </b> <c> c1 </c> </r1>
<r1><a> a1 </a> <b> b1 </b> <c> c1 </c> </r1>
<r2><c> c2 </c> <d> d2 </d> </r2>
<r2><c> c3 </c> <d> d3 </d> </r2>
There
<r2><c> c4 </c> <d> d4 </d> Internet
</r2> Technologies
</db>
is a small problem….
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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)>
The order of the relations
<!ELEMENT b (#PCDATA)>
<!ELEMENT c (#PCDATA)>
should not count and neither
<!ELEMENT d (#PCDATA)>
should the order of
within rows.
]>
columns
<db>
<r1><a> a1 </a> <b> b1 </b> <c> c1 </c> </r1>
<r1><a> a1 </a> <b> b1 </b> <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>
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</db>
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Attributes
An attribute is associated with a particular element by the DTD
and 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 referInternet
to an
ID
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<?xml version="1.0" encoding="utf-8"?>
<!ELEMENT FixedFloatSwap (Notional, Fixed_Rate, NumYears, NumPayments ) >
<!ELEMENT Notional (#PCDATA) >
<!ELEMENT Fixed_Rate (#PCDATA) >
DTD
<!ELEMENT NumYears (#PCDATA) >
<!ELEMENT NumPayments (#PCDATA) >
<!ATTLIST Notional currency (Dollars | Pounds) #REQUIRED>
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE FixedFloatSwap SYSTEM "FixedFloatSwap.dtd">
<FixedFloatSwap>
XML Document
<Notional>100</Notional>
<Fixed_Rate>5</Fixed_Rate>
<NumYears>3</NumYears>
<NumPayments>6</NumPayments>
</FixedFloatSwap>
C:\McCarthy\www\46-928\examples\sax>java Validate FixedFloatSwap.xml
org.xml.sax.SAXParseException: Attribute value for "currency" is #REQUIRED.
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Valid document
false
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<?xml version="1.0" encoding="utf-8"?>
<!ELEMENT FixedFloatSwap (Notional, Fixed_Rate, NumYears, NumPayments ) >
<!ELEMENT Notional (#PCDATA) >
<!ELEMENT Fixed_Rate (#PCDATA) >
DTD
<!ELEMENT NumYears (#PCDATA) >
<!ELEMENT NumPayments (#PCDATA) >
<!ATTLIST Notional currency (Dollars | Pounds) #REQUIRED>
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE FixedFloatSwap SYSTEM "FixedFloatSwap.dtd">
<FixedFloatSwap>
XML Document
<Notional currency = “Pounds”>100</Notional>
<Fixed_Rate>5</Fixed_Rate>
<NumYears>3</NumYears>
<NumPayments>6</NumPayments>
Valid document is true
</FixedFloatSwap>
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<?xml version="1.0" encoding="utf-8"?>
<!ELEMENT FixedFloatSwap (Notional, Fixed_Rate, NumYears, NumPayments ) >
<!ELEMENT Notional (#PCDATA) >
<!ELEMENT Fixed_Rate (#PCDATA) >
DTD
<!ELEMENT NumYears (#PCDATA) >
<!ELEMENT NumPayments (#PCDATA) >
<!ATTLIST Notional currency (Dollars | Pounds) #REQUIRED>
<!ATTLIST FixedFloatSwap note CDATA #IMPLIED>
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE FixedFloatSwap SYSTEM "FixedFloatSwap.dtd">
<FixedFloatSwap>
XML Document
<Notional currency = “Pounds”>100</Notional>
<Fixed_Rate>5</Fixed_Rate>
<NumYears>3</NumYears>
<NumPayments>6</NumPayments>
Valid document is true
</FixedFloatSwap>
#IMPLIED means optional
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<?xml version="1.0" encoding="utf-8"?>
<!ELEMENT FixedFloatSwap (Notional, Fixed_Rate, NumYears, NumPayments ) >
<!ELEMENT Notional (#PCDATA) >
<!ELEMENT Fixed_Rate (#PCDATA) >
DTD
<!ELEMENT NumYears (#PCDATA) >
<!ELEMENT NumPayments (#PCDATA) >
<!ATTLIST Notional currency (Dollars | Pounds) #REQUIRED>
<!ATTLIST FixedFloatSwap note CDATA #IMPLIED>
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE FixedFloatSwap SYSTEM "FixedFloatSwap.dtd">
<FixedFloatSwap note = “For your eyes only”>
XML Document
<Notional currency = “Pounds”>100</Notional>
<Fixed_Rate>5</Fixed_Rate>
<NumYears>3</NumYears>
<NumPayments>6</NumPayments>
Valid document is true
</FixedFloatSwap>
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ID and IDREF Attributes
We can represent complex relationships within an XML
document using ID and IDREF attributes.
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An Undirected Graph
edge
vertex
v
u
x
y
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z
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A Directed Graph
u
w
y
x
v
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Geom100
Math 100
Calc100
CS1
Calc200
CS2
Calc300
Philo45
This is called a DAG (Directed Acyclic Graph)
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<?xml version="1.0"?>
<!DOCTYPE Course_Descriptions SYSTEM
"course_descriptions.dtd">
<Course_Descriptions>
This course has an ID
<Course>
<Course-ID id = "Math100" />
<Title>Algebra I</Title>
<Description> Students in this course study
introductory algebra.
</Description>
But no prerequisites
<Prerequisites/>
</Course>
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<Course>
<Course-ID id = "Geom100" />
The DTD will force
this to be unique.
<Title>Geometry I</Title>
<Description> Students in this course study how to
prove several theorems in geometry.
</Description>
<Prerequisites/>
</Course>
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<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 to
ID’s. (IDREFS)
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<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 name
be a unique id defined within this
document. Otherwise, the document
is invalid.
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<Course>
<Course-ID id = "Calc300" />
<Title>Calculus II</Title>
<Description> Students in this course study the derivative
and the integral (in 3-space).
</Description>
<Prerequisites pre="Calc200" />
</Course>
Prerequisites is an EMPTY
element. It’s used only for its
attributes.
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<Course>
<Course-ID id = "CS1" />
<Title>Introduction to Computer Science I</Title>
<Description> In this course we study Turing machines.
</Description>
<Prerequisites pre="Calc100" />
</Course>
<Course>
IDREF
ID
A One-to-one link
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<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>
ID
IDREFS
ID
One-to-many links
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<Course-ID id = "Philo45" />
<Title>Ethical Implications of Information Technology</Title>
<Description> TBA
</Description>
<Prerequisites/>
</Course>
</Course_Descriptions>
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The Course_Descriptions.dtd
<?xml version="1.0"?>
<!-- Course Description DTD -->
<!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>
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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. They
may then be referenced in the document.
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<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE FixedFloatSwap SYSTEM "FixedFloatSwap.dtd" [
<!ENTITY bankname "Mellon National Bank and Trust" >
]
>
<FixedFloatSwap>
Document using
<Bank>&bankname;</Bank>
a General Entity
<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 ) >
DTD
<!ELEMENT Bank (#PCDATA) >
<!ELEMENT Notional (#PCDATA) >
Validate is true
<!ELEMENT Fixed_Rate (#PCDATA) >
<!ELEMENT NumYears (#PCDATA) >
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<!ELEMENT NumPayments (#PCDATA) >
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The general entity is replaced before xslt sees it.
<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>
XSLT Program
<xsl:template match = "Notional | Fixed_Rate | NumYears | NumPayments">
</xsl:template>
</xsl:stylesheet>
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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 FixedFloatSwa
p.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
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<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE FixedFloatSwap SYSTEM "FixedFloatSwap.dtd" [
<!ENTITY bankname SYSTEM "JustAFile.dat" >
]
>
An external text entity
<FixedFloatSwap>
<Bank>&bankname;</Bank>
<Notional>100</Notional>
<Fixed_Rate>5</Fixed_Rate>
<NumYears>3</NumYears>
<NumPayments>6</NumPayments>
</FixedFloatSwap>
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JustAFile.dat
Mellon Bank And Trust Corporation
Pittsburgh PA
XSLT Output
<?xml version="1.0" encoding="utf-8"?>
<WML><CARD>Mellon Bank And Trust Corporation
Pittsburgh PA</CARD></WML>
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Parameter Entities %
While general entities are used to place text into the XML document
parameter entities are used to modify the DTD.
We want to build modular DTD’s so that we can create new DTD’s
using existing ones.
We’ll look at slide from www.fpml.org and the see some examples.
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FpML is a Complete Description of
the TradeVanilla Swap
Trade
Vanilla Fixed Float Swap
Cancellable
Swaption
FX Spot
FX Outright
FX Swap
Forward Rate Agreement...
Trade ID
Product
Adjustable Period
Rate
Notional
Party
Party
Pool of modular components
Rate
grouped into separate namespaces
Money
Product
Date Schedule
Adjustable Period
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Date
Notional
56
<?xml version="1.0" encoding="utf-8"?>
<!ELEMENT FixedFloatSwap (Notional, Fixed_Rate, NumYears,
NumPayments ) >
DTD
<!ENTITY % parsedCharacterData "(#PCDATA)">
<!ELEMENT Notional %parsedCharacterData; >
<!ELEMENT Fixed_Rate (#PCDATA) >
Internal Parameter Entities
<!ELEMENT NumYears (#PCDATA) >
<!ELEMENT NumPayments (#PCDATA) >
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE FixedFloatSwap SYSTEM "FixedFloatSwap.dtd">
<FixedFloatSwap>
<Notional>100</Notional>
<Fixed_Rate>5</Fixed_Rate>
<NumYears>3</NumYears>
XML Document
<NumPayments>6</NumPayments>
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</FixedFloatSwap>
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External Parameter Entities and
DTD
Components
<?xml version="1.0" encoding = "UTF-8"?>
<!DOCTYPE ORDER SYSTEM "order.dtd">
<!-- example order form from “XML A Manager’s Guide” -->
<ORDER SOURCE ="web" CUSTOMERTYPE="consumer" CURRENCY="USD">
<addresses>
<address ADDTYPE="billship">
Order.xml
<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>
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<address ADDTYPE="bill">
An order may
<firstname>Kevin</firstname>
address.
<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>
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have more than one
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Several products
may be purchased.
<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>
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The payment is with
Visa card.
<payment>
a
<card CARDTYPE="VISA">
<cardholder>Kevin S. Dick</cardholder>
<cardnumber>11111-22222-33333</cardnumber>
<expiration>01/01</expiration>
</card>
</payment>
</ORDER>
We want this document to be validated.
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order.dtd
<?xml version="1.0" encoding="UTF-8"?>
<!-- Example Order form DTD adapted from XML: A Manager's Guide -->
<!-- Define an ORDER element -->
<!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.
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<!ENTITY % anAddress SYSTEM "address.dtd" >
%anAddress;
<!-- Collection of Addresses -->
<!ELEMENT addresses (address+)>
External parameter
entity declaration %
<!ENTITY % aLineItem SYSTEM "lineitem.dtd" >
%aLineItem;
<!-- Collection of LineItems -->
<!ELEMENT lineitems (lineitem+)>
External parameter
entity reference %
<!ENTITY % aPayment SYSTEM "payment.dtd" >
%aPayment;
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address.dtd
<!-- Address Structure -->
<!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>
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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)>
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payment.dtd
<!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>
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66
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
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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
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XSDL - A Simple Purchase Order
<?xml version="1.0" encoding="UTF-8"?>
<!-- po.xml -->
<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"
>
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<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>
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Purchase Order XSDL
<?xml version="1.0" encoding="utf-8"?> <!-- po.xsd -->
<xs:schema
xmlns:xs="http://www.w3.org/2001/XMLSchema"
xmlns="http://www.cds-r-us.com"
targetNamespace="http://www.cds-r-us.com"
>
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<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>
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<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>
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<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>
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<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>
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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.*;
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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;
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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);
}
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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]);
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}
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);
}
}
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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>
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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>
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<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>
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D:..95-733\examples\XSDL\testing>ant run
Buildfile: build.xml
run:
Running Validate.java on itemList-xsd.xml
Valid Document is true
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Another Example
<?xml version="1.0" encoding="UTF-8"?> <!-- po.xml -->
<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"
>
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<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.
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<myns:order>
<myns:cd artist="Brooks Williams" title="Little Lion" />
<myns:cd artist="David Wilcox" title="What you whispered" />
</myns:order>
</myns:purchaseOrder>
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XSDL Grammar po.xsd
<?xml version="1.0" encoding="utf-8"?> <!-- po.xsd -->
<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>
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</xs:element>
88
<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>
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<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>
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<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>
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Running Validate
D:..\examples\XSDL\testing>ant run
Buildfile: 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
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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
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Introduce a Namespace Error
<?xml version="1.0" encoding="UTF-8"?>
<!-- po.xml -->
<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"
>
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<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>
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<myns:order>
<myns:cd artist="Brooks Williams" title="Little Lion" />
<myns:cd artist="David Wilcox" title="What you whispered" />
</myns:order>
</myns:purchaseOrder>
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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
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Code Generation
• Run JAXB against the .xsd file
• Code generated will present an API
allowing us to process that style of
document
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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>
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<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>
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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.java
generated\impl\ItemListImpl.java
generated\impl\ItemListTypeImpl.java
generated\impl\ItemTypeImpl.java
generated\impl\NameImpl.java
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generated\impl\QuantityImpl.java
generated\Item.java
generated\ItemList.java
generated\ItemListType.java
generated\ItemType.java
generated\Name.java
generated\ObjectFactory.java
generated\Quantity.java
generated\bgm.ser
generated\jaxb.properties
Write Java Code That uses NEW the api
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The build script used for these
examples
<?xml version="1.0"?>
<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"/>
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<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>
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<!-- compile Java source files -->
<target name="compile">
<!-- compile all of the java sources -->
<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>
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