The Bleeding Edge of XML

The Bleeding Edge of XML Elliotte Rusty Harold XML and Web Services 2003 London Monday, March 17, 2003 elharo@metalab.unc.edu http://www.cafeconleche.org//

Outline

• Part I: XML Infoset, Canonical XML, Digital Signatures, and Encryption

• Part II: XML 1.1

• Part III: XInclude

• Part IV: SAX 2.1

• Part V: DOM Level 3

• Part VI: XOM

Part I: Semantics and Syntax

The Infoset is the unfortunate standard to which those in retreat from the radical and most useful implications of well-formedness have rallied. At its core the Infoset insists that there is 'more' to XML than the straightforward syntax of well-formedness. By imposing its canonical semantics the Infoset obviates the infinite other semantic outcomes which might be elaborated in particular unique circumstances from an instance of well-formed XML 1.0 syntax. The question we should be asking is not whether the Infoset has chosen the correct canonical semantics, but whether the syntactic possibilities of XML 1.0 should be curtailed in this way at all.

A normal XML document

<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<?xml-stylesheet type="text/css" href="song.css"?>
<!DOCTYPE SONG SYSTEM "song.dtd">
<SONG xmlns="http://www.cafeconleche.org/namespace/song"
      xmlns:xlink="http://www.w3.org/1999/xlink">
  <TITLE>Hot Cop</TITLE>
  <PHOTO 
    xlink:type="simple" xlink:show="onLoad" xlink:href="hotcop.jpg"
    ALT="Victor Willis in Cop Outfit" WIDTH="100" HEIGHT="200"/>
  <COMPOSER>Jacques Morali</COMPOSER>
  <COMPOSER>Henri Belolo</COMPOSER>
  <COMPOSER>Victor Willis</COMPOSER>
  <PRODUCER>Jacques Morali</PRODUCER>
  <!-- The publisher is actually Polygram but I needed 
       an example of a general entity reference. -->
  <PUBLISHER xlink:type="simple" xlink:href="http://www.amrecords.com/">
    A &amp; M Records
  </PUBLISHER>
  <LENGTH>6:20</LENGTH>
  <YEAR>1978</YEAR>
  <ARTIST>Village People</ARTIST>
</SONG>
<!-- You can tell what album I was 
     listening to when I wrote this example -->

A canonical XML document

<?xml-stylesheet type="text/css" href="song.css"?>
<SONG xmlns="http://www.cafeconleche.org/namespace/song" xmlns:xlink="http://www.w3.org/1999/xlink">
  <TITLE>Hot Cop</TITLE>
  <PHOTO ALT="Victor Willis in Cop Outfit" HEIGHT="200" WIDTH="100" xlink:href="hotcop.jpg" xlink:show="onLoad" xlink:type="simple"></PHOTO>
  <COMPOSER>Jacques Morali</COMPOSER>
  <COMPOSER>Henri Belolo</COMPOSER>
  <COMPOSER>Victor Willis</COMPOSER>
  <PRODUCER>Jacques Morali</PRODUCER>
  
  <PUBLISHER xlink:href="http://www.amrecords.com/" xlink:type="simple">
    A &amp; M Records
  </PUBLISHER>
  <LENGTH>6:20</LENGTH>
  <YEAR>1978</YEAR>
  <ARTIST>Village People</ARTIST>
</SONG>

An org.w3c.dom.Document object formed by reading hotcop.xml

import org.apache.xerces.parsers.*;
import org.w3c.dom.*;
import org.xml.sax.*;
import java.io.*;

public class DOMHotCop {

  public static void main(String[] args) {

    DOMParser parser = new DOMParser();

    try {
      parser.parse("hot_cop.xml");
      Document d = parser.getDocument();
    }
    catch (SAXException e) {
      System.err.println(e);
    }
    catch (IOException e) {
      System.err.println(e);
    }

  }

}

An encrypted hotcop.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE EncryptedData SYSTEM "song.dtd">
<?xml-stylesheet type="text/css" href="song.css"?><EncryptedData Id="ed1" Type="http://www.w3.org/2001/04/xmlenc#Element" xmlns="http://www.w3.org/2001/04/xmlenc#">
  <EncryptionMethod Algorithm="http://www.w3.org/2001/04/xmlenc#tripledes-cbc"/>
  <KeyInfo xmlns="http://www.w3.org/2000/09/xmldsig#">
    <EncryptedKey xmlns="http://www.w3.org/2001/04/xmlenc#">
      <EncryptionMethod Algorithm="http://www.w3.org/2001/04/xmlenc#rsa-1_5"/>
      <KeyInfo xmlns="http://www.w3.org/2000/09/xmldsig#">
        <KeyName>Alice</KeyName>
      </KeyInfo>
      <CipherData>
        <CipherValue/>
      </CipherData>
    </EncryptedKey>
  </KeyInfo>
  <CipherData>
    <CipherValue>yyIIMYu1mpIm+5MVokRnJ0hnfvZt/x/3ly311l6dK0v1GvynMJP1rkb+/YGfr6Zy00nL4plqxFgo5pJuVmxzj+R7q6f7sF6acfU0XBABICE9ZXfJ5gnainHVuaWbHnVPgT3fi2ohxhEmXp/JF7NhqDvsH9PULZLCIaRS9tKsrNrzdX/EQM3enQHkyc0aJAuAFLTwU710Hta7pf3qXX62i3UGSqjxy2Di8fOs+d/P4nysE9428SZmOM6fe4/m8YyRayRxMNr2RoOQIiYkiJ1krEGQzQ0XGJwIWmAR56CsMljTyT1G/2BDp39k/jCEiqARPekTwHZ1m7Pyh81nr4lnfm9lF3/NzlYe7wpnfSBp2u6IytoWWOeP27h5HTsu5jYfkRhht2h2R4nyIj07YkOsPmd9ubu3cq/SYU4DuvtKrKEIkhnYg4ZUVGjMKlffGzLNAaS2G1PRVIENJHNRoJwivY6+cPqjOhXUvioNQ/WQTOeo5cvTlJaD/od5VWGTJ75ZR8tkZfwFbop8JbhNN6ZODZNSNndnMJ1jEJeeFobOel5Vw0/ClPGh12LxkEJX/h3A+GyUtEfoAmB8ANb3xTsqiTyea1ZBJaS9hhcAFt3Ck+gTHPzwYS+y6x5qRTCfPyZS5PHvKjjIkAEXv+0p9zlQT9hBH1BJB6jXtWjd5sZAE3rMQC/7MXyXvN3ms/TFypBaQsWzKRg+JvxToErD1MtJXT1g8uZr59ubVlBcyjTWcCLMf+QUDxaY0iqPneNSGHAr1isuFc8PZOwJemYjnsySB0R8NN2LcCdFtK8IcB2+QLY7QCj8CAPy4uIZyHbCx6ojg5KWyGOIM5vmWGq6p6Tg+Y3nbc1uFOr1CbXCIbaNC9DI3N+HAcnW7439/JpMhMRa9s02RZsVqhjo4rYz04lkjI/44ffrBVsxk0/sk6XyCnZHQAwpd4y5gXofyPzW83yXA1iXZh7SQfs=</CipherValue>
  </CipherData>
</EncryptedData><!-- You can tell what album I was 
     listening to when I wrote this example -->

Are these four the same thing or not?

• The customary form of an XML document

• The canonical form of an XML document

• The object form of an XML document

• The encrypted form of an XML document

What is the XML Infoset?

• A W3C proposed recommendation providing "a consistent set of definitions for use in other specifications that need to refer to the information in a well-formed XML document." This is considerably weaker than originally planned.

• What it used to be: A W3C standard for what is and is not significant in an XML document

• Not everyone agrees that this is a good thing! or that this is the right list!

The Infoset defines 11 kinds of Information Items

• The Document Information Item

• Element Information Items

• Attribute Information Items

• Processing Instruction Information Items

• Unparsed Entity Information Items

• Unexpanded Entity Information Items

• Character Information Items

• Comment Information Items

• The Document Type Declaration Information Item

• Notation Information Items

• Namespace Information Items

The Document Information Item

• Represents the entire document; not just the root element

• Properties:

  • Children

    • One Element Information Item for the root element

    • One Comment Information Item for each Comment

    • One Processing Instruction Information Item for each Processing Instruction

  • Document Element

  • Character Encoding Scheme

  • Notation Declarations

  • Entity Declarations

  • Base URI

  • Standalone Declaration

  • Version Declaration

  • All declarations processed

Elements

<PHOTO 
  xlink:type="simple" xlink:show="onLoad" xlink:href="hotcop.jpg"
  ALT="Victor Willis in Cop Outfit" WIDTH="100" HEIGHT="200"/>
  
<COMPOSER>Jacques Morali</COMPOSER>

<COMPOSER>
  <PERSON>
    <NAME>
      <FIRST>Henri</FIRST>
      <LAST>Belolo</LAST>
    </NAME>
  </PERSON>
</COMPOSER>

<rdf:RDF xmlns:rdf="http://www.w3.org/TR/REC-rdf-syntax#">
  <rdf:Description xmlns:dc="http://purl.org/dc/"
     about="http://www.ibiblio.org/examples/impressionists.xml">
    <dc:title> Impressionist Paintings </dc:title>
    <dc:creator> Elliotte Rusty Harold </dc:creator>
    <dc:description> 
      A list of famous impressionist paintings organized 
      by painter and date 
    </dc:description>
    <dc:date>2000-08-22</dc:date>
  </rdf:Description>
</rdf:RDF>

Element Information Items

An Element Information Item Includes:

• namespace name; e.g. the absolute URI for the element's namespace

• local name

• prefix

• children: a list of element, processing instruction, unexpanded entity, character, and comment information items, one for each element, processing instruction, unexpanded entity, data character, and comment appearing immediately within the current element

• attributes: an unordered set of attribute information items, one for each of the attributes (specified or defaulted from the DTD) of this element. xmlns attributes are not included.

• namespace attributes: an unordered set of attribute information items, one for each of the namespaces declared either in the start-tag of this element or defaulted from the DTD.

• in-scope namespaces: An unordered set of namespace information items, one for each of the namespaces in effect for this element

• base URI: The absolute URI of the external entity in which this element appears, as defined in XML Base. If this is not known, this property is null.

• parent

Attributes

xlink:type="simple"
xlink:href="http://www.amrecords.com/"
xlink:type =  "simple"
xlink:show = "onLoad"
xlink:href="hotcop.jpg"
ALT="Victor Willis in Cop Outfit"
WIDTH=" 100 "
HEIGHT=' 200 '

An Attribute Information Item Includes:

• namespace name

• local name

• prefix

• normalized value

• specified: A flag indicating whether this attribute was actually specified in the start-tag of its element, or was defaulted from the DTD

• attribute type:

  • ID

  • IDREF

  • IDREFS

  • ENTITY

  • ENTITIES

  • NMTOKEN

  • NMTOKENS

  • NOTATION

  • CDATA

  • ENUMERATED

• owner element

• references: only for IDREF, IDREFS, ENTITY, ENTITIES, and NOTATION type attributes; an ordered list of the things this attribute points to

Comments

  <!-- The publisher is actually Polygram but I needed 
       an example of a general entity reference. -->
<!--  <PUBLISHER xlink:type="simple" xlink:href="http://www.amrecords.com/">
    A &amp; M Records
  </PUBLISHER>
  <LENGTH>6:20</LENGTH>
  <YEAR>1978</YEAR>
  <ARTIST>Village People</ARTIST>
</SONG> -->
<!-- You can tell what album I was 
     listening to when I wrote this example -->

A comment Information Item includes:

• content

• parent

A Processing Instruction Information Item Includes:

<?robots index="yes" follow="no"?>
<?php 
  mysql_connect("database.unc.edu", "clerk", "password"); 
  $result = mysql("CYNW", "SELECT LastName, FirstName FROM Employees 
    ORDER BY LastName, FirstName"); 
  $i = 0;
  while ($i < mysql_numrows ($result)) {
     $fields = mysql_fetch_row($result);
     echo "<person>$fields[1] $fields[0] </person>\r\n";
     $i++;
  }
  mysql_close();
?>

• target

• content

• notation

• base URI

• parent

Characters

• A character is one Unicode character in the content of an element, attribute value, comment or processing instruction data.

• A Character Information Item includes:

  character code

  The Unicode value of the character in the range 0 to #x10FFFF.

  element content whitespace

  A flag indicating whether the character is whitespace appearing within element content

  parent

• Note that Unicode is not a two-byte character set

Namespaces

• An element has one namespace information item for each namespace in scope on the element. This is not the same as the namespaces declared on the element.

• A Namespace Information Item includes:

  • prefix

  • namespace name

• There is no obvious representation of namespace information items in the syntax of an XML document.

• These are namespace declaration attributes, not namespace information items:

  xmlns:rdf="http://www.w3.org/TR/REC-rdf-syntax#"
  xmlns:dc="http://purl.org/dc/"
  xmlns="http://www.w3.org/2000/svg"
  

• Consider this document:

  <svg:svg width="5cm" height="4cm"
   xmlns:svg="http://www.w3.org/2000/svg">
    <svg:desc>Two rectangles</svg:desc>
    <svg:rect x="1.5cm" y="3.5cm" width="12cm" height="9.9cm"/>
    <svg:rect x="2.5cm" y="2.8cm" width="3cm" height="17cm"/>
  </svg:svg>

  Each of the four elements has a namespace information item with the prefix svg and the namespace name http://www.w3.org/2000/svg

Document Type Declaration

<!DOCTYPE SONG SYSTEM "song.dtd">
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
                       "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">

A Document Type Declaration Information Item includes:

• SYSTEM ID

• PUBLIC ID

• children: only the comment and processing instruction information items in the internal DTD subset and external DTD subsets.

• parent

Document Type Definition

<!ELEMENT SONG (TITLE, PHOTO?, COMPOSER+, PRODUCER*, 
 PUBLISHER*, LENGTH?, YEAR?, ARTIST+)>
<!ATTLIST SONG xmlns       CDATA #REQUIRED
               xmlns:xlink CDATA #REQUIRED>
<!ELEMENT TITLE (#PCDATA)>

<!ELEMENT PHOTO EMPTY>
<!ATTLIST PHOTO xlink:type CDATA #FIXED "simple"
                xlink:href CDATA #REQUIRED
                xlink:show CDATA #IMPLIED
                ALT        CDATA #REQUIRED
                WIDTH      CDATA #REQUIRED
                HEIGHT     CDATA #REQUIRED
>

<!ELEMENT COMPOSER (#PCDATA)>
<!ELEMENT PRODUCER (#PCDATA)>
<!ELEMENT PUBLISHER (#PCDATA)>
<!ATTLIST PUBLISHER xlink:type CDATA #IMPLIED
                    xlink:href CDATA #IMPLIED
>

<!ELEMENT LENGTH (#PCDATA)>
<!-- This should be a four digit year like "1999",
     not a two-digit year like "99" -->
<!ELEMENT YEAR (#PCDATA)>

<!ELEMENT ARTIST (#PCDATA)>

• There is no information item for this.

• Comments and processing instructions in the DTD are reported as children of the Document Type Declaration information item

• Notation and general entity declarations are reported as properties of the Document information item

• Attribute types and default values are reported on the actual attributes in the document instance.

• Everything else is not reported!

Entities

• An XML document is made up of one or more physical storage units called entities

• Entity references :

  • Parsed internal general entity references like &

  • Parsed external general entity references

  • Unparsed external general entity references

  • External parameter entity references

  • Internal parameter entity references

• Reading an XML document is not the same thing as reading an XML file

• The XML file contains entity references.

• The XML document contains the entities' replacement text.

• When you use a parser to read a document you'll get the text including characters like <. You will not see the entity references.

Entity Information Items

• Two kinds of entity information items:

  • Unparsed Entity Information Item

  • Unexpanded Entity Information Items

• Other entities are not reported

Unparsed Entity Information Items

• name

• system identifier

• public identifier

• Notation

Unexpanded Entity Information Items

• name

• entity

• parent

The Infoset Omits:

• The internal and external DTD subsets; especially ELEMENT and ATTLIST declarations

• Schema types

• CDATA sections

• Character references

• Expanded, parsed entity references

• Whether an empty element uses two tags or one

• What kind of quotes surround attributes

• Insignificant white space in attributes

• White space that occurs between attributes

• Attribute order

The PSVI

• A schema assigns a type to each element

• Schema validation produces a Post Schema Validation Infoset, PSVI for short

• Schema aware applications using schema aware parsers and APIs can make use of the types of elements

Canonical XML

• A W3C proposed standard serialization format of an XML document instance

• Not everyone agrees that this is a good thing! or that this is the right format! It's totally unsuitable for editors and validation.

• Based on the XPath 1.0 data model

• Not really Infoset compatible

• Something of this nature is nonetheless clearly needed for non-XML aware tools like digital signatures, change management, hash functions, and the like.

How are documents canonicalized?

1. The document is encoded in UTF-8

2. Line breaks are normalized to a linefeed (ASCII , \n)

3. Attribute values are normalized, as if by a validating processor

4. Character and parsed entity references are replaced

5. CDATA sections are replaced with their character content

6. The XML and document type declarations are removed

7. Empty elements are converted to start tag-end tag pairs

8. White space outside of the document element and within start and end tags is normalized

9. All white space in character content is retained (except for characters removed during linefeed normalization)

10. Attribute value delimiters are set to double quotes

11. Special characters in attribute values and character content are replaced by character references

12. Superfluous namespace declarations are removed from each element

13. Default attributes are added to each element

14. Lexicographic order is imposed on the namespace declarations and attributes of each element

Canonicalization software

XML Canonicalizer from IBM's XML Security Suite:

• http://www.alphaworks.ibm.com/tech/xmlsecuritysuite

• c14n.C14nDOM reads an XML document from stdin and writes the canonicalized output to stdout:

  % java c14n.C14nDOM -xpath < hotcop.xml > canonicalized_hotcop.xml

• -xpath option necessary to support the final draft of Canonical XML 1.0.

• API in com.ibm.xml.dsig.Canonicalizer

  package com.ibm.xml.dsig;
  
  public interface Canonicalizer {
  
    public static final String W3C 
     = "http://www.w3.org/TR/2000/WD-xml-c14n-20000119"
    public static final java.lang.String W3C2 
     = "http://www.w3.org/TR/2001/REC-xml-c14n-20010315"
    public static final java.lang.String W3C2WC 
     = "http://www.w3.org/TR/2001/REC-xml-c14n-20010315#WithComments"
    public static final java.lang.String EXCLUSIVE;
    public static final java.lang.String EXCLUSIVEWC;
  
    public String getURI();
    public void canonicalize(org.w3c.dom.Node node, OutputStream stream)
     throws IOException;
  
  }

• Implementations include:

  • com.ibm.xml.dsig.transform.ExclusiveC11r

  • com.ibm.xml.dsig.transform.ExclusiveC11rWC

  • com.ibm.xml.dsig.transform.W3CCanonicalizer

  • com.ibm.xml.dsig.transform.W3CCanonicalizer2

  • com.ibm.xml.dsig.transform.W3CCanonicalizer2WC

  All can be created with no-args constructors

Apache XML Security Suite

• http://xml.apache.org/security/

A standard feature for DOM level 3's DOMWriter

• http://www.w3.org/TR/DOM-Level-3-ASLS/load-save.html#LS-Interfaces-DOMWriter

XOM

Digital Signatures

• W3C/IETF Joint Recommendation, February 12, 2002

• XML Signatures provide:

• Integrity

• Message authentication

• Signer authentication

• For data of any type

Not Just for Signing XML

• Signed data can be located within the XML that includes the signature or elsewhere.

• An enveloped signature is enclosed inside the XML element it signs

• An enveloping signature signs XML data it contains.

• A detached signature signs data external to the Signature element, possibly in another document entirely.

Generic Digital Signature Process

1. The signature processor calculates a hash code for some data using a strong, one-way hash function.

2. The processor encrypts the hash code using a private key.

3. The verifier calculates the hash code for the data it's received.

4. It then decrypts the encrypted hash code using the public key to see if the hash codes match.

XML Signature Process

1. The signature processor digests (calculates the hash code for) a data object.

2. The processor places the digest value in a Signature element.

3. The processor digests the Signature element.

4. The processor cryptographically signs the Signature element.

XML Digital Signature software

• SampleSign2 and VerifyGUI from IBM's XML Security Suite: http://www.alphaworks.ibm.com/tech/xmlsecuritysuite

• First use the JDK's keytool to generate a key:

  % keytool -genkey -dname "CN=Elliotte Rusty Harold, OU=Metrotech, O=Polytechnic, L=Brooklyn, S=New York, C=US" -alias elharo -storepass mypassword -keypass mykeypassword

• SampleSign2 reads an XML document from stdin and writes the signature to stdout:

  % java dsig.SampleSign2 elharo mypassword mykeypassword -ext file:///home/elharo/speaking/xmlone/london2003/bleeding/examples/hotcop.xml > hotcop_signature.xml
  Key store: C:\Documents and Settings\Administrator\.keystore
  Sign: 7030ms

• VerifyGUI reads signature from stdin and warns of changes to signed content.

  C:\>java dsig.VerifyGUI < hotcop_signature.xml
  The signature has a KeyValue element.
  The signature has one or more X509Data elements.
  Checks an X509Data:
  It has 1 certificate(s).
  Certificate Information:
  Version: 1
  Validity: OK
  SubjectDN: CN=Elliotte Rusty Harold, OU=Metrotech, O=Polytechnic, L=Brooklyn, ST=New York, C=US
  IssuerDN: CN=Elliotte Rusty Harold, OU=Metrotech, O=Polytechnic, L=Brooklyn, ST=New York, C=US
  Serial#: 983556890
  Time to verify: 951 [msec]

A Detached Signature for hotcop.xml

<Signature xmlns="http://www.w3.org/2000/09/xmldsig#">
  <SignedInfo>
    <CanonicalizationMethod Algorithm="http://www.w3.org/TR/2001/REC-xml-c14n-20010315"></CanonicalizationMethod>
    <SignatureMethod Algorithm="http://www.w3.org/2000/09/xmldsig#dsa-sha1"></SignatureMethod>
    <Reference URI="file:///home/elharo/speaking/xmlone/london2003/bleeding/examples/hotcop.xml">
      <DigestMethod Algorithm="http://www.w3.org/2000/09/xmldsig#sha1"></DigestMethod>
      <DigestValue>i9y8sGT7gjSa0tkQI9aVsl7P6zg=</DigestValue>
    </Reference>
  </SignedInfo>
  <SignatureValue>
    RBIqdgwjHB8yufwiwScaf/L1P95u4SknSU2NLEeBH1yUAdyzjD/B3A==
  </SignatureValue>
  <KeyInfo>
    <KeyValue>
      <DSAKeyValue>
        <P>
          /X9TgR11EilS30qcLuzk5/YRt1I870QAwx4/gLZRJmlFXUAiUftZPY1Y+r/F9bow9s
          ubVWzXgTuAHTRv8mZgt2uZUKWkn5/oBHsQIsJPu6nX/rfGG/g7V+fGqKYVDwT7g/bT
          xR7DAjVUE1oWkTL2dfOuK2HXKu/yIgMZndFIAcc=
        </P>
        <Q>l2BQjxUjC8yykrmCouuEC/BYHPU=</Q>
        <G>
          9+GghdabPd7LvKtcNrhXuXmUr7v6OuqC+VdMCz0HgmdRWVeOutRZT+ZxBxCBgLRJFn
          Ej6EwoFhO3zwkyjMim4TwWeotUfI0o4KOuHiuzpnWRbqN/C/ohNWLx+2J6ASQ7zKTx
          vqhRkImog9/hWuWfBpKLZl6Ae1UlZAFMO/7PSSo=
        </G>
        <Y>
          /U3X04lzUKj+2NSxcV1SHBQe8Jyvhj2sMneglMBDZ9nwdTvyuYG10uMgHYmd5Id9lr
          vGbGSz2O+xBU2oh20hR5knKx4MmPZsbheKlUFrpd+3z71CzN8isfDuyvjT7hUt6Br8
          zDx/N5Av8Y205khGFwgE9qkabH20u2JG4LW+LLo=
        </Y>
      </DSAKeyValue>
    </KeyValue>
    <X509Data>
      <X509IssuerSerial>
        <X509IssuerName>CN=Elliotte Rusty Harold,OU=Metrotech,O=Polytechnic,L=Brooklyn,ST=New York,C=US</X509IssuerName>
        <X509SerialNumber>1047659081</X509SerialNumber>
      </X509IssuerSerial>
      <X509SubjectName>CN=Elliotte Rusty Harold,OU=Metrotech,O=Polytechnic,L=Brooklyn,ST=New York,C=US</X509SubjectName>
      <X509Certificate>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      </X509Certificate>
    </X509Data>
  </KeyInfo>
</Signature>

An enveloping signature for hotcop.xml

<Signature xmlns="http://www.w3.org/2000/09/xmldsig#">
  <SignedInfo>
    <CanonicalizationMethod Algorithm="http://www.w3.org/TR/2001/REC-xml-c14n-20010315"></CanonicalizationMethod>
    <SignatureMethod Algorithm="http://www.w3.org/2000/09/xmldsig#dsa-sha1"></SignatureMethod>
    <Reference URI="#Res0">
      <Transforms>
        <Transform Algorithm="http://www.w3.org/TR/2001/REC-xml-c14n-20010315"></Transform>
      </Transforms>
      <DigestMethod Algorithm="http://www.w3.org/2000/09/xmldsig#sha1"></DigestMethod>
      <DigestValue>D9oQKdI9sEcHhJM6CTHDDKVjwSo=</DigestValue>
    </Reference>
  </SignedInfo>
  <SignatureValue>
    AqD5Zjfr0S64qAMPrOtznEhFBl1bXJ7aCosaY5pPMLHzGuzN7u1doQ==
  </SignatureValue>
  <KeyInfo>
    <KeyValue>
      <DSAKeyValue>
        <P>
          /X9TgR11EilS30qcLuzk5/YRt1I870QAwx4/gLZRJmlFXUAiUftZPY1Y+r/F9bow9s
          ubVWzXgTuAHTRv8mZgt2uZUKWkn5/oBHsQIsJPu6nX/rfGG/g7V+fGqKYVDwT7g/bT
          xR7DAjVUE1oWkTL2dfOuK2HXKu/yIgMZndFIAcc=
        </P>
        <Q>l2BQjxUjC8yykrmCouuEC/BYHPU=</Q>
        <G>
          9+GghdabPd7LvKtcNrhXuXmUr7v6OuqC+VdMCz0HgmdRWVeOutRZT+ZxBxCBgLRJFn
          Ej6EwoFhO3zwkyjMim4TwWeotUfI0o4KOuHiuzpnWRbqN/C/ohNWLx+2J6ASQ7zKTx
          vqhRkImog9/hWuWfBpKLZl6Ae1UlZAFMO/7PSSo=
        </G>
        <Y>
          /U3X04lzUKj+2NSxcV1SHBQe8Jyvhj2sMneglMBDZ9nwdTvyuYG10uMgHYmd5Id9lr
          vGbGSz2O+xBU2oh20hR5knKx4MmPZsbheKlUFrpd+3z71CzN8isfDuyvjT7hUt6Br8
          zDx/N5Av8Y205khGFwgE9qkabH20u2JG4LW+LLo=
        </Y>
      </DSAKeyValue>
    </KeyValue>
    <X509Data>
      <X509IssuerSerial>
        <X509IssuerName>CN=Elliotte Rusty Harold,OU=Metrotech,O=Polytechnic,L=Brooklyn,ST=New York,C=US</X509IssuerName>
        <X509SerialNumber>1047659081</X509SerialNumber>
      </X509IssuerSerial>
      <X509SubjectName>CN=Elliotte Rusty Harold,OU=Metrotech,O=Polytechnic,L=Brooklyn,ST=New York,C=US</X509SubjectName>
      <X509Certificate>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      </X509Certificate>
    </X509Data>
  </KeyInfo>
  <dsig:Object xmlns="" xmlns:dsig="http://www.w3.org/2000/09/xmldsig#" Id="Res0"><?xml-stylesheet type="text/css" href="song.css"?><SONG xmlns="http://www.cafeconleche.org/namespace/song" xmlns:xlink="http://www.w3.org/1999/xlink">
  <TITLE>Hot Cop</TITLE>
  <PHOTO ALT="Victor Willis in Cop Outfit" HEIGHT="200" WIDTH="100" xlink:href="hotcop.jpg" xlink:show="onLoad" xlink:type="simple"></PHOTO>
  <COMPOSER>Jacques Morali</COMPOSER>
  <COMPOSER>Henri Belolo</COMPOSER>
  <COMPOSER>Victor Willis</COMPOSER>
  <PRODUCER>Jacques Morali</PRODUCER>
  <!-- The publisher is actually Polygram but I needed 
       an example of a general entity reference. -->
  <PUBLISHER xlink:href="http://www.amrecords.com/" xlink:type="simple">
    A &amp; M Records
  </PUBLISHER>
  <LENGTH>6:20</LENGTH>
  <YEAR>1978</YEAR>
  <ARTIST>Village People</ARTIST>
</SONG><!-- You can tell what album I was 
     listening to when I wrote this example --></dsig:Object>
</Signature>

XML Encryption

• Can encrypt:

  • An XML element

  • The content of an XML element

  • Arbitrary binary data with a URI

• The ciphertext can be stored in an EncryptedData element or referenced (through a URI) by an EncryptedData element.

XML Encryption Algorithms

• Arbitrary encryption algorithms are supported.

• Required encryption algorithms include:

  • AES with CMS keylength

  • 3DES

  • RSA-OAEP used with AES

  • RSA-v1.5 used with 3DES

• Required key transport algorithms include:

  • RSA-OAEP used with AES

  • RSA-v1.5 used with 3DES

• Required Symmetric Key Wrap algorithms include:

  • AES KeyWrap

  • CMS-KeyWrap-3DES

Complete standard algorithm list

From the spec:

Block Encryption

1. REQUIRED TRIPLEDES
   http://www.w3.org/2001/04/xmlenc#tripledes-cbc

2. REQUIRED AES-128
   http://www.w3.org/2001/04/xmlenc#aes128-cbc

3. REQUIRED AES-256
   http://www.w3.org/2001/04/xmlenc#aes256-cbc

4. OPTIONAL AES-192
   http://www.w3.org/2001/04/xmlenc#aes192-cbc

Key Transport

1. REQUIRED RSA-v1.5
   http://www.w3.org/2001/04/xmlenc#rsa-1_5

2. REQUIRED RSA-OAEP
   http://www.w3.org/2001/04/xmlenc#rsa-oaep-mgf1p

Key Agreement

1. OPTIONAL Diffie-Hellman
   http://www.w3.org/2001/04/xmlenc#dh

Symmetric Key Wrap

1. REQUIRED TRIPLEDES KeyWrap
   http://www.w3.org/2001/04/xmlenc#kw-tripledes

2. REQUIRED AES-128 KeyWrap
   http://www.w3.org/2001/04/xmlenc#kw-aes128

3. REQUIRED AES-256 KeyWrap
   http://www.w3.org/2001/04/xmlenc#kw-aes256

4. OPTIONAL AES-192 KeyWrap
   http://www.w3.org/2001/04/xmlenc#kw-aes192

Message Digest

1. REQUIRED SHA1
   http://www.w3.org/2000/09/xmldsig#sha1

2. RECOMMENDED SHA256
   http://www.w3.org/2001/04/xmlenc#sha256

3. OPTIONAL SHA512
   http://www.w3.org/2001/04/xmlenc#sha512

4. OPTIONAL RIPEMD-160
   http://www.w3.org/2001/04/xmlenc#ripemd160

Message Authentication

1. RECOMMENDED XML Digital Signature
   http://www.w3.org/TR/2001/CR-xmldsig-core-20010419/

Canonicalization

1. OPTIONAL Canonical XML with Comments
   http://www.w3.org/TR/2001/REC-xml-c14n-20010315#WithComments

2. OPTIONAL Canonical XML (omits comments)
   http://www.w3.org/TR/2001/REC-xml-c14n-20010315

Encoding

1. REQUIRED base64
   http://www.w3.org/2000/09/xmldsig#base64

XML Encryption Syntax

• Namespace URI http://www.w3.org/2001/04/xmlenc# (Normally mapped to the xenc prefix or default namespace)

• Uses some elements from XML digital signatures for keys

• Typical form:

  <EncryptedData Id="unique_value" 
        Type="http://www.w3.org/2001/04/xmlenc#Element |
        http://www.w3.org/2001/04/xmlenc#Content |
        MIME media type URI">
    <EncryptionMethod Algorithm="URI"/>
    <ds:KeyInfo>
      <ds:KeyName>Plain text name of key</ds:KeyName>
      <ds:RetrievalMethod URI="key location"
       Type="http://www.w3.org/2001/04/xmlenc#EncryptedKey" />
    </ds:KeyInfo>
    <CipherData>
      <CipherValue>Base-64 encoded cipher text</CipherValue>
      <CipherReference URI="URL of cipher text">
        <Transforms>
          <ds:Transform 
            Algorithm="http://www.w3.org/TR/1999/REC-xpath-19991116">
            <ds:XPath xmlns:rep="http://www.example.org/repository">
               self::text()[parent::CipherValue[@id="example1"]]
            </ds:XPath>
          <ds:Transform>
          <ds:Transform Algorithm="http://www.w3.org/2000/09/xmldsig#base64"/>
        </Transforms>
      </CipherReference>
    </CipherData>
  </EncryptedData>

• At a minimum, each EncryptedData must contain a CipherData which contains either a CipherValue or a CipherReference. Everything else is optional.

An XML Document containing sensitive information

<?xml version='1.0'?>
<PaymentInfo xmlns="http://example.org/payment">
  <Name>Elliotte Rusty Harold<Name/>
  <CreditCard Limit='1000' Currency='USD'>
    <Number>1234 5678 9012 3456</Number>
    <Issuer>Citibank</Issuer>
    <Expiration>03/02</Expiration>
  </CreditCard>
</PaymentInfo>

An XML Document containing an encrypted element

<?xml version='1.0'?>
<PaymentInfo xmlns="http://example.org/payment">
  <Name>Elliotte Rusty Harold<Name/>
  <EncryptedData Type='http://www.w3.org/2001/04/xmlenc#Element'
     xmlns='http://www.w3.org/2001/04/xmlenc#'>
    <EncryptionMethod
      Algorithm="http://www.w3.org/2001/04/xmlenc#3des-cbc"/>
    <CipherData>
      <CipherValue>A23B45C56CABE4BE33327</CipherValue>
    </CipherData>
  </EncryptedData>
</PaymentInfo>

An XML Document containing encrypted element data

<?xml version='1.0'?>
<PaymentInfo xmlns="http://example.org/payment">
  <Name>Elliotte Rusty Harold<Name/>
  <CreditCard Limit="1000" Currency="USD">
     <EncryptedData Type="http://www.w3.org/2001/04/xmlenc#Content"
        xmlns="http://www.w3.org/2001/04/xmlenc#">
      <EncryptionMethod
        Algorithm="http://www.w3.org/2001/04/xmlenc#3des-cbc"/>
      <CipherData>
        <CipherValue>A23B45C56CABE4BE3</CipherValue>
      </CipherData>
    </EncryptedData>
  </CreditCard>
</PaymentInfo>

An XML Document containing encrypted text

<?xml version='1.0'?>
<PaymentInfo xmlns="http://example.org/payment">
  <Name>Elliotte Rusty Harold<Name/>
  <CreditCard Limit='1000' Currency='USD'>
    <Number>
      <EncryptedData Type="http://www.w3.org/2001/04/xmlenc#Content"
                     xmlns="http://www.w3.org/2001/04/xmlenc#">
        <EncryptionMethod
          Algorithm="http://www.w3.org/2001/04/xmlenc#3des-cbc"/>
        <CipherData>
          <CipherValue>A23B45C56CABE4BE</CipherValue>
        </CipherData>
      </EncryptedData>
    </Number>
    <Issuer>Citibank</Issuer>
    <Expiration>03/02</Expiration>
  </CreditCard>
</PaymentInfo>

A completely encrypted XML Document

<?xml version='1.0'?>
<EncryptedData 
   Type="http://www.isi.edu/in-notes/iana/assignments/media-types/text/xml"
   xmlns="http://www.w3.org/2001/04/xmlenc#">
  <EncryptionMethod Algorithm="http://www.w3.org/2001/04/xmlenc#3des-cbc"/>
  <CipherData>
    <CipherValue>A23B45C56CABE4BE7687989219C4E5DEADBEEFCAFEBABE</CipherValue>
  </CipherData>
</EncryptedData>

XML Encryption Software

xss4j, IBM's XML Security Suite:

• http://www.alphaworks.ibm.com/tech/xmlsecuritysuite

• enc.XMLCipher2 reads an XML document and encrypts the part of it specified by an XPath expression using a template file:

  % java enc.XMLCipher2 -e keyinfo.xml hotcop.xml /SONG/PUBLISHER template1.xml

• API

Apache XML Security Suite

• http://xml.apache.org/security/

Commericial implementations from Baltimore and Phaos

JSR-106: XML Digital Encryption APIs

• http://jcp.org/jsr/detail/106.jsp

Issues XML Encryption doesn't address

• Authentication

• Authorization

• Access Control

To Learn More

• XML Infoset Specification: http://www.w3.org/TR/xml-infoset

• Canonical XML Specification: http://www.w3.org/TR/xml-c14n

• XML Signature Specification: http://www.w3.org/TR/xmldsig-core/

• XML Encryption Requirements: http://www.w3.org/TR/xml-encryption-req

• XML Encryption Syntax and Processing: http://www.w3.org/TR/xmlenc-core/

Part II: XML 1.1

Discriminating against languages simply because their scripts were not encoded in Unicode 2.0 is inherently unjust.

--XML Blueberry Requirements

New features

• Changes the definition of white space

• Enables native language markup in Ethiopic, Burmese, and Cambodian

• Breaks compatibility with XML 1.0

• Undeclare namespace prefixes

• C1 controls must be represented as character references

• C0 controls can be used but must be represented as character references (except for the tab, line feed, carriage return, and space

Changes in XML 1.1

• Most well-formed and valid XML 1.0 documents remain well-formed and valid XML 1.1 documents.

• version attribute in the XML declaration has the value 1.1:

  <?xml version="1.1">

• Characters from many more scripts are allowed as name characters, i.e tag names, attribute names, entity names, ID attribute values, etc.

• Most C0 controls (vertical tab, bell, formfeed, etc.) are now allowed in element content. However, they must be escaped as character references such as &#x0B;, &#7; &#12;, etc.

• NEL (0x85) is now allowed as white space along with carriage return and linefeed.

• All of these cause major interoperability problems and should not be used.

White Space

• XML 1.0 defines white space thusly:

  [3] S ::= (#x20 | #x9 | #xD | #xA)+

• With XML 1.1 this is the same, but the parser converts #x85 to #xA on input

• Supports IBM mainframe editors

• Breaks everybody else's software

Native language markup

• Currently only scripts defined in Unicode 2.0 are allowed in XML element and attribute names

• All scripts defined in Unicode are allowed in element and attribute content

• Unicode 3.0 adds:

  • Ethiopic (Amharic, Geez, etc.)

  • Burmese

  • Cambodian

  • Mongolian

  • Dvihehi

  • Yi syllabary

• Also:

  • Cherokee

  • Canadian aboriginal languages

• Perhaps:

  • Japanese

  • Cantonese

• Unicode 3.1 adds:

  • Deseret

  • Old Italic

  • Gothic

• Unicode 4.0 adds:

  • Linear B

  • Ugaritic

  • Shavian

  • Osmanya

• Is this enough to justify breaking compatibility?

Name characters

• XML 1.0 explicitly lists them; everything not permitted is forbidden

• XML 1.1:

  
  [4] NameStartChar := ":" | [A-Z] | "_" | [a-z] | [#xC0-#x02FF] 
                      | [#x0370-#x037D] | [#x037F-#x2027] 
                      | [#x202A-#x218F] | [#x2800-#xD7FF] 
                      | [#xE000-#xFDCF] | [#xFDE0-#xFFEF] 
                      | [#x10000-#x10FFFF]
  [4a] NameChar := NameStartChar | "-" | "." | [0-9] | #xB7 | [#x0300-#x036F]

• Many of these characters aren't defined yet in Unicode

• Many of these characters are very surprising; e.g. musical and mathematical sybols

Harm Reduction proposals

• 1.0.1

• Mandate non-1.1 for documents that don't use 1.1

• Well-formedness error?

• Non-fatal error?

• All of these were rejected by the working group.

Namespaces 1.1

• Requires XML 1.1

• Uses IRIs rather than URIs

• Can undeclare prefixes

IRIs

• Internationalized Resource Identifiers

• Not limited to ASCII

• For example,

  • http://www.example.fr/présidence

  • http://www.example.he/λεξικό

• Percent escapes are not decoded when comparing. These are all different:

  • http://www.example.fr/présidence

  • http://www.example.fr/pr%a9sidence

  • http://www.example.fr/pr%A9sidence

• XML escapes are decoded. These are the same:

  • xmlns:λεξ="http://www.example.he/λεξικό"

  • xmlns:λεξ="http://www.example.he/λεξικό"

  • xmlns:λεξ="http://www.example.he/λεξικό"

Undeclaring prefixes

• xmlns:prefix="" is now legal

• Important in applications such as XSLT and W3C XML Schema Language that use prefixes in attribute values and element content

• Example from the spec:

  <?xml version="1.1"?>
  <x xmlns:n1="http://www.w3.org">
      <n1:a/>               <!-- legal; the prefix n1 is bound to http://www.w3.org -->
      <x xmlns:n1="">
          <n1:a/>           <!-- illegal; the prefix n1 is not bound here -->
  	<x xmlns:n1="http://www.w3.org">
              <n1:a/>       <!-- legal; the prefix n1 is bound again -->
          </x>
      </x>
  </x>

Part III: XInclude

The problem is that we're not providing the tools. We're providing the specs. That's a whole different ball game. If tools existed for actually making really interesting use of RDF and XLink and XInclude then people would use them. If IE and/or Mozilla supported the full gamut of specs, from XSLT 1.0 to XLink and XInclude (OK, so they're not quite REC's, but with time...) then you would find people using them more.

What is XInclude?

• A means of including one XML document inside another, irrespective of validation.

• W3C Candidate Recommendation, September 17, 2002

• Based on the XML Infoset; a source infoset is transformed into a result infoset

Alternatives (and why they don't work)

• xlink:show="embed" only graphically includes, like the IMG element in HTML. It does not merge infosets.

• External parsed entities:

  • Require a DTD

  • Can only handle very limited documents; i.e. not all well-formed XML documents are well-formed external parsed entities. In particular XML declarations can be and document type declarations are a problem.

  • Doesn't allow unparsed text inserted as CDATA

• XSLT document() function

  • Only handles XSLT

  • No unparsed, pure-text includes

• Server side includes:

  • HTML only

  • Server dependent

• Custom code or XSLT extension functions

The include element

• href attribute identifies the document (or part thereof) to be included

• In the http://www.w3.org/2001/XInclude namespace.

• The prefixes xinclude or xi are customary.

<book xmlns:xinclude="http://www.w3.org/2001/XInclude">
  <title>Processing XML with Java</title>
  <chapter><xinclude:include href="dom.xml"/></chapter>
  <chapter><xinclude:include href="sax.xml"/></chapter>
  <chapter><xinclude:include href="jdom.xml"/></chapter>
</book>

The parse attribute

parse="xml"

The resource must be parsed as XML and the infosets merged. This is the default.

parse="text"

The resource must be treated as pure text and inserted as a text node. When serialized, this means that characters like < will change to < and so forth.

<slide xmlns:xinclude="http://www.w3.org/2001/XInclude">
  <title>The href attribute</title>
  
<ul>
  <li>Identifies the document to be included with a URI</li>
  <li>The document at the URI replaces the <code>include</code> 
      element in the including document</li>
  <li>The <code>xinclude</code> prefix is bound to the http://www.w3.org/2001/XInclude
  namespace URI. 
  </li>
</ul>  

<pre><code><xinclude:include parse="text" href="processing_xml_with_java.xml"/>
</code></pre>
        
  <description>
      A slide from Elliotte Rusty Harold's Bleeding Edge of XML presentation at
      <host_ref/>, <date_ref/>
    </description>
  <last_modified>October 26, 2000</last_modified>
</slide>

The encoding attribute

• Used when parse="text"

• Value is the name of the text file's character encoding, as in the encoding declaration in the XML declaration

• e.g. ISO-8859-1, UTF-8, UTF-16, MacRoman, etc.

<slide xmlns:xinclude="http://www.w3.org/2001/XInclude">
  <title>The href attribute</title>
  
<ul>
  <li>Identifies the document to be included with a URI</li>
  <li>The document at the URI replaces the <code>include</code> 
      element in the including document</li>
  <li>The <code>xinclude</code> prefix is bound to the http://www.w3.org/2001/XInclude
  namespace URI. 
  </li>
</ul>  

<pre><code><xinclude:include parse="text" encoding="ISO-8859-1" 
                  href="processing_xml_with_java.xml"/>
</code></pre>
        
  <description>
      A slide from Elliotte Rusty Harold's Bleeding Edge of XML presentation at
      <host_ref/>, <date_ref/>
    </description>
  <last_modified>October 26, 2000</last_modified>
</slide>

The fallback element

Implementation as a SAX filter

SAX XInclude Driver

Implementation as JDOM

Implementation as DOM

To Learn More

• This presentation: http://www.cafeconleche.org/slides/xmlone/amsterdam2001/hypertext/

• XInclude Specification: http://www.w3.org/TR/xinclude

• XML Bible, Gold edition

  • Elliotte Rusty Harold

  • Hungry Minds, 2001

  • ISBN 0-7645-4819-0

  
  

Part IV: SAX 2.1

Actually, SAX2 has ** MUCH ** better infoset support than DOM does. Yes, I've done the detailed analysis.

--David Brownell on the xml-dev mailing list

Goals

• Full Infoset support

• Backwards compatible with SAX2

• Much less radical changes than from SAX1 to SAX2

Specified vs. Defaulted Attributes

• Infoset includes a flag saying whether a given attribute value was specified in the instance document or defaulted from the DTD.

• DOM also wants to know this

• Solution:

  package org.xml.sax.ext;
  
  public interface Attributes2 extends Attributes {
  
    public boolean isSpecified (int index);
    public boolean isSpecified (String uri, String localName);
    public boolean isSpecified (String qualifiedName);
    
    public boolean isDeclared (int index);
    public boolean isDeclared (String uri, String localName);
    public boolean isDeclared (String qualifiedName);
    
  }

• The isDeclared methods return false unless the attribute was declared in the DTD.

• This interface would be implemented by SAX 2.1 Attributes objects provided in startElement() callbacks

• The read-only http://xml.org/sax/features/use-attributes2 feature specifies whether Attributes2 is available

standalone declaration

<?xml version="1.0" standalone="yes"?>

• The XML Infoset includes a standalone property for documents

• Not currently exposed by SAX2

• Solution: Define a new read-only feature: http://xml.org/sax/features/is-standalone

The version and encoding properties

<?xml version="1.0" encoding="UTF-16"?>

• Infoset includes the version and encoding from the XML declaration; SAX2 does not.

• Unlike standalone, these apply to all parsed entities; not just the document entity

• Solution:

  package org.xml.sax.ext;
  
  public interface Locator2 extends Locator {
    public String getXMLVersion ();
    public String getEncoding ();
  }

  This would be implemented by Locator objects passed to setDocumentLocator() methods

  The read-only feature http://xml.org/sax/features/use-locator2 says whether Locator2's are used.

• To make matters worse, there can be as many as three encodings:

  • What's declared in the document using an encoding declaration in the XML declaration

  • The MIME type encoding, as specified by the the HTTP header

  • The name of the encoding used by a java.io.InputStreamReader (UTF8 vs. UTF-8)

Feature/Property discovery

• There's no way to find out what features and properties a given XMLReader recognizes.

• Solution: Define two new read-only properties:

  http://xml.org/sax/properties/supported-features

  The value of this property is an array of Strings containing the names of all the features supported by this XMLReader.

  http://xml.org/sax/properties/supported-properties

  The value of this property is an array of Strings containing the names of all the properties supported by this XMLReader.

• Or perhaps a method instead of a property?

DefaultHandler infoset extensions

• The DeclHandler and LexicalHandler extension handlers are not supported by the DefaultHandler convenience class.

• Solution:

  Define a new org.xml.sax.ext class implementing those two interfaces, inheriting from org.xml.sax.helpers.DefaultHandler

  public class DefaultHandler2 extends DefaultHandler 
    implements DeclHandler, LexicalHandler, EntityResolver2 { 
    
      // LexicalHandler methods
    public void startDTD(String name, String publicId, String systemId)
        throws SAXException {}
    public void endDTD() throws SAXException {} 
    public void startEntity(String name) throws SAXException {}
    public void endEntity(String name) throws SAXException {}
    public void startCDATA() throws SAXException {}
    public void endCDATA() throws SAXException {}
    public void comment(char[] ch, int start, int length)
        throws SAXException {}
        
      // DeclHandler methods
    public void elementDecl(String name, String model)
        throws SAXException {}
    public void attributeDecl(String elementName,
        String attributeName, String type,
        String valueDefault, String value)
        throws SAXException {}
    public void internalEntityDecl(String name, String value)
        throws SAXException {}
    public void externalEntityDecl(String name, String publicID, 
        String systemID) throws SAXException {}
    
  }

• Alternately, update DefaultHandler.

Parser identification

• Problem: There is no conventional way for applications to identify the version of the parser they are using, for purposes of diagnostics or other kinds of troubleshooting.

• The best the JVM supports is the JDK 1.2 java.lang.Package facility, which is dependent on the JAR file metadata. It provides a partial solution, at the price of portability (JDK 1.1 APIs are much more portable) and assumptions like "one parser per package".

• Solution: Define a new standard read-only property:

  http://xml.org/sax/properties/reader-version

  Returns a string identifying the reader and its version for use in diagnostics.

  Parsers could support that if desired, probably using some sort of resource-based mechanism (not necessarily Package) to keep such release-specific strings out of the source code.

• Open issue: Should there be separate strings to ID the reader (likely a constant value) and its version (ideally assigned in release engineering)?

xmlns URI

• The http://xml.org/sax/features/xmlns-uris feature "Controls whether, when the namespace-prefixes feature is set, the parser treats namespace declaration attributes as being in the http://www.w3.org/2000/xmlns/ namespace. By default, SAX2 conforms to the original "Namespaces in XML" Recommendation, which explicitly states that such attributes are not in any namespace. Setting this optional flag to true makes the SAX2 events conform to a later backwards-incompatible revision of that recommendation, placing those attributes in a namespace."

Error IDs

• SAXParseException has a new getExceptionId() method to identify which kind of error is being reported:

  public String getExceptionId()

• Since diagnostic message vary between parsers, these identifiers are URIs so parsers can define nonstandard IDs.

• Standard IDs look like:

  • http://xml.org/sax/exception/xml/rule-66

  • http://xml.org/sax/exception/xml/wfc-PEInInternalSubset

  • http://xml.org/sax/exception/xml/vc-roottype

  • http://xml.org/sax/exception/xml/nsc-NSDeclared

• http://xml.org/sax/exception/xml/rule-number indicates a BNF grammar violation by production

• http://xml.org/sax/exception/xml/wfc-id indicates a well-formedness constraint violation by ID attribute

• http://xml.org/sax/exception/xml/vc-id indicates a validity constraint violation by ID attribute

• http://xml.org/sax/exception/xmlns/nsc-id indicates a namespace violation by ID attribute

• Some well-formedness violations can be attributed to more than one grammar rule. The most specific applicable rule should be used.

To Learn More

• http://sax.sourceforge.net/

• Subscribe to the xml-dev mailing list, http://lists.xml.org/archives/xml-dev/

Part V: DOM Level 3

of all of the things the W3C has given us, the DOM is probably the one with the least value.

--Michael Brennan on the xml-dev mailing list

DOM Evolution

• DOM Level 0: what was implemented for JavaScript in Netscape 3/IE3

• DOM Level 1, a W3C Standard

• DOM Level 2, a W3C Standard

• DOM Level 3: Several Working Drafts:

  • Document Object Model (DOM) Level 3 Core Specification

  • Document Object Model (DOM) Level 3 Views and Formatting Specification

  • Document Object Model (DOM) Level 3 Abstract Schemas and Load and Save Specification Version 1.0

  • Document Object Model (DOM) Level 3 Events Specification Version 1.0

  • Document Object Model (DOM) Level 3 XPath Specification

New Features in DOM Level 3

• Validation

• Extra (IDL) attributes on Entity, Document, Node, and Text interfaces

• Document normalization

• Standard means of loading and saving XML documents.

• Bootstrapping new documents

• Key events

DOM Level 3 Core Changes

• DOMUserData

• Node

• Document

• Text

• Entity

• Bootstrapping

New methods in Node interface

• Adds:

  Base URI

  The URI this document came from. May be null.

  Tree position

  The order of a node relative to another reference node in tree order

  Methods to set the text content of a node

  Methods to test for equality

  Methods to work with namespaces

  Methods to associate user data with each node

• I will only show the new members. Currently, the plan is to simply add these to the existing Node interface.

• Java binding:

  package org.w3c.dom;
  
  public interface Node {
  
    public String getBaseURI();
  
      public static final short DOCUMENT_POSITION_DISCONNECTED = 0x01;
      public static final short DOCUMENT_POSITION_PRECEDING = 0x02;
      public static final short DOCUMENT_POSITION_FOLLOWING = 0x04;
      public static final short DOCUMENT_POSITION_CONTAINS = 0x08;
      public static final short DOCUMENT_POSITION_IS_CONTAINED = 0x10;
      public static final short DOCUMENT_POSITION_IMPLEMENTATION_SPECIFIC = 0x20;
  
      public short compareDocumentPosition(Node other) throws DOMException;
  
      public String  getTextContent() throws DOMException;
      public void    setTextContent(String textContent) throws DOMException;
      public boolean isSameNode(Node other);
      public String  lookupPrefix(String namespaceURI);
      public boolean isDefaultNamespace(String namespaceURI);
      public String  lookupNamespaceURI(String prefix);
      public boolean isEqualNode(Node arg);
      public Node    getFeature(String feature, String version);
      public Object  setUserData(String key, Object data, UserDataHandler handler);
      public Object  getUserData(String key);
  
  }

User Data

New methods in Entity

• XML documents may be built from multiple parsed entities, each of which is not necessarily a well-formed XML document, but is at least a plausible part of a well-formed XML document.

• Each entity may have its own text declaration. This is like an XML declaration without a standalone attribute and with an optional version attribute:

  <?xml version="1.0"?>
  <?xml version="1.0" encoding="ISO-8859-9"?>
  <?xml encoding="ISO-8859-9"?>
  

• DOM3 adds:

  encoding

  A string specifying what encoding the the text declaration claims this entity uses. This is null if this entity is not an external parsed entity.

  actualEncoding

  A string specifying the actual encoding of this entity. This is null if this entity is not an external parsed entity.

  version

  A string specifying the XML version given in the text declaration. This is null if this entity is not an external parsed entity.

• Java binding:

  
  package org.w3c.dom;
  
  public interface Entity extends Node {
    
      public String getActualEncoding();
      public void   setActualEncoding(String actualEncoding);
      public String getEncoding();
      public void   setEncoding(String encoding);
      public String getVersion();
      public void   setVersion(String version);  
      
  }

New methods in Document

• Adds:

  XML declaration

  encoding, version, and standalone attributes:

  <?xml version="1.0"?>
  <?xml version="1.0" encoding="ISO-8859-9"?>
  <?xml version="1.0" encoding="ISO-8859-9" standalone="no"?>
  <?xml version="1.0" standalone="yes"?>
  

  adoptNode()

  Method to move node from one document to another

  setBaseURI()

  Method to set the base URI of the document

  Normalization methods

  Methods to determine the normal form of a document and transform the document into that form

  renameNode()

  A method that changes the name and namespace URI of a node in the document.

  Error Handlers

  Specify a DOMErrorHandler that will be called in the event "that an error is encountered while performing an operation on a document"

• Java binding:

  package org.w3c.dom;
  
  public interface Document extends Node {
  
    public String  getActualEncoding();
    public void    setActualEncoding(String actualEncoding);
  
    public String  getEncoding();
    public void    setEncoding(String encoding);
  
    public boolean getStandalone();
    public void    setStandalone(boolean standalone);
  
    public boolean getStrictErrorChecking();
    public void    setStrictErrorChecking(boolean strictErrorChecking);
  
    public String  getVersion();
    public void    setVersion(String version);
  
    public Node    adoptNode(Node source) throws DOMException;
  
    public DOMErrorHandler getErrorHandler();
    public void setErrorHandler(DOMErrorHandler errorHandler);
  
    public String getDocumentURI();
    public void   setDocumentURI(String documentURI);
  
    public void    normalizeDocument();
  
    public Node renameNode(Node n, String namespaceURI, String qualifiedName)
     throws DOMException;
  
    public DOMConfiguration getConfig();
  
    
  }

New methods in Text

• Adds:

  isWhitespaceInElementContent()

  Returns true if this node contains "ignorable" whitespace

  wholeText()

  Returns all text of Text nodes logically-adjacent to this node; i.e. the XPath value of the text node

• Java binding:

  package org.w3c.dom;
    
    public interface Text extends Node {
    
    public boolean getIsWhitespaceInElementContent();
      
    public String  getWholeText();
    public Text    replaceWholeText(String content) throws DOMException;
  
    }

Bootstrapping

• DOM2 has no implementation-independent means to create a new Document object

• Implementation-dependent methods tend to be fairly complex. For example, in Xerces-J:

  DOMImplementation impl = DOMImplementationImpl.getDOMImplementation();
Document fibonacci = impl.createDocument(null, "Fibonacci_Numbers", null);

DOM3 Bootstrapping

• Still no language-independent means to create a new Document object

• Does provide an implementation-independent method for Java only:

  DOMImplementation impl = DOMImplementationRegistry.getDOMImplementation("XML");

• package org.w3c.dom.bootstrap;
  
  public class DOMImplementationRegistry { 
  
      public final static String PROPERTY =
          "org.w3c.dom.DOMImplementationSourceList";
  
      public static DOMImplementationRegistry newInstance()       
              throws ClassNotFoundException, InstantiationException, 
              IllegalAccessException;
      public DOMImplementation getDOMImplementation(String features)
              throws ClassNotFoundException,
              InstantiationException, IllegalAccessException, ClassCastException;
      public DOMImplementationList getDOMImplementations(String features)
              throws ClassNotFoundException,
              InstantiationException, IllegalAccessException, ClassCastException;
      public void addSource(DOMImplementationSource s)
              throws ClassNotFoundException,
              InstantiationException, IllegalAccessException;
              
  }

DOM Error Handler Interfaces

• DOMErrorHandler

• DOMLocator

The DOMErrorHandler Interface

• Similar to SAX2's ErrorHandler interface.

• A callback interface

• An application implements this interface and then registers it with the setErrorHandler() method to provide warnings, errors, and fatal errors.

• Java binding:

  package org.w3c.dom;
  
  public interface DOMErrorHandler {
    
    public boolean handleError(DOMError error);
  
  }

The DOMError Interface

package org.w3c.dom;

public interface DOMError {
    // ErrorSeverity
    public static final short SEVERITY_WARNING          = 0;
    public static final short SEVERITY_ERROR            = 1;
    public static final short SEVERITY_FATAL_ERROR      = 2;

    public short  getSeverity();
    public String getMessage();
    public String getType();
    public Object getRelatedException();
    public Object getRelatedData();
    public DOMLocator getLocation();

}

The DOMLocator Interface

• Similar to SAX2's Locator interface. An application can implement this interface and then register it with the setLocator() method to find out in which line and column and file a given node appears.

• Java binding:

  package org.w3c.dom;
  
  public interface DOMLocator {
  
    public int    getLineNumber();
    public int    getColumnNumber();
    public int    getOffset();
    public Node   getRelatedNode();
    public String getUri();
  
  }

Load and Save

• Loading: parsing an existing XML document to produce a Document object

• Saving: serializing a Document object into a file or onto a stream

• Completely implementation dependent in DOM2

The DOM Process

1. Library specific code creates a parser

2. The parser parses the document and returns a DOM org.w3c.dom.Document object.

3. The entire document is stored in memory.

4. DOM methods and interfaces are used to extract data from this object

Parsing documents with DOM2

This program parses with Xerces. Other parsers are different.

import org.apache.xerces.parsers.*;
import org.w3c.dom.*;
import org.xml.sax.*;
import java.io.*;

public class DOMParserMaker {

  public static void main(String[] args) {
     
    DOMParser parser = new DOMParser();
    
    for (int i = 0; i < args.length; i++) {
      try {
        parser.parse(args[i]); 
       
        Document d = parser.getDocument();
      }
      catch (SAXException e) {
        System.err.println(e); 
      }
      catch (IOException e) {
        System.err.println(e); 
      }
      
    }
   
  }

}

Parsing documents with JAXP

import javax.xml.parsers.*; // JAXP
import org.xml.sax.SAXException;
import java.io.IOException;


public class JAXPParserMaker {

  public static void main(String[] args) {
     
    if (args.length <= 0) {
      System.out.println("Usage: java JAXPParserMaker URL");
      return;
    }
    String document = args[0];
    
    try {
      DocumentBuilderFactory factory 
       = DocumentBuilderFactory.newInstance();
      DocumentBuilder parser = factory.newDocumentBuilder();
      parser.parse(document); 
      System.out.println(document + " is well-formed.");
    }
    catch (SAXException e) {
      System.out.println(document + " is not well-formed.");
    }
    catch (IOException e) { 
      System.out.println(
       "Due to an IOException, the parser could not check " 
       + document
      ); 
    }
    catch (FactoryConfigurationError e) { 
      // JAXP suffers from excessive brain-damage caused by 
      // intellectual in-breeding at Sun. (Basically the Sun 
      // engineers spend way too much time talking to each other
      // and not nearly enough time talking to people outside 
      // Sun.) Fortunately, you can happily ignore most of the 
      // JAXP brain damage and not be any the poorer for it.
      
      // This, however, is one of the few problems you can't 
      // avoid if you're going to use JAXP at all. 
      // DocumentBuilderFactory.newInstance() should throw a 
      // ClassNotFoundException if it can't locate the factory
      // class. However, what it does throw is an Error,
      // specifically a FactoryConfigurationError. Very few 
      // programs are prepared to respond to errors as opposed
      // to exceptions. You should catch this error in your 
      // JAXP programs as quickly as possible even though the
      // compiler won't require you to, and you should 
      // never rethrow it or otherwise let it escape from the 
      // method that produced it. 
      System.out.println("Could not locate a factory class"); 
    }
    catch (ParserConfigurationException e) { 
      System.out.println("Could not locate a JAXP parser"); 
    }
   
  }

}

Parsing documents with DOM3

import org.w3c.dom.*;

public class DOM3ParserMaker {

  public static void main(String[] args) {

    DOMImplementation impl 
     = DOMImplementationRegistry.getDOMImplementation("XML 1.0 LS-Load 3.0");
    DOMImplementationLS implls = (DOMImplementationLS) impl;
    DOMBuilder parser = implls.getDOMBuilder();

    for (int i = 0; i < args.length; i++) {
      try {
        Document d = parser.parseURI(args[i]);
      }
      catch (DOMSystemException e) {
        System.err.println(e);
      }
      catch (DOMException e) {
        System.err.println(e);
      }

    }

  }

}

This code will not actually compile or run until some parser supports DOM3 Load and Save.

Load and Save

DOMImplementationLS

A sub-interface od DOMImplementation that provides the factory methods for creating the objects required for loading and saving.

DOMBuilder

A parser interface

DOMInputSource

Encapsulate information about the source of the XML to be loaded, like SAX's InputSource

DOMEntityResolver

During loading, provides a way for applications to redirect references to external entities.

DOMBuilderFilter

Provide the ability to examine and optionally remove Element nodes as they are being processed during the parsing of a document. like SAX filters.

DOMWriter

An interface for serializing DOM documents onto a stream or string.

DOMWriterFilter

Provide the ability to examine and optionally remove or modify nodes as they are being output.

DocumentLS

A "mechanism by which the content of a document can be replaced with the DOM tree produced when loading a URL, or parsing a string."

ParserErrorEvent

Some sort of error detected in the input document (well-formedness? validity?)

LSLoadEvent

A document has been completely loaded

LSProgressEvent

A document has been partially loaded

DOMImplementationLS

• Factory interface to create new DOMBuilder and DOMWriter implementations.

• Java Binding:

  package org.w3c.dom.ls;
  
  public interface DOMImplementationLS {
  
    public static final short MODE_SYNCHRONOUS  = 1;
    public static final short MODE_ASYNCHRONOUS = 2;
    
    public DOMBuilder     createDOMBuilder(short mode) throws DOMException;
    public DOMWriter      createDOMWriter();
    public DOMInputSource createDOMInputSource();
  
  }

Creating DOMImplementationLS Objects

1. Use the feature "LS-Load" to find a DOMImplementation object that supports Load and Save.

2. Cast the DOMImplementation object to DOMImplementationLS.

DOMImplementation impl 
 = DOMImplementationRegistry.getDOMImplementation("XML 1.0 LS-Load 3.0");
  if (impl != null) {
    DOMImplementationLS implls = (DOMImplementationLS) impl;
    // ...
  }

DOMBuilder

• Provides an implementation-independent API for parsing XML documents to produce a DOM Document object.

• Instances are built by the createDOMBuilder() method in DOMImplementationLS.

• Java Binding:

  package org.w3c.dom.ls;
  
  public interface DOMBuilder {
  
    public DOMEntityResolver getEntityResolver();
    public void setEntityResolver(DOMEntityResolver entityResolver);
  
    public DOMErrorHandler getErrorHandler();
    public void setErrorHandler(DOMErrorHandler errorHandler);
  
    public DOMBuilderFilter getFilter();
    public void setFilter(DOMBuilderFilter filter);
  
    public void setFeature(String name, boolean state)
     throws DOMException;
    public boolean canSetFeature(String name, boolean state);
    public boolean getFeature(String name)
     throws DOMException;
    public Document parseURI(String uri) throws Exception;
    public Document parse(DOMInputSource is) throws Exception;
  
    // ACTION_TYPES
      public static final short ACTION_APPEND_AS_CHILDREN = 1;
      public static final short ACTION_REPLACE_CHILDREN   = 2;
      public static final short ACTION_INSERT_BEFORE      = 3;
      public static final short ACTION_INSERT_AFTER       = 4;
      public static final short ACTION_REPLACE            = 5;
  
    public void parseWithContext(DOMInputSource is,
     Node contextNode, short action) throws DOMException;
     
      public DOMConfiguration getConfig();
  
      public boolean getAsync();
      public boolean getBusy();
  
      public void abort();      
  
  }

DOMInputSource

• Like SAX2's InputSource class, this interface is an abstraction of all the different things (streams, files, byte arrays, sockets, URLs, etc.) from which an XML document can be read.

• Java Binding:

  package org.w3c.dom.ls;
  
  public interface DOMInputSource {
  
    public InputStream getByteStream();
    public void        setByteStream(InputStream in);
    public Reader      getCharacterStream();
    public void        setCharacterStream(Reader in);
  
    public String getStringData();
    public void   setStringData(String data);
    public String getEncoding();
    public void   setEncoding(String encoding);
    public String getPublicId();
    public void   setPublicId(String publicId);
    public String getSystemId();
    public void   setSystemId(String systemId);
  
  }

DOMEntityResolver

• Like SAX2's EntityResolver interface, this interface lets applications redirect references to external entities.

• Java Binding:

  package org.w3c.dom.ls;
  
  public interface DOMEntityResolver {
  
    public DOMInputSource resolveEntity(String publicID, 
     String systemID, String baseURI) throws DOMSystemException;
  
  }
  

DOMWriter

• Provides an API for serializing (writing) a DOM document out as a sequence of bytes onto a stream, file, socket, byte array, etc.

• Java Binding:

  package org.w3c.dom.ls;
  
  public interface DOMWriter {
  
    public DOMConfiguration getConfig();
  
    public DOMWriterFilter getFilter();
    public void setFilter(DOMWriterFilter filter);
    
    public String getEncoding();
    public void   setEncoding(String encoding);
    public String getNewLine();
    public void   setNewLine(String newLine);
    
    public boolean writeNode(OutputStream destination, Node wnode)
     throws Exception;
    public String writeToString(Node node) throws DOMException;
  
  }

DOMBuilderFilter

• Lets applications examine nodes as they are being constructed during a parse.

• As each node is examined, it may be modified or removed, or parsing may be aborted.

• Java Binding:

  package org.w3c.dom.ls;
  
  public interface DOMBuilderFilter {
  
      // Constants returned by startElement and acceptNode
      public static final short FILTER_ACCEPT     = 1;
      public static final short FILTER_REJECT     = 2;
      public static final short FILTER_SKIP       = 3;
      public static final short FILTER_INTERRUPT  = 4;
  
      public short startElement(Element element);
      public short acceptNode(Node node);
      public int   getWhatToShow();
      
  }

DOMWriterFilter

• Lets applications examine nodes as they are being output.

• As each element is examined, it may be modified or removed, or output may be aborted.

• Java Binding:

  package org.w3c.dom.ls;
  
  public interface DOMWriterFilter extends NodeFilter {
  
    public int getWhatToShow();
  
  }

DocumentLS

• An instance of the DocumentLS interface can be obtained by casting an instance of the Document interface to DocumentLS.

• Java Binding:

  package org.w3c.dom.ls;
  
  import org.w3c.dom.Node;
  import org.w3c.dom.DOMException;
  
  public interface DocumentLS {
  
    public boolean getAsync();
    public void    setAsync(boolean async);
  
    public void    abort();
    public boolean load(String url);
    public boolean loadXML(String source);
    public String  saveXML(Node node) throws DOMException;
  
  }

ParserErrorEvent

• Represents an error (of what kind?) in the document being parsed

• Java Binding:

  package org.w3c.dom.ls;
  
  public interface ParseErrorEvent extends Event {
  
    public DOMError getError();
  
  }

Validation

To Learn More

• Document Object Model (DOM) Level 3 Core Specification Version 1.0: http://www.w3.org/TR/DOM-Level-3-Core

• Document Object Model (DOM) Level 3 Validation Specification: http://www.w3.org/TR/DOM-Level-3-Val/

• Document Object Model (DOM) Level 3 Load and Save Specification: http://www.w3.org/TR/DOM-Level-3-LS/

• Document Object Model (DOM) Requirements: http://www.w3.org/TR/DOM-Requirements/

• Document Object Model (DOM) Level 3 Views and Formatting Specification: http://www.w3.org/TR/DOM-Level-3-Views/

• Document Object Model (DOM) Level 3 XPath Specification: http://www.w3.org/TR/DOM-Level-3-Events/

• Document Object Model (DOM) Level 3 Events Specification: http://www.w3.org/TR/DOM-Level-3-Views/

Part VI: XOM

To Learn More

• This presentation: http://www.cafeconleche.org/slides/xmlone/london2003/bleeding/

• XOM Web Site: http://www.cafeconleche.org/XOM

• XML Infoset Specification: http://www.w3.org/TR/xml-infoset

• Processing XML with Java: http://www.cafeconleche.org/books/xmljava/

• XInclude Specification: http://www.w3.org/TR/xinclude