http://xml.apache.org/commons/components/external/: xml-commons provides an Apache-hosted set of DOM, SAX, and JAXP interfaces for use in other xml-based projects. Our hope is that we can standardize on both a common version and packaging scheme for these critical XML standards interfaces to make the lives of both our developers and users easier. The External Components portion of xml-commons contains interfaces that are defined by external standards organizations. For DOM, that's the W3C; for SAX it's David Megginson and sax.sourceforge.net; for JAXP it's Sun. 
/*
 * Copyright (c) 2004 World Wide Web Consortium,
 *
 * (Massachusetts Institute of Technology, European Research Consortium for
 * Informatics and Mathematics, Keio University). All Rights Reserved. This
 * work is distributed under the W3C(r) Software License [1] in the hope that
 * it will be useful, but WITHOUT ANY WARRANTY; without even the implied
 * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 *
 * [1] http://www.w3.org/Consortium/Legal/2002/copyright-software-20021231
 */

package org.w3c.dom;


The Attr interface represents an attribute in an 
Element object. Typically the allowable values for the 
attribute are defined in a schema associated with the document.

Attr objects inherit the Node interface, but 
since they are not actually child nodes of the element they describe, the 
DOM does not consider them part of the document tree. Thus, the 
Node attributes parentNode, 
previousSibling, and nextSibling have a 
null value for Attr objects. The DOM takes the 
view that attributes are properties of elements rather than having a 
separate identity from the elements they are associated with; this should 
make it more efficient to implement such features as default attributes 
associated with all elements of a given type. Furthermore, 
Attr nodes may not be immediate children of a 
DocumentFragment. However, they can be associated with 
Element nodes contained within a 
DocumentFragment. In short, users and implementors of the 
DOM need to be aware that Attr nodes have some things in 
common with other objects inheriting the Node interface, but 
they also are quite distinct.

The attribute's effective value is determined as follows: if this 
attribute has been explicitly assigned any value, that value is the 
attribute's effective value; otherwise, if there is a declaration for 
this attribute, and that declaration includes a default value, then that 
default value is the attribute's effective value; otherwise, the 
attribute does not exist on this element in the structure model until it 
has been explicitly added. Note that the Node.nodeValue 
attribute on the Attr instance can also be used to retrieve 
the string version of the attribute's value(s).

 If the attribute was not explicitly given a value in the instance 
document but has a default value provided by the schema associated with 
the document, an attribute node will be created with 
specified set to false. Removing attribute 
nodes for which a default value is defined in the schema generates a new 
attribute node with the default value and specified set to 
false. If validation occurred while invoking 
Document.normalizeDocument(), attribute nodes with 
specified equals to false are recomputed 
according to the default attribute values provided by the schema. If no 
default value is associate with this attribute in the schema, the 
attribute node is discarded. 

In XML, where the value of an attribute can contain entity references, 
the child nodes of the Attr node may be either 
Text or EntityReference nodes (when these are 
in use; see the description of EntityReference for 
discussion). 

The DOM Core represents all attribute values as simple strings, even if 
the DTD or schema associated with the document declares them of some 
specific type such as tokenized. 

The way attribute value normalization is performed by the DOM 
implementation depends on how much the implementation knows about the 
schema in use. Typically, the value and 
nodeValue attributes of an Attr node initially 
returns the normalized value given by the parser. It is also the case 
after Document.normalizeDocument() is called (assuming the 
right options have been set). But this may not be the case after 
mutation, independently of whether the mutation is performed by setting 
the string value directly or by changing the Attr child 
nodes. In particular, this is true when character 
references are involved, given that they are not represented in the DOM and they 
impact attribute value normalization. On the other hand, if the 
implementation knows about the schema in use when the attribute value is 
changed, and it is of a different type than CDATA, it may normalize it 
again at that time. This is especially true of specialized DOM 
implementations, such as SVG DOM implementations, which store attribute 
values in an internal form different from a string.

The following table gives some examples of the relations between the 
attribute value in the original document (parsed attribute), the value as 
exposed in the DOM, and the serialization of the value: 




Examples
Parsed 
attribute value
Initial Attr.value
Serialized attribute value





Character reference


"x²=5"




"x\u00b2=5"




"x²=5"






Built-in 
character entity


"y<6"




"y<6"




"y&lt;6"






Literal newline between


"x=5&#10;y=6"




"x=5 y=6"




"x=5&#10;y=6"






Normalized newline between


"x=5 
y=6"




"x=5 y=6"




"x=5 y=6"






Entity e with literal newline


<!ENTITY e '...&#10;...'> [...]> "x=5&e;y=6"


Dependent on Implementation and Load Options
Dependent on Implementation and Load/Save Options





See also the Document Object Model (DOM) Level 3 Core Specification.

/**
 * The <code>Attr</code> interface represents an attribute in an 
 * <code>Element</code> object. Typically the allowable values for the 
 * attribute are defined in a schema associated with the document.
 * <p><code>Attr</code> objects inherit the <code>Node</code> interface, but 
 * since they are not actually child nodes of the element they describe, the 
 * DOM does not consider them part of the document tree. Thus, the 
 * <code>Node</code> attributes <code>parentNode</code>, 
 * <code>previousSibling</code>, and <code>nextSibling</code> have a 
 * <code>null</code> value for <code>Attr</code> objects. The DOM takes the 
 * view that attributes are properties of elements rather than having a 
 * separate identity from the elements they are associated with; this should 
 * make it more efficient to implement such features as default attributes 
 * associated with all elements of a given type. Furthermore, 
 * <code>Attr</code> nodes may not be immediate children of a 
 * <code>DocumentFragment</code>. However, they can be associated with 
 * <code>Element</code> nodes contained within a 
 * <code>DocumentFragment</code>. In short, users and implementors of the 
 * DOM need to be aware that <code>Attr</code> nodes have some things in 
 * common with other objects inheriting the <code>Node</code> interface, but 
 * they also are quite distinct.
 * <p>The attribute's effective value is determined as follows: if this 
 * attribute has been explicitly assigned any value, that value is the 
 * attribute's effective value; otherwise, if there is a declaration for 
 * this attribute, and that declaration includes a default value, then that 
 * default value is the attribute's effective value; otherwise, the 
 * attribute does not exist on this element in the structure model until it 
 * has been explicitly added. Note that the <code>Node.nodeValue</code> 
 * attribute on the <code>Attr</code> instance can also be used to retrieve 
 * the string version of the attribute's value(s).
 * <p> If the attribute was not explicitly given a value in the instance 
 * document but has a default value provided by the schema associated with 
 * the document, an attribute node will be created with 
 * <code>specified</code> set to <code>false</code>. Removing attribute 
 * nodes for which a default value is defined in the schema generates a new 
 * attribute node with the default value and <code>specified</code> set to 
 * <code>false</code>. If validation occurred while invoking 
 * <code>Document.normalizeDocument()</code>, attribute nodes with 
 * <code>specified</code> equals to <code>false</code> are recomputed 
 * according to the default attribute values provided by the schema. If no 
 * default value is associate with this attribute in the schema, the 
 * attribute node is discarded. 
 * <p>In XML, where the value of an attribute can contain entity references, 
 * the child nodes of the <code>Attr</code> node may be either 
 * <code>Text</code> or <code>EntityReference</code> nodes (when these are 
 * in use; see the description of <code>EntityReference</code> for 
 * discussion). 
 * <p>The DOM Core represents all attribute values as simple strings, even if 
 * the DTD or schema associated with the document declares them of some 
 * specific type such as tokenized. 
 * <p>The way attribute value normalization is performed by the DOM 
 * implementation depends on how much the implementation knows about the 
 * schema in use. Typically, the <code>value</code> and 
 * <code>nodeValue</code> attributes of an <code>Attr</code> node initially 
 * returns the normalized value given by the parser. It is also the case 
 * after <code>Document.normalizeDocument()</code> is called (assuming the 
 * right options have been set). But this may not be the case after 
 * mutation, independently of whether the mutation is performed by setting 
 * the string value directly or by changing the <code>Attr</code> child 
 * nodes. In particular, this is true when <a href='http://www.w3.org/TR/2004/REC-xml-20040204#dt-charref'>character 
 * references</a> are involved, given that they are not represented in the DOM and they 
 * impact attribute value normalization. On the other hand, if the 
 * implementation knows about the schema in use when the attribute value is 
 * changed, and it is of a different type than CDATA, it may normalize it 
 * again at that time. This is especially true of specialized DOM 
 * implementations, such as SVG DOM implementations, which store attribute 
 * values in an internal form different from a string.
 * <p>The following table gives some examples of the relations between the 
 * attribute value in the original document (parsed attribute), the value as 
 * exposed in the DOM, and the serialization of the value: 
 * <table border='1' cellpadding='3'>
 * <tr>
 * <th>Examples</th>
 * <th>Parsed 
 * attribute value</th>
 * <th>Initial <code>Attr.value</code></th>
 * <th>Serialized attribute value</th>
 * </tr>
 * <tr>
 * <td valign='top' rowspan='1' colspan='1'>
 * Character reference</td>
 * <td valign='top' rowspan='1' colspan='1'>
 * <pre>"x&amp;#178;=5"</pre>
 * </td>
 * <td valign='top' rowspan='1' colspan='1'>
 * <pre>"x\u00b2=5"</pre>
 * </td>
 * <td valign='top' rowspan='1' colspan='1'>
 * <pre>"x&amp;#178;=5"</pre>
 * </td>
 * </tr>
 * <tr>
 * <td valign='top' rowspan='1' colspan='1'>Built-in 
 * character entity</td>
 * <td valign='top' rowspan='1' colspan='1'>
 * <pre>"y&amp;lt;6"</pre>
 * </td>
 * <td valign='top' rowspan='1' colspan='1'>
 * <pre>"y&lt;6"</pre>
 * </td>
 * <td valign='top' rowspan='1' colspan='1'>
 * <pre>"y&amp;lt;6"</pre>
 * </td>
 * </tr>
 * <tr>
 * <td valign='top' rowspan='1' colspan='1'>Literal newline between</td>
 * <td valign='top' rowspan='1' colspan='1'>
 * <pre>
 * "x=5&amp;#10;y=6"</pre>
 * </td>
 * <td valign='top' rowspan='1' colspan='1'>
 * <pre>"x=5 y=6"</pre>
 * </td>
 * <td valign='top' rowspan='1' colspan='1'>
 * <pre>"x=5&amp;#10;y=6"</pre>
 * </td>
 * </tr>
 * <tr>
 * <td valign='top' rowspan='1' colspan='1'>Normalized newline between</td>
 * <td valign='top' rowspan='1' colspan='1'>
 * <pre>"x=5 
 * y=6"</pre>
 * </td>
 * <td valign='top' rowspan='1' colspan='1'>
 * <pre>"x=5 y=6"</pre>
 * </td>
 * <td valign='top' rowspan='1' colspan='1'>
 * <pre>"x=5 y=6"</pre>
 * </td>
 * </tr>
 * <tr>
 * <td valign='top' rowspan='1' colspan='1'>Entity <code>e</code> with literal newline</td>
 * <td valign='top' rowspan='1' colspan='1'>
 * <pre>
 * &lt;!ENTITY e '...&amp;#10;...'&gt; [...]&gt; "x=5&amp;e;y=6"</pre>
 * </td>
 * <td valign='top' rowspan='1' colspan='1'><em>Dependent on Implementation and Load Options</em></td>
 * <td valign='top' rowspan='1' colspan='1'><em>Dependent on Implementation and Load/Save Options</em></td>
 * </tr>
 * </table>
 * <p>See also the <a href='http://www.w3.org/TR/2004/REC-DOM-Level-3-Core-20040407'>Document Object Model (DOM) Level 3 Core Specification</a>.
 */
public interface Attr extends Node {
    
Returns the name of this attribute. If Node.localName is 
different from null, this attribute is a qualified name.

/**
     * Returns the name of this attribute. If <code>Node.localName</code> is 
     * different from <code>null</code>, this attribute is a qualified name.
     */
    public String getName();

    
 True if this attribute was explicitly given a value in 
the instance document, false otherwise. If the 
application changed the value of this attribute node (even if it ends 
up having the same value as the default value) then it is set to 
true. The implementation may handle attributes with 
default values from other schemas similarly but applications should 
use Document.normalizeDocument() to guarantee this 
information is up-to-date. 

/**
     *  <code>True</code> if this attribute was explicitly given a value in 
     * the instance document, <code>false</code> otherwise. If the 
     * application changed the value of this attribute node (even if it ends 
     * up having the same value as the default value) then it is set to 
     * <code>true</code>. The implementation may handle attributes with 
     * default values from other schemas similarly but applications should 
     * use <code>Document.normalizeDocument()</code> to guarantee this 
     * information is up-to-date. 
     */
    public boolean getSpecified();

    
On retrieval, the value of the attribute is returned as a string. 
Character and general entity references are replaced with their 
values. See also the method getAttribute on the 
Element interface.

On setting, this creates a Text node with the unparsed 
contents of the string, i.e. any characters that an XML processor 
would recognize as markup are instead treated as literal text. See 
also the method Element.setAttribute().

 Some specialized implementations, such as some [SVG 1.1] 
implementations, may do normalization automatically, even after 
mutation; in such case, the value on retrieval may differ from the 
value on setting. 

/**
     * On retrieval, the value of the attribute is returned as a string. 
     * Character and general entity references are replaced with their 
     * values. See also the method <code>getAttribute</code> on the 
     * <code>Element</code> interface.
     * <br>On setting, this creates a <code>Text</code> node with the unparsed 
     * contents of the string, i.e. any characters that an XML processor 
     * would recognize as markup are instead treated as literal text. See 
     * also the method <code>Element.setAttribute()</code>.
     * <br> Some specialized implementations, such as some [<a href='http://www.w3.org/TR/2003/REC-SVG11-20030114/'>SVG 1.1</a>] 
     * implementations, may do normalization automatically, even after 
     * mutation; in such case, the value on retrieval may differ from the 
     * value on setting. 
     */
    public String getValue();
    
On retrieval, the value of the attribute is returned as a string. 
Character and general entity references are replaced with their 
values. See also the method getAttribute on the 
Element interface.

On setting, this creates a Text node with the unparsed 
contents of the string, i.e. any characters that an XML processor 
would recognize as markup are instead treated as literal text. See 
also the method Element.setAttribute().

 Some specialized implementations, such as some [SVG 1.1] 
implementations, may do normalization automatically, even after 
mutation; in such case, the value on retrieval may differ from the 
value on setting. 

Throws:
  • DOMException – 
  NO_MODIFICATION_ALLOWED_ERR: Raised when the node is readonly.
/**
     * On retrieval, the value of the attribute is returned as a string. 
     * Character and general entity references are replaced with their 
     * values. See also the method <code>getAttribute</code> on the 
     * <code>Element</code> interface.
     * <br>On setting, this creates a <code>Text</code> node with the unparsed 
     * contents of the string, i.e. any characters that an XML processor 
     * would recognize as markup are instead treated as literal text. See 
     * also the method <code>Element.setAttribute()</code>.
     * <br> Some specialized implementations, such as some [<a href='http://www.w3.org/TR/2003/REC-SVG11-20030114/'>SVG 1.1</a>] 
     * implementations, may do normalization automatically, even after 
     * mutation; in such case, the value on retrieval may differ from the 
     * value on setting. 
     * @exception DOMException
     *   NO_MODIFICATION_ALLOWED_ERR: Raised when the node is readonly.
     */
    public void setValue(String value)
                            throws DOMException;

    
The Element node this attribute is attached to or 
null if this attribute is not in use.

Since:DOM Level 2
/**
     * The <code>Element</code> node this attribute is attached to or 
     * <code>null</code> if this attribute is not in use.
     * @since DOM Level 2
     */
    public Element getOwnerElement();

    
 The type information associated with this attribute. While the type 
information contained in this attribute is guarantee to be correct 
after loading the document or invoking 
Document.normalizeDocument(), schemaTypeInfo
 may not be reliable if the node was moved. 

Since:DOM Level 3
/**
     *  The type information associated with this attribute. While the type 
     * information contained in this attribute is guarantee to be correct 
     * after loading the document or invoking 
     * <code>Document.normalizeDocument()</code>, <code>schemaTypeInfo</code>
     *  may not be reliable if the node was moved. 
     * @since DOM Level 3
     */
    public TypeInfo getSchemaTypeInfo();

    
 Returns whether this attribute is known to be of type ID (i.e. to 
contain an identifier for its owner element) or not. When it is and 
its value is unique, the ownerElement of this attribute 
can be retrieved using the method Document.getElementById
. The implementation could use several ways to determine if an 
attribute node is known to contain an identifier: 

    

  •  If validation 
occurred using an XML Schema [XML Schema Part 1]
 while loading the document or while invoking 
Document.normalizeDocument(), the post-schema-validation 
infoset contributions (PSVI contributions) values are used to 
determine if this attribute is a schema-determined ID attribute using 
the 
schema-determined ID definition in [XPointer]
. 

    • 

  •  If validation occurred using a DTD while loading the document or 
while invoking Document.normalizeDocument(), the infoset [type definition] value is used to determine if this attribute is a DTD-determined ID 
attribute using the 
DTD-determined ID definition in [XPointer]
. 

    • 

  •  from the use of the methods Element.setIdAttribute(), 
Element.setIdAttributeNS(), or 
Element.setIdAttributeNode(), i.e. it is an 
user-determined ID attribute; 

    Note:  XPointer framework (see section 3.2 in [XPointer]
) consider the DOM user-determined ID attribute as being part of the 
XPointer externally-determined ID definition. 

    • 

  •  using mechanisms that 
are outside the scope of this specification, it is then an 
externally-determined ID attribute. This includes using schema 
languages different from XML schema and DTD. 

    • 



 If validation occurred while invoking 
Document.normalizeDocument(), all user-determined ID 
attributes are reset and all attribute nodes ID information are then 
reevaluated in accordance to the schema used. As a consequence, if 
the Attr.schemaTypeInfo attribute contains an ID type, 
isId will always return true. 

Since:DOM Level 3
/**
     *  Returns whether this attribute is known to be of type ID (i.e. to 
     * contain an identifier for its owner element) or not. When it is and 
     * its value is unique, the <code>ownerElement</code> of this attribute 
     * can be retrieved using the method <code>Document.getElementById</code>
     * . The implementation could use several ways to determine if an 
     * attribute node is known to contain an identifier: 
     * <ul>
     * <li> If validation 
     * occurred using an XML Schema [<a href='http://www.w3.org/TR/2001/REC-xmlschema-1-20010502/'>XML Schema Part 1</a>]
     *  while loading the document or while invoking 
     * <code>Document.normalizeDocument()</code>, the post-schema-validation 
     * infoset contributions (PSVI contributions) values are used to 
     * determine if this attribute is a schema-determined ID attribute using 
     * the <a href='http://www.w3.org/TR/2003/REC-xptr-framework-20030325/#term-sdi'>
     * schema-determined ID</a> definition in [<a href='http://www.w3.org/TR/2003/REC-xptr-framework-20030325/'>XPointer</a>]
     * . 
     * </li>
     * <li> If validation occurred using a DTD while loading the document or 
     * while invoking <code>Document.normalizeDocument()</code>, the infoset <b>[type definition]</b> value is used to determine if this attribute is a DTD-determined ID 
     * attribute using the <a href='http://www.w3.org/TR/2003/REC-xptr-framework-20030325/#term-ddi'>
     * DTD-determined ID</a> definition in [<a href='http://www.w3.org/TR/2003/REC-xptr-framework-20030325/'>XPointer</a>]
     * . 
     * </li>
     * <li> from the use of the methods <code>Element.setIdAttribute()</code>, 
     * <code>Element.setIdAttributeNS()</code>, or 
     * <code>Element.setIdAttributeNode()</code>, i.e. it is an 
     * user-determined ID attribute; 
     * <p ><b>Note:</b>  XPointer framework (see section 3.2 in [<a href='http://www.w3.org/TR/2003/REC-xptr-framework-20030325/'>XPointer</a>]
     * ) consider the DOM user-determined ID attribute as being part of the 
     * XPointer externally-determined ID definition. 
     * </li>
     * <li> using mechanisms that 
     * are outside the scope of this specification, it is then an 
     * externally-determined ID attribute. This includes using schema 
     * languages different from XML schema and DTD. 
     * </li>
     * </ul>
     * <br> If validation occurred while invoking 
     * <code>Document.normalizeDocument()</code>, all user-determined ID 
     * attributes are reset and all attribute nodes ID information are then 
     * reevaluated in accordance to the schema used. As a consequence, if 
     * the <code>Attr.schemaTypeInfo</code> attribute contains an ID type, 
     * <code>isId</code> will always return true. 
     * @since DOM Level 3
     */
    public boolean isId();

}