1. Document Object Model Load and Save

1.1 Overview of the Interfaces

The interfaces involved with the loading and saving of XML documents are:

• DOMImplementationLS -- An extended DOMImplementation interface that provides the factory methods for creating the objects required for loading and saving.
• LSParser -- An interface for parsing data into DOM documents.
• LSInput -- Encapsulates information about the data to be loaded.
• LSResourceResolver -- Provides a way for applications to redirect references to external resources when parsing.
• LSParserFilter -- Provides the ability to examine and optionally remove nodes as they are being processed while parsing.
• LSSerializer -- An interface for serializing DOM documents or nodes.
• LSOutput -- Encapsulates information about the destination for the data to be output.
• LSSerializerFilter -- Provides the ability to examine and filter DOM nodes as they are being processed for the serialization.

1.2 Basic Types

To ensure interoperability, this specification specifies the following basic types used in various DOM modules. Even though the DOM uses the basic types in the interfaces, bindings may use different types and normative bindings are only given for Java and ECMAScript in this specification.

1.3 Fundamental Interfaces

The interfaces within this section are considered fundamental, and must be fully implemented by all conforming implementations of the DOM Load and Save module.

A DOM application may use the hasFeature(feature, version) method of the DOMImplementation interface with parameter values "LS" (or "LS-Async") and "3.0" (respectively) to determine whether or not these interfaces are supported by the implementation. In order to fully support them, an implementation must also support the "Core" feature defined in [DOM Level 2 Core].

A DOM application may use the hasFeature(feature, version) method of the DOMImplementation interface with parameter values "LS-Async" and "3.0" (respectively) to determine whether or not the asynchronous mode is supported by the implementation. In order to fully support the asynchronous mode, an implementation must also support the "LS" feature defined in this section.

For additional information about conformance, please see the DOM Level 3 Core specification [DOM Level 3 Core].

Exception LSException

Parser or write operations may throw an LSException if the processing is stopped. The processing can be stopped due to a DOMError with a severity of DOMError.SEVERITY_FATAL_ERROR or a non recovered DOMError.SEVERITY_ERROR, or if DOMErrorHandler.handleError() returned false.

Note: As suggested in the definition of the constants in the DOMError interface, a DOM implementation may choose to continue after a fatal error, but the resulting DOM tree is then implementation dependent.

IDL Definition

exception LSException {
  unsigned short   code;
};
// LSExceptionCode
const unsigned short      PARSE_ERR                      = 81;
const unsigned short      SERIALIZE_ERR                  = 82;

Definition group LSExceptionCode

An integer indicating the type of error generated.

Defined Constants

PARSE_ERR

If an attempt was made to load a document, or an XML Fragment, using LSParser and the processing has been stopped.

SERIALIZE_ERR

If an attempt was made to serialize a Node using LSSerializer and the processing has been stopped.

Interface DOMImplementationLS

DOMImplementationLS contains the factory methods for creating Load and Save objects.

The expectation is that an instance of the DOMImplementationLS interface can be obtained by using binding-specific casting methods on an instance of the DOMImplementation interface or, if the Document supports the feature "Core" version "3.0" defined in [DOM Level 3 Core], by using the method DOMImplementation.getFeature with parameter values "LS" (or "LS-Async") and "3.0" (respectively).

IDL Definition

interface DOMImplementationLS {

  // DOMImplementationLSMode
  const unsigned short      MODE_SYNCHRONOUS               = 1;
  const unsigned short      MODE_ASYNCHRONOUS              = 2;

  LSParser           createLSParser(in unsigned short mode, 
                                    in DOMString schemaType)
                                        raises(DOMException);
  LSSerializer       createLSSerializer();
  LSInput            createLSInput();
  LSOutput           createLSOutput();
};

Definition group DOMImplementationLSMode

Integer parser mode constants.

Defined Constants

MODE_ASYNCHRONOUS

Create an asynchronous LSParser.

MODE_SYNCHRONOUS

Create a synchronous LSParser.

Methods

createLSInput

Create a new empty input source object where LSInput.characterStream, LSInput.byteStream, LSInput.stringData LSInput.systemId, LSInput.publicId, LSInput.baseURI, and LSInput.encoding are null, and LSInput.certifiedText is false.

Return Value

LSInput

The newly created input object.

No Parameters

No Exceptions

createLSOutput

Create a new empty output destination object where LSOutput.characterStream, LSOutput.byteStream, LSOutput.systemId, LSOutput.encoding are null.

Return Value

LSOutput

The newly created output object.

No Parameters

No Exceptions

createLSParser

Create a new LSParser. The newly constructed parser may then be configured by means of its DOMConfiguration object, and used to parse documents by means of its parse method.

Parameters

mode of type unsigned short

The mode argument is either MODE_SYNCHRONOUS or MODE_ASYNCHRONOUS, if mode is MODE_SYNCHRONOUS then the LSParser that is created will operate in synchronous mode, if it's MODE_ASYNCHRONOUS then the LSParser that is created will operate in asynchronous mode.

schemaType of type DOMString

An absolute URI representing the type of the schema language used during the load of a Document using the newly created LSParser. Note that no lexical checking is done on the absolute URI. In order to create a LSParser for any kind of schema types (i.e. the LSParser will be free to use any schema found), use the value null.

Note: For W3C XML Schema [XML Schema Part 1], applications must use the value "http://www.w3.org/2001/XMLSchema". For XML DTD [XML 1.0], applications must use the value "http://www.w3.org/TR/REC-xml". Other Schema languages are outside the scope of the W3C and therefore should recommend an absolute URI in order to use this method.

Return Value

LSParser

The newly created LSParser object. This LSParser is either synchronous or asynchronous depending on the value of the mode argument. Note: By default, the newly created LSParser does not contain a DOMErrorHandler, i.e. the value of the "error-handler" configuration parameter is null. However, implementations may provide a default error handler at creation time. In that case, the initial value of the "error-handler" configuration parameter on the new LSParser object contains a reference to the default error handler.

Exceptions

DOMException

NOT_SUPPORTED_ERR: Raised if the requested mode or schema type is not supported.

createLSSerializer

Create a new LSSerializer object.

Return Value

LSSerializer

The newly created LSSerializer object. Note: By default, the newly created LSSerializer has no DOMErrorHandler, i.e. the value of the "error-handler" configuration parameter is null. However, implementations may provide a default error handler at creation time. In that case, the initial value of the "error-handler" configuration parameter on the new LSSerializer object contains a reference to the default error handler.

No Parameters

No Exceptions

Interface LSParser

An interface to an object that is able to build, or augment, a DOM tree from various input sources.

LSParser provides an API for parsing XML and building the corresponding DOM document structure. A LSParser instance can be obtained by invoking the DOMImplementationLS.createLSParser() method.

As specified in [DOM Level 3 Core], when a document is first made available via the LSParser:

• there will never be two adjacent nodes of type NODE_TEXT, and there will never be empty text nodes.
• it is expected that the value and nodeValue attributes of an Attr node initially return the XML 1.0 normalized value. However, if the parameters "validate-if-schema" and "datatype-normalization" are set to true, depending on the attribute normalization used, the attribute values may differ from the ones obtained by the XML 1.0 attribute normalization. If the parameters "datatype-normalization" is set to false, the XML 1.0 attribute normalization is guaranteed to occur, and if the attributes list does not contain namespace declarations, the attributes attribute on Element node represents the property [attributes] defined in [XML Information Set].

Asynchronous LSParser objects are expected to also implement the events::EventTarget interface so that event listeners can be registered on asynchronous LSParser objects.

Events supported by asynchronous LSParser objects are:

load

The LSParser finishes to load the document. See also the definition of the LSLoadEvent interface.

progress

The LSParser signals progress as data is parsed.
This specification does not attempt to define exactly when progress events should be dispatched. That is intentionally left as implementation-dependent. Here is one example of how an application might dispatch progress events: Once the parser starts receiving data, a progress event is dispatched to indicate that the parsing starts. From there on, a progress event is dispatched for every 4096 bytes of data that is received and processed. This is only one example, though, and implementations can choose to dispatch progress events at any time while parsing, or not dispatch them at all.
See also the definition of the LSProgressEvent interface.

Note: All events defined in this specification use the namespace URI "http://www.w3.org/2002/DOMLS".

While parsing an input source, errors are reported to the application through the error handler (LSParser.domConfig's "error-handler" parameter). This specification does in no way try to define all possible errors that can occur while parsing XML, or any other markup, but some common error cases are defined. The types (DOMError.type) of errors and warnings defined by this specification are:

"check-character-normalization-failure" [error]

Raised if the parameter "check-character-normalization" is set to true and a string is encountered that fails normalization checking.

"doctype-not-allowed" [fatal]

Raised if the configuration parameter "disallow-doctype" is set to true and a doctype is encountered.

"no-input-specified" [fatal]

Raised when loading a document and no input is specified in the LSInput object.

"pi-base-uri-not-preserved" [warning]

Raised if a processing instruction is encountered in a location where the base URI of the processing instruction can not be preserved.
One example of a case where this warning will be raised is if the configuration parameter "entities" is set to false and the following XML file is parsed:

<!DOCTYPE root [
<!ENTITY e SYSTEM 'subdir/myentity.ent'
]>

<root>
&e;
</root>

And subdir/myentity.ent contains:

<one>
  <two/>
</one>
<?pi 3.14159?>
<more/>

"unbound-prefix-in-entity" [warning]

An implementation dependent warning that may be raised if the configuration parameter "namespaces" is set to true and an unbound namespace prefix is encountered in an entity's replacement text. Raising this warning is not enforced since some existing parsers may not recognize unbound namespace prefixes in the replacement text of entities.

"unknown-character-denormalization" [fatal]

Raised if the configuration parameter "ignore-unknown-character-denormalizations" is set to false and a character is encountered for which the processor cannot determine the normalization properties.

"unsupported-encoding" [fatal]

Raised if an unsupported encoding is encountered.

"unsupported-media-type" [fatal]

Raised if the configuration parameter "supported-media-types-only" is set to true and an unsupported media type is encountered.

In addition to raising the defined errors and warnings, implementations are expected to raise implementation specific errors and warnings for any other error and warning cases such as IO errors (file not found, permission denied,...), XML well-formedness errors, and so on.

IDL Definition

interface LSParser {
  readonly attribute DOMConfiguration domConfig;
           attribute LSParserFilter  filter;
  readonly attribute boolean         async;
  readonly attribute boolean         busy;
  Document           parse(in LSInput input)
                                        raises(DOMException, 
                                               LSException);
  Document           parseURI(in DOMString uri)
                                        raises(DOMException, 
                                               LSException);

  // ACTION_TYPES
  const unsigned short      ACTION_APPEND_AS_CHILDREN      = 1;
  const unsigned short      ACTION_REPLACE_CHILDREN        = 2;
  const unsigned short      ACTION_INSERT_BEFORE           = 3;
  const unsigned short      ACTION_INSERT_AFTER            = 4;
  const unsigned short      ACTION_REPLACE                 = 5;

  Node               parseWithContext(in LSInput input, 
                                      in Node contextArg, 
                                      in unsigned short action)
                                        raises(DOMException, 
                                               LSException);
  void               abort();
};

Definition group ACTION_TYPES

A set of possible actions for the parseWithContext method.

Defined Constants

ACTION_APPEND_AS_CHILDREN

Append the result of the parse operation as children of the context node. For this action to work, the context node must be an Element or a DocumentFragment.

ACTION_INSERT_AFTER

Insert the result of the parse operation as the immediately following sibling of the context node. For this action to work the context node's parent must be an Element or a DocumentFragment.

ACTION_INSERT_BEFORE

Insert the result of the parse operation as the immediately preceding sibling of the context node. For this action to work the context node's parent must be an Element or a DocumentFragment.

ACTION_REPLACE

Replace the context node with the result of the parse operation. For this action to work, the context node must have a parent, and the parent must be an Element or a DocumentFragment.

ACTION_REPLACE_CHILDREN

Replace all the children of the context node with the result of the parse operation. For this action to work, the context node must be an Element, a Document, or a DocumentFragment.

Attributes

async of type boolean, readonly

true if the LSParser is asynchronous, false if it is synchronous.

busy of type boolean, readonly

true if the LSParser is currently busy loading a document, otherwise false.

domConfig of type DOMConfiguration, readonly

The DOMConfiguration object used when parsing an input source. This DOMConfiguration is specific to the parse operation. No parameter values from this DOMConfiguration object are passed automatically to the DOMConfiguration object on the Document that is created, or used, by the parse operation. The DOM application is responsible for passing any needed parameter values from this DOMConfiguration object to the DOMConfiguration object referenced by the Document object.
In addition to the parameters recognized in on the DOMConfiguration interface defined in [DOM Level 3 Core], the DOMConfiguration objects for LSParser add or modify the following parameters:

"charset-overrides-xml-encoding"

true

[optional] (default)
If a higher level protocol such as HTTP [IETF RFC 2616] provides an indication of the character encoding of the input stream being processed, that will override any encoding specified in the XML declaration or the Text declaration (see also section 4.3.3, "Character Encoding in Entities", in [XML 1.0]). Explicitly setting an encoding in the LSInput overrides any encoding from the protocol.

false

[required]
The parser ignores any character set encoding information from higher-level protocols.

"disallow-doctype"

true

[optional]
Throw a fatal "doctype-not-allowed" error if a doctype node is found while parsing the document. This is useful when dealing with things like SOAP envelopes where doctype nodes are not allowed.

false

[required] (default)
Allow doctype nodes in the document.

"ignore-unknown-character-denormalizations"

true

[required] (default)
If, while verifying full normalization when [XML 1.1] is supported, a processor encounters characters for which it cannot determine the normalization properties, then the processor will ignore any possible denormalizations caused by these characters.
This parameter is ignored for [XML 1.0].

false

[optional]
Report an fatal "unknown-character-denormalization" error if a character is encountered for which the processor cannot determine the normalization properties.

"infoset"

See the definition of DOMConfiguration for a description of this parameter. Unlike in [DOM Level 3 Core], this parameter will default to true for LSParser.

"namespaces"

true

[required] (default)
Perform the namespace processing as defined in [XML Namespaces] and [XML Namespaces 1.1].

false

[optional]
Do not perform the namespace processing.

"resource-resolver"

[required]
A reference to a LSResourceResolver object, or null. If the value of this parameter is not null when an external resource (such as an external XML entity or an XML schema location) is encountered, the implementation will request that the LSResourceResolver referenced in this parameter resolves the resource.

"supported-media-types-only"

true

[optional]
Check that the media type of the parsed resource is a supported media type. If an unsupported media type is encountered, a fatal error of type "unsupported-media-type" will be raised. The media types defined in [IETF RFC 3023] must always be accepted.

false

[required] (default)
Accept any media type.

"validate"

See the definition of DOMConfiguration for a description of this parameter. Unlike in [DOM Level 3 Core], the processing of the internal subset is always accomplished, even if this parameter is set to false.

"validate-if-schema"

See the definition of DOMConfiguration for a description of this parameter. Unlike in [DOM Level 3 Core], the processing of the internal subset is always accomplished, even if this parameter is set to false.

"well-formed"

See the definition of DOMConfiguration for a description of this parameter. Unlike in [DOM Level 3 Core], this parameter cannot be set to false.

filter of type LSParserFilter

When a filter is provided, the implementation will call out to the filter as it is constructing the DOM tree structure. The filter can choose to remove elements from the document being constructed, or to terminate the parsing early.
The filter is invoked after the operations requested by the DOMConfiguration parameters have been applied. For example, if "validate" is set to true, the validation is done before invoking the filter.

Methods

abort

Abort the loading of the document that is currently being loaded by the LSParser. If the LSParser is currently not busy, a call to this method does nothing.

No Parameters

No Return Value

No Exceptions

parse

Parse an XML document from a resource identified by a LSInput.

Parameters

input of type LSInput

The LSInput from which the source of the document is to be read.

Return Value

Document

If the LSParser is a synchronous LSParser, the newly created and populated Document is returned. If the LSParser is asynchronous, null is returned since the document object may not yet be constructed when this method returns.

Exceptions

DOMException	INVALID_STATE_ERR: Raised if the LSParser's LSParser.busy attribute is true.
LSException	PARSE_ERR: Raised if the LSParser was unable to load the XML document. DOM applications should attach a DOMErrorHandler using the parameter "error-handler" if they wish to get details on the error.

parseURI

Parse an XML document from a location identified by a URI reference [IETF RFC 2396]. If the URI contains a fragment identifier (see section 4.1 in [IETF RFC 2396]), the behavior is not defined by this specification, future versions of this specification may define the behavior.

Parameters

uri of type DOMString

The location of the XML document to be read.

Return Value

Document

If the LSParser is a synchronous LSParser, the newly created and populated Document is returned, or null if an error occured. If the LSParser is asynchronous, null is returned since the document object may not yet be constructed when this method returns.

Exceptions

DOMException	INVALID_STATE_ERR: Raised if the LSParser.busy attribute is true.
LSException	PARSE_ERR: Raised if the LSParser was unable to load the XML document. DOM applications should attach a DOMErrorHandler using the parameter "error-handler" if they wish to get details on the error.

parseWithContext

Parse an XML fragment from a resource identified by a LSInput and insert the content into an existing document at the position specified with the context and action arguments. When parsing the input stream, the context node (or its parent, depending on where the result will be inserted) is used for resolving unbound namespace prefixes. The context node's ownerDocument node (or the node itself if the node of type DOCUMENT_NODE) is used to resolve default attributes and entity references.
As the new data is inserted into the document, at least one mutation event is fired per new immediate child or sibling of the context node.
If the context node is a Document node and the action is ACTION_REPLACE_CHILDREN, then the document that is passed as the context node will be changed such that its xmlEncoding, documentURI, xmlVersion, inputEncoding, xmlStandalone, and all other such attributes are set to what they would be set to if the input source was parsed using LSParser.parse().
This method is always synchronous, even if the LSParser is asynchronous (LSParser.async is true).
If an error occurs while parsing, the caller is notified through the ErrorHandler instance associated with the "error-handler" parameter of the DOMConfiguration.
When calling parseWithContext, the values of the following configuration parameters will be ignored and their default values will always be used instead: "validate", "validate-if-schema", and "element-content-whitespace". Other parameters will be treated normally, and the parser is expected to call the LSParserFilter just as if a whole document was parsed.

Parameters

input of type LSInput

The LSInput from which the source document is to be read. The source document must be an XML fragment, i.e. anything except a complete XML document (except in the case where the context node of type DOCUMENT_NODE, and the action is ACTION_REPLACE_CHILDREN), a DOCTYPE (internal subset), entity declaration(s), notation declaration(s), or XML or text declaration(s).

contextArg of type Node

The node that is used as the context for the data that is being parsed. This node must be a Document node, a DocumentFragment node, or a node of a type that is allowed as a child of an Element node, e.g. it cannot be an Attribute node.

action of type unsigned short

This parameter describes which action should be taken between the new set of nodes being inserted and the existing children of the context node. The set of possible actions is defined in ACTION_TYPES above.

Return Value

Node	Return the node that is the result of the parse operation. If the result is more than one top-level node, the first one is returned.

Exceptions

DOMException

HIERARCHY_REQUEST_ERR: Raised if the content cannot replace, be inserted before, after, or as a child of the context node (see also Node.insertBefore or Node.replaceChild in [DOM Level 3 Core]). NOT_SUPPORTED_ERR: Raised if the LSParser doesn't support this method, or if the context node is of type Document and the DOM implementation doesn't support the replacement of the DocumentType child or Element child. NO_MODIFICATION_ALLOWED_ERR: Raised if the context node is a read only node and the content is being appended to its child list, or if the parent node of the context node is read only node and the content is being inserted in its child list. INVALID_STATE_ERR: Raised if the LSParser.busy attribute is true.

LSException

PARSE_ERR: Raised if the LSParser was unable to load the XML fragment. DOM applications should attach a DOMErrorHandler using the parameter "error-handler" if they wish to get details on the error.

Interface LSInput

This interface represents an input source for data.

This interface allows an application to encapsulate information about an input source in a single object, which may include a public identifier, a system identifier, a byte stream (possibly with a specified encoding), a base URI, and/or a character stream.

The exact definitions of a byte stream and a character stream are binding dependent.

The application is expected to provide objects that implement this interface whenever such objects are needed. The application can either provide its own objects that implement this interface, or it can use the generic factory method DOMImplementationLS.createLSInput() to create objects that implement this interface.

The LSParser will use the LSInput object to determine how to read data. The LSParser will look at the different inputs specified in the LSInput in the following order to know which one to read from, the first one that is not null and not an empty string will be used:

1. LSInput.characterStream
2. LSInput.byteStream
3. LSInput.stringData
4. LSInput.systemId
5. LSInput.publicId

If all inputs are null, the LSParser will report a DOMError with its DOMError.type set to "no-input-specified" and its DOMError.severity set to DOMError.SEVERITY_FATAL_ERROR.

LSInput objects belong to the application. The DOM implementation will never modify them (though it may make copies and modify the copies, if necessary).

IDL Definition

interface LSInput {
  // Depending on the language binding in use,
  // this attribute may not be available.
           attribute LSReader        characterStream;
           attribute LSInputStream   byteStream;
           attribute DOMString       stringData;
           attribute DOMString       systemId;
           attribute DOMString       publicId;
           attribute DOMString       baseURI;
           attribute DOMString       encoding;
           attribute boolean         certifiedText;
};

Attributes

baseURI of type DOMString

The base URI to be used (see section 5.1.4 in [IETF RFC 2396]) for resolving a relative systemId to an absolute URI.
If, when used, the base URI is itself a relative URI, an empty string, or null, the behavior is implementation dependent.

byteStream of type LSInputStream

An attribute of a language and binding dependent type that represents a stream of bytes.
If the application knows the character encoding of the byte stream, it should set the encoding attribute. Setting the encoding in this way will override any encoding specified in an XML declaration in the data.

certifiedText of type boolean

If set to true, assume that the input is certified (see section 2.13 in [XML 1.1]) when parsing [XML 1.1].

characterStream of type LSReader
Depending on the language binding in use, this attribute may not be available.

An attribute of a language and binding dependent type that represents a stream of 16-bit units. The application must encode the stream using UTF-16 (defined in [Unicode] and in [ISO/IEC 10646]). It is not a requirement to have an XML declaration when using character streams. If an XML declaration is present, the value of the encoding attribute will be ignored.

encoding of type DOMString

The character encoding, if known. The encoding must be a string acceptable for an XML encoding declaration ([XML 1.0] section 4.3.3 "Character Encoding in Entities").
This attribute has no effect when the application provides a character stream or string data. For other sources of input, an encoding specified by means of this attribute will override any encoding specified in the XML declaration or the Text declaration, or an encoding obtained from a higher level protocol, such as HTTP [IETF RFC 2616].

publicId of type DOMString

The public identifier for this input source. This may be mapped to an input source using an implementation dependent mechanism (such as catalogues or other mappings). The public identifier, if specified, may also be reported as part of the location information when errors are reported.

stringData of type DOMString

String data to parse. If provided, this will always be treated as a sequence of 16-bit units (UTF-16 encoded characters). It is not a requirement to have an XML declaration when using stringData. If an XML declaration is present, the value of the encoding attribute will be ignored.

systemId of type DOMString

The system identifier, a URI reference [IETF RFC 2396], for this input source. The system identifier is optional if there is a byte stream, a character stream, or string data. It is still useful to provide one, since the application will use it to resolve any relative URIs and can include it in error messages and warnings. (The LSParser will only attempt to fetch the resource identified by the URI reference if there is no other input available in the input source.)
If the application knows the character encoding of the object pointed to by the system identifier, it can set the encoding using the encoding attribute.
If the specified system ID is a relative URI reference (see section 5 in [IETF RFC 2396]), the DOM implementation will attempt to resolve the relative URI with the baseURI as the base, if that fails, the behavior is implementation dependent.

Interface LSResourceResolver

LSResourceResolver provides a way for applications to redirect references to external resources.

Applications needing to implement custom handling for external resources can implement this interface and register their implementation by setting the "resource-resolver" parameter of DOMConfiguration objects attached to LSParser and LSSerializer. It can also be register on DOMConfiguration objects attached to Document if the "LS" feature is supported.

The LSParser will then allow the application to intercept any external entities, including the external DTD subset and external parameter entities, before including them. The top-level document entity is never passed to the resolveResource method.

Many DOM applications will not need to implement this interface, but it will be especially useful for applications that build XML documents from databases or other specialized input sources, or for applications that use URNs.

Note: LSResourceResolver is based on the SAX2 [SAX] EntityResolver interface.

IDL Definition

interface LSResourceResolver {
  LSInput            resolveResource(in DOMString type, 
                                     in DOMString namespaceURI, 
                                     in DOMString publicId, 
                                     in DOMString systemId, 
                                     in DOMString baseURI);
};

Methods

resolveResource

Allow the application to resolve external resources.
The LSParser will call this method before opening any external resource, including the external DTD subset, external entities referenced within the DTD, and external entities referenced within the document element (however, the top-level document entity is not passed to this method). The application may then request that the LSParser resolve the external resource itself, that it use an alternative URI, or that it use an entirely different input source.
Application writers can use this method to redirect external system identifiers to secure and/or local URI, to look up public identifiers in a catalogue, or to read an entity from a database or other input source (including, for example, a dialog box).

Parameters

type of type DOMString

The type of the resource being resolved. For XML [XML 1.0] resources (i.e. entities), applications must use the value "http://www.w3.org/TR/REC-xml". For XML Schema [XML Schema Part 1], applications must use the value "http://www.w3.org/2001/XMLSchema". Other types of resources are outside the scope of this specification and therefore should recommend an absolute URI in order to use this method.

namespaceURI of type DOMString

The namespace of the resource being resolved, e.g. the target namespace of the XML Schema [XML Schema Part 1] when resolving XML Schema resources.

publicId of type DOMString

The public identifier of the external entity being referenced, or null if no public identifier was supplied or if the resource is not an entity.

systemId of type DOMString

The system identifier, a URI reference [IETF RFC 2396], of the external resource being referenced, or null if no system identifier was supplied.

baseURI of type DOMString

The absolute base URI of the resource being parsed, or null if there is no base URI.

Return Value

LSInput

A LSInput object describing the new input source, or null to request that the parser open a regular URI connection to the resource.

No Exceptions

Interface LSParserFilter

LSParserFilters provide applications the ability to examine nodes as they are being constructed while parsing. As each node is examined, it may be modified or removed, or the entire parse may be terminated early.

At the time any of the filter methods are called by the parser, the owner Document and DOMImplementation objects exist and are accessible. The document element is never passed to the LSParserFilter methods, i.e. it is not possible to filter out the document element. Document, DocumentType, Notation, Entity, and Attr nodes are never passed to the acceptNode method on the filter. The child nodes of an EntityReference node are passed to the filter if the parameter "entities" is set to false. Note that, as described by the parameter "entities", unexpanded entity reference nodes are never discarded and are always passed to the filter.

All validity checking while parsing a document occurs on the source document as it appears on the input stream, not on the DOM document as it is built in memory. With filters, the document in memory may be a subset of the document on the stream, and its validity may have been affected by the filtering.

All default attributes must be present on elements when the elements are passed to the filter methods. All other default content must be passed to the filter methods.

DOM applications must not raise exceptions in a filter. The effect of throwing exceptions from a filter is DOM implementation dependent.

IDL Definition

interface LSParserFilter {

  // Constants returned by startElement and acceptNode
  const short               FILTER_ACCEPT                  = 1;
  const short               FILTER_REJECT                  = 2;
  const short               FILTER_SKIP                    = 3;
  const short               FILTER_INTERRUPT               = 4;

  unsigned short     startElement(in Element elementArg);
  unsigned short     acceptNode(in Node nodeArg);
  readonly attribute unsigned long   whatToShow;
};

Definition group Constants returned by startElement and acceptNode

Constants returned by startElement and acceptNode.

Defined Constants

FILTER_ACCEPT

Accept the node.

FILTER_INTERRUPT

Interrupt the normal processing of the document.

FILTER_REJECT

Reject the node and its children.

FILTER_SKIP

Skip this single node. The children of this node will still be considered.

Attributes

whatToShow of type unsigned long, readonly

Tells the LSParser what types of nodes to show to the method LSParserFilter.acceptNode. If a node is not shown to the filter using this attribute, it is automatically included in the DOM document being built. See NodeFilter for definition of the constants. The constants SHOW_ATTRIBUTE, SHOW_DOCUMENT, SHOW_DOCUMENT_TYPE, SHOW_NOTATION, SHOW_ENTITY, and SHOW_DOCUMENT_FRAGMENT are meaningless here. Those nodes will never be passed to LSParserFilter.acceptNode.
The constants used here are defined in [DOM Level 2 Traversal and Range].

Methods

acceptNode

This method will be called by the parser at the completion of the parsing of each node. The node and all of its descendants will exist and be complete. The parent node will also exist, although it may be incomplete, i.e. it may have additional children that have not yet been parsed. Attribute nodes are never passed to this function.
From within this method, the new node may be freely modified - children may be added or removed, text nodes modified, etc. The state of the rest of the document outside this node is not defined, and the affect of any attempt to navigate to, or to modify any other part of the document is undefined.
For validating parsers, the checks are made on the original document, before any modification by the filter. No validity checks are made on any document modifications made by the filter.
If this new node is rejected, the parser might reuse the new node and any of its descendants.

Parameters

nodeArg of type Node

The newly constructed element. At the time this method is called, the element is complete - it has all of its children (and their children, recursively) and attributes, and is attached as a child to its parent.

Return Value

unsigned short

FILTER_ACCEPT if this Node should be included in the DOM document being built. FILTER_REJECT if the Node and all of its children should be rejected. FILTER_SKIP if the Node should be skipped and the Node should be replaced by all the children of the Node. FILTER_INTERRUPT if the filter wants to stop the processing of the document. Interrupting the processing of the document does no longer guarantee that the resulting DOM tree is XML well-formed. The Node is accepted and will be the last completely parsed node.

No Exceptions

startElement

The parser will call this method after each Element start tag has been scanned, but before the remainder of the Element is processed. The intent is to allow the element, including any children, to be efficiently skipped. Note that only element nodes are passed to the startElement function.
The element node passed to startElement for filtering will include all of the Element's attributes, but none of the children nodes. The Element may not yet be in place in the document being constructed (it may not have a parent node.)
A startElement filter function may access or change the attributes for the Element. Changing Namespace declarations will have no effect on namespace resolution by the parser.
For efficiency, the Element node passed to the filter may not be the same one as is actually placed in the tree if the node is accepted. And the actual node (node object identity) may be reused during the process of reading in and filtering a document.

Parameters

elementArg of type Element

The newly encountered element. At the time this method is called, the element is incomplete - it will have its attributes, but no children.

Return Value

unsigned short

FILTER_ACCEPT if the Element should be included in the DOM document being built. FILTER_REJECT if the Element and all of its children should be rejected. FILTER_SKIP if the Element should be skipped. All of its children are inserted in place of the skipped Element node. FILTER_INTERRUPT if the filter wants to stop the processing of the document. Interrupting the processing of the document does no longer guarantee that the resulting DOM tree is XML well-formed. The Element is rejected. Returning any other values will result in unspecified behavior.

No Exceptions

Interface LSProgressEvent

This interface represents a progress event object that notifies the application about progress as a document is parsed. It extends the Event interface defined in [DOM Level 3 Events].

The units used for the attributes position and totalSize are not specified and can be implementation and input dependent.

IDL Definition

interface LSProgressEvent : events::Event {
  readonly attribute LSInput         input;
  readonly attribute unsigned long   position;
  readonly attribute unsigned long   totalSize;
};

Attributes

input of type LSInput, readonly

The input source that is being parsed.

position of type unsigned long, readonly

The current position in the input source, including all external entities and other resources that have been read.

totalSize of type unsigned long, readonly

The total size of the document including all external resources, this number might change as a document is being parsed if references to more external resources are seen. A value of 0 is returned if the total size cannot be determined or estimated.

Interface LSLoadEvent

This interface represents a load event object that signals the completion of a document load.

IDL Definition

interface LSLoadEvent : events::Event {
  readonly attribute Document        newDocument;
  readonly attribute LSInput         input;
};

Attributes

input of type LSInput, readonly

The input source that was parsed.

newDocument of type Document, readonly

The document that finished loading.

Interface LSSerializer

A LSSerializer provides an API for serializing (writing) a DOM document out into XML. The XML data is written to a string or an output stream. Any changes or fixups made during the serialization affect only the serialized data. The Document object and its children are never altered by the serialization operation.

During serialization of XML data, namespace fixup is done as defined in [DOM Level 3 Core], Appendix B. [DOM Level 2 Core] allows empty strings as a real namespace URI. If the namespaceURI of a Node is empty string, the serialization will treat them as null, ignoring the prefix if any.

LSSerializer accepts any node type for serialization. For nodes of type Document or Entity, well-formed XML will be created when possible (well-formedness is guaranteed if the document or entity comes from a parse operation and is unchanged since it was created). The serialized output for these node types is either as a XML document or an External XML Entity, respectively, and is acceptable input for an XML parser. For all other types of nodes the serialized form is implementation dependent.

Within a Document, DocumentFragment, or Entity being serialized, Nodes are processed as follows

• Document nodes are written, including the XML declaration (unless the parameter "xml-declaration" is set to false) and a DTD subset, if one exists in the DOM. Writing a Document node serializes the entire document.
• Entity nodes, when written directly by LSSerializer.write, outputs the entity expansion but no namespace fixup is done. The resulting output will be valid as an external entity.
• If the parameter "entities" is set to true, EntityReference nodes are serialized as an entity reference of the form "&entityName;" in the output. Child nodes (the expansion) of the entity reference are ignored. If the parameter "entities" is set to false, only the children of the entity reference are serialized. EntityReference nodes with no children (no corresponding Entity node or the corresponding Entity nodes have no children) are always serialized.
• CDATAsections containing content characters that cannot be represented in the specified output encoding are handled according to the "split-cdata-sections" parameter.
  If the parameter is set to true, CDATAsections are split, and the unrepresentable characters are serialized as numeric character references in ordinary content. The exact position and number of splits is not specified.
  If the parameter is set to false, unrepresentable characters in a CDATAsection are reported as "wf-invalid-character" errors if the parameter "well-formed" is set to true. The error is not recoverable - there is no mechanism for supplying alternative characters and continuing with the serialization.
• DocumentFragment nodes are serialized by serializing the children of the document fragment in the order they appear in the document fragment.
• All other node types (Element, Text, etc.) are serialized to their corresponding XML source form.

Note: The serialization of a Node does not always generate a well-formed XML document, i.e. a LSParser might throw fatal errors when parsing the resulting serialization.

Within the character data of a document (outside of markup), any characters that cannot be represented directly are replaced with character references. Occurrences of '<' and '&' are replaced by the predefined entities &lt; and &amp;. The other predefined entities (&gt;, &apos;, and &quot;) might not be used, except where needed (e.g. using &gt; in cases such as ']]>'). Any characters that cannot be represented directly in the output character encoding are serialized as numeric character references (and since character encoding standards commonly use hexadecimal representations of characters, using the hexadecimal representation when serializing character references is encouraged).

To allow attribute values to contain both single and double quotes, the apostrophe or single-quote character (') may be represented as "&apos;", and the double-quote character (") as "&quot;". New line characters and other characters that cannot be represented directly in attribute values in the output character encoding are serialized as a numeric character reference.

Within markup, but outside of attributes, any occurrence of a character that cannot be represented in the output character encoding is reported as a DOMError fatal error. An example would be serializing the element <LaCañada/> with encoding="us-ascii". This will result with a generation of a DOMError "wf-invalid-character-in-node-name" (as proposed in "well-formed").

When requested by setting the parameter "normalize-characters" on LSSerializer to true, character normalization is performed according to the definition of fully normalized characters included in appendix E of [XML 1.1] on all data to be serialized, both markup and character data. The character normalization process affects only the data as it is being written; it does not alter the DOM's view of the document after serialization has completed.

Implementations are required to support the encodings "UTF-8", "UTF-16", "UTF-16BE", and "UTF-16LE" to guarantee that data is serializable in all encodings that are required to be supported by all XML parsers. When the encoding is UTF-8, whether or not a byte order mark is serialized, or if the output is big-endian or little-endian, is implementation dependent. When the encoding is UTF-16, whether or not the output is big-endian or little-endian is implementation dependent, but a Byte Order Mark must be generated for non-character outputs, such as LSOutput.byteStream or LSOutput.systemId. If the Byte Order Mark is not generated, a "byte-order-mark-needed" warning is reported. When the encoding is UTF-16LE or UTF-16BE, the output is big-endian (UTF-16BE) or little-endian (UTF-16LE) and the Byte Order Mark is not be generated. In all cases, the encoding declaration, if generated, will correspond to the encoding used during the serialization (e.g. encoding="UTF-16" will appear if UTF-16 was requested).

Namespaces are fixed up during serialization, the serialization process will verify that namespace declarations, namespace prefixes and the namespace URI associated with elements and attributes are consistent. If inconsistencies are found, the serialized form of the document will be altered to remove them. The method used for doing the namespace fixup while serializing a document is the algorithm defined in Appendix B.1, "Namespace normalization", of [DOM Level 3 Core].

While serializing a document, the parameter "discard-default-content" controls whether or not non-specified data is serialized.

While serializing, errors and warnings are reported to the application through the error handler (LSSerializer.domConfig's "error-handler" parameter). This specification does in no way try to define all possible errors and warnings that can occur while serializing a DOM node, but some common error and warning cases are defined. The types (DOMError.type) of errors and warnings defined by this specification are:

"no-output-specified" [fatal]

Raised when writing to a LSOutput if no output is specified in the LSOutput.

"unbound-prefix-in-entity-reference" [fatal]

Raised if the configuration parameter "namespaces" is set to true and an entity whose replacement text contains unbound namespace prefixes is referenced in a location where there are no bindings for the namespace prefixes.

"unsupported-encoding" [fatal]

Raised if an unsupported encoding is encountered.

In addition to raising the defined errors and warnings, implementations are expected to raise implementation specific errors and warnings for any other error and warning cases such as IO errors (file not found, permission denied,...) and so on.

IDL Definition

interface LSSerializer {
  readonly attribute DOMConfiguration domConfig;
           attribute DOMString       newLine;
           attribute LSSerializerFilter filter;
  boolean            write(in Node nodeArg, 
                           in LSOutput destination)
                                        raises(LSException);
  boolean            writeToURI(in Node nodeArg, 
                                in DOMString uri)
                                        raises(LSException);
  DOMString          writeToString(in Node nodeArg)
                                        raises(DOMException, 
                                               LSException);
};

Attributes

domConfig of type DOMConfiguration, readonly

The DOMConfiguration object used by the LSSerializer when serializing a DOM node.
In addition to the parameters recognized by the DOMConfiguration interface defined in [DOM Level 3 Core], the DOMConfiguration objects for LSSerializer adds, or modifies, the following parameters:

"canonical-form"

true

[optional]
Writes the document according to the rules specified in [Canonical XML]. In addition to the behavior described in "canonical-form" [DOM Level 3 Core], setting this parameter to true will set the parameters "format-pretty-print", "discard-default-content", and "xml-declaration", to false. Setting one of those parameters to true will set this parameter to false. Serializing an XML 1.1 document when "canonical-form" is true will generate a fatal error.

false

[required] (default)
Do not canonicalize the output.

"discard-default-content"

true

[required] (default)
Use the Attr.specified attribute to decide what attributes should be discarded. Note that some implementations might use whatever information available to the implementation (i.e. XML schema, DTD, the Attr.specified attribute, and so on) to determine what attributes and content to discard if this parameter is set to true.

false

[required]
Keep all attributes and all content.

"format-pretty-print"

true

[optional]
Formatting the output by adding whitespace to produce a pretty-printed, indented, human-readable form. The exact form of the transformations is not specified by this specification. Pretty-printing changes the content of the document and may affect the validity of the document, validating implementations should preserve validity.

false

[required] (default)
Don't pretty-print the result.

"ignore-unknown-character-denormalizations"

true

[required] (default)
If, while verifying full normalization when [XML 1.1] is supported, a character is encountered for which the normalization properties cannot be determined, then raise a "unknown-character-denormalization" warning (instead of raising an error, if this parameter is not set) and ignore any possible denormalizations caused by these characters.

false

[optional]
Report a fatal error if a character is encountered for which the processor cannot determine the normalization properties.

"normalize-characters"

This parameter is equivalent to the one defined by DOMConfiguration in [DOM Level 3 Core]. Unlike in the Core, the default value for this parameter is true. While DOM implementations are not required to support fully normalizing the characters in the document according to appendix E of [XML 1.1], this parameter must be activated by default if supported.

"xml-declaration"

true

[required] (default)
If a Document, Element, or Entity node is serialized, the XML declaration, or text declaration, should be included. The version (Document.xmlVersion if the document is a Level 3 document and the version is non-null, otherwise use the value "1.0"), and the output encoding (see LSSerializer.write for details on how to find the output encoding) are specified in the serialized XML declaration.

false

[required]
Do not serialize the XML and text declarations. Report a "xml-declaration-needed" warning if this will cause problems (i.e. the serialized data is of an XML version other than [XML 1.0], or an encoding would be needed to be able to re-parse the serialized data).

filter of type LSSerializerFilter

When the application provides a filter, the serializer will call out to the filter before serializing each Node. The filter implementation can choose to remove the node from the stream or to terminate the serialization early.
The filter is invoked after the operations requested by the DOMConfiguration parameters have been applied. For example, CDATA sections won't be passed to the filter if "cdata-sections" is set to false.

newLine of type DOMString

The end-of-line sequence of characters to be used in the XML being written out. Any string is supported, but XML treats only a certain set of characters sequence as end-of-line (See section 2.11, "End-of-Line Handling" in [XML 1.0], if the serialized content is XML 1.0 or section 2.11, "End-of-Line Handling" in [XML 1.1], if the serialized content is XML 1.1). Using other character sequences than the recommended ones can result in a document that is either not serializable or not well-formed).
On retrieval, the default value of this attribute is the implementation specific default end-of-line sequence. DOM implementations should choose the default to match the usual convention for text files in the environment being used. Implementations must choose a default sequence that matches one of those allowed by XML 1.0 or XML 1.1, depending on the serialized content. Setting this attribute to null will reset its value to the default value.

Methods

write

Serialize the specified node as described above in the general description of the LSSerializer interface. The output is written to the supplied LSOutput.
When writing to a LSOutput, the encoding is found by looking at the encoding information that is reachable through the LSOutput and the item to be written (or its owner document) in this order:

1. LSOutput.encoding,
2. Document.inputEncoding,
3. Document.xmlEncoding.

If no encoding is reachable through the above properties, a default encoding of "UTF-8" will be used. If the specified encoding is not supported an "unsupported-encoding" fatal error is raised.
If no output is specified in the LSOutput, a "no-output-specified" fatal error is raised.
The implementation is responsible of associating the appropriate media type with the serialized data.
When writing to a HTTP URI, a HTTP PUT is performed. When writing to other types of URIs, the mechanism for writing the data to the URI is implementation dependent.

Parameters

nodeArg of type Node

The node to serialize.

destination of type LSOutput

The destination for the serialized DOM.

Return Value

boolean

Returns true if node was successfully serialized. Return false in case the normal processing stopped but the implementation kept serializing the document; the result of the serialization being implementation dependent then.

Exceptions

LSException

SERIALIZE_ERR: Raised if the LSSerializer was unable to serialize the node. DOM applications should attach a DOMErrorHandler using the parameter "error-handler" if they wish to get details on the error.

writeToString

Serialize the specified node as described above in the general description of the LSSerializer interface. The output is written to a DOMString that is returned to the caller. The encoding used is the encoding of the DOMString type, i.e. UTF-16. Note that no Byte Order Mark is generated in a DOMString object.

Parameters

nodeArg of type Node

The node to serialize.

Return Value

DOMString

Returns the serialized data.

Exceptions

DOMException	DOMSTRING_SIZE_ERR: Raised if the resulting string is too long to fit in a DOMString.
LSException	SERIALIZE_ERR: Raised if the LSSerializer was unable to serialize the node. DOM applications should attach a DOMErrorHandler using the parameter "error-handler" if they wish to get details on the error.

writeToURI

A convenience method that acts as if LSSerializer.write was called with a LSOutput with no encoding specified and LSOutput.systemId set to the uri argument.

Parameters

nodeArg of type Node

The node to serialize.

uri of type DOMString

The URI to write to.

Return Value

boolean

Returns true if node was successfully serialized. Return false in case the normal processing stopped but the implementation kept serializing the document; the result of the serialization being implementation dependent then.

Exceptions

LSException

SERIALIZE_ERR: Raised if the LSSerializer was unable to serialize the node. DOM applications should attach a DOMErrorHandler using the parameter "error-handler" if they wish to get details on the error.

Interface LSOutput

This interface represents an output destination for data.

This interface allows an application to encapsulate information about an output destination in a single object, which may include a URI, a byte stream (possibly with a specified encoding), a base URI, and/or a character stream.

The exact definitions of a byte stream and a character stream are binding dependent.

The application is expected to provide objects that implement this interface whenever such objects are needed. The application can either provide its own objects that implement this interface, or it can use the generic factory method DOMImplementationLS.createLSOutput() to create objects that implement this interface.

The LSSerializer will use the LSOutput object to determine where to serialize the output to. The LSSerializer will look at the different outputs specified in the LSOutput in the following order to know which one to output to, the first one that is not null and not an empty string will be used:

1. LSOutput.characterStream
2. LSOutput.byteStream
3. LSOutput.systemId

LSOutput objects belong to the application. The DOM implementation will never modify them (though it may make copies and modify the copies, if necessary).

IDL Definition

interface LSOutput {
  // Depending on the language binding in use,
  // this attribute may not be available.
           attribute LSWriter        characterStream;
           attribute LSOutputStream  byteStream;
           attribute DOMString       systemId;
           attribute DOMString       encoding;
};

Attributes

byteStream of type LSOutputStream

An attribute of a language and binding dependent type that represents a writable stream of bytes.

characterStream of type LSWriter
Depending on the language binding in use, this attribute may not be available.

An attribute of a language and binding dependent type that represents a writable stream to which 16-bit units can be output.

encoding of type DOMString

The character encoding to use for the output. The encoding must be a string acceptable for an XML encoding declaration ([XML 1.0] section 4.3.3 "Character Encoding in Entities"), it is recommended that character encodings registered (as charsets) with the Internet Assigned Numbers Authority [IANA-CHARSETS] should be referred to using their registered names.

systemId of type DOMString

The system identifier, a URI reference [IETF RFC 2396], for this output destination.
If the system ID is a relative URI reference (see section 5 in [IETF RFC 2396]), the behavior is implementation dependent.

Interface LSSerializerFilter

LSSerializerFilters provide applications the ability to examine nodes as they are being serialized and decide what nodes should be serialized or not. The LSSerializerFilter interface is based on the NodeFilter interface defined in [DOM Level 2 Traversal and Range].

Document, DocumentType, DocumentFragment, Notation, Entity, and children of Attr nodes are not passed to the filter. The child nodes of an EntityReference node are only passed to the filter if the EntityReference node is skipped by the method LSParserFilter.acceptNode().

When serializing an Element, the element is passed to the filter before any of its attributes are passed to the filter. Namespace declaration attributes, and default attributes (except in the case when "discard-default-content" is set to false), are never passed to the filter.

The result of any attempt to modify a node passed to a LSSerializerFilter is implementation dependent.

DOM applications must not raise exceptions in a filter. The effect of throwing exceptions from a filter is DOM implementation dependent.

For efficiency, a node passed to the filter may not be the same as the one that is actually in the tree. And the actual node (node object identity) may be reused during the process of filtering and serializing a document.

IDL Definition

interface LSSerializerFilter : traversal::NodeFilter {
  readonly attribute unsigned long   whatToShow;
};

Attributes

whatToShow of type unsigned long, readonly

Tells the LSSerializer what types of nodes to show to the filter. If a node is not shown to the filter using this attribute, it is automatically serialized. See NodeFilter for definition of the constants. The constants SHOW_DOCUMENT, SHOW_DOCUMENT_TYPE, SHOW_DOCUMENT_FRAGMENT, SHOW_NOTATION, and SHOW_ENTITY are meaningless here, such nodes will never be passed to a LSSerializerFilter.
Unlike [DOM Level 2 Traversal and Range], the SHOW_ATTRIBUTE constant indicates that the Attr nodes are shown and passed to the filter.
The constants used here are defined in [DOM Level 2 Traversal and Range].