[W3C] Document Object Model (DOM) Level 3 Content Models and Load and Save Specification Version 1.0 W3C Working Draft 19 April 2001 This version: http://www.w3.org/TR/2001/WD-DOM-Level-3-CMLS-20010419 ( PostScript file , PDF file , plain text , ZIP file , single HTML file) Latest version: http://www.w3.org/TR/DOM-Level-3-CMLS Previous version: http://www.w3.org/TR/2001/WD-DOM-Level-3-CMLS-20010209 Editors: Ben Chang, Oracle Andy Heninger, IBM Joe Kesselman, IBM Rezaur Rahman, Intel Corporation Copyright ©2001 W3C® (MIT, INRIA, Keio), All Rights Reserved. W3C liability, trademark, document use and software licensing rules apply. ---------------------------------------------------------------------------- Abstract This specification defines the Document Object Model Content Models and Load and Save Level 3, a platform- and language-neutral interface that allows programs and scripts to dynamically access and update the content, structure and style of documents. The Document Object Model Content Models and Load and Save Level 3 builds on the Document Object Model Core Level 3. Status of this document This section describes the status of this document at the time of its publication. Other documents may supersede this document. The latest status of this document series is maintained at the W3C. This is a W3C Working Draft for review by W3C members and other interested parties. It is a draft document and may be updated, replaced or obsoleted by other documents at any time. It is inappropriate to use W3C Working Drafts as reference material or to cite them as other than "work in progress". This is work in progress and does not imply endorsement by, or the consensus of, either W3C or members of the DOM working group. Comments on this document are invited and are to be sent to the public mailing list www-dom@w3.org. An archive is available at http://lists.w3.org/Archives/Public/www-dom/. This document has been produced as part of the W3C DOM Activity. The authors of this document are the DOM WG members. A list of current W3C Recommendations and other technical documents can be found at http://www.w3.org/TR. Table of contents * Expanded Table of Contents * Copyright Notice * Chapter 1: Content Models and Validation * Chapter 2: Document Object Model Load and Save * Appendix A: IDL Definitions * Appendix B: Java Language Binding * Appendix C: ECMA Script Language Binding * References * Index 19 April 2001 Expanded Table of Contents * Expanded Table of Contents * Copyright Notice o W3C Document Copyright Notice and License o W3C Software Copyright Notice and License * Chapter 1: Content Models and Validation o 1.1. Overview + 1.1.1. General Characteristics + 1.1.2. Use Cases and Requirements o 1.2. Content Model and CM-Editing Interfaces o 1.3. Validation and Other Interfaces o 1.4. Document-Editing Interfaces o 1.5. DOM Error Handler Interfaces o 1.6. Editing and Generating a Content Model o 1.7. Content Model-directed Document Manipulation o 1.8. Validating a Document Against a Content Model o 1.9. Well-formedness Testing * Chapter 2: Document Object Model Load and Save o 2.1. Load and Save Requirements + 2.1.1. General Requirements + 2.1.2. Load Requirements + 2.1.3. XML Writer Requirements + 2.1.4. Other Items Under Consideration o 2.2. Issue List + 2.2.1. Open Issues + 2.2.2. Resolved Issues o 2.3. Interfaces + 2.3.1. Interface Summary + 2.3.2. Interfaces * Appendix A: IDL Definitions * Appendix B: Java Language Binding * Appendix C: ECMA Script Language Binding * References o 1. Normative references * Index 19 April 2001 Copyright Notice Copyright © 2001 World Wide Web Consortium, (Massachusetts Institute of Technology, Institut National de Recherche en Informatique et en Automatique, Keio University). All Rights Reserved. This document is published under the W3C Document Copyright Notice and License. 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Content Models and Validation Editors Ben Chang, Oracle Joe Kesselman, IBM Rezaur Rahman, Intel Corporation Table of contents * 1.1. Overview o 1.1.1. General Characteristics o 1.1.2. Use Cases and Requirements * 1.2. Content Model and CM-Editing Interfaces o CMModel, CMExternalModel, CMNode, CMNodeList, CMNamedNodeMap, CMDataType, CMPrimitiveType, CMElementDeclaration, CMChildren, CMAttributeDeclaration, CMEntityDeclaration, CMNotationDeclaration * 1.3. Validation and Other Interfaces o Document, DocumentCM, DOMImplementationCM * 1.4. Document-Editing Interfaces o NodeCM, ElementCM, CharacterDataCM, DocumentTypeCM, AttributeCM * 1.5. DOM Error Handler Interfaces o DOMErrorHandler, DOMLocator * 1.6. Editing and Generating a Content Model * 1.7. Content Model-directed Document Manipulation * 1.8. Validating a Document Against a Content Model * 1.9. Well-formedness Testing 1.1. Overview This chapter describes the optional DOM Level 3 Content Model (CM) feature. This module provides a representation for XML content models, e.g., DTDs and XML Schemas, together with operations on the content models, and how such information within the content models could be applied to XML documents used in both the document-editing and CM-editing worlds. It also provides additional tests for well-formedness of XML documents, including Namespace well-formedness. A DOM application can use the hasFeature method of theDOMImplementation interface to determine whether a given DOM supports these capabilities or not. One feature string for the CM-editing interfaces listed in this section is "CM-EDIT" and another feature string for document-editing interfaces is "CM-DOC". This chapter interacts strongly with the Load and Save chapter, which is also under development in DOM Level 3. Not only will that code serialize/deserialize content models, but it may also wind up defining its well-formedness and validity checks in terms of what is defined in this chapter. In addition, the CM and Load/Save functional areas will share a common error-reporting mechanism allowing user-registered error callbacks. Note that this may not imply that the parser actually calls the DOM's validation code -- it may be able to achieve better performance via its own -- but the appearance to the user should probably be "as if" the DOM has been asked to validate the document, and parsers should probably be able to validate newly loaded documents in terms of a previously loaded DOM CM. Finally, this chapter will have separate sections to address the needs of the document-editing and CM-editing worlds, along with a section that details overlapping areas such as validation. In this manner, the document-editing world's focuses on editing aspects and usage of information in the CM are made distinct from the CM-editing world's focuses on defining and manipulating the information in the CM. 1.1.1. General Characteristics In the October 9, 1997 DOM requirements document, the following appeared: "There will be a way to determine the presence of a DTD. There will be a way to add, remove, and change declarations in the underlying DTD (if available). There will be a way to test conformance of all or part of the given document against a DTD (if available)." In later discussions, the following was added, "There will be a way to query element/attribute (and maybe other) declarations in the underlying DTD (if available)," supplementing the primitive support for these in Level 1. That work was deferred past Level 2, in the hope that XML Schemas would be addressed as well. It is anticipated that lowest common denominator general APIs generated in this chapter can support both DTDs and XML Schemas, and other XML content models down the road. The kinds of information that a Content Model must make available are mostly self-evident from the definitions of Infoset, DTDs, and XML Schemas. Note that some kinds of information on which the DOM already relies, e.g., default values for attributes, will finally be given a visible representation here, however. 1.1.2. Use Cases and Requirements The content model referenced in these use cases/requirements is an abstraction and does not refer solely to DTDs or XML Schemas. For the CM-editing and document-editing worlds, the following use cases and requirements are common to both and could be labeled as the "Validation and Other Common Functionality" section: Use Cases: 1. CU1. Associating a content model (external and/or internal) with a document, or changing the current association. 2. CU2. Using the same external content model with several documents, without having to reload it. Requirements: 1. CR1. Validate against the content model. 2. CR2. Retrieve information from content model. 3. CR3. Load an existing content model, perhaps independently from a document. 4. CR4. Being able to determine if a document has a content model associated with it. 5. CR5. Associate a CM with a document and make it the active CM. Specific to the CM-editing world, the following are use cases and requirements and could be labeled as the "CM-editing" section: Use Cases: 1. CMU1. Clone/map all or parts of an existing content model to a new or existing content model. 2. CMU2. Save a content model in a separate file. For example, if a DTD can be broken up into reusable pieces, which are then brought in via entity references, these can then be saved in a separate file. Note that the external subset of a DTD, which includes both an internal and external subset, is a special case of dividing a content model into entities. 3. CMU3. Modify an existing content model. 4. CMU4. Create a new content model. 5. CMU5. Partial content model checking. For example, the document need only be validated against a selected portion of the content model. Requirements: 1. CMR1. View and modify all parts of the content model. 2. CMR2. Validate the content model itself. 3. CMR3. Serialize the content model. 4. CMR4. Clone all or parts of an existing content model. 5. CMR5. Create a new content model object. 6. CMR6. Validate portions of the XML document against the content model. Specific to the document-editing world, the following are use cases and requirements and could be labeled as the "Document-editing" section: Use Cases: 1. DU1. For editing documents with an associated content model, provide the guidance necessary so that valid documents can be modified and remain valid. 2. DU2. For editing documents with an associated content model, provide the guidance necessary to transform an invalid document into a valid one. Requirements: 1. DR1. Be able to determine if the document is well-formed, and if not, be given enough guidance to locate the error. 2. DR2. Be able to determine if the document is namespace well-formed, and if not, be given enough guidance to locate the error. 3. DR3. Be able to determine if the document is valid with respect to its associated content model, and if not, give enough guidance to locate the error. 4. DR4. Be able to determine if specific modifications to a document would make it become invalid. 5. DR5. Retrieve information from all content models. One example might be getting a list of all the defined element names for document editing purposes. General Issues: 1. I1. Some concerns exist regarding whether a single abstract Content Model structure can successfully represent both namespace-unaware, e.g., DTD, and namespace-aware, e.g., XML Schema, models of document's content. For example, when you ask what elements can be inserted in a specific place, the former will report the element's QName, e.g., foo:bar, whereas the latter will report its namespace and local name, e.g., {http://my.namespace}bar. We have added the isNamespaceAware attribute to the generic CM object to help applications determine which of these fields are important, but we are still analyzing this challenge. 2. I2. An XML document may be associated with multiple CMs. We have decided that only one of these is "active" (for validation and guidance) at a time. DOM applications may switch which CM is active, remove CMs that are no longer relevant, or add CMs to the list. If it becomes necessary to simultaneously consult more than one CM, it should be possible to write a "union" CM which provides that capability within this framework. 3. I3. Content model being able to handle more datatypes than strings. Currently, this functionality is not available and should be dealt with in the future. 4. I4. Round-trippability for include/ignore statements and other constructs such as parameter entities, e.g., "macro-like" constructs, will not be supported since no data representation exists to support these constructs without having to re-parse them. 5. I5. Basic interface for a common error handler for both CM and Load/Save. Agreement has been to utilize user-registered callbacks but other details to be worked out. 1.2. Content Model and CM-Editing Interfaces A list of the proposed Content Model data structures and functions follow, starting off with the data structures and "CM-editing" methods. Interface CMModel CMModel is an abstract object that could map to a DTD, an XML Schema, a database schema, etc. It's a generalized content model object, that has both an internal and external subset. The internal subset would always exist, even if empty, with the external subset (if present) being represented as by an "active" CMExternalModel. Many CMExternalModels could exist, but only one can be specified as "active"; it is also possible that none are "active". The issue of multiple content models is misleading since in this architecture, only one CMModel exists, with an internal subset that references the external subset. If the external subset changes to another "acitve" CMExternalModel, the internal subset is "fixed up." The CMModel also contains the factory methods needed to create a various types of CMNodes like CMElementDeclaration, CMAttributeDeclaration, etc. IDL Definition interface CMModel : CMNode { readonly attribute boolean isNamespaceAware; attribute CMElementDeclaration rootElementDecl; DOMString getLocation(); nsElement getCMNamespace(); CMNamedNodeMap getCMNodes(); boolean removeNode(in CMNode node); boolean insertBefore(in CMNode newNode, in CMNode refNode); boolean validate(); CMElementDeclaration createCMElementDeclaration(inout DOMString namespaceURI, in DOMString qualifiedElementName, in int contentSpec) raises(DOMException); CMAttributeDeclaration createCMAttributeDeclaration(inout DOMString namespaceURI, in DOMString qualifiedName) raises(DOMException); CMNotationDeclaration createCMNotationDeclaration(in DOMString name, in DOMString systemIdentifier, inout DOMString publicIdentifier) raises(DOMException); CMEntityDeclaration createCMEntityDeclaration(in DOMString name) raises(DOMException); CMChildren createCMChildren(in unsigned long minOccurs, in unsigned long maxOccurs, inout unsigned short operator) raises(DOMException); }; Attributes isNamespaceAware of type boolean, readonly True if this content model defines the document structure in terms of namespaces and local names; false if the document structure is defined only in terms of QNames. rootElementDecl of type CMElementDeclaration The root element declaration for the content model. Although a root element is specified in the document instance, when a content model is generated, a user should be able to chose the root element for editing purpose. This is just a placeholder for that element. It could also be null. For validating an XML document, root element must be defined in its active content model. CMModel.rootElementDecl provides access to that root element declaration. This recommendation does not say how to fill in the rootElementdecl. It could be manually done by the user before validating a document, in some cases where possible, the CMModle loader may be able to fill it in etc. Methods createCMAttributeDeclaration Creates an attribute declaration. The returned object implements CMAttributeDeclaration interface. Parameters namespaceURI of type DOMString qualifiedName of type DOMString The name of the attribute being declared. Return Value CMAttributeDeclaration A new CMAttributeDeclaration object with attributeName attribute set to input qualifiedname parameter. Exceptions DOMException INVALID_CHARACTER_ERR: Raised if the specified name contains an illegal character. createCMChildren Creates a new CMChildren object. The subModels of the CMChildren is build using CMChildren interface methods. Parameters minOccurs of type unsigned long The minimum occurance for the subModels of this CMChildren. maxOccurs of type unsigned long The maximum occurance for the subModels of this CMChildren. operator of type unsigned short operator of type CHOICE, SEQ or NONE Return Value CMChildren A new CMChildren object. Exceptions DOMException INVALID_CHARACTER_ERR: Raised if the specified name contains an illegal character. createCMElementDeclaration Creates an element declaration for the element type specified. The returned object implements CMElementDeclaration interface. Parameters namespaceURI of type DOMString qualifiedElementName of type DOMString The qualified name of the element type being declared. contentSpec of type int Constant for MIXED, EMPTY, ANY and CHILDREN. Return Value CMElementDeclaration A new CMElementDeclaration object with name attribute set to qualifiedElementName and the contentType set to contentSpec. Other attributes of the element declaration are set through CMElementDeclaration interface methods. Exceptions DOMException INVALID_CHARACTER_ERR: Raised if the specified name contains an illegal character. DUPLICATE_NAME_ERR:Raised if an element declaration already exists with the same name for a given CMModel. createCMEntityDeclaration Creates a new entity declaration. The returned object implements CMEntityDeclaration interface. Parameters name of type DOMString The name of the entity being declared. Return Value CMEntityDeclaration A new CMNotationDeclaration object with entityName attribute set to name. Exceptions DOMException INVALID_CHARACTER_ERR: Raised if the specified name contains an illegal character. createCMNotationDeclaration Creates a new notation declaration. The returned object implements CMNotationDeclaration interface. Parameters name of type DOMString The name of the notation being declared. systemIdentifier of type DOMString The system identifier for the notation declaration. publicIdentifier of type DOMString The public identifier for the notation declaraiton. Return Value CMNotationDeclaration A new CMNotationDeclaration object with notationName attribute set to name. Exceptions DOMException INVALID_CHARACTER_ERR: Raised if the specified name contains an illegal character. DUPLICATE_NAME_ERR:Raised if a notation declaration already exists with the same name for a given CMModel. getCMNamespace Determines namespace of CMModel. Return Value nsElement Namespace of CMModel. No Parameters No Exceptions getCMNodes Returns CMNode list of all the constituent nodes in the content model. Return Value CMNamedNodeMap List of all CMNodes of the content model. No Parameters No Exceptions getLocation Location of the document describing the content model defined in this CMModel. Return Value DOMString This method returns a DOMString defining the absolute location from which this document is retrieved including the document name. No Parameters No Exceptions insertBefore Insert CMNode. Parameters newNode of type CMNode CMNode to be inserted. refNode of type CMNode CMNode to be inserted before. Return Value boolean Success or failure.. No Exceptions removeNode Removes the specifiedCMNode. Parameters node of type CMNode CMNode to be removed. Return Value boolean Success or failure.. No Exceptions validate Determines if a CMModel and CMExternalModel itself is valid, i.e., confirming that it's well-formed and valid per its own formal grammar. Note that within a CMModel, a pointer to a CMExternalModel can exist. Return Value boolean Is the CM valid? No Parameters No Exceptions Interface CMExternalModel CMExternalModel is an abstract object that could map to a DTD, an XML Schema, a database schema, etc. It's a generalized content model object that is not bound to a particular XML document. IDL Definition interface CMExternalModel : CMModel { }; Interface CMNode CMNodeis analogous to a Node in the Core DOM, e.g., an element declaration. This can exist for both CMExternalModel and CMModel. It should be able to handle constructs such as comments and processing instructions. Opaque. IDL Definition interface CMNode { const unsigned short CM_ELEMENT_DECLARATION = 1; const unsigned short CM_ATTRIBUTE_DECLARATION = 2; const unsigned short CM_NOTATION_DECLARATION = 3; const unsigned short CM_ENTITY_DECLARATION = 4; const unsigned short CM_CHILDREN = 5; const unsigned short CM_MODEL = 6; const unsigned short CM_EXTERNALMODEL = 7; readonly attribute unsigned short cmNodeType; attribute CMModel ownerCMModel; attribute DOMString nodeName; attribute DOMString prefix; attribute DOMString localName; attribute DOMString namespaceURI; CMNode clone(); }; Constant CM_ELEMENT_DECLARATION The node is an CMElementDeclaration. Constant CM_ATTRIBUTE_DECLARATION The node is an CMAttributeDeclaration. Constant CM_NOTATION_DECLARATION The node is a CMNotationDeclaration. Constant CM_ENTITY_DECLARATION The node is an CMEntityDeclaration. Constant CM_CHILDREN The node is a CMChildren. Constant CM_MODEL The node is a CMModel. Constant CM_EXTERNALMODEL The node is a CMExternalModel. Attributes cmNodeType of type unsigned short, readonly A code representing the underlying object as defined above. localName of type DOMString Returns the local part of the qualified name of this CMNode. namespaceURI of type DOMString The namespace URI of this node, or null if it is unspecified. nodeName of type DOMString The qualified name of this CMNode depending on the CMNode type. ownerCMModel of type CMModel The CMModel object associated with this CMNode. For a node of type CM_MODEL, this is null. prefix of type DOMString The namespace prefix of this node, or null if it is unspecified. Methods clone Creates a copy of CMNode. Return Value CMNode Cloned CMNode. No Parameters No Exceptions Interface CMNodeList CMNodeList is the CM analogue to NodeList; the document order is meaningful, as opposed to CMNamedNodeMap. IDL Definition interface CMNodeList { }; Interface CMNamedNodeMap CMNamedNodeMap is the CM analogue to NamedNodeMap. The order is not meaningful. IDL Definition interface CMNamedNodeMap { }; Interface CMDataType The primitive datatypes supported by base DOM CM implementation is: string type only. IDL Definition interface CMDataType { const short STRING_DATATYPE = 1; short getCMPrimitiveType(); }; Constant STRING_DATATYPE code representing the string data type as defined in XML Schema Datatypes. Methods getCMPrimitiveType Returns one of the enumerated code representing the primitive data type. Return Value short code representing the primitive type of the attached data item. No Parameters No Exceptions Interface CMPrimitiveType The primitive types supported by optional DOM CM implelementations. A DOM application can use the hasFeature method of the DOMImplementation interface to determine whether this interface is supported or not. The feature string for all the interfaces listed in this section is "CMPTYPES" and the version is "3.0". IDL Definition interface CMPrimitiveType : CMDataType { const short BOOLEAN_DATATYPE = 2; const short FLOAT_DATATYPE = 3; const short DOUBLE_DATATYPE = 4; const short DECIMAL_DATATYPE = 5; const short HEXBINARY_DATATYPE = 6; const short BASE64BINARY_DATATYPE = 7; const short ANYURI_DATATYPE = 8; const short QNAME_DATATYPE = 9; const short DURATION_DATATYPE = 10; const short DATETIME_DATATYPE = 11; const short DATE_DATATYPE = 12; const short TIME_DATATYPE = 13; const short YEARMONTH_DATATYPE = 14; const short YEAR_DATATYPE = 15; const short MONTHDAY_DATATYPE = 16; const short DAY_DATATYPE = 17; const short MONTH_DATATYPE = 18; const short NOTATION_DATATYPE = 19; attribute decimal lowValue; attribute decimal highValue; }; Constant BOOLEAN_DATATYPE code representing the boolean data type as defined in XML Schema Datatypes. Constant FLOAT_DATATYPE code representing the float data type as defined in XML Schema Datatypes. Constant DOUBLE_DATATYPE code representing the double data type as defined in XML Schema Datatypes. Constant DECIMAL_DATATYPE code representing a decimal data type as defined in XML Schema Datatypes. Constant HEXBINARY_DATATYPE code representing a hexbinary data type as defined in XML Schema Datatypes. Constant BASE64BINARY_DATATYPE code representing a base64binary data type as defined in XML Schema Datatypes. Constant ANYURI_DATATYPE code representing an uri reference data type as defined in XML Schema Datatypes. Note: @@uriReference is no longer part of the XML Schema PR draft. Constant QNAME_DATATYPE code representing an XML qualified name data type as defined in XML Schema Datatypes. Constant DURATION_DATATYPE code representing a duration data type as defined in XML Schema Datatypes. Constant DATETIME_DATATYPE code representing adatetime data type as defined in XML Schema Datatypes. Constant DATE_DATATYPE code representing adate data type as defined in XML Schema Datatypes. Constant TIME_DATATYPE code representing a time data type as defined in XML Schema Datatypes. Constant YEARMONTH_DATATYPE code representing a yearmonth data type as defined in XML Schema Datatypes. Constant YEAR_DATATYPE code representing a year data type as defined in XML Schema Datatypes. Constant MONTHDAY_DATATYPE code representing a monthday data type as defined in XML Schema Datatypes. Constant DAY_DATATYPE code representing a day data type as defined in XML Schema Datatypes. Constant MONTH_DATATYPE code representing a month data type as defined in XML Schema Datatypes. Constant NOTATION_DATATYPE code representing aNOTATIONdata type as defined in XML Schema Datatypes. Attributes highValue of type decimal The high value for a primitive DECIMAL_DATATYPE in the value range. lowValue of type decimal The low value for a primitive DECIMAL_DATATYPE in the value range. Interface CMElementDeclaration The element name along with the content specification in the context of a CMNode. IDL Definition interface CMElementDeclaration : CMNode { attribute CMDataType elementType; readonly attribute boolean isPCDataOnly; attribute DOMString tagName; int getContentType(); CMChildren getCMChildren(); CMNamedNodeMap getCMAttributes(); CMNamedNodeMap getCMGrandChildren(); }; Attributes elementType of type CMDataType Datatype of the element. isPCDataOnly of type boolean, readonly Boolean defining whether the element type contains child elements and PCDATA or PCDATA only for mixed element types. True if the element is of type PCDATA only. Relevant only for mixed content type elements. tagName of type DOMString tagName of the element being declared. Methods getCMAttributes Returns a CMNamedNodeMap containing CMAttributeDeclarations for all the attributes that can appear on this type of element. Return Value CMNamedNodeMap Attributes list for this CMNode. No Parameters No Exceptions getCMChildren Gets content model of element. Return Value CMChildren Content model of element. No Parameters No Exceptions getCMGrandChildren Returns a CMNamedNodeMap containing CMElementDeclarations for all the Elements that can appear as children of this type of element. Note that which ones can actually appear, and in what order, is defined by the CMChildren. Return Value CMNamedNodeMap Children list for this CMNode. No Parameters No Exceptions getContentType Gets content type, e.g., empty, any, mixed, elements, PCDATA, of an element. Return Value int Content type constant. No Parameters No Exceptions Interface CMChildren The content model of a declared element. IDL Definition interface CMChildren : CMNode { const unsigned long UNBOUNDED = MAX_LONG; const unsigned short NONE = 0; const unsigned short SEQUENCE = 1; const unsigned short CHOICE = 2; attribute unsigned short listOperator; attribute unsigned long minOccurs; attribute unsigned long maxOccurs; attribute CMNodeList subModels; CMNode removeCMNode(in unsigned long nodeIndex); int insertCMNode(in unsigned long nodeIndex, in CMNode newNode); int appendCMNode(in CMNode newNode); }; Constant UNBOUNDED Signifies unbounded upper limit. The MAX_LONG value is the maximum value of an unsigned long integer for a given language binding. Constant NONE No operators defined on the subModels. This is usually the case where the subModels contain a single element declaration. Constant SEQUENCE This constant value signifies a sequence operator ",". Constant CHOICE This constant value signifies a choice operator "|". Attributes listOperator of type unsigned short One of CHOICE or SEQUENCE. The operator is applied to all the components(CMNodes) in the the subModels. For example, if the list operator is CHOICE and the components in subModels are a, b and c then the content model for the element being declared is (a|b|c) maxOccurs of type unsigned long maximum occurrence for this content particle. Valid values are from 0 to UNBOUNDED. minOccurs of type unsigned long min occurrence for this content particle. Valid values are from 0 to UNBOUNDED. subModels of type CMNodeList Additional CMNodes in which the element can be defined. Methods appendCMNode Appends a new node to the end of the list representing thesubModels. Parameters newNode of type CMNode The new node to be appended. Return Value int the length of the subModels. No Exceptions insertCMNode Inserts a new node at a position in the submodel referred to by the nodeIndex. Node already exisiting in the list is moved as needed. Parameters nodeIndex of type unsigned long The position of where the newNode is inserted. newNode of type CMNode The new node to be inserted. Return Value int The index value at which it is inserted. If the nodeIndex is outside the bound of the subModels list, the item is inserted at the back of the list. No Exceptions removeCMNode Removes the CMNode at the indicated index position in the submodel. Parameters nodeIndex of type unsigned long Index of the node being removed. Return Value CMNode The node removed is returned as a result of this method call. The method returns null if the index is outside the bounds of the subModels list. No Exceptions Interface CMAttributeDeclaration An attribute declaration in the context of a CMNode. IDL Definition interface CMAttributeDeclaration : CMNode { const short NO_VALUE_CONSTRAINT = 0; const short DEFAULT_VALUE_CONSTRAINT = 1; const short FIXED_VALUE_CONSTRAINT = 2; attribute DOMString attrName; attribute CMDataType attrType; attribute DOMString attributeValue; attribute DOMString enumAttr; attribute CMNodeList ownerElement; attribute short constraintType; }; Constant NO_VALUE_CONSTRAINT Describes that the attribute does not have any value constraint. Constant DEFAULT_VALUE_CONSTRAINT Indicates that the there is a default value constraint. Constant FIXED_VALUE_CONSTRAINT Indicates that there is a fixed value constraint for this attribute. Attributes attrName of type DOMString Name of the attribute. attrType of type CMDataType Datatype of the attribute. attributeValue of type DOMString Default value. constraintType of type short Constraint type if any for this attribute. enumAttr of type DOMString Enumeration of attribute. ownerElement of type CMNodeList Owner element CMNode of attribute. Interface CMEntityDeclaration Models a general entity declaration in a content model. (ED: The content model does not handle any parameter entity. It is assumed that the parameter entiites are expanded by the implementation as the content model is built.) IDL Definition interface CMEntityDeclaration : CMNode { const short INTERNAL_ENTITY = 1; const short EXTERNAL_ENTITY = 2; attribute short entityType; attribute DOMString entityName; attribute DOMString entityValue; attribute DOMString systemId; attribute DOMString publicId; attribute DOMString notationName; }; Constant INTERNAL_ENTITY constant defining an internal entity. Constant EXTERNAL_ENTITY constant defining an external entity. Attributes entityName of type DOMString The name of the declared general entity. entityType of type short One of the INTERNAL_ENTITY or EXTERNAL_ENTITY. entityValue of type DOMString The replacement text for the internal entity. The entity references within the replacement text is kept intact. For entity of type EXTERNAL_ENTITY this is null. notationName of type DOMString For unparsed entities, the name of the notation declaration for the entity. For parsed entities, this is null. publicId of type DOMString The public identifier associated with the entity, if specified. If the public identifier was not specified, this is null. systemId of type DOMString The system identifier associated with the entity, if specified. If the system identifier was not specified, this is null. Interface CMNotationDeclaration This interface represents a notation declaration. IDL Definition interface CMNotationDeclaration : CMNode { attribute DOMString notationName; attribute DOMString systemId; attribute DOMString publicId; }; Attributes notationName of type DOMString The name of this notation declaration. publicId of type DOMString The string representing the public identifier for this notation declaration. systemId of type DOMString the URI representing the system identifier for the notation declaration, if present, null otherwise. 1.3. Validation and Other Interfaces This section contains "Validation and Other" methods common to both the document-editing and CM-editing worlds (includes Document, DOMImplementation, and DOMErrorHandler methods). Interface Document The setErrorHandler method is off of the Document interface. IDL Definition interface Document { void setErrorHandler(in DOMErrorHandler handler); }; Methods setErrorHandler Allow an application to register an error event handler. Parameters handler of type DOMErrorHandler The error handler No Return Value No Exceptions Interface DocumentCM This interface extends the Document interface with additional methods for both document and CM editing. IDL Definition interface DocumentCM : Document { const short WF_CHECK = 1; const short NS_WF_CHECK = 2; const short PARTIAL_VALIDITY_CHECK = 3; const short STRICT_VALIDITY_CHECK = 4; attribute boolean continuousValidityChecking; attribute short wfValidityCheckLevel; int numCMs(); CMModel getInternalCM(); CMNodeList getCMs(); CMModel getActiveCM(); void addCM(in CMModel cm); void removeCM(in CMModel cm); boolean activateCM(in CMModel cm); }; Constant WF_CHECK Check for well-formedness of the document. Constant NS_WF_CHECK Check for namespace well-formedness includes WF_CHECK. Constant PARTIAL_VALIDITY_CHECK Checks for whether the document is partially valid. It includes NS_WF_CHECK. A document is said to be partially valid if it contains elments/attributes for which an element/attribute declaration has not been made in the active content model. However, if the element or the attribute has a declaration in the content model, it must be valid with respect to those declarations. Constant STRICT_VALIDITY_CHECK Checks for strict validity of the document with respect to active CM which by defiition includes NS_WF_CHECK. Attributes continuousValidityChecking of type boolean An attribute specifying whether continuous checking for the validity of the document is enforced or not. When set to true the implementation is free to raise the VALIDATION_ERR exception on DOM operations that would make the document invalid with respect to "partial validity". This attribute is false by default. (ED: Add VALIDATION_ERR code to the list of constants in DOMException.) wfValidityCheckLevel of type short This attribute defines the level at which the validity and welformedness testing is done by the isValid method. Methods activateCM Make the given CMModel active. Note that if a user wants to activate one CM to get default attribute values and then activate another to do validation, a user can do that; however, only one CM is active at a time. In case where an attribute is declared in an internal subset and corresponding ownerElement points to CMElementDeclaration defined in an external subset, changing active CM will cause the ownerElement to be re-computed. If the owner element is not defined in the newly active CM, the ownerElement will be an empty node list. Parameters cm of type CMModel CM to be active for the document. The CMModel points to a list of CMExternalModels; with this call, only the specified CM will be active. Return Value boolean True if the CMModel has already been associated with the document using addCM(); false if not. No Exceptions addCM Associate a CMModel with a document. Can be invoked multiple times to result in a list of CMExternalModels. Note that only one sole internal CMModel is associated with the document, however, and that only one of the possible list of CMExternalModels is active at any one time. Parameters cm of type CMModel CM to be associated with the document. No Return Value No Exceptions getActiveCM Find the active CMExternalModel for a document. Return Value CMModel CMModel with a pointer to the active CMExternalModel of document. No Parameters No Exceptions getCMs Obtains list of CMNodes of typeCM_EXTERNALMODELs associated with the document.This list arises when addCM() is invoked. Return Value CMNodeList A list of CMExternalModels associated with a document. No Parameters No Exceptions getInternalCM Find the sole CMModel of a document. Only one CMModel may be associated with the document. Return Value CMModel CMModel. No Parameters No Exceptions numCMs Determines number of CMExternalModels associated with the document. Only one CMModel can be associated with the document, but it may point to a list of CMExternalModels. Return Value int Non-negative number of external CM objects. No Parameters No Exceptions removeCM Removes a CM associated with a document; actually removes a CMExternalModel. Can be invoked multiple times to remove a number of these in the list of CMExternalModels. Parameters cm of type CMModel CM to be removed. No Return Value No Exceptions Interface DOMImplementationCM This interface extends the DOMImplementation interface with additional methods. IDL Definition interface DOMImplementationCM : DOMImplementation { CMModel createCM(); CMExternalModel createExternalCM(); }; Methods createCM Creates a CMModel. Return Value CMModel A NULL return indicates failure. No Parameters No Exceptions createExternalCM Creates a CMExternalModel. Return Value CMExternalModel A NULL return indicates failure. No Parameters No Exceptions 1.4. Document-Editing Interfaces This section contains "Document-editing" methods (includes Node, Element, Text and Document methods). Interface NodeCM This interface extends the Node interface with additional methods for guided document editing. IDL Definition interface NodeCM : Node { boolean canInsertBefore(in Node newChild, in Node refChild) raises(DOMException); boolean canRemoveChild(in Node oldChild) raises(DOMException); boolean canReplaceChild(in Node newChild, in Node oldChild) raises(DOMException); boolean canAppendChild(in Node newChild) raises(DOMException); boolean isValid() raises(DOMException); }; Methods canAppendChild Has the same args as AppendChild. Parameters newChild of type Node Node to be appended. Return Value boolean Success or failure. Exceptions DOMException DOMException. canInsertBefore Determines whether the Node::InsertBefore operation would make this document invalid with respect to the currently active CM. ISSUE: Describe "valid" when referring to partially completed documents. Parameters newChild of type Node Node to be inserted. refChild of type Node Reference Node. Return Value boolean A boolean that is true if the Node::InsertBefore operation is allowed. Exceptions DOMException DOMException. canRemoveChild Has the same args as RemoveChild. Parameters oldChild of type Node Node to be removed. Return Value boolean Success or failure. Exceptions DOMException DOMException. canReplaceChild Has the same args as ReplaceChild. Parameters newChild of type Node New Node. oldChild of type Node Node to be replaced. Return Value boolean Success or failure. Exceptions DOMException DOMException. isValid Determines if the Node is valid relative to currently active CM. Return Value boolean True if the node is valid/well-formed in the current context and check level defined by wfValidityCheckLevel, false if not. Exceptions DOMException NO_CM_AVAILABLE: Exception is raised if the DocumentCM related to this node does not have any activeCM and wfValidityCheckLevel is set to STRICT_VALIDITY_CHECK. No Parameters Interface ElementCM This interface extends the Element interface with additional methods for guided document editing. IDL Definition interface ElementCM : Element,NodeCM { int contentType(); CMElementDeclaration getElementDeclaration() raises(DOMException); boolean canSetAttribute(in DOMString attrname, in DOMString attrval); boolean canSetAttributeNode(in Node node); boolean canSetAttributeNodeNS(in Node node); boolean canSetAttributeNS(in DOMString attrname, in DOMString attrval, in DOMString namespaceURI, in DOMString localName); boolean canRemoveAttribute(in DOMString attrname); boolean canRemoveAttributeNS(in DOMString attrname, inout DOMString namespaceURI); boolean canRemoveAttributeNode(in Node node); }; Methods canRemoveAttribute Verifies if an attribute by the given name can be removed. Parameters attrname of type DOMString Name of attribute. Return Value boolean true or false. No Exceptions canRemoveAttributeNS Verifies if an attribute by the given name and namespace can be removed. Parameters attrname of type DOMString Qualified name of the attribute to be removed. namespaceURI of type DOMString The namespace URI of the attribute to remove. Return Value boolean true or false. No Exceptions canRemoveAttributeNode Determines if an attribute node can be removed. Parameters node of type Node The Attr node to remove from the attribute list. Return Value boolean true or false. No Exceptions canSetAttribute Determines if the value for specified attribute can be set. Parameters attrname of type DOMString Name of attribute. attrval of type DOMString Value to be assigned to the attribute. Return Value boolean true or false. No Exceptions canSetAttributeNS Determines if the attribute with given namespace and local name can be created if not already present in the attribute list of the element. If the attribute with same local name and namespaceURI is already present in the elements attribute list it sets the value of the attribute and its prefix to the new value. See DOM core setAttributeNS. Parameters attrname of type DOMString Name of attribute. attrval of type DOMString Value to be assigned to the attribute. namespaceURI of type DOMString namespaceURI of namespace. localName of type DOMString localName of namespace. Return Value boolean Success or failure. No Exceptions canSetAttributeNode Determines if attribute node can be added. Parameters node of type Node Node in which the attribute can possibly be set. Return Value boolean Success or failure. No Exceptions canSetAttributeNodeNS Determines if the attribute node with the given namespace can be added. Parameters node of type Node The Attr to be added to the attribute list. Return Value boolean Success or failure. No Exceptions contentType Determines element content type. Return Value int Constant for mixed, empty, any, etc. No Parameters No Exceptions getElementDeclaration gets the CM editing object describing this element Return Value CMElementDeclaration CMElementDeclaration object Exceptions DOMException If no DTD is present raises this exception No Parameters Interface CharacterDataCM This interface extends the CharacterData interface with additional methods for document editing. IDL Definition interface CharacterDataCM : Text,NodeCM { boolean isWhitespaceOnly(); boolean canSetData(in unsigned long offset, in DOMString arg) raises(DOMException); boolean canAppendData(in DOMString arg) raises(DOMException); boolean canReplaceData(in unsigned long offset, in unsigned long count, in DOMString arg) raises(DOMException); boolean canInsertData(in unsigned long offset, in DOMString arg) raises(DOMException); boolean canDeleteData(in unsigned long offset, in DOMString arg) raises(DOMException); }; Methods canAppendData Determines if data can be appended. Parameters arg of type DOMString Argument to be appended. Return Value boolean Success or failure. Exceptions DOMException DOMException. canDeleteData Determines if data can be deleted. Parameters offset of type unsigned long Offset. arg of type DOMString Argument to be set. Return Value boolean Success or failure. Exceptions DOMException DOMException. canInsertData Determines if data can be inserted. Parameters offset of type unsigned long Offset. arg of type DOMString Argument to be set. Return Value boolean Success or failure. Exceptions DOMException DOMException. canReplaceData Determines if data can be replaced. Parameters offset of type unsigned long Offset. count of type unsigned long Replacement. arg of type DOMString Argument to be set. Return Value boolean Success or failure. Exceptions DOMException DOMException. canSetData Determines if data can be set. Parameters offset of type unsigned long Offset. arg of type DOMString Argument to be set. Return Value boolean Success or failure. Exceptions DOMException DOMException. isWhitespaceOnly Determines if content is only whitespace. Return Value boolean True if content only whitespace; false for non-whitespace if it is a text node in element content. No Parameters No Exceptions Interface DocumentTypeCM This interface extends the DocumentType interface with additional methods for document editing. IDL Definition interface DocumentTypeCM : DocumentType,NodeCM { boolean isElementDefined(in DOMString elemTypeName); boolean isElementDefinedNS(in DOMString elemTypeName, in DOMString namespaceURI, in DOMString localName); boolean isAttributeDefined(in DOMString elemTypeName, in DOMString attrName); boolean isAttributeDefinedNS(in DOMString elemTypeName, in DOMString attrName, in DOMString namespaceURI, in DOMString localName); boolean isEntityDefined(in DOMString entName); }; Methods isAttributeDefined Determines if this attribute is defined for this element in the currently active CM. Parameters elemTypeName of type DOMString Name of the element. attrName of type DOMString Name of the attribute. Return Value boolean Success or failure. No Exceptions isAttributeDefinedNS Determines if this attribute's namespace is defined in the currently active CM. Parameters elemTypeName of type DOMString Name of element. attrName of type DOMString Name of attribute. namespaceURI of type DOMString namespaceURI of namespace. localName of type DOMString localName of namespace. Return Value boolean Success or failure. No Exceptions isElementDefined Determines if this element is defined in the currently active CM. Parameters elemTypeName of type DOMString Name of element. Return Value boolean Success or failure. No Exceptions isElementDefinedNS Determines if this element's namespace is defined in the currently active CM. Parameters elemTypeName of type DOMString Name of element. namespaceURI of type DOMString namespaceURI of namespace. localName of type DOMString localName of namespace. Return Value boolean Success or failure. No Exceptions isEntityDefined Determines if an entity is defined in the document. ISSUE: Should methods be added to the DocumentTypeCM for the complete list of defined elements and for a particular element type, the complete list of defined attributes. These two methods might return a list of strings which is a type not yet described in the DOM spec. Parameters entName of type DOMString Name of entity. Return Value boolean Success or failure. No Exceptions Interface AttributeCM This interface extends Attr to provide guided editing of an XML document. IDL Definition interface AttributeCM : Attr,NodeCM { CMAttributeDeclaration getAttributeDeclaration(); CMNotationDeclaration getNotation() raises(DOMException); }; Methods getAttributeDeclaration returns the corresponding attribute declaration in the content model. Return Value CMAttributeDeclaration The attribute declaration corresponding to this attribute No Parameters No Exceptions getNotation Returns the notation declaration for the attributes defined of type NOTATION. Return Value CMNotationDeclaration Returns the notation declaration for this attribute if the type is of notation type, null otherwise. Exceptions DOMException DOMException No Parameters 1.5. DOM Error Handler Interfaces This section contains DOM error handling interfaces. Interface DOMErrorHandler Basic interface for DOM error handlers. If an application needs to implement customized error handling for DOM such as CM or Load/Save, it must implement this interface and then register an instance using the setErrorHandler method. All errors and warnings will then be reported through this interface. Application writers can override the methods in a subclass to take user-specified actions. IDL Definition interface DOMErrorHandler { void warning(in DOMLocator where, in DOMString how, in DOMString why) raises(DOMSystemException); void fatalError(in DOMLocator where, in DOMString how, in DOMString why) raises(DOMSystemException); void error(in DOMLocator where, in DOMString how, in DOMString why) raises(DOMSystemException); }; Methods error Receive notification of a recoverable error per section 1.2 of the W3C XML 1.0 recommendation. The default behavior if the user doesn't register a handler is to report conditions that are not fatal errors, and allow the calling application to continue processing. Parameters where of type DOMLocator Location of the error, which could be either a source position in the case of loading, or a node reference for later validation. The public ID and system ID for the error location could be some of the information. how of type DOMString How the error occurred. why of type DOMString Why the error occurred. Exceptions DOMSystemException A subclass of DOMException. No Return Value fatalError Report a fatal, non-recoverable CM or Load/Save error per section 1.2 of the W3C XML 1.0 recommendation. The default behavior if the user doesn't register a handler is to throw a DOMSystemException and stop all further processing. Parameters where of type DOMLocator Location of the fatal error, which could be either a source position in the case of loading, or a node reference for later validation. The public ID and system ID for the error location could be some of the information. how of type DOMString How the fatal error occurred. why of type DOMString Why the fatal error occurred. Exceptions DOMSystemException A subclass of DOMException. No Return Value warning Receive notification of a warning per the W3C XML 1.0 recommendation. The default behavior if the user doesn't register a handler is to report conditions that are not errors or fatal errors, and then allow the calling application to continue even after invoking this method. Parameters where of type DOMLocator Location of the warning, which could be either a source position in the case of loading, or a node reference for later validation. The public ID and system ID for the error location could be some of the information. how of type DOMString How the warning occurred. why of type DOMString Why the warning occurred. Exceptions DOMSystemException A subclass of DOMException. No Return Value Interface DOMLocator This interface provides document location information and is similar to a SAX locator object. IDL Definition interface DOMLocator { int getColumnNumber(); int getLineNumber(); DOMString getPublicID(); DOMString getSystemID(); Node getNode(); }; Methods getColumnNumber Return the column number. Return Value int The column number, or -1 if none is available. No Parameters No Exceptions getLineNumber Return the line number. Return Value int The line number, or -1 if none is available. No Parameters No Exceptions getNode Return the Node. Return Value Node The NODE, or null if none is available. No Parameters No Exceptions getPublicID Return the public identifier. Return Value DOMString A string containing the public identifier, or null if none is available. No Parameters No Exceptions getSystemID Return the system identifier. Return Value DOMString A string containing the system identifier, or null if none is available. No Parameters No Exceptions 1.6. Editing and Generating a Content Model Editing and generating a content model falls in the CM-editing world. The most obvious requirement for this set of requirements is for tools that author content models, either under user control, i.e., explicitly designed document types, or generated from other representations. The latter class includes transcoding tools, e.g., synthesizing an XML representation to match a database schema. It's important to note here that a DTD's "internal subset" is part of the Content Model, yet is loaded, stored, and maintained as part of the individual document instance. This implies that even tools which do not want to let users change the definition of the Document Type may need to support editing operations upon this portion of the CM. It also means that our representation of the CM must be aware of where each portion of its content resides, so that when the serializer processes this document it can write out just the internal subset. A similar issue may arise with external parsed entities, or if schemas introduce the ability to reference other schemas. Finally, the internal-subset case suggests that we may want at least a two-level representation of content models, so a single DOM representation of a DTD can be shared among several documents, each potentially also having its own internal subset; it's possible that entity layering may be represented the same way. The API for altering the content model may also be the CM's official interface with parsers. One of the ongoing problems in the DOM is that there is some information which must currently be created via completely undocumented mechanisms, which limits the ability to mix and match DOMs and parsers. Given that specialized DOMs are going to become more common (sub-classed, or wrappers around other kinds of storage, or optimized for specific tasks), we must avoid that situation and provide a "builder" API. Particular pairs of DOMs and parsers may bypass it, but it's required as a portability mechanism. Note that several of these applications require that a CM be able to be created, loaded, and manipulated without/before being bound to a specific Document. A related issue is that we'd want to be able to share a single representation of a CM among several documents, both for storage efficiency and so that changes in the CM can quickly be tested by validating it against a set of known-good documents. Similarly, there is a known problem in DOM Level 2 where we assume that the DocumentType will be created before the Document, which is fine for newly-constructed documents but not a good match for the order in which an XML parser encounters this data; being able to "rebind" a Document to a new CM, after it has been created may be desirable. As noted earlier, questions about whether one can alter the content of the CM via its syntax, via higher-level abstractions, or both, exist. It's also worth noting that many of the editing concepts from the Document tree still apply; users should probably be able to clone part of a CM, remove and re-insert parts, and so on. 1.7. Content Model-directed Document Manipulation In addition to using the content model to validate a document instance, applications would like to be able to use it to guide construction and editing of documents, which falls into the document-editing world. Examples of this sort of guided editing already exist, and are becoming more common. The necessary queries can be phrased in several ways, the most useful of which may be a combination of "what does the DTD allow me to insert here" and "if I insert this here, will the document still be valid". The former is better suited to presentation to humans via a user interface, and when taken together with sub-tree validation may subsume the latter. It has been proposed that in addition to asking questions about specific parts of the content model, there should be a reasonable way to obtain a list of all the defined symbols of a given type (element, attribute, entity) independent of whether they're valid in a given location; that might be useful in building a list in a user-interface, which could then be updated to reflect which of these are relevant for the program's current state. Remember that namespaces also weigh in on this issue, in the case of attributes, a "can-this-go-there" may prompt a namespace-well-formedness check and warn you if you're about to conflict with or overwrite another attribute with the same namespaceURI/localName but different prefix... or same nodeName but different namespaceURI. As mentioned above, we have to deal with the fact that the shortest distance between two valid documents may be through an invalid one. Users may want to know several levels of detail (all the possible children, those which would be valid given what precedes this point, those which would be valid given both preceding and following siblings). Also, once XML Schemas introduce context sensitive validity, we may have to consider the effect of children as well as the individual node being inserted. 1.8. Validating a Document Against a Content Model The most obvious use for a content model (DTD or XML Schema or any Content Model) is to use it to validate that a given XML document is in fact a properly constructed instance of the document type described by this CM. This again falls into the document-editing world. The XML spec only discusses performing this test at the time the document is loaded into the "processor", which most of us have taken to mean that this check should be performed at parse time. But it is obviously desirable to be able to validate again a document -- or selected subtrees -- at other times. One such case would be validating an edited or newly constructed document before serializing it or otherwise passing it to other users. This issue also arises if the "internal subset" is altered -- or if the whole Content Model changes. In the past, the DOM has allowed users to create invalid documents, and assumed the serializer would accept the task of detecting problems and announcing/repairing them when the document was written out in XML syntax... or that they would be checked for validity when read back in. We considered adding validity checks to the DOM's existing editing operations to prevent creation of invalid documents, but are currently inclined against this for several reasons. First, it would impose a significant amount of computational overhead to the DOM, which might be unnecessary in many situations, e.g., if the change is occurring in a context where we know the result will be valid. Second, "the shortest distance between two good documents may be through a bad document". Preventing a document from becoming temporarily invalid may impose a considerable amount of additional work on higher-level code and users Hence our current plan is to continue to permit editing to produce invalid DOMs, but provide operations which permit a user to check the validity of a node on demand. Note that validation includes checking that ID attributes are unique, and that IDREFs point to IDs which actually exist. 1.9. Well-formedness Testing XML defined the "well-formed" (WF) state for documents which are parsed without reference to their DTDs. Knowing that a document is well-formed may be useful by itself even when a DTD is available. For example, users may wish to deliberately save an invalid document, perhaps as a checkpoint before further editing. Hence, the CM feature will permit both full validity checking (see previous section) and "lightweight" WF checking, as requested by the caller, as well as processing entity declarations in the CM even if validation is not turned on. This falls within the document-editing world. While the DOM inherently enforces some of XML's well-formedness conditions (proper nesting of elements, constraints on which children may be placed within each node), there are some checks that are not yet performed. These include: * Character restrictions for text content and attribute values. Some characters aren't permitted even when expressed as numeric character entities * The three-character sequence "]]>" in CDATASections. * The two-character sequence "--" in comments. (Which, be it noted, some XML validators don't currently remember to test...) In addition, Namespaces introduce their own concepts of well-formedness. Specifically: * No two attributes on a single Element may have the same combination of namespaceURI and localName, even if their prefixes are different and hence they don't conflict under XML 1.0 rules. * NamespaceURIs must be legal URI syntax. (Note that once we have this code, it may be reusable for the URI "datatype" in document content; see discussion of datatypes.) * The mapping of namespace prefixes to their URIs must be declared and consistent. That isn't required during normal DOM operation, since we perform "early binding" and thereafter refer to nodes primarily via their namespaceURIs and localName. But it does become an issue when we want to serialize the DOM to XML syntax, and may be an issue if an application is assuming that all the declarations are present and correct. This may imply that we should provide a namespaceNormalize operation, which would create the implied declarations and reconcile conflicts in some reasonably standardized manner. This may be a major undertaking, since some DOMs may be using the namespace to direct subclassing of the nodes or similar special treatment; as with the existing normalize method, you may be left with a different-but-equivalent set of node objects. In the past, the DOM has allowed users to create documents which violate these rules, and assumed the serializer would accept the task of detecting problems and announcing/repairing them when the document was written out in XML syntax. We considered adding WF checks to the DOM's existing editing operations to prevent WF violations from arising, but are currently inclined against this for two reasons. First, it would impose a significant amount of computational overhead to the DOM, which might be unnecessary in many situations (for example, if the change is occurring in a context where we know the illegal characters have already been prevented from arising). Second, "the shortest distance between two good documents may be through a bad document" -- preventing a document from becoming temporarily ill-formed may impose a considerable amount of additional work on higher-level code and users. (Note possible issue for Serialization: In some applications, being able to save and reload marginally poorly-formed DOMs might be useful -- editor checkpoint files, for example.) Hence our current plan is to continue to permit editing to produce ill-formed DOMs, but provide operations which permit a user to check the well-formedness of a node on demand, and possibly provide some of the primitive (e.g., string-checking) functions directly. 19 April 2001 2. Document Object Model Load and Save Editors Andy Heninger, IBM Table of contents * 2.1. Load and Save Requirements o 2.1.1. General Requirements o 2.1.2. Load Requirements o 2.1.3. XML Writer Requirements o 2.1.4. Other Items Under Consideration * 2.2. Issue List o 2.2.1. Open Issues o 2.2.2. Resolved Issues * 2.3. Interfaces o 2.3.1. Interface Summary o 2.3.2. Interfaces + DOMImplementationLS, DOMBuilder, DOMInputSource, DOMEntityResolver, DOMBuilderFilter, DOMWriter, DocumentLS, ParserErrorEvent 2.1. Load and Save Requirements DOM Level 3 will provide an API for loading XML source documents into a DOM representation and for saving a DOM representation as a XML document. Some environments, such as the Java platform or COM, have their own ways to persist objects to streams and to restore them. There is no direct relationship between these mechanisms and the DOM load/save mechanism. This specification defines how to serialize documents only to and from XML format. 2.1.1. General Requirements Requirements that apply to both loading and saving documents. 2.1.1.1. Document Sources Documents must be able to be parsed from and saved to the following sources: * Input and Output Streams * URIs * Files Note that Input and Output streams take care of the in memory case. One point of caution is that a stream doesn't allow a base URI to be defined against which all relative URIs in the document are resolved. 2.1.1.2. Content Model Loading While creating a new document using the DOM API, a mechanism must be provided to specify that the new document uses a pre-existing Content Model and to cause that Content Model to be loaded. Note that while DOM Level 2 creation can specify a Content Model when creating a document (public and system IDs for the external subset, and a string for the subset), DOM Level 2 implementations do not process the Content Model's content. For DOM Level 3, the Content Model's content must be read. 2.1.1.3. Content Model Reuse When processing a series of documents, all of which use the same Content Model, implementations should be able to reuse the already parsed and loaded Content Model rather than parsing it again for each new document. This feature may not have an explicit DOM API associated with it, but it does require that nothing in this section, or the Content Model section, of this specification block it or make it difficult to implement. 2.1.1.4. Entity Resolution Some means is required to allow applications to map public and system IDs to the correct document. This facility should provide sufficient capability to allow the implementation of catalogs, but providing catalogs themselves is not a requirement. In addition XML Base needs to be addressed. 2.1.1.5. Error Reporting Loading a document can cause the generation of errors including: * I/O Errors, such as the inability to find or open the specified document. XML well formedness errors. Validity errors Saving a document can cause the generation of errors including: * I/O Errors, such as the inability to write to a specified stream, URL, or file. Improper constructs, such as '--' in comments, in the DOM that cannot be represented as well formed XML. This section, as well as the DOM Level 3 Content Model section should use a common error reporting mechanism. Well-formedness and validity checking are in the domain of the Content Model section, even though they may be commonly generated in response to an application asking that a document be loaded. 2.1.2. Load Requirements The following requirements apply to loading documents. 2.1.2.1. Parser Properties and Options Parsers may have properties or options that can be set by applications. Examples include: * Expansion of entity references. * Creation of entity ref nodes. * Handling of white space in element content. * Enabling of namespace handling. * Enabling of content model validation. A mechanism to set properties, query the state of properties, and to query the set of properties supported by a particular DOM implementation is required. 2.1.3. XML Writer Requirements The fundamental requirement is to write a DOM document as XML source. All information to be serialized should be available via the normal DOM API. 2.1.3.1. XML Writer Properties and Options There are several options that can be defined when saving an XML document. Some of these are: * Saving to Canonical XML format. * Pretty Printing. * Specify the encoding in which a document is written. * How and when to use character entities. * Namespace prefix handling. * Saving of Content Models. * Handling of external entities. 2.1.3.2. Content Model Saving Requirement from the Content Model group. 2.1.4. Other Items Under Consideration The following items are not committed to, but are under consideration. Public feedback on these items is especially requested. 2.1.4.1. Incremental and/or Concurrent Parsing Provide the ability for a thread that requested the loading of a document to continue execution without blocking while the document is being loaded. This would require some sort of notification or completion event when the loading process was done. Provide the ability to examine the partial DOM representation before it has been fully loaded. In one form, a document may be loaded asynchronously while a DOM based application is accessing the document. In another form, the application may explicitly ask for the next incremental portion of a document to be loaded. 2.1.4.2. Filtered Save Provide the capability to write out only a part of a document. May be able to leverage TreeWalkers, or the Filters associated with TreeWalkers, or Ranges as a means of specifying the portion of the document to be written. 2.1.4.3. Document Fragments Document fragments, as specified by the XML Fragment specification, should be able to be loaded. This is useful to applications that only need to process some part of a large document. Because the DOM is typically implemented as an in-memory representation of a document, fully loading large documents can require large amounts of memory. XPath should also be considered as a way to identify XML Document fragments to load. 2.1.4.4. Document Fragments in Context of Existing DOM Document fragments, as specified by the XML Fragment specification, should be able to be loaded into the context of an existing document at a point specified by a node position, or perhaps a range. This is a separate feature than simply loading document fragments as a new Node. 2.2. Issue List 2.2.1. Open Issues Issue LS-Issue-10: Error Reporting. Loading will be reporting well-formedness and validation errors, just like CM. A common error reporting mechanism needs to be developed. Issue LS-Issue-16: Loading and saving of content models - DTDs or Schemas - outside of the context of a document is not addressed. Issue LS-Issue-17: Loading while validating using an already loaded content model is not addressed. Applications should be able to load a content model (issue 16), and then repeatedly reuse it during the loading of additional documents. Issue LS-Issue-20: Action from September f2f to "add issues raised by schema discussion. What were these? Issue LS-Issue-22: What do the bindings for things like InputStream look like in ECMA Script? Tentative resolution - InputStream will map to a binding dependent class or interface. For environments where nothing appropriate exists, a new interface will be created. This question is still being discussed. Issue LS-Issue-27: How is validation during document loading handled when there are multiple possible content models associated with the document? How is one selected? The same question exists for documents in general, outside of the context of loading. Resolving the question for loading probably needs to wait until the more general question is understood. Issue LS-Issue-32: Mimetypes. If the input being parsed is from http or something else that supplies types, and the type is something other than text/xml, should we parse it anyhow, or should we complain. Should there be an option? Tentative resolution: always parse, never complain. Reasons: 1. This is what all parsers do now, and no one has ever complained, at least not that I'm aware of. 2. Applications must have a pretty good reason to suspect that they're getting xml or they wouldn't have invoked the parser. 3. All the test would do is to take something that might have worked (xml that is not known to the server) and turn it into an error. Non-xml is exceptionally unlikely to successfully parse (be well formed.) Issue LS-Issue-34: Features 2.1.4.1, 2 - XML Fragment Support. Should these be dropped? (Yes!) Issue LS-Issue-35: XPath based document load filter. It would be plausible to have a partial (filtered) document load based on selecting the portion of the document to load with an XPath expression. This facility could be in addition to the node-by-node filtering currently specified. Or we could drop the existing filter. Implementing an XPath based selective load would require that there be an XPath processor present in addition to the parser itself. 2.2.2. Resolved Issues Issue LS-Issue-1: Should these methods be in a new interface, or should they be added to the existing DOMImplementation Interface? I think that adding them to the existing interface is cleaner, because it helps avoid an explosion of new interfaces. The methods are in a separate interface in this description for convenience in preparing the doc, so that I don't need to edit Core to add the methods. (The same argument could perhaps be made for implementations.) Resolution: The methods are in a separate DOMImplementationLS interface. Because Load/Save is an optional module, we don't want to add its to the core DOMImplementation interface. Issue LS-Issue-2: SAX handles the setting of parser attributes differently. Rather than having distinct getters and setters for each attribute, it has a generic setter and getter of named properties, where properties are specified by a URL. This has an advantage in that implementations do not need to extend the interface when providing additional attributes. If we choose to use strings, their syntax needs to be chosen. URIs would make sense, except for the fact that these are just names that do not refer to any resources. Dereferencing them would be meaningless. Yet the direction of the W3C is that all URIs must be dereferencable, and refer to something on the web. Resolution: Use strings for properties. Use Java package name syntax for the identifying names. The question was revisited at the July f2f, with the same conclusion. But some discussion of using URLs continues. This issue was revisited once again at the 9/2000 meeting. Now all DOM properties or features will be short, descriptive names, and we will recommend that all vendor-specific extensions be prefixed to avoid collisions, but will not make specific recommendations for the syntax of the prefix. Issue LS-Issue-3: It's not obvious what name to choose for the parser interface. Taking any of the names already in use by parser implementations would create problems when trying to support both the new API and the existing old API. That leaves out DocumentBuilder (Sun) and DOMParser (Xerces). Resolution: This is issue really just a comment. The "resolution" is in the names appearing in the API. Issue LS-Issue-4: Question: should ResolveEntity pass a baseURI string back to the application, in addition to the publicId, systemId, and/or stream? Particularly in the case of an input stream. Resolution: No. Sax2 explicitly says that the system ID URI must be fully resolved before passing it out to the entity resolve. We will follow SAX's lead on this unless some additional use case surfaces. This is from the 9/2000 f2f, and reverses an earlier decision. Issue LS-Issue-5: When parsing a document that contains errors, should the whole document be decreed unusable, or should we say that portions prior to the point where the error was detected are OK? Resolution: In the case of errors in the XML source, what, if any, document is returned is implementation dependent. Issue LS-Issue-6: The relationship between SAXExceptions and DOM exceptions seems confusing. Resolution: This issue goes away because we are no longer using SAX. Any exceptions will be DOM Exceptions. Issue LS-Issue-7: Question: In the original Java definition, are the strings returned from the methods SAXException.toString() and SAXException.getMessage() always the same? If not, we need to add another attribute. Resolution: No longer an issue because we are no longer using SAX. Issue LS-Issue-8: JAXP defines a mechanism, based on Java system properties, by which the Document Builder Factory locates the specific parser implementation to be used. This ability to redirect to different parsers is a key feature of JAXP. How this redirection works in the context of this design may be something that needs to be defined separately for each language binding. This question was discussed at the July f2f, without resolution. Agreed that the feature is not critical to the rest of the API, and can be postponed. Resolution: The issue is moving to core, where it is part of the bigger question of where does the DOM implementation come from, and how do multiple implementations coexist. Allowing separate, or mix-and-match, specification of the parser and the rest of the DOM is not generally practical because parsers generally have some degree of private knowledge about their DOMs. Issue LS-Issue-9: The use of interfaces from SAX2 raises some questions. The Java bindings for these interfaces need to be exactly the SAX2 definitions, including the original org.xml.sax package name. The IDL presented here for these interfaces is an attempt to map the Java into IDL, but it will certainly not round-trip accurately - Java bindings generated from the IDL will not match the original Java. The reasons for using the SAX interfaces are that they are well designed, widely implemented and used, and provide what is needed. Designing something new would create confusion for application developers (which should be used?) and make extra work for implementers of the DOM, most of whom probably already provide SAX, all for no real gain. Resolution: Problem is gone. We are not using SAX2. The design will borrow features and concepts from SAX2 when it makes sense to do so. Issue LS-Issue-11: Another Error Reporting Question. We decided at the June f2f that validity errors should not be exceptions. This means that a document load operation could encounter multiple errors. Should these be collected and delivered as some sort of collection at the (otherwise) successful completion of the load, or should there be some sort of callback? Callbacks are harder for applications to deal with. Resolution: Provide a callback mechanism. Provide a default error handler that throws an exception and stops further processing. From July f2f. Issue LS-Issue-12: Definition of "Non-validating". Exactly how much processing is done by "non-validating" parsers is not fully defined by the XML specification. In particular, they are not required to read any external entities, but are not prohibited from doing so. Another common user request: a mode that completely ignores DTDs, both and external. Such a parser would not conform to XML 1.0, however. For the documents produced by a non-validating load to be the same, we need to tie down exactly what processing must be done. The XML Core WG also has question as an open issue . Some discussion is at http://lists.w3.org/Archives/Member/w3c-xml-core-wg/2000JanMar/0192.html Here is proposal: Have three classes of parsers o Minimal. No external entities of any type are accessed. DTD subset is processes normally, as required by XML 1.0, including all entity definitions it contains. o Non-Validating. All external entities are read. Does everything except validation. o Validating. As defined by XML 1.0 rec. Resolution: Use the options from SAX2. These provide separate flags for validation, reading of external general entities and reading of external parameter entities. Issue LS-Issue-13: Use of System or Language specific types for Input and Output Loading and Saving requires that one of the possible sources or destinations of the XML data be some sort of stream that can be used with io streams or memory buffers, or anything else that might take or supply data. The type will vary, depending on the language binding. The question is, what should be put into the IDL interfaces for these? Should we define an XML stream to abstract out the dependency, or use system classes directly in the bindings? Resolution: Define IDL types for use in the rest of the interface definitions. These types will be mapped directly to system types for each language binding Issue LS-Issue-14: Should there be separate DOM modules for browser or scripting style loading (document.load("whatever")) and server style parsers? It's probably easy for the server style parsers to implement the browser style interface, but the reverse may not be true. Resolution: Yes. A client application style API will be provided. Issue LS-Issue-15: System Exceptions. Loading involves file opens and reads, and these can result in a variety of system errors that may already have associated system exceptions. Should these system exceptions pass through as is, or should they be some how wrapped in DOMExceptions, or should there be a parallel set DOM Exceptions, or what? Resolution: Introduce a new DOMSystemException to standardize the reporting of common I/O errors across different DOM environments. Let it wrap an underlying system exception or error code when appropriate. To be defined in the common ErrorReporting module, to be shared with ContentModel. Issue LS-Issue-18: For the list of parser properties, which must all implementations recognize, which settings must all implementations support, and which are optional? Resolution: Done Issue LS-Issue-19: DOMOutputStream: should this be an interface with methods, or just an opaque type that maps onto an appropriate binding-specific stream type? If we specify an actual interface with methods, applications can implement it to wrap any arbitrary destination that they may have. If we go with the system type it's simpler to output to that type of stream, but harder otherwise. Resolution: Opaque. Issue LS-Issue-21: Define exceptions. A DOMSystemException needs to be defined as part of the error handling module that is to be shared with CM. Common I/O type errors need to be defined for it, so that they can be reported in a uniform way. A way to embed errors or exceptions from the OS or language environment is needed, to provide full information to applications that want it. Resolution: Duplicate of issue #15 Issue LS-Issue-23: To Do: Add a method or methods to DOMBuilder that will provide information about a parser feature - is the name recognized, which (boolean) values are supported - without throwing exceptions. Resolution: Done. Added canSetFeature. Issue LS-Issue-24: Clearly identify which of the parser properties must be recognized, and which of their settings must be supported by all conforming implementations. Resolution: Done. All must be recognized. Issue LS-Issue-25: How does the validation property work in SAX, and how should it work for us? The default value in SAX2 is "true". Non-validating parsers only support a value of false. Does this mean that the default depends on the parser, or that some sort of an error happens if a parse is attempted before resetting the property, or what? The same question applies to the External Entities properties too. Resolution: Make the default value for the validation property be false. Issue LS-Issue-26: Do we want to rename the "auto-validation" property to "validate-if-cm"? Proposed at f2f. Resolution unclear. Resolution: Changed the name to "validate-if-cm". Issue LS-Issue-29: Should all properties except namespaces default to false? Discussed at f2f. I'm not so sure now. Some of the properties have somewhat non-standard behavior when false - leaving out ER nodes or whitespace, for example - and support of false will probably not even be required. Resolution: Not all properties should default to false. But validation should. Issue LS-Issue-28: To do: add new parser property "createEntityNodes". default is true. Illegal for it to be false and createEntityReferenceNodes to be true. Is this really what we want? Resolution: new feature added. Issue LS-Issue-30: Possible additional parser features - option to not create CDATA nodes, and to merge CDATA contents with adjacent TEXT nodes if they exist. Otherwise just create a TEXT node. Option to omit Comments. Resolution: new feature added. Issue LS-Issue-31: We now have an option for fixing up name space declarations and prefixes on serialization. Should we specify how this is done, so that the documents from different implementations of serialization will use the same declarations and prefixes, or should we leave the details up to the implementation? Resolution: The exact form of the name space fixup is implementation dependent. The only requirement is that all elements and attributes end up with the correct name space URI. Issue LS-Issue-33: Unicode Character Normalization Problems. It turns out that for some code pages, normalizing a Unicode representation, translating to the code page, then translating back to Unicode can result in un-normalized Unicode. Mark Davis says that this can happen with Vietnamese and maybe with Hebrew. This means that the suggested W3C model of normalization on serialization (early normalization) may not work, and that the receiver of the data may need to normalize it again, just in case. Resolution: The scenario described is a quality-of-implementation issue. A transcoder converting from the one of the troublesome code pages to a Unicode representation should be responsible for re-normalizing the output. 2.3. Interfaces This section defines an API for loading (parsing) XML source documents into a DOM representation and for saving (serializing) a DOM representation as an XML document. The proposal for loading is influenced by Sun's JAXP API for XML Parsing in Java, http://java.sun.com/xml/download.html, and by SAX2, available at http://www.megginson.com/SAX/index.html 2.3.1. Interface Summary Here is a list of each of the interfaces involved with the Loading and Saving XML documents. * DOMImplementationLS -- A new DOMImplementation interface 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. * 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. * DOMWriter -- An interface for writing out or serializing DOM documents. * DocumentLS -- Provides a client or browser style interface for loading and saving. * ParserErrorEvent -- ParserErrorEvent is the event that is fired if there's an error in the XML document being parsed using the methods of DocumentLS. 2.3.2. Interfaces Interface DOMImplementationLS DOMImplementationLS contains the factory methods for creating objects implementing the DOMBuilder (parser) and DOMWriter interfaces. An object implementing DOMImplementationLS is obtained by casting from DOMImplementation to DOMImplementationLS, using the customary casting facilities from the programming language in use. Implementations supporting the Load and Save feature must implement the DOMImplementationLS interface on whatever object implements the DOMImplementation interface. IDL Definition interface DOMImplementationLS { DOMBuilder createDOMBuilder(); DOMWriter createDOMWriter(); }; Methods createDOMBuilder Create a new DOMBuilder. The newly constructed parser may then be configured by means of its setFeature() method, and used to parse documents by means of its parse() method. Return Value DOMBuilder The newly created parser object. No Parameters No Exceptions createDOMWriter Create a new DOMWriter object. DOMWriters are used to serialize a DOM tree back into source XML form. Return Value DOMWriter The newly created DOMWriter object. No Parameters No Exceptions Interface DOMBuilder A parser interface. DOMBuilder provides an API for parsing XML documents and building the corresponding DOM document tree. A DOMBuilder instance is obtained from the DOMImplementationLS interface by invoking its createDOMBuilder()method. DOMBuilders have a number of named properties that can be queried or set. Here is a list of properties that must be recognized by all implementations. o namespaces true: perform Namespace processing. false: do not perform name space processing. default: true. supported values: true: required; false: optional o namespace-declarations true: include namespace declarations (xmlns attributes) in the DOM document. false: discard all namespace declarations. In either case, namespace prefixes will be retained. default: true. supported values: true: required; false: optional o validation true: report validation errors (setting true also will force the external-general-entities and external-parameter-entities properties to be set true.) Also note that the validate-if-cm feature will alter the validation behavior when this feature is set true. false: do not report validation errors. default: false. supported values: true: optional; false: required o external-general-entities true: include all external general (text) entities. false: do not include external general entities. default: true. supported values: true: required; false: optional o external-parameter-entities true: include all external parameter entities. false: do not include external parameter entities. default: true. supported values: true: required; false: optional o validate-if-cm true: when both this feature and validation are true, enable validation only when the document being processed has a content model. Documents without content models are parsed without validation. false: the validation feature alone controls whether the document is checked for validity. Documents without content models are not valid. default: false. supported values: true: optional; false: required o create-entity-ref-nodes true: create entity reference nodes in the DOM document. Setting this value true will also set create-entity-nodes to be true false: omit all entity reference nodes from the DOM document, putting the entity expansions directly in their place. default: true. supported values: true: required; false: optional o entity-nodes true: create entity nodes in the DOM document. false: omit all entity nodes from the DOM document. Setting this value false will also set create-entity-ref-nodes false. default: true. supported values: true: required; false: optional o white-space-in-element-content true: include white space in element content in the DOM document. This is sometimes referred to as ignorable white space false: omit said white space. Note that white space in element content will only be omitted if it can be identified as such, and not all parsers may be able to do so. default: true. supported values: true: required; false: optional o cdata-nodes true: Create DOM CDATA nodes in response to the appearance of CDATA sections in the source XML. false: Do not create CDATA nodes in the DOM document. The content of any CDATA sections in the source XML appears in the DOM as if it had been normal (non-CDATA) content. If a CDATA section is adjacent to other content, the combined content appears in a single TEXT node. The DOM Document produced by the DOMBuilder will not have adjacent TEXT nodes. default: true supported values: false: optional; true: required o comments true: Include XML comments in the DOM document false: Discard XML comments, do not create Comment nodes in the DOM Document resulting from a parse. default: true supported values: false: required; true: required o charset-overrides-xml-encoding true: If a higher level protocol such as http provides an indication of the character encoding of the input stream being processed, that will override any encoding specified in the XML or TEXT declaration of the XML. Explicitly setting an encoding in the DOMInputSource overrides encodings from the protocol. false: Any character set encoding information from higher level protocols is ignored by the parser. default: true supported values: false: required; true: required IDL Definition interface DOMBuilder { attribute DOMEntityResolver entityResolver; attribute DOMErrorHandler errorHandler; attribute DOMBuilderFilter filter; void setFeature(in DOMString name, in boolean state) raises(DOMException); boolean supportsFeature(in DOMString name); boolean canSetFeature(in DOMString name, in boolean state); boolean getFeature(in DOMString name) raises(DOMException); Document parseURI(in DOMString uri) raises(DOMException, DOMSystemException); Document parseDOMInputSource(in DOMInputSource is) raises(DOMException, DOMSystemException); }; Attributes entityResolver of type DOMEntityResolver If a DOMEntityResolver has been specified, each time a reference to an external entity is encountered the DOMBuilder will pass the public and system IDs to the entity resolver, which can then specify the actual source of the entity. errorHandler of type DOMErrorHandler In the event that an error is encountered in the XML document being parsed, the DOMDcoumentBuilder will call back to the errorHandler with the error information. Note: The DOMErrorHandler interface is being developed separately, in conjunction with the design of the content model and validation module. filter of type DOMBuilderFilter When the application provides a filter, the parser will call out to the filter at the completion of the construction of each Element node. The filter implementation can choose to remove the element from the document being constructed or to terminate the parse early. Methods canSetFeature query whether setting a feature is supported. The feature name has the same form as a DOM hasFeature string. It is possible for a DOMBuilder to recognize a feature name but to be unable to set its value. Parameters name of type DOMString The feature name, which is a DOM has-feature style string. state of type boolean The requested state of the feature (true or false). Return Value boolean true if the feature could be successfully set to the specified value, or false if the feature is not recognized or the requested value is not supported. The value of the feature itself is not changed. No Exceptions getFeature Look up the value of a feature. The feature name has the same form as a DOM hasFeature string Parameters name of type DOMString The feature name, which is a string with DOM has-feature syntax. Return Value boolean The current state of the feature (true or false). Exceptions DOMException Raise a NOT_FOUND_ERR When the DOMBuilder does not recognize the feature name. parseDOMInputSource Parse an XML document from a location identified by an DOMInputSource. Parameters is of type DOMInputSource The DOMInputSource from which the source document is to be read. Return Value Document The newly created and populatedDocument. Exceptions DOMException Exceptions raised by parseDOMInputSource() originate with the installed ErrorHandler, and thus depend on the implementation of the DOMErrorHandler interfaces. The default ErrorHandlers will raise a DOMException if any form of XML validation or well formedness error or warning occurs during the parse, but application defined errorHandlers are not required to do so. DOMSystemException Exceptions raised by parseDOMInputSource() originate with the installed ErrorHandler, and thus depend on the implementation of the DOMErrorHandler interfaces. The default ErrorHandlers will raise a DOMSystemException if any form I/O or other system error occurs during the parse, but application defined ErrorHandlers are not required to do so. parseURI Parse an XML document from a location identified by an URI. Parameters uri of type DOMString The location of the XML document to be read. Return Value Document The newly created and populatedDocument. Exceptions DOMException Exceptions raised by parseURI() originate with the installed ErrorHandler, and thus depend on the implementation of the DOMErrorHandler interfaces. The default error handlers will raise a DOMException if any form of XML validation or well formedness error or warning occurs during the parse, but application defined errorHandlers are not required to do so. DOMSystemException Exceptions raised by parseURI() originate with the installed ErrorHandler, and thus depend on the implementation of the DOMErrorHandler interfaces. The default error handlers will raise a DOMSystemException if any form I/O or other system error occurs during the parse, but application defined error handlers are not required to do so.