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This section describes the status of this document at the time of its publication. Other documents may supersede this document. A list of current W3C publications and the latest revision of this technical report can be found in the W3C technical reports index at http://www.w3.org/TR/.
This is a Working Draft as described in the Process Document. It was developed by the W3C XML Query Working Group, which is part of the XML Activity. The Working Group expects to eventually publish this document as a Working Group Note.
This document is not intended to become a Recommendation of the W3C, but will instead become a Working Group Note as described in the Process Document.
These Requirements identify extensions to the XQuery 1.0 Recommendation, published 23 January 2007, that have been requested by WG participants and by reviewers who do not participate in the W3C activities. The XML Query WG has reviewed these requirements and accepted them to the degree reflected in this document.
No substantive changes have been made to this specification since its previous publication as a Working Draft.
Please report errors in this document using W3C's public Bugzilla system (instructions can be found at http://www.w3.org/XML/2005/04/qt-bugzilla). If access to that system is not feasible, you may send your comments to the W3C XSLT/XPath/XQuery public comments mailing list, public-qt-comments@w3.org. It will be very helpful if you include the string “[XQuery30Req]” in the subject line of your report, whether made in Bugzilla or in email. Please use multiple Bugzilla entries (or, if necessary, multiple email messages) if you have more than one comment to make. Archives of the comments and responses are available at http://lists.w3.org/Archives/Public/public-qt-comments/.
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1 Goals
2 Requirements
2.1 Terminology
2.2 General
Requirements
2.2.1 Backward compatibility
2.2.2 Extension compatibility
2.3 XML
Query Functionality
2.3.1 Value-based grouping
2.3.2 Error processing and
recovery
2.3.3 Numeric formatting
2.3.4 Date formatting
2.3.5 Default values for
external variables
2.3.6 Non-deterministic external
functions
2.3.7 Positional grouping
2.3.8 Windowing
2.3.9 Output numbering
2.3.10 Dynamic creation of
namespace bindings
2.3.11 Declaration of
serialization parameters
2.3.12 Node references
2.3.13 Outer for
2.3.14 Type declaration for context
item
2.3.15 Support for new data types
2.3.16 Higher order functions
2.3.17 Conditional constructors
2.3.18 Validation
2.3.20 Module composition
restrictions
2.3.21 Invocation of external
functionality
2.3.22 Static typing extensions
3 References
3.1 Normative
3.2 Non-normative
The goal of XML Query 3.0 is to extend XML Query 1.0 with additional functionality in response to requests from users and implementors.
Satisfying these goals may require changes to the set of seven documents that have progressed to Recommendation together (Data Model, Functions and Operators, Serialization, XPath 2.0, XQuery 1.0, XQueryX, and XSLT 2.0).
The following keywords are used throughout the document to specify the extent to which an item is a requirement for the work of the XML Query Working Group:
The item is an absolute requirement.
There may exist valid reasons not to treat this item as a requirement, but the full implications should be understood and the case carefully weighed before discarding this item.
An item deserves attention, but further study is needed to determine whether the item should be treated as a requirement.
When the words MUST, SHOULD, or MAY are used in this technical sense [IETF RFC 2119], they occur as a hyperlink to these definitions. These words will also be used with their conventional English meaning, in which case there is no hyperlink. For instance, the phrase "the full implications should be understood" uses the word "should" in its conventional English sense, and therefore occurs without the hyperlink.
Each requirement also includes a status section, indicating its current situation in the XQuery/XPath/XSLT family of specifications. Three status levels are used:
This indicates that the requirement, according to
its original formulation, has been completely met. Optional
clarifying text may follow.
This indicates that the requirement has been
partially met according to its original formulation. When this
happens, explanatory text is provided to better clarify the current
scope of the requirement.
This indicates that the requirement, according to
its original formulation, has not been met. If this is the case,
explanatory text is provided.
XQuery 3.0 MUST be compatible with XQuery 1.0 extensions developed by the XML Query Working Group, including XQuery Update Facility and XQuery 1.0 and XPath 2.0 Full-Text.
Status: this requirement has been
met.
XQuery 3.0 MUST include a language facility to specify value-based grouping.
Status: this requirement has been
met.
XQuery 3.0 MUST have a mechanism to specify default values for external variables.
Status: this requirement has been
met.
XQuery 3.0 MUST provide a way to denote that an external function is non-deterministic.
Status: this requirement has not been
met.
XQuery 3.0 SHOULD provide a facility for positional grouping of items in a sequence according to specified partitioning conditions.
Status: this requirement has been
met.
XQuery 3.0 SHOULD provide a way to iterate over a sequence by several values at a time.
Status: this requirement has been
met.
XQuery 3.0 SHOULD provide a mechanism to associate ordinal numbers with the items returned by a FLWOR expression.
Status: this requirement has been
met.
XQuery 3.0 SHOULD allow dynamic creation of namespace bindings.
Status: this requirement has been
met.
XQuery 3.0 SHOULD have a mechanism to specify serialization parameters in the query prolog.
Status: this requirement has been
met.
XQuery 3.0 SHOULD support creation of a reference to an existing node having the following properties:
a) the reference could be included in a constructed element
b) the reference can be dereferenced, returning the original node with the original node id.
Status: this requirement has not been
met.
XQuery 3.0 SHOULD provide additional mechanisms to specify joins between sequences. A possible approach would be to add an "outer-for" clause to the FLWOR expression to specify variable binding which is guaranteed to be bound to an empty sequence if there are no other bindings generated.
Status: this requirement has been
met.
XQuery 3.0 SHOULD allow explicit type declaration for the context item.
Status: this requirement has been
met.
XQuery 3.0 SHOULD support new data types introduced in XML Schema 1.1.
Status: this requirement has been
met.
XQuery 3.0 MAY provide an ability to pass a function as an argument to another function and to invoke a function that has been passed as an argument.
Status: this requirement has been met.
(The proposal is not yet integrated into our internal Working
Draft.)
XQuery 3.0 MAY also provide the ability to define anonymous functions e.g., lambda expressions.
Status: this requirement has been met.
(The proposal is not yet integrated into our internal Working
Draft.)
XQuery 3.0 MAY add a language extension to the node constructors to specify, in a compact notation, that a node should be constructed only if its typed value would not be an empty sequence or if it would satisfy some other condition.
Status: this requirement is already met
by XQuery 1.0, there is no need to introduce new syntax. Either of
the following solutions works:
if ($mentor) then attribute mentor { $mentor } else ()
(attribute mentor { $mentor })[$mentor]
XQuery 3.0 MAY provide a mechanism to validate an element or document node with respect to a global named type
Status: this requirement has been
met.
or against non-global element declarations or types.
Status: this requirement has not been
met.
XQuery 3.0 MAY provide a mechanism to validate an element or document node against a named schema without importing the schema.
Status: this requirement has not been
met.
XQuery 3.0 MAY relax the restrictions on the module import feature relating to forward references and circular imports.
Status: this requirement has been
met.
XQuery 3.0 MAY provide a normative way to invoke external functions and modules that are not implemented in XQuery, such as functions defined as web services or XSLT functions and templates.
Status: this requirement has not been
met.
XQuery 3.0 MAY extend static typing rules.
Status: this requirement has not been met.
Static typing is no longer a normative part of XQuery 3.0.
The following references are some of the works considered by the WG in deriving its requirements.