This chapter documents the relationship of Galax to the target W3C working drafts. Galax 1.0 is a prototype implementation, and therefore it is not (yet) completely aligned with the relevant W3C working drafts (WDs). This chapter also document the non-standard features in Galax 1.0 and the known bugs and limitations.
Galax 1.0 implements the January, 2007 XQuery 1.0 and XPath 2.0 Candidate Recommendations, the XML 1.0 Recommendation, the Namespaces in XML Recommendation, and XML Schema Recommendation (Parts 1 and 2).
Galax 1.0 implements the XQuery 1.0 Recommendations:
Galax 1.0 fully supports the XQuery 1.0 and XPath 2.0 Data Model.
Galax 1.0 implements an xsd:float value as an xsd:double value.
The alignment issues in this section follow the outline of the "Expressions" section in http://www.w3c.org/TR/xquery. If a subsection is not listed here, it means that Galax 1.0 implements the semantics described in that section.
Galax 1.0 does not support:
The implicit timezone is set to the local timezone.
Galax’s processing model is similar to XQuery’s abstract processing model. See Section 7 for more information on Galax’s internal processing model.
Galax 1.0 does not check that a numeric value is equal to NaN when computing an effective boolean value.
Galax 1.0 does not support the fn:collection() function.
The context item and values for external variables can be specified on the command line or in the API. See Sections 5.1.1 and 6.2.
Galax requires that all actual types, that is, those types that annotate input documents be in the in-scope schema definitions. Galax will raise a dynamic error if it encounters a type in a document that is not imported into the query by an import schema prolog statement.
Galax supports the Schema Import, Static Typing, and Full Axis features.
Galax 1.0 supports the Module feature.
Galax 1.0 does not support the Pragmas feature.
Galax 1.0 does not support must-understand extensions.
Galax 1.0 does not support static typing extensions.
Galax 1.0 implements an xsd:float value as an xsd:double value.
Galax 1.0 supports all axes with the exception of the preceding and following axes.
When constructing a new element, Galax 1.0always erases/eliminates type annotations on copied elements.
When constructing a new element, Galax 1.0requires that the new element’s attributes precede its other content.
Namespace declarations in input and output documents and in input queries are not handled consistently. We are working on this.
Galax 1.0 will accept queries that contain the ordered or unordered expressions, but they have no effect on query evaluation (i.e., they are no-ops).
Galax 1.0 supports the Module feature.
Galax 1.0 does not support collations.
Galax 1.0 does not support the construction declaration.
Galax 1.0 does not support the default ordering declaration.
Schema components in an imported schema are mapped into XQuery types according to the mapping rules specified in the XQuery 1.0 Formal Semantics (see below).
The XQuery 1.0 formal semantics defines the mapping of every XQuery expression into an expression in the XQuery core, and it defines the static and dynamic semantics of each core expression. The formal semantics also defines how imported schemas are mapped into internal XQuery types.
Galax 1.0 implements the static and dynamic semantics of core expressions defined in the XQuery 1.0 Formal Semantics.
Galax 1.0 supports most of the functions in the XQuery 1.0 and XPath 2.0 Functions and Operators document. The signatures of supported functions are listed in $GALAXLIB/pervasive.xq.
Galax 1.0 does not support the following functions:
fn:id fn:idref fn:collection
The fn:trace function emits its input sequence and message are to standard output.
Galax 1.0does not support constructor functions for user-defined types.
Galax 1.0 does not support any functions on binary data.
See $GALAXHOME/usecases/STATUS
Type values are available in a query by either importing a predefined XML schema using the import schema declaration in the query prolog or by defining XQuery types explicitly in the query prolog.
Galax 1.0 supports the definition of XQuery types in the query prolog using the internal type syntax defined in the XQuery 1.0 Formal Semantics. The grammar is provided here for reference:
TypeDeclaration ::= ("define" "element" QName "{" TypeDefn? "}")
| ("define" "attribute" QName "{" TypeDefn? "}")
| ("define" "type" QName "{" TypeDefn? "}")
TypeDefn ::= TypeUnion
| TypeBoth
| TypeSequence
| TypeSimpleType
| TypeAttributeRef
| TypeElementRef
| TypeTypeRef
| TypeParenthesized
| TypeNone
TypeUnion ::= TypeDefn "|" TypeDefn
TypeBoth ::= TypeDefn "&" TypeDefn
TypeSequence ::= TypeDefn "," TypeDefn
TypeSimpleType ::= QName OccurrenceIndicator
TypeAttributeRef ::= "attribute" NameTest ("{" TypeDefn? "}")? OccurrenceIndicator
TypeElementRef ::= "element" NameTest ("{" TypeDefn? "}")? OccurrenceIndicator
TypeTypeRef ::= "type" NameTest OccurrenceIndicator
TypeParenthesized::= "(" TypeDefn? ")" OccurrenceIndicator
TypeNone ::= "none"
Galax-only functions are put in the Galax namespace (http://www.galaxquery.org), which is bound by default to the glx: prefix.
See $GALAXHOME/lib/pervasive.xq for a complete list of functions in the Galax namespace.