A Namespace Proposal
I've been thinking about the various namespace ideas that have appeared on the list, in particular Michael Kay's proposal for namespaces, but also trying to make sure it works for Amy's automated XML1.0 to XML??? converter principle, without requiring heuristics to map things like http://www.w3.org/1999/XSL/Transform to org.w3c.www.1999.XSL.Transform. I think this is important because a parser ideally wants to present http://www.w3.org/1999/XSL/Transform to higher layers rather than org.w3c.www.1999.XSL.Transform in this case. So here goes: Namespaces SHOULD use the reversed domain name form, e.g. org.example.schema. For compatibility with XML 1.0, namespaces MAY use the URI form via setting up namespace aliases which is discussed later in the proposal. An element or attribute name has the form: name = ( (namespace | namespace_alias ) ":" )? local_name e.g.: org.example.schema:my_name The namespace used in an element's name becomes the active namespace and is applied to all of its children that don't themselves have an explicitly specified namespace. Thus, in: <org.example.schema:foo> <bar/> </org.example.schema:foo> 'bar' is in the org.example.schema namespace and the example is equivalent to: <org.example.schema:foo> <org.example.schema:bar/> </org.example.schema:foo> To set no namespace, leave the namespace part of the name empty, but include the ':' that separates the namespace from the local name, for example: <:foo/> For compatibility with XML 1.0, an attribute name without a namespace or namespace_alias is always in the empty namespace, as opposed to the active namespace. Thus for an attribute the name 'foo' is always equivalent to ':foo'. To allow compatibility with XML 1.0, and to a lesser degree brevity, namespace aliases maybe setup. This is done using 'magic' PIs that have the name 'xml:nsalias' which contain multiple attributes in which the name of the attribute specifies an alias name and the value of the attribute specifies the namespace name. These PIs are primarily intended for the parser and in general are not presented to the application. Thus: <?xml:nsalias xsl="http://www.w3.org/1999/XSL/Transform" ?> establishes "xsl" as an alias of "http://www.w3.org/1999/XSL/Transform". XML alias mappings exist from the point at which they are defined until the end of the XML document. (In other words, there is a single namespace alias mapping repository that is not aware of the element nesting.) Aliases SHOULD NOT be reassigned from one namespace to another. A namespace alias must match XML's NCName production. To reduce the potential for conflicts with explicit namespaces, namespace aliases SHOULD NOT contain the '.' character. Wherever an aliases character sequence matches the prefix of an element or attribute name, the namespace of the element or attribute becomes that of the namespace associated with the alias. For example, if the above alias is set up: xsl:stylesheet is conceptually equivalent to: http://www.w3.org/1999/XSL/Transform:stylesheet although of course the latter is not a valid XML name. As in the case of specifying the namespace directly (e.g. org.example.schema:foo), the namespace associated with the namespace alias becomes the active namespace. A namespace alias may also be used in the interests of brevity, for example the following is equivalent to the earlier example: <?xml:nsalias s="org.example.schema"?> <s:foo> <bar/> </s:foo> Any thoughts? Pete Cordell Codalogic Ltd Interface XML to C++ the easy way using C++ XML data binding to convert XSD schemas to C++ classes. Visit http://codalogic.com/lmx/ or http://www.xml2cpp.com for more info
[Date Prev] | [Thread Prev] | [Thread Next] | [Date Next] -- [Date Index] | [Thread Index]
PURCHASE STYLUS STUDIO ONLINE TODAY!
Purchasing Stylus Studio from our online shop is Easy, Secure and Value Priced!
Download The World's Best XML IDE!
Accelerate XML development with our award-winning XML IDE - Download a free trial today!
Subscribe in XML format