ISSUE-39: importing components from another namespace

ISSUE-39: importing components from another namespace

http://www.w3.org/2005/06/tracker/databinding/issues/39

Raised by: Paul Downey
On product: Basic

1) We currently have no basic patterns for importing
schema components from another namespace. 

2) The 'hint' nature of the xs:import schemaLocation
is a source of confusion and interoperability problems

3) There is a common convention of referring to another
schema already 'known' to a processor by not providing
a schemaLocation attribute.

Proposal:

Provide the following Basic patterns:

<xs:import namespace="{xs:anyURI}" schemaLocation="{xs:anyURI}" />

The schemaLocation attribute when present MUST be a single URI which 
when dereferenced resolves to a document whose whose root element 
is "schema" from the namespace "http://www.w3.org/2001/XMLSchema".

<xs:import namespace="{xs:anyURI}" />

The absence of a schemaLocation attribute indicates there is a 
schema document defining components already 'known' to the processor 
within the current context, e.g. both the importing and imported 
documents are contained within the same WSDL "types" section.