Interface CollectionURIResolver

All Superinterfaces:
All Known Implementing Classes:

public interface CollectionURIResolver
extends Serializable

This interface defines a CollectionURIResolver. This is a counterpart to the JAXP URIResolver, but is used to map the URI of collection into a sequence of documents. It is used to support the fn:collection() and fn:uri-collection() functions.

Method Summary
 SequenceIterator resolve(String href, String base, XPathContext context)
          Resolve a URI.

Method Detail


SequenceIterator resolve(String href,
                         String base,
                         XPathContext context)
                         throws XPathException
Resolve a URI.

href - The relative URI of the collection. This corresponds to the argument supplied to the collection() function. If the collection() function was called with no arguments (to get the "default collection") this argument will be null.
base - The base URI that should be used. This is the base URI of the static context in which the call to collection() was made, typically the URI of the stylesheet or query module
context - The dynamic execution context
an Iterator over the documents in the collection. The items returned by this iterator must be instances either of xs:anyURI, or of node() (specifically, NodeInfo).

When the fn:uri-collection() function is called: the result will consist of (a) any items that are xs:anyURI values, and (b) any items that are nodes, provided that they are document nodes with a document URI.

When the fn:collection() function is called: if xs:anyURI values are returned, the corresponding document will be retrieved as if by a call to the fn:doc() function: this means that the system first checks to see if the document is already loaded, and if not, calls the registered URIResolver to dereference the URI. This is the recommended approach to ensure that the resulting collection is stable: however, it has the consequence that the documents will by default remain in memory for the duration of the query or transformation.

If the collection URI is not recognized, the method may either return an empty iterator, in which case no error is reported, or it may throw an exception, in which case the query or transformation fails. Returning null has the same effect as returning an empty iterator.


Copyright (c) 2004-2010 Saxonica Limited. All rights reserved.