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https://issues.apache.org/jira/browse/XERCESJ-1586?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Andreas Veithen updated XERCESJ-1586:
-------------------------------------
Affects Version/s: 2.11.0
> lookupNamespaceURI may return unexpected result when looking up default
> namespace
> ---------------------------------------------------------------------------------
>
> Key: XERCESJ-1586
> URL: https://issues.apache.org/jira/browse/XERCESJ-1586
> Project: Xerces2-J
> Issue Type: Bug
> Components: DOM (Level 3 Core)
> Affects Versions: 2.9.1, 2.11.0
> Reporter: Andreas Veithen
> Priority: Minor
>
> Consider the following XML document:
> <root xmlns="urn:test"><child xmlns=""/></root>
> Assume that the document is constructed programmatically without explicitly
> adding the namespace declarations:
> Document document =
> DocumentBuilderFactory.newInstance().newDocumentBuilder().newDocument();
> Element root = document.createElementNS("urn:test", "root");
> document.appendChild(root);
> Element child = document.createElementNS(null, "child");
> root.appendChild(child);
> The expectation is that when looking up the default namespace on the child
> element, the result is null. However, this is not the case, as demonstrated
> by the following code:
> System.out.println("uri=" + child.lookupNamespaceURI(null));
> In fact, the output is:
> uri=urn:test
> Moreover, the result changes after normalizing the document:
> document.normalizeDocument();
> System.out.println("uri=" + child.lookupNamespaceURI(null));
> The output with Xerces 2.9.1 is now (Note that the result is still not
> correct because one would expect uri=null, but this has been fixed in recent
> Xerces versions; see XERCESJ-1394):
> uri=
> The reason is that normalizeDocument adds xmlns="" to the child node (as
> expected).
> Actually, the behavior of lookupNamespaceURI shown here strictly conforms to
> the DOM Level 3 Core specification, as described in appendix B.4. That is
> because of the namespace != null condition in the following part of the
> pseudo code:
> if ( Element's namespace != null and Element's prefix == prefix )
> {
> // Note: prefix could be "null" in this case we are looking
> for default namespace
> return (Element's namespace);
> }
> However, if one strictly follows the specification, then normalizeDocument
> should also not add xmlns="" to the child element. In fact, the action taken
> by normalizeDocument to fixup the namespace of that element is described by
> the following part of the pseudo code in appendix B.1:
> // Element has no pseudo-prefix
> if ( there's a conflicting local default namespace declaration
> already present )
> {
> ==> change its value to use this empty namespace.
> }
> // NOTE that this may break other nodes within this Element's
> // subtree, if they're already using the default namespaces.
> // They will be repaired when we reach them.
> Since there is no conflicting _local_ default namespace declaration on the
> child element, according to the specification, nothing should be done. This
> is obviously not what one wants in this case, and Xerces ignores that aspect
> of the specification. However, for consistency, Xerces should then also
> ignore the namespace != null condition in appendix B.4.
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