[prev in list] [next in list] [prev in thread] [next in thread] 

List:       xmlrpc-user
Subject:    [jira] [Created] (AXIOM-402) The namespace repairing performed by
From:       "Andreas Veithen (Created) (JIRA)" <jira () apache ! org>
Date:       2011-11-29 22:49:39
Message-ID: 1967519060.23644.1322606979904.JavaMail.tomcat () hel ! zones ! apache ! org
[Download RAW message or body]

The namespace repairing performed by the serializer should be configurable
--------------------------------------------------------------------------

                 Key: AXIOM-402
                 URL: https://issues.apache.org/jira/browse/AXIOM-402
             Project: Axiom
          Issue Type: Improvement
          Components: API
            Reporter: Andreas Veithen
            Priority: Minor


When serializing (with or without caching) an object model tree, Axiom performs \
namespace repairing. This comprises two things:

1. Axiom generates namespace declarations for namespace bindings that are visibly \
used (in element or attribute names) but for which no corresponding declaration is in \
scope. This is important for two reasons:

* It ensures that Axiom always produces XML that is well-formed with respect to \
                namespaces, even when serializing a subtree.
* Some operations (such as moving elements from one location to another) may result \
in an object model that is not well-formed with respect to namespaces. The serializer \
therefore needs to add the missing namespace declarations on-the-fly.

2. Redundant namespace declarations are removed. A namespace declaration is \
considered redundant if it corresponds to a namespace binding for which another \
namespace declaration is already in scope. The primary reason for this is that when \
creating or modifying a tree programmatically, it will in general contain such \
redundant namespace declarations. This occurs when creating an orphaned element and \
adding it to a location in the tree where an appropriate namespace declaration is \
already in scope (this contrasts with the case where the element is created directly \
as the child of an existing element). It is also likely that OMSourcedElements backed \
by some types of OMDataSources would generate lots of redundant namespace \
declarations.


It should be noted that these operations don't alter the namespace context of any of \
the elements being serialized. They don't alter the XPath data model in any way \
either. This is a consequence of section 5.4 (as well as the last sentence of section \
5.3) of the XPath 1.0 specification. Therefore other standards based on the XPath \
data model (such as XML C14N and XML Signature) are not affected by the removal of \
redundant namespace declarations. Finally in the XML infoset (as defined by the XML \
Information Set specification) the removal of a namespace declaration only modifies \
the [namespace attributes] property (which contains attribute information items, and \
not namespace information items) of the element information item, but not the \
[in-scope namespaces] property.

There will nevertheless be a problem in some very particular situations, e.g. when a \
document containing a redundant namespace is parsed into an Axiom tree and later \
serialized and processed by an application or service that fails to implement the \
aforementioned standards correctly. For these situations, Axiom should allow to \
disable the removal of redundant namespace declarations.

One can also see that if one parses an XML document and later serializes it again \
without doing any structural modifications, then it will automatically be well formed \
with respect to namespaces. In that case, namespace repairing is just unnecessary \
overhead. Therefore Axiom should also allow to disable namespace repairing \
altogether.

To summarize, Axiom should have a configuration option (e.g. in OMOutputFormat) to \
                choose the namespace repairing mode, with three supported modes:
* Default: complete namespace repairing with removal of redundant namespace \
                declarations.
* Namespace repairing without removal of redundant namespace declarations.
* No namespace repairing at all.

--
This message is automatically generated by JIRA.
If you think it was sent incorrectly, please contact your JIRA administrators: \
https://issues.apache.org/jira/secure/ContactAdministrators!default.jspa For more \
information on JIRA, see: http://www.atlassian.com/software/jira

        

---------------------------------------------------------------------
To unsubscribe, e-mail: dev-unsubscribe@ws.apache.org
For additional commands, e-mail: dev-help@ws.apache.org


[prev in list] [next in list] [prev in thread] [next in thread]