Hello all
Continuing the work on the XML side of things (ISO 19139), there is two
classes worth to note:
ObjectResolver [1]
---------------
ISO 19139 XML documents sometime contain an empty element with only a
"xlink:href", "idref" ou "uuidref" attribute. The full object definition
shall be fetched from the reference. When such attribute is found at
unmarshalling time, the proposed mechanism is to invoke the
corresponding "resolve" method from the ObjectResolver class. The user
can provide its own ObjectResolver instance as a Marshaller property.
The "idref" attributes are local to the current XML document and can be
partially handled by the standard @XmlID JAXB annotation. But "uuidref"
is a UUID to a document that may be defined anywhere. It could be a
primary key in a database internal to an agency. With the proposed
ObjectResolver class, user can override the resolve(MarshalContext,
UUID) method for returning the metadata object for the given UUID using
whatever method is appropriate for his application. I'm hesitant about
whether the default implementation should unconditionally returns null,
or use a UUID list of objects previously created in the currently
running JVM (using weak references).
ObjectConverters [2]
-----------------
By default, JAXB parses URL, URI, UUID etc. using the standard methods
(e.g. new URI(String)). However in practice, we are often facing badly
formatted metadata documents with invalid URL (a very common case is
users putting a file path in Windows syntax instead of URL).
ObjectConverters is a proposed hook for giving developers a chance to
catch those situations and handle the errors as appropriate for their
application. By default, the conversions are strict: invalid URL or URI
or UUID cause the parsing to fail. But users can override the methods
and, for example, replace some URL on-the-fly.
Comments are always welcome,
Martin
[1]
https://builds.apache.org/job/sis-jdk7/site/apidocs/org/apache/sis/xml/ObjectResolver.html
[2]
https://builds.apache.org/job/sis-jdk7/site/apidocs/org/apache/sis/xml/ObjectConverters.html
