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Achieving object model independence
I would like to solicit the list's opinion about the best way to achieve
object model independence in a library that makes use of XML at a higher
application level. Specifically, I have a Swing-based implementation of
xforms, and it is currently based on DOM (Xerces). I would like to change
it so that it will work not only with Xerces, but with dom4j, JDOM, or any
other object model.
There are three possibilities I'm currently looking at:
1. Build a Navigator similar to that in use by Jaxen/Saxpath, only mutable,
and pass that around instead of documents/elements/attributes/etc.
2. Create my own set of basic interfaces that mirror common object model
components (Document, Element, Attribute), subclass the implementation
classes of the corresponding dom4j/JDOM/DOM classes, set the appropriate
factory methods to create instances of the subclasses that implement my
common interfaces, and return those common interfaces to the rest of my
I currently use this method with Xerces in order to implement undo/redo of
DOM mutations, and it is quite effective. Nevertheless this approach makes
me uneasy because it is dependent on utilizing "nonpublic" components (that
is, having to subclass the default implementation classes which, though
often public in the sense of Java scoping, are sometimes left out of
documentation and presumably more subject to change than the rest of the
APIs. Is this true, or am I being overly worrisome?)
3. Similar to 2 in that I create my own set of basic interfaces that mirror
common object model components, but instead of the subclass/factory scheme,
make wrappers around the implementation classes of the corresponding
dom4j/JDOM/DOM classes, and again return those common interfaces to the
rest of my library.
My questions are:
1. Is there a better method that I'm overlooking?
2. How are other people tackling the problem of object model independence
in cases where higher level libraries might be used in different contexts
with different object models?
I would very much appreciate any expert advice and insights into this
problem, and how it can be best approached, and maybe hearing that this is
an easily (and perhaps already solved) problem... :)
Many thanks in advance,
Open Source Software
Java - XML - Speech Recognition