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Hi, 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 library. 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, Jim -- www.jbrix.org Open Source Software Java - XML - Speech Recognition
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