Re: [xml-dev] Achieving object model independence

[Jim Wissner <jim@jbrix.org>]

At 07:51 PM 11/18/2001 +0100, Bruno Dumon wrote:
>Jim Wissner wrote:
>
>[snip]
>>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?)
>
>Not related to the original subject, but:
>
>To implement undo when using Xerces, you could as well use the DOM 
>mutation events, which Xerces supports. Just register event listeners on 
>the document node for all mutation events. Then it is easy to record all 
>changes so that they can be undone later.
>
>--
>Bruno Dumon
>
>

Yes, thanks..  It's probably a better way to go as far as Xerces is 
concerned.  I believe this is new in DOM Level 2.  I don't remember it 
existing when I originally wrote the undo/redo mechanisms long, long ago. 
I'm reluctant to change to this event system, since of course not all 
object models implement DOM level 2. I'd really like to find a way to make 
these features available to my apps in a cross-object-model way.

Care to comment on this original topic?  Please?  :)  I'm still waiting for 
some great advice.

Thanks,
Jim


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