XOM API for Processing XML with Java

[Elliotte Rusty Harold <elharo AT metalab.unc.edu>]

At 5:43 PM -0800 2/17/04, Wolfgang Hoschek wrote:

> ParentNode.checkInsertChild
> ParentNode.checkRemoveChild
> Element.checkAddAttribute
> Element.checkRemoveAttribute
> Element.checkAddNamespaceDeclaration
> Element.checkRemoveNamespaceDeclaration
> Element.checkLocalName
> Attribute.checkLocalName
> Attribute.checkNamespace
> Element.checkNamespacePrefix
> Element.checkNamespaceURI
> Element.checkAddNamespaceDeclaration
> Element.checkAddAttribute
> Node.checkDetach
> DocType.checkPublicID
> DocType.checkSystemID
> Document.checkRoot
> DocType.checkRootElementName
> ProcessingInstruction.checkTarget
> Attribute.checkType
> {Attribute,Comment,ProcessingInstruction,Text}.checkValue
> (Search for methods matching "check*")

I'm mulling over whether checkDetach() and checkRemoveChild() can be 
combined, Otherwise, I'm fairly fond of them. It's not just that they 
allow subclasses to add constraints. They let subclasses hook into 
and monitor essentially any operation of interest. For instance, if a 
document were being logged to a database, every time the document was 
modified, you could use these methods to capture and log that change.

It is a big batch of methods I admit, but they are protected so 
they're fairly obviously distinguished from the basic public methods.

> Similarly, there is no real need for "somewhat atomic" 
> inserts/removes as seem to be currently shaping up in CVS. They are 
> nice goodies, but introduce complexity for little real benefit. My 
> take is that usecases are not particularly convincing and that it 
> looks a little like a solution searching for a problem.

Glad to know someone's watching CVS. :-) They're no longer somewhat 
atomic. They are atomic. The complexity is all in the internals. It 
has little if any affect on the public API. In general, I think this 
is a good thing. I think it's good for removeChildren() and 
replaceChild() to either succeed or fail without changing anything. 
Failing halfway through is too unpredictable. If anyone else notices 
any non-atomic core operations, please let me know, though I think 
these too are the major ones.

--

  Elliotte Rusty Harold
  elharo AT metalab.unc.edu
  Effective XML (Addison-Wesley, 2003)
  http://www.cafeconleche.org/books/effectivexml
  http://www.amazon.com/exec/obidos/ISBN%3D0321150406/ref%3Dnosim/cafeaulaitA