The Peace Process: DOM and namespaces...

Tyler Baker tyler at
Thu Feb 11 12:54:14 GMT 1999

David Megginson wrote:

> Tyler Baker writes:
>  > > Preprocess your information, whatever its source.
>  >
>  > From an entire database.  Pass over the entire document tree and
>  > prepreprocess everything before actually presenting it to the
>  > application.  This is not practical.  In my limited experience on
>  > these matters I have seen this tried before and with horrendous
>  > results.  Nevertheless, it does not take a computer scientist to
>  > see the real world problem with this approach.
> That would be silly -- lazy evaluation works fine for this kind of
> thing.  I hate to sound stupid, but I still fail to see how Namespaces
> causes any problems at all for someone dynamically generating a
> document from a database -- if you want to use names with a URI part,
> use them; if not, don't.

Well you have the choice of doing an entire pass over the document and
building a map directly or else try and lazily evaluate things and then
cache the results of the namespace processing.  Then for each time you
find a node, you need to look it up in a hashtable somehow.  Hashtables
are cheap, but not that cheap if you need to do a table lookup for every
node you process.  So iterating over the entire source tree and building
an indexed table may in some circumstances be more efficient than the lazy

But you are still faced with the problem of illegal XML Names.  If you
write the DOM Document out to an XML file or stream you will be emitting
illegal XML Names unless you have some URI -> prefix hack to get things
back to legal XML.


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