SAX2: DeclHandler

David Brownell david-b at
Wed Dec 22 16:15:11 GMT 1999

>  > However, there are two other declarations that should show
>  > up in a DeclHandler:
>  >
>  >      - The root element name.
> You can get that from the LexicalHandler start/endDTD methods already.
> Do you imagine validation modules will require DeclHandler but not
> LexicalHandler?

Absolutely; nothing else in the LexicalHandler interface relates
to validity constraints.  It's annoying to need half a dozen
methods in the filter that do nothing more than pass irrelevent
lexical events to the next stage.

>  >      - Flag saying it it's standalone.
> Slippery slope, domino effect, etc., but perhaps we do need an xmlDecl
> callback.  What do others think?

My slipperly slope had brakes on it!  _Only_ the standalone flag
shows up in a validity constraint, so that's all that's necessary.

The real slippery slope comes in when exposing encoding decls,
which may be inside external entities.  XML decls and text decls
have different rules re whether "encoding=..." and "version=..."
are optional.

Were there an interest in encoding decls (there is -- how strong?)
as well as version decls (XML 1.1?) I'd say those belong in the
LexicalHandler -- they really don't relate to validation.

- Dave

>  > If those show up, then I think it'll be possible to use the
>  > DeclHandler (and to-be-renamed DtdHandler) to provide a
>  > cleanly layered XML validation module.  Else ...

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