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tnc(n)									tnc(n)

______________________________________________________________________________

NAME
       tnc  -  tnc is an expat parser object extension,	that validates the XML
       stream against the document DTD while parsing.

SYNOPSIS
       package require tdom
       package require tnc

       set parser [expat]

       tnc $parser enable
_________________________________________________________________

DESCRIPTION
       tnc adds	the C handler set "tnc"	to a tcl expat parser obj.  This  han-
       dler  set is a simple DTD validator. If the validator detects a valida-
       tion error, it sets the interp result, signals error and	stops parsing.
       There  isn't  any  validation  error recovering.	As a consequence, only
       valid documents are completely parsed.

       This handler set	has only three methods:

       tnc parserObj enable

	      Adds the tnc C handler set to a Tcl expat	parser object.

       tnc parserObj remove

	      Removes the tnc validatore from the parser parserObj  and	 frees
	      all information, stored by it.

       tnc parserObj getValidateCmd ?validateCmdName?

	      Returns  a  new  created validation command, if one is avaliable
	      from the parser command, otherwise it signals error. The name of
	      the  validation command is the validateCmdName, if this optional
	      argument was given, or a random choosen name. A validation  com-
	      mand  is	avaliable  in a	parser command,	if the parser with tnc
	      enabled was previously used, to parse an	XML  document  with  a
	      valid  doctype  declaration, a valid external subset, if one was
	      given by the doctype declaration,	and a valid  internal  subset.
	      The further document doesn't need	to be valid, to	make the vali-
	      dation command avaliable.	The validation command	can  only  get
	      received	one  time from the parser command. The created valida-
	      tion command has this syntax:

		     validationCmd method ?args?

	      The valid	methods	are:

	      validateDocument domDocument ?varName?
		     Checks, if	the given domDocument is valid against the DTD
		     information  represented  by  the validation command. Re-
		     turns 1, if the document ist valid, 0 otherwise.  If  the
		     varName  argument is given, then the variable it names is
		     set to the	detected reason	for the	validation error or to
		     the empty string in case of a valid document.

	      validateTree elementNode ?varName?
		     Checks, if	the given subtree with domNode as root element
		     is	a posible valid	subtree	of a  document	conforming  to
		     the  DTD  information  represented	by teh validation com-
		     mand. IDREF could not checked, while  validating  only  a
		     subtree, but it is	checked, that every known ID attribute
		     in	the subtree is unique. Returns 1, if  the  subtree  is
		     OK,  0  otherwise.	If the varName argument	is given, then
		     the variable it names is set to the detected  reason  for
		     the  validation error or to the empty string in case of a
		     valid subtree.

	      validateAttributes elementNode ?varName?
		     Checks, if	there is an element declaration	for  the  name
		     of	 the elementNode in the	DTD represented	by the valida-
		     tion command and, if yes, if the attributes of  the  ele-
		     mentNode are conform to the ATTLIST declarations for that
		     element in	the DTD. Returns  1,  if  the  attributes  and
		     there value types are OK, 0 otherwise. If the varName ar-
		     gument is given, then the variable	it names is set	to the
		     detected  reason for the validation error or to the empty
		     string in case the	 element  has  all  its	 required  at-
		     tributes,	only declared attributes and the values	of the
		     attributes	matches	there type.

	      delete Deletes the validation command and	frees the memory  used
		     by	it. Returns the	empty string.

BUGS
       The  validation	error reports could be much more informative and user-
       friendly.

       The validator doesn't detect ambiguous content models (see XML recomen-
       dation  Section	3.2.1  and  Appendix  E).  Most	 Java  validators also
       doesn't,	but handle such	content	models right anyhow. Tnc does not;  if
       your  DTD  has such ambiguous content models, tnc can not used to vali-
       date documents against such (not	completely XML spec compliant) DTDs.

       It isn't	possible to validate XML documents  with  standalone="yes"  in
       the XML Declaration

       Violations  of  the  validity  constraints  Proper Group/PE Nesting and
       Proper Conditional Section/PE Nesting are not detected. They could only
       happen inside a invalid DTD, not	in the content of a document.

KEYWORDS
       Validation, DTD

Tcl									tnc(n)

NAME | SYNOPSIS | DESCRIPTION | BUGS | KEYWORDS

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