XOM API for Processing XML with Java

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

John Cowan wrote:
> Currently, XOM throws an error if the system identifier in a DOCTYPE
> declaration is not a well-formed URI.  But that's too stringent:  the
> XML Recommendation says that a system identifier has to be *convertible*
> to a well-formed URI by escaping inappropriate characters.  The ipsissima
> verba are in Section 4.2.2 of XML 1.0:
>
>         System identifiers (and other XML strings meant to be used as URI
>         references) may contain characters that, according to [IETF RFC
>         3986], must be escaped before a URI can be used to retrieve the
>         referenced resource. The characters to be escaped are the control
>         characters #x0 to #x1F and #x7F (most of which cannot appear in
>         XML), space #x20, the delimiters '<' #x3C, '>' #x3E and '"' #x22,
>         the unwise characters '{' #x7B, '}' #x7D, '|' #x7C, '\' #x5C,
>         '^' #x5E and '`' #x60, as well as all characters above #x7F.

At first glance, this appears to be another incompatible change 
introduced as an erratum; this time in the 3rd edition of XML 1.0. In 
the 2nd edition I find this text instead:

[Definition: The SystemLiteral is called the entity's system identifier. 
It is a URI reference (as defined in [IETF RFC 2396], updated by [IETF 
RFC 2732]), meant to be dereferenced to obtain input for the XML 
processor to construct the entity's replacement text.] It is an error 
for a fragment identifier (beginning with a # character) to be part of a 
system identifier. Unless otherwise provided by information outside the 
scope of this specification (e.g. a special XML element type defined by 
a particular DTD, or a processing instruction defined by a particular 
application specification), relative URIs are relative to the location 
of the resource within which the entity declaration occurs. A URI might 
thus be relative to the document entity, to the entity containing the 
external DTD subset, or to some other external parameter entity.

Thus the system identifier is a URI, not merely a string that is 
converted to a URI. It is an error for a URI to contain an unescaped 
linefeed, and XOM should throw an exception in that case.

If I misread you and XOM is disallowing a properly escaped linefeed in a 
URI, then that may be a bug I'll have to look at.

--
Elliotte