XMLWF(1)XMLWF(1)NAMExmlwf - Determines if an XML document is well-formed
SYNOPSISxmlwf [ -s] [ -n] [ -p] [ -x] [ -e encoding] [ -w] [
-d output-dir] [ -c] [ -m] [ -r] [ -t] [ -v] [ file
...]
DESCRIPTIONxmlwf uses the Expat library to determine if an XML docu-
ment is well-formed. It is non-validating.
If you do not specify any files on the command-line, and
you have a recent version of xmlwf, the input file will be
read from standard input.
WELL-FORMED DOCUMENTS
A well-formed document must adhere to the following rules:
o The file begins with an XML declaration. For instance,
<?xml version="1.0" standalone="yes"?>. NOTE: xmlwf
does not currently check for a valid XML declaration.
o Every start tag is either empty (<tag/>) or has a corre-
sponding end tag.
o There is exactly one root element. This element must
contain all other elements in the document. Only com-
ments, white space, and processing instructions may come
after the close of the root element.
o All elements nest properly.
o All attribute values are enclosed in quotes (either sin-
gle or double).
If the document has a DTD, and it strictly complies with
that DTD, then the document is also considered valid.
xmlwf is a non-validating parser -- it does not check the
DTD. However, it does support external entities (see the
-x option).
OPTIONS
When an option includes an argument, you may specify the
argument either separately ("-d output") or concatenated
with the option ("-doutput"). xmlwf supports both.
-c If the input file is well-formed and xmlwf doesn't
encounter any errors, the input file is simply
copied to the output directory unchanged. This
implies no namespaces (turns off -n) and requires
-d to specify an output file.
-d output-dir
Specifies a directory to contain transformed repre-
sentations of the input files. By default, -d out-
puts a canonical representation (described below).
You can select different output formats using -c
and -m.
The output filenames will be exactly the same as
the input filenames or "STDIN" if the input is com-
ing from standard input. Therefore, you must be
careful that the output file does not go into the
same directory as the input file. Otherwise, xmlwf
will delete the input file before it generates the
output file (just like running cat < file > file in
most shells).
Two structurally equivalent XML documents have a
byte-for-byte identical canonical XML representa-
tion. Note that ignorable white space is consid-
ered significant and is treated equivalently to
data. More on canonical XML can be found at
http://www.jclark.com/xml/canonxml.html .
-e encoding
Specifies the character encoding for the document,
overriding any document encoding declaration.
xmlwf supports four built-in encodings: US-ASCII,
UTF-8, UTF-16, and ISO-8859-1. Also see the -w
option.
-m Outputs some strange sort of XML file that com-
pletely describes the the input file, including
character postitions. Requires -d to specify an
output file.
-n Turns on namespace processing. (describe names-
paces) -c disables namespaces.
-p Tells xmlwf to process external DTDs and parameter
entities.
Normally xmlwf never parses parameter entities. -p
tells it to always parse them. -p implies -x.
-r Normally xmlwf memory-maps the XML file before
parsing; this can result in faster parsing on many
platforms. -r turns off memory-mapping and uses
normal file IO calls instead. Of course, memory-
mapping is automatically turned off when reading
from standard input.
Use of memory-mapping can cause some platforms to
report substantially higher memory usage for xmlwf,
but this appears to be a matter of the operating
system reporting memory in a strange way; there is
not a leak in xmlwf.
-s Prints an error if the document is not standalone.
A document is standalone if it has no external sub-
set and no references to parameter entities.
-t Turns on timings. This tells Expat to parse the
entire file, but not perform any processing. This
gives a fairly accurate idea of the raw speed of
Expat itself without client overhead. -t turns off
most of the output options (-d, -m, -c, ...).
-v Prints the version of the Expat library being used,
including some information on the compile-time con-
figuration of the library, and then exits.
-w Enables support for Windows code pages. Normally,
xmlwf will throw an error if it runs across an
encoding that it is not equipped to handle itself.
With -w, xmlwf will try to use a Windows code page.
See also -e.
-x Turns on parsing external entities.
Non-validating parsers are not required to resolve
external entities, or even expand entities at all.
Expat always expands internal entities (?), but
external entity parsing must be enabled explicitly.
External entities are simply entities that obtain
their data from outside the XML file currently
being parsed.
This is an example of an internal entity:
<!ENTITY vers '1.0.2'>
And here are some examples of external entities:
<!ENTITY header SYSTEM "header-&vers;.xml"> (parsed)
<!ENTITY logo SYSTEM "logo.png" PNG> (unparsed)
-- (Two hyphens.) Terminates the list of options.
This is only needed if a filename starts with a
hyphen. For example:
xmlwf-- -myfile.xml
will run xmlwf on the file -myfile.xml.
Older versions of xmlwf do not support reading from stan-
dard input.
OUTPUT
If an input file is not well-formed, xmlwf prints a single
line describing the problem to standard output. If a file
is well formed, xmlwf outputs nothing. Note that the
result code is not set.
BUGS
According to the W3C standard, an XML file without a dec-
laration at the beginning is not considered well-formed.
However, xmlwf allows this to pass.
xmlwf returns a 0 - noerr result, even if the file is not
well-formed. There is no good way for a program to use
xmlwf to quickly check a file -- it must parse xmlwf's
standard output.
The errors should go to standard error, not standard out-
put.
There should be a way to get -d to send its output to
standard output rather than forcing the user to send it to
a file.
I have no idea why anyone would want to use the -d, -c,
and -m options. If someone could explain it to me, I'd
like to add this information to this manpage.
ALTERNATIVES
Here are some XML validators on the web:
http://www.hcrc.ed.ac.uk/~richard/xml-check.html
http://www.stg.brown.edu/service/xmlvalid/
http://www.scripting.com/frontier5/xml/code/xmlValidator.html
http://www.xml.com/pub/a/tools/ruwf/check.html
SEE ALSO
The Expat home page: http://www.libexpat.org/
The W3 XML specification: http://www.w3.org/TR/REC-xml
AUTHOR
This manual page was written by Scott Bronson <bron-
son@rinspin.com> for the Debian GNU/Linux system (but may
be used by others). Permission is granted to copy, dis-
tribute and/or modify this document under the terms of the
GNU Free Documentation License, Version 1.1.
24 January 2003 XMLWF(1)
