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Message-ID: <488DF54A.2070207@gmail.com>
Date: Mon, 28 Jul 2008 18:35:22 +0200
From: Roberto Rigamonti <roby1984@gmail.com>
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To: c-users@xerces.apache.org
Subject: Null XML document root in some contexts (but working fine in some
 others with the same code) [huge question]
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Good evening, I'm working to a project that involves the parsing of some 
XML files, and up to now I've successfully used the Xerces library to do 
so (I've written a couple of messages some months ago for some questions 
regarding the correct use of the library, but now everything seemed to 
be ok).

--- Brief resume of my project ---
I have to develop a 3D visor using wxWidgets and OpenGL, that is an 
application that reads an XML file (local file or sent through the 
network), loads a set of drawing plugins (e.g. the plugin that draws 
lines, the one that draws polygons, ...) and displays the objects 
specified in the XML file in a three dimensional, navigable world. A 
snapshot of the current project can be downloaded from:
http://roby1984.netsons.org/3DVisor-0.0.3.tar.bz2
The small client that will be used to send the files can be downloaded from:
http://roby1984.netsons.org/client.tar.bz2
and compiled using
g++ -c client.cc `wx-config --cxxflags` -ggdb
g++ client.o `wx-config --gl-libs` -lglut `wx-config --libs` 
-L/usr/X11R6/lib -lXi -lXmu -o client
# Requested libraries:
- Xerces :)
- wxWidgets
- Boost
- GSL
- Mesa
- libXi
- libXmu
- some others that I'm probably missing now but that configure should
   signal you promptly :)
# Build & run example (file downloaded in /home/roby/Download/):
-> tar xjvf 3DVisor-0.0.3.tar.bz2
-> cd 3DVisor-0.0.3/
-> ./configure --prefix=/home/roby/Download/3DVisor-0.0.3/sandbox
[to avoid installing it somewhere in the system, so that we can install 
it without being root]
-> make
-> make install
-> cd sandbox/bin
-> ./3DVisor

The problem that I've encountered is the following:
if I use the visor in "local mode" and select the file "visor.xml", 
everything works fine, but if I enable the "remote mode", start up the 
client program (after copying in the same directory of the client 
program the file "visor.xml" renamed as "in.txt") and send the file, the 
SAME code used for the local file but applied to a temporary file where 
the data sent is stored gives me the following result:

Temporary filename: /tmp/fileygUK8t  <--- changes everytime and is
                                           removed as soon as processing
                                           finishes
XMLManager::fillVariablesMap() : Empty XML document

(that is, after getting the DOMDocument, when trying to get the root of 
the DOMDocument it gets a NULL root via getDocumentElement()), even if 
the XML file is non-empty (it is removed immediately after processing, 
but when it is processed is filled with correct entries, I've 
triple-checked it by putting some std::cins to stop the execution and 
checking it by hand, so I'm sure of that).

The application's code is huge and intricate, but everything regarding 
the XML management should be restricted to the XMLManager.* files, in 
particular to the load3DObjects() and fillVariablesMap() methods, 
eventually I can put specific sections of code upon request (I've put 
everything on the web site just to avoid filling this message with 
chunks of code).
I know that a big effort was requested just to read my entire message, 
but I'm really going crazy on this (the code used in both cases IS THE 
SAME!!!!).
Thanks in advance to anyone willing to help me.
                                                Roberto