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Date: Sun, 31 Mar 2013 12:20:22 +0200
From: Sorin Manolache <sorinm@gmail.com>
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To: modules-dev@httpd.apache.org
Subject: Re: Apache fails to start when Xerces library is used in a C++ module
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On 2013-03-31 11:06, Sindhi Sindhi wrote:
> Hello,
>
> I have written a C++ module to invoke the Xerces C++ XML library to parse a
> XML file. I'm unable to start httpd.exe with these changes. Here are the
> details -
>
> a) Apache server version: httpd-2.4.4-win64
> b) Xerces version: xerces-c-3.1.1-x86_64-windows-vc-10.0
> c) Development envt: Visual Studio 2010 with SP1
>
> Following are the settings I have made in Visual Studio so that the C++
> module refers to the Xerces library:
> 1. Additional Include Directories =
> E:\xerces-c-3.1.1-x86_64-windows-vc-10.0\xerces-c-3.1.1-x86_64-windows-vc-10.0\include
>
> 2. Additional Dependencies = xerces-c_3.lib and xerces-c_static_3.lib
>
> 3. Additional library directories =
> E:\xerces-c-3.1.1-x86_64-windows-vc-10.0\xerces-c-3.1.1-x86_64-windows-vc-10.0\lib
>
> 4. Debugging -> Environment:
> PATH=E:\xerces-c-3.1.1-x86_64-windows-vc-10.0\xerces-c-3.1.1-x86_64-windows-vc-10.0\bin
>
> 5. In the Operating System environment variables, added the path
> E:\xerces-c-3.1.1-x86_64-windows-vc-10.0\xerces-c-3.1.1-x86_64-windows-vc-10.0\bin
> to the environment variable PATH
>
> 6. The code in my C++ module to invoke the Xerces library routine goes like
> this -
>
> try {
> XMLPlatformUtils::Initialize();  // Initialize Xerces infrastructure
> }
> catch( XMLException& e ) {
> char* message = XMLString::transcode( e.getMessage() );
> XMLString::release( &message );
> }
> XMLPlatformUtils::Terminate();
>
> 7. Added the below in httpd.conf file -
> LoadModule filter_module modules/XercesDLL.dll
> AddOutputFilterByType TagFilter text/html text/plain text/css
>
> 8. If i try to launch httpd.exe from command prompt, I see the below error -
>> httpd.exe
> httpd.exe: Syntax error on line 172 of
> E:/httpd-2.4.4-win64/Apache24/conf/httpd.conf: Cannot load
> modules/XercesDLL.dll into server: The specified module could not be found.
>
> Even if I comment out the above C++ code in step 6, Apache still fails to
> start. That means Apache is failing to load the Xerces library version I'm
> using, irrespective of the way I'm invoking the library.
>
> However, If I write a standalone DLL that invokes the above Xerces library
> version, and invoke this DLL from an EXE then I'm successfully able to
> parse the XML. This means, the Xerces library fails to get loaded only by
> the Apache server for some reason.
>
> I think its got something to do with the C to C++ linkage, not sure tho.
>
> Any help is highly appreciated.


Hello,

Try

LoadFile /absolute/path/to/the/xerces/lib1
LoadFile /absolute/path/to/the/xerces/lib2
...
LoadModule /absolute/path/to/XercesDLL.dll

For example

LoadFile 
E:\xerces-c-3.1.1-x86_64-windows-vc-10.0\xerces-c-3.1.1-x86_64-windows-vc-10.0\lib\xerces-c_3.lib 
and xerces-c_static_3.lib
LoadFile 
E:\xerces-c-3.1.1-x86_64-windows-vc-10.0\xerces-c-3.1.1-x86_64-windows-vc-10.0\lib\xerces-c_3.lib 
and xerces-c_3.lib
LoadModule E:\workspace\XercesDLL.dll

Maybe you do not need both LoadFiles. Experiment.

Sorin