Hi,
I just finish to setup a pratical (and experimental) solution to give OTRS customer users an upload area in the otrs server:

Quite simple and powerfull: in apache conf just enable webdav with custum OTRS auth provider

Every customer has a private webdav folder https://upload.mycompany.com/{$otrsCustomerID}
OTRS agents can read/write in every folder and can create new customers root folder.

WebDav clients tested: Cyberduck, BitKinex and Curl (command line)

It's a pleasure to use the OTRS api.

Francesco

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Custom OTRS Auth Provider: http://pastebin.com/bC1vZfNW

Apache conf follow.

<VirtualHost *:443>
ServerName upload.mycompany.com
DAVLockDB ${APACHE_LOCK_DIR}/DAVLock
SSLEngine on
SSLCertificateFile /etc/apache2/ssl/upload_ssl.cert
SSLCertificateKeyFile /etc/apache2/ssl/upload_ssl.key

DocumentRoot "/var/www/upload"
PerlLoadModule Apache::AuthenHook
PerlModule My::OTRS_SimpleAuthProvider
Perlrequire /opt/otrs/scripts/apache2-perl-startup.pl

PerlModule Apache2::Reload
PerlInitHandler Apache2::Reload
PerlModule Apache2::RequestRec


<Directory /var/www/upload>

   DAV On
   SetEnv redirect-carefully
   ForceType application/x-downloadable

   Options MultiViews Indexes
   AllowOverride None
   Order deny,allow
   Allow from all
   AuthType Basic
   AuthName "OTRS Upload area"
   AuthBasicProvider My::OTRS_SimpleAuthProvider
   Require valid-user
</Directory>
</VirtualHost>