seeddms-code/doc/README.WebDAV

WebDAV
-----------------------------------------------

SeedDMS has support for WebDAV which allows to easily add, delete,
move, copy and modify documents. All operating systems have support
for WebDAV as well, but the implemtations and their behaviour varys
and consequently you may run into various problems. If this happens
just file a bug report at https://sourceforge.net/projects/seeddms

The folder structure in SeedDMS is similar to a regular file system
but it is not identical. SeedDMS distinguishes between a document
and its content, while a file system knows just files.
In SeedDMS a document is uniquely identified
by its document id and not neccessarily by its name. A filesystem
requires a unique paths for each file. Two identical files in the
same folder are not possible. SeedDMS can handle identically named
documents in one folder. In order to prevent any problems arising from
this, you should always disallow identical document names in the
settings. By definition a file in WebDAV is mapped on the latest
version of a document in SeedDMS. There is no way to access previous
versions of a document via WebDAV. Whenever you modify a file and
upload it with the web gui,
a new version will be created. Unfortunately, this has some very
nasty side effects when you edit a document version via WebDAV and
often save it, because any save
operation will create a new version. This is why the WebDAV
server has a configuration option which allows to either replace
the content of document or creating a new
version if a document is saved.

Configuring davfs2
===================

On Linux it is quite simple to mount the SeedDMS WebDAV server with
davfs2. Just place a line like the following in your /etc/fstab

http://seeddms.your-domain.com/webdav/index.php /media/webdav davfs noauto,user,rw,uid=1000,gid=1000

and mount it as root with

mount /media/webdav davfs

You may as well want to configure davfs2 in /etc/davfs2/davfs2.conf by setting

[/media/webdav]
use_locks 0
gui_optimize 1

and possibly add your login data to /etc/davfs2/secrets

/media/webdav admin secret

Making applications work with WebDAV
=====================================

Various programms have differnt strategies to save files to disk and
prevent data lost under all circumstances. Those strategies often don't
work very well an a WebDAV-Server. The following will list some of those
strategies.

VIM
=========================

vim does a lot more than just reading and writing the file you want
to edit. It creates swap and backup files for data recovery if vim crashes
or is being killed unexpectively. On a low bandwidth connection this can
slow down the editing. For that reason you should either not create the
swap file at all or create it outside the WebDAV server. A second problem
arises from how vim modifіes the file you are editing. Before a file
is saved a backup is created by renaming the file to the same name with a
'~' at the end and writing the file content into a new
file with the name of the original file. Afterwards vim deleteѕ the backup
file. On a regular file system you
won't see a difference between the file before and after saving, though
it is actually a new one. In SeedDMS you won't notice a difference either
by just looking at the document name. It's still the same, but the
document id has changed. So saving a document will delete the
old document and create a new one instead of creating a new version of
the old document. If you don't want this behaviour, then tell vim
to not create the backup file. You can do that by either passing additional
parameters to vim

vi "+set nobackup" "+set nowritebackup" -n test.txt

or by setting them in your .vimrc

set nobackup
set nowritebackup
set noswapfile

Creating the backup file in a directory outside of WebDAV doesn't help in
this case, because it still does the file renaming which is turned of by
'nowritebackup'.