VOSpace vs WebDAV

[Walter Landry]

Hello Everyone,

At our datacenter, we want to implement some kind of workspace for our
users.  So the natural thing to do is to look at VOSpace and see if it
could be bent to our needs.  However, I am also familiar with WebDAV [1],
and I am having a hard time understanding what advantages VOSpace
brings.  Just to run down the basics about WebDAV:

1) WebDAV supports much of the functionality in VOSpace, including
   all of these items lifted directly from the VOSpace introduction

    * add or delete data objects
    * manipulate metadata for the data objects
    * obtain URIs through which the content of the data objects can be
      accessed

2) WebDAV is a mature, established standard deployed worldwide on a
   variety of machines.  Every major desktop OS has WebDAV built in,
   and you can get clients and servers for every operating system on
   almost any hardware, including phones, tablets, and supercomputers.

3) WebDAV has a number of implementations of the client and server in
   every programming language you can think of.

4) WebDAV is based on http, so it is easy to layer any of a number of
   authentication schemes on top.

5) WebDAV has an easily understood filesystem-like API.

In contrast, the only compelling feature of VOSpace I can think of is
the ability to initiate 3rd party transfers.  But it would seem better
to add a trivial extension to WebDAV rather than creating a completely
new protocol.

Moreover, the API for VOSpace is much more complicated, with a lot of
indirection.  The vos: URI scheme in particular feels like a
reinvention of DNS for a benefit that I do not see.  It almost goes
without saying that I have not seen much interest in VOSpace outside
of astronomy.

Given all this, it feels like the best use of my time would be to
install mod_dav on my Apache server and be done in short order.  I
would guess that my users would even be happier than if I used
VOSpace.  It is pretty addictive to be able to drag and drop from your
desktop to a remote WebDAV folder using the standard file browser.

Now, I am aware that this has been discussed before.  I have also
spoken personally with one of the authors of VOSpace.  Yet I still do
not quite see the need for VOSpace.  Could someone enlighten me?

Thanks,
Walter Landry
wlandry at caltech.edu

[1] http://webdav.org/
[2] http://www.ivoa.net/forum/grid/2007-March/001713.html
    http://www.us-vo.org/pipermail/techwg/2005-February/000793.html