What are your experiences implementing/using WebDAV?

Question

For a current project, I was thinking of implementing WebDAV to present a virtual file store that clients can access. I have only done Google research so far but it looks like I can get away with only implementing two methods:

GET, PROPFIND

I think that this is great. I was just curious though. If I wanted to implement file uploading via:

PUT

I haven't implemented it, but it seems simple enough. My only concern is whether a progress meter will be displayed for the user if they are using standard Vista Explorer or OSX Finder.

I guess I'm looking for some stories from people experienced with WebDAV.

Answer 1

If you run Apache Jackrabbit under, say, Tomcat, it can be configured to offer WebDAV and store uploaded files. Perhaps that will be a useful model, or even a good enough replacement for the planned implementation.

Apache Jackrabbit Support for WebDAV

Also, you may want to be aware of the BitKinex client (free 30 day trial), which I have found to be a useful tool for testing a WebDAV server.

BitKinex Home Page

Answer 2

We use WebDAV internally to provide a folder-based view of some file shares to clients outside of our firewall. We're using IIS6 for this.

Basically, it boils down to creating a Virtual Directory in IIS that maps to each network file system that you want to make available via WebDAV. Set it up with the content coming from "A share located on another computer" -- use the UNC path to the share for the Network Directory value. We turn on all options except Index this resource. Disable all default content pages. Turn on Windows Integrated Authentication (ours is set up using SSL as well). I have the root set up to deny access to anonymous and allow access to any authenticated user. We also have a wildcard MIME mapping (.* to application/octet-stream). Enable the WebDAV web service extension in IIS. You also need to set up the web server to delegate permissions to all the file servers you may be accessing so it can pass on the user's credentials.

If you have Macintosh clients you may also need an ISAPI filter that maps 401 to 403 errors for Darwin clients. Microsoft and Apple disagree on how to handle the situation when you don't have permission to write to a directory. Apple keeps resending the credentials on a 401 (Access Denied) error, translating it to a 403 (Forbidden) error keeps this from happening. By default Apple likes to write a "dot" file to every directory it accesses. Navigating through directories where you don't have write access will end up crashing the Finder if you don't have the filter. I have source code for this if needed.

This is all off the top of my head. It's possible (probable?) that I may have missed something. Feel free to contact me via the contact information on my web site if you have problems.

Answer 3

I've found OS X's Finder WebDAV support to be really finicky. In order to get read-write support, you have to implement LOCK, in addition to other bits.

I wrote a WebDAV interface to a Postres database, where python modules were stored in the database in a hierarchical folder-like structure. Accessing it with cadaver worked fine, and IIRC a GUI windows browser worked too, but Finder refused to mount the share as anything other than read-only.

So, I don't know if if would give a progress bar. The files I was dealing with were small enough that a read/copy from them was virtually instantaneous. I think a copy of a large file using the Finder would probably give a progress bar - it does for any other type of mounted share.

Answer 4

For many WebDAV clients and even for read only access, you will also need to support OPTIONS. If you want to support upload, PUT obviously is required, and some clients (MacOS X?) will require locking support.

(btw, RFC 4918 is the authorative source of information).

Answer 5

We have a webDAV servlet on our web based product.

i've found Apache Jackrabbit a good help for implementing it. however webDav is a serious P.I.T.A on the client side support.

many client implementation differ widely in their behavior and you most likely will have to support several different kinds of bugged implementations.

some examples: MS vista only supports authentication over SSL

most windows based webDAV client assume your webdav-server/let is a sharepoint server and will act accordingly (thus not according to the webDAV protocol)

one example of this is that you NEED to allow and Unauthenticated LOCK request on the root of your server (ie yourdomain.com/ not yourdomain.com/where/webdav/should/live) else you wont be able to get write acces in MS windows. (this is a serious P.I.T.A on a tomcat machine where your stuff usualy lives in server.com/servlets/paths/thelocation)

most(all?) versions of MS office respond different to webdav links.

i guess my point is integrating webdav support into an existing product can be a LOT harder then you would expect. and if possible i would advice to use a (semi)-standalone webDAV server such as jackrabbit webdavServer, or apache mod_webdav

Answer 6

Bit late to the party, but I've implemented most of the webdav protocol and I can tell with confidence you'll need to implement most of the protocol.

For OS/X you'll need class-2 WebDAV support, which includes LOCK and UNLOCK (I found it particularly difficult to fully implement the http If: header, but for Finder you'll only need a bit of that.)

These are some of my personal findings: http://code.google.com/p/sabredav/wiki/Windows http://code.google.com/p/sabredav/wiki/Finder

Hope this helps

Answer 7

Here is another open source project for WSGI WebDAV http://code.google.com/p/wsgidav/ where I picked up the PyFileServer project.

Answer 8

I implemented most of the WebDAV protocol in about a day's work: http://github.com/nfarina/simpledav

I wrote it in Python to run on Google App Engine, and I expect any other language would be a similar effort. All in all, it's about two pages of code.

I implemented following methods: OPTIONS, PROPFIND, MKCOL, DELETE, MOVE, PUT, GET. So far I've tested Transmit and Cyberduck and both work great with it.

Hopefully this can provide some guidance for the next person out there interested in implementing a WebDAV server. It's not a difficult protocol, it's just very dense with abstracted language like 'depth' and 'collections' and blah.

Here's the spec: http://www.webdav.org/specs/rfc4918.html

But the best way to understand the protocol is to watch a client interacting with a working server. I used Transmit to connect to Box.net's WebDAV server and monitored traffic with Charles Proxy.