I've looked online for ways to do this, and I've found two PHP methods for accesing WebDAV:
http://freshmeat.net/projects/class%5Fwebdav%5Fclient/
This is less than ideal, because it doesn't support WebDAV at a sub-path of the server; it cannot access, say,
http://my-dav-server/configuration
, onlyhttp://my-dav-server
http://php-webdav.pureftpd.org/project/php-webdav
This requires me to compile a new PHP module, which might be necessary, but is a bit of a pain. Plus, it's not clear from the docs how to do simple things like report errors or which versions of PHP it supports.
Basically, I want a WebDAV API - doesn't matter how complex, really - that can get/put files with HTTP BASIC authentication. I don't need anything more complex than that. I'm backing this with a subversion autoversioning DAV server, but I can foresee using it in other ways, too, so I don't want to lock myself in to subversion by using an SVN-specific API.