WebDAV and partial reads/writes?

Question

Here is a good discussion of WebDAV vs FTP features, there was also mentioned a support for partial reads/writes via WebDAV.

I'm experimenting with WebDAV-based storages being mapped as a drive letter (on winXP-SP3 and win7, with their native features).

My observation is that a file is always downloaded and uploaded as a whole, no matter how small a change to the file's content was.

Is there a way to configure window's built-in (mrxdav.sys) client to try partial data transfers?

My goal is to save traffic while accessing a TrueCrypt container located at a WebDAV-based storage.

Thank you in advance for any information and advises.

Answer 1

There is unfortunately no internet standard that describes partial uploads. I sincerely doubt that windows has support for a version of thisthis. You are probably better off writing your own client.

Answer 2

While there is a standard for partial reads (using Range header in request and Content-Range header in response) there is no standard for partial uploads, so with normal (e.g. standardized) WebDAV partial writes are not possible, but partial reads are.

Answer 3

MS has a range of propietary, but openly published, protocols which i believe support delta calculation and file sync.

Eg http://msdn.microsoft.com/en-us/library/dd956856%28v=office.12%29.aspx

But this is not a webdav protocol and will not work with webdav servers generally.

Answer 4

Both the client and the server would need to support block level access. You would need to write proprietary extensions on both sides, as this is not supported in standard WebDAV protocol.