Subject: Re: Draft IETF DeltaV Versioning

From: Hartmut Warncke <[email-masked]>
Date: Fri, 01 Dec 2000 11:21:45 +0100

Hi all,

> Dear Colleges,
>
> >From the experience we have gathered trying to implement the DeltaV
> protocol, we have some basic comments and suggestions to make before the
> end of the last call period for the DeltaV protocol.  We regard these
> issues to be important for the future development of DeltaV and WebDAV.
> This message is cross posted to the WebDAV mailing list because the main
> points pertain as much to WebDAV as to DeltaV.
>
> Valid XML should be used in WebDAV instead of simply well formed XML
> ====================================================================
>
> Using simply well formed XML misses half the benefit of XML: the
> automatic detection of syntactic errors.  This is the best way to insure
> that a protocol stays open and correct.  Any client or server can be
> easily tested for at least syntactic conformance.  This does not means
> that every transaction must be validated, but ensuring that it can is
> important.

I totally agree! If you look, for example, at implementations of RFC2518 you will
come to the conclusion that a lot of problems of the "realworld" WebDAV client
server communication are caused by the fact that a lot of clients and servers do
*not*  implement the DTD of RFC 2518 exactly because they don't have to. To my mind
a protocol should define a precise language which every client and server has to
speak in order to guarantee a perfect client server communication. Moreover clients
and servers are easier to implement if they are based on  strict rules to which
they have to obey.

Best, Hartmut

---

From: Greg Stein <[email-masked]>
Date: Fri, 1 Dec 2000 18:56:12 -0800

On Fri, Dec 01, 2000 at 11:21:45AM +0100, Hartmut Warncke wrote:
>...
> *not*  implement the DTD of RFC 2518 exactly because they don't have to.

Do you have some examples of infractions like this?

Or more close to home :-), have you seen any problems like this with mod_dav?
(because I'm unaware of them at this time, but would love to correct them if
they exist!)

thx,
-g

-- 
Greg Stein, http://www.lyra.org/

---

From: Hartmut Warncke <[email-masked]>
Date: Mon, 04 Dec 2000 09:48:01 +0100

Greg,

I think mod_dav is quite clean regarding that problem. But, for instance,  IIS sends a
status tag first and then a prop tag in a propstat although the DTD states:

<!ELEMNENT propstat (prop, status, responsedescription?)>

There are a few other samples like this one but I think the main problem is that the
server and the client must be implemented in a way that they are able to handle
requests and responses which are  *not*  correct regarding the DAV-DTD in RFC2518. I
think the whole situation would be much easier and cleaner if clients and servers
*must*  use that DTD. Moreover it is maybe possible to get rid of some of the "ANY"s in
that DTD.

Best, Hartmut