Re: What's the correct response for a not supported report?

Tue, 18 Jan 2005 11:36:51 -0800

"Precondition failed" is a very attractive response code to use in many situations because as English it's so vague, but in HTTP the meaning of Precondition is very clear: it's a header from a limited set of headers that put conditions on the success of the response. HTTP 2616 defined If-Modified-Since, If-Not-Modified, If-Match and If-Not-Match. HTTP 2518 added the If header to that list.

I think interoperability is slightly better if we continue to limit use of 412 Precondition Failed to cases where the client put a Precondition header on the request and that's the reason why it failed.

RFC3253 uses the word "precondition" in a slightly different although clearly related sense -- these are the preconditions that the *spec* has for success of the request, rather than preconditions defined by the *client* in its request. For specification preconditions, RFC3253 recommends using 403 or 409 as the response code. This para from 3253:

A "precondition" of a method describes the state of the server that must be true for that method to be performed. A "postcondition" of a method describes the state of the server that must be true after that method has been completed. If a method precondition or postcondition for a request is not satisfied, the response status of the request MUST be either 403 (Forbidden) if the request should not be repeated because it will always fail, or 409 (Conflict) if it is expected that the user might be able to resolve the conflict and resubmit the request. 

And there is a specification precondition defined for this precise case:

 Preconditions:

(DAV:supported-report): The specified report MUST be supported by the resource identified by the request-URL.

So putting these together, the spec recommends a response of 403 with a body containing <DAV:supported-report/> in the error element.

Lisa


On Jan 17, 2005, at 6:50 AM, Stefan L�tzkendorf wrote:

Hello Folks,
I have a question regarding WebDAV specifications.

Question: what is the correct response to an request of an unsupported report?

E.g. how should we answer to a "version-tree report" request on a resource that is not version controlled?

Currently slide returns some thing like this:

HTTP/1.1 207 Multi-Status
Transfer-Encoding: chunked
Date: Mon, 17 Jan 2005 14:03:15 GMT
Server: Apache-Coyote/1.1

<?xml version="1.0" encoding="UTF-8"?>
<D:multistatus xmlns:D="DAV:">
    <D:response>
      <D:href>/webdav/BCS/Projekte/Dok2.doc</D:href>
        <D:propstat>
            <D:status>HTTP/1.1 403 Forbidden</D:status>
            <D:responsedescription>
                <D:error>
                    <D:supported-report />
                </D:error>
            </D:responsedescription>
        </D:propstat>
    </D:response>
</D:multistatus>

This looks weird, because we return a <propstat> element that does not contains any <prop> element.

I think a 412 (Precondition Failed) response is more appropriate, because supported-report is a statet precondition of REPORT in RFC3253.
So i'd like to response as the following:

HTTP/1.1 412 Precondition Failed
Transfer-Encoding: chunked
Date: Mon, 17 Jan 2005 14:03:15 GMT
Server: Apache-Coyote/1.1

<D:error>
  <D:supported-report />
</D:error>


Any thoughts? What is the most conformant form?

Thanks in advance,
Stefan



--
Stefan L�tzkendorf  --  [EMAIL PROTECTED]



---------------------------------------------------------------------
To unsubscribe, e-mail: [EMAIL PROTECTED]
For additional commands, e-mail: [EMAIL PROTECTED]



---------------------------------------------------------------------
To unsubscribe, e-mail: [EMAIL PROTECTED]
For additional commands, e-mail: [EMAIL PROTECTED]

Reply via email to