Re: app:accept and Atom entry MIME type

[Peter Keane <pkeane@xxxxxxxxxxxxxxx>]

Hi Nikunj-

On Mon, May 18, 2009 at 12:29 PM, Nikunj Mehta <nikunj.mehta@xxxxxxxxxx> wrote:
> Here's an issue we came across in reviewing the CMIS spec and I wanted to
> draw the atom-protocol community's attention to it and solicit feedback.
> Synopsis:
> CMIS is a fairly sophisticated AtomPub extension. A CMIS server will
> advertise collections that are writable using the same mechanisms we all
> know and use, i.e., app:accept. Some CMIS servers, though, further restrict
> the atom:entry documents that they will successfully process for POST
> requests. Others may accept any valid Atom entry. I have blogged about the
> consequences of such diverse behavior [1, 2] and the basic problem is that a
> client would not know the nice kind from the restrictive kind of CMIS
> server.

Here is an excerpt from RFC 5023

This is the basis of my suggestion of using atom:category to specify
that an atom:entry is of a particular "kind" or exhibits particular
properties.  And filtering on such is already built into the AtomPub
spec:

---------------

8.3.6 The "app:categories" Element

The "app:categories" element provides a list of the categories that
can be applied to the members of a Collection. See Section 7.2.1 for
the detailed definition of app:categories.

The server MAY reject attempts to create or store members whose
categories are not present in its categories list. A Collection that
indicates the category set is open SHOULD NOT reject otherwise
acceptable members whose categories are not in its categories list.
The absence of an app:categories element means that the category
handling of the Collection is unspecified. A "fixed" category list
that contains zero categories indicates the Collection does not accept
category data.

-----------------------------------------

--peter

> Solutions:
> The basic question is whether, for standard AtomPub clients that don't
> understand any CMIS extensions, there is benefit to receiving better
> app:accept advertisements. In other words, is there some additional
> information about app:accept that will help clients better determine whether
> a request is likely to be accepted by the server. I know there is no
> must-understand extension mechanism for app:collection, so I don't know what
> would be the best alternative:
> 1. Use a new MIME type parameter on app:accept for the Atom entry content
> type
> 2. Use a new attribute on app:accept
> 3. Use an extension element in app:collection to identify CMIS requirements
> Why should you care?
> Of course, there are many AtomPub servers out there that wouldn't accept any
> arbitrary valid atom:content but CMIS is a case that is quite close to
> blogging and that is being standardized (publicly, if I may say so). This is
> an opportunity for the atom-protocol community to weigh in on the
> consequence of how AtomPub advertisements are used in CMIS.
> As a disclaimer, I am not a member of the CMIS TC, although Oracle is.
> Nikunj
> http://o-micron.blogspot.com
> [1] CMIS II: (C)MISsing good old AtomPub
> [2] CMIS X: Is CMIS a good AtomPub citizen?