- From: Judith Slein <slein@wrc.xerox.com>
- Date: Fri, 7 Feb 1997 09:07:07 PST
- To: Jim Whitehead <ejw@ics.uci.edu>
- Cc: w3c-dist-auth@w3.org
I have a number of concerns about how the spec treats attributes. Some are related to the very basic fact that we treat attributes as independent resources, linked to the resource they apply to. Others are separate concerns: Treating attributes as resources has some desirable consequences: - Attributes are resources, and so can themselves have attributes. They can be versioned. Content negotiation can be done for them. Etc. - An attribute can be shared by many resources. - Attributes of a single resource can be distributed across multiple servers. But treating attributes as resources also causes some serious problems: 1. For many applications, the most important reason for having attributes is for searching. It needs to be possible to search for a resource based upon the values of its attributes. We may not want to specify anything about search syntax, but we do need to make sure that our attribute model can support reasonably efficient searches. The very fact that our attributes are independent resources makes this difficult, and I don't see that we require attributes to point back to their resources, which would make it impossible. 2. There is no way to set multiple attributes at a time. You would like to be able to set all attribute values for a document at the same time you put its content on the server, and change multiple attribute values in a single step at any time. 3. This approach makes it extremely difficult to manage attributes. In the typical case, attributes should automatically get deleted when a document gets deleted - this won't happen. Neither will they get moved automatically with their document or copied automatically with their document. 4. Since attributes are resources, they can be linked to more than one resource. So a link back to the parent is required in order to know whether an attribute can be deleted when one of its parents is deleted. Other issues about attributes: 5. How can you find out the constraints on values of attributes supported by a given server? Does this information come back when you ask for DAV.SupportedLinkTypes? You need (arguably) to be able to find out the data type of an attribute, maximum length, valid values, whether its value can be a list, etc. 6. Is there a way to find out whether a server will let you assign attributes to a resource that do not belong to any well-known schema? A thought: If links seem like the right implementation of attributes, we might want to have a separate section on links (which are really infrastructure on which attributes are based, and useful for many other things besides attributes) and a separate section on attributes. I think this would make more certain that we address all issues related to attributes. --Judy Name: Judith A. Slein E-Mail: slein@wrc.xerox.com Internal Phone: 8*222-5169 External Phone: (716) 422-5169 Fax: (716) 265-7133 MailStop: 128-29E
Received on Friday, 7 February 1997 12:05:15 UTC