- From: Sankar Virdhagriswaran <sv@hunchuen.crystaliz.com>
- Date: Fri, 29 Aug 1997 11:37:41 -0400
- To: w3c-dist-auth@w3.org
The point in this email is an orthogonal point, but is related to the discussion of variants. If an approach is being developed to deal with variants, then that approach should consider configurations also. As long as we allow a collection (or a linked set of documents) as one conceptual entity, then we could also use the same mechanism for identifying semantically consistent versions (which is what a configuration is). When I had asked this question previously, Jim had mentioned that cookies can be used to implement such a mechanism. This is certainly plausible, although I would like to hear some scenarios. In any case, however, all the problems that are being visited here with respect to authoring tools will also show up in configurations. Cookies may indeed give a mechanism on the client side to keep the state of active configurations, but that does not say anything about how a server will identify a configuration. So the answer to Jim is: cookies might very well be sufficient, except that to our knowledge there is no cookie standard that defines versions and configurations, and cookies are useless for interoperable versioning purposes if there is no standard way of identifying versions and configurations. This also relates to the naming of versions. Here's my take on naming versions of objects. When a new version is created, it has to be given a specific version name, and that name has to be generated by someone. This someone has to be either the client or the server. If there are no standards version naming, as the WebDAV draft says, then the client can't invent names, since it can't know what names will be permitted by the server (e.g. one server might require a number following a period, while another might have alphabetic characters following a percent sign or /). If the name is assigned by the server, then the client has to find out the name at the time the version is written, so that it can consistently refer to the version that it just wrote. Therefore writing a version has to be atomic with finding out the version written; otherwise an intermediate write could screw up the version name discovery. I agree with Jim that version ordering (predecessor/successor) is an important question, but I don't think it's central. They are only needed when you want to do an "undo" or "replay" without knowing to which version one wants to revert; you can do an awful lot without storing sequence information in a systematic way. Accessing multiple variants -- for an individual object, isn't that done just by accessing the appropriate member of a container? That is, if /foo/bar names the containers holding all versions of document bar, then /foo/bar/13 might be version 13. On my quick read of the WebDAV documents I've seen, this seems to be implicit; but I don't remember seeing any particularly concrete descriptions of how the protocol is intended to be used. For configurations consisting of consistent versions of a set of objects, perhaps we can create new containers with external links to the specific versions of all of the objects of interest? I don't know. I don't think configurations in the sense Jim defines (the configuration goes to a new version any time any member object does) are going to be helpful, since they don't scale.
Received on Friday, 29 August 1997 11:35:33 UTC