Re: How to create configurations

Geoffrey M. Clemm (gclemm@atria.com)
Wed, 7 Apr 1999 07:41:44 -0400 

Date: Wed, 7 Apr 1999 07:41:44 -0400
From: gclemm@atria.com (Geoffrey M. Clemm)
Message-Id: <9904071141.AA28284@tantalum>
To: ietf-dav-versioning@w3.org, jamsden@us.ibm.com
Subject: Re: How to create configurations

Another reason to explicitly identify an immutable set of immutable
revisions as an identifiable resource is that it has a variety of very
important implementation characteristics (especially in a distributed
environment) due to its immutable nature.  If even a single member
of a configuration were mutable (e.g. by being a mutable revision or
by being a versionable resource), then none of these characteristics
hold.

Like Jim, I believe that labels are an appropriate way to support the
concept of a "mutable configuration".

Cheers,
Geoff


> From: jamsden@us.ibm.com
> 
> 
> Bruce,
> No, I meant immutable revisions. It makes no sense to put a mutable
> revision or unversioned resource in a configuration as the point of a
> configuration is to select an immutable set of revisions. If the revision
> can change, then the configuration can't return the same set of revisions.
> 
> The role of a configuration is to capture and reproduce a consistent set of
> revisions that represent some deliverable. If a member of a configuration
> is mutable, the configuration cannot guarantee that what you get at some
> future point in time is the consistent set you created. The changed
> revision(s) may result in an inconsistent set that does not meet the
> expectation of the original configuration which would be lost. Labels can
> be used to simulate mutable configurations.
> 
> 
> 
> 
> 
> "Bruce Cragun" <BCragun.ORM2-1.OREM2@novell.com> on 04/06/99 10:51:58 AM
> 
> To:   Jim Amsden/Raleigh/IBM
> 
> Subject:  Re: How to create configurations
> 
> Do you really mean to exclude non-versioned resources?  A configuration
> will likely contain *primarily* versioned resources, but why couldn't it
> contain a resource that isn't yet versioned?  Perhaps you meant to say
> "versionable resource"????
> 
> >>> <jamsden@us.ibm.com> 04/05/99 09:50AM >>>
> (just an excerpt):
> A configuration is a versionable resource whose members specify the
> mapping
> between URLs and revision GUIDs. A configuration can be created and
> members
> can be added and/or removed. Adding a resource to a configuration adds
> the
> URL of the resource and its parent collections recursively up the
> collection hierarchy to the root. The URL must refer to a versioned
> resource, and the revisions selecded for the configuration must be
> immutable. Adding a collection to a configuration also recursively adds
> the
> URLs of its members. This ensures the namespace for any resource added
> to a
> configuration is also added to the configuration so that when the
> configuration is used as a revision selector in a workspace, the
> resource
> namespace can be resolved as it was when the member was added to the
> configuration.
> 
> 
> 
> 
> 
>