[DAS2] version=

[Nomi Harris]

i think it would be nice to have it work both ways--the version is
reported by the server, but the client can also request a particular
version as you suggest.

whatever we decide on, can we please make the version IDs numerical so
that they can be compared easily (e.g. "if (dasversion > 1.3) ...")?

     Nomi


On 6 February 2006, Steve Chervitz wrote:
 > Andrew Dalke wrote on Mon, 6 Feb 2006 18:42:24
 > > 
 > > If we add a version= field to the Content-Type, or whatever
 > > mechanism is proposed
 > > 
 > > Content-Type: application/x-das2features+xml; version=12345
 > > 
 > > What will a client do when it gets a version number it has
 > > never heard of?  Should it use the newest version it supports?
 > > The oldest?  Abort?
 > 
 > Rather than have version data be something that the client has to discover
 > in the response, an then have to react to in some intelligent way, how about
 > adding an optional dasversion field to all requests, such as:
 > 
 > http://www.wormbase.org/das/genome/volvox/1/type?dasversion=1.1
 > 
 > The server would then either:
 > 
 > 1) return the appropriate response document if the server supports the
 > requested version or a later version that is backward compatible with it,
 > or
 > 2) return a 505 error 'DAS Version Not Supported', which we already have in
 > the spec.
 > 
 > This puts the onus on the server rather than the client, but I think it
 > would be less trouble on the server than the alternative scheme would be for
 > the client. The client can now be fairly dumb about versioning and assume
 > everything is kosher unless it gets an error.
 > 
 > We could put some of the onus for DAS version support on the revisers of the
 > spec: When a new version of the spec is released, we'll know right then what
 > parts will be backward compatible and what parts will not be. The reviser
 > could document whether the new version of the spec is backwards compatible
 > with which previous versions, with the appropriate level of granularity
 > (e.g., "all requests are backward compatible except for the types request").
 > This would serve as a guide for maintainers of das2 servers.
 > 
 > Thoughts?
 > 
 > Steve