Sorry for being imprecise about URIs, what I meant to say was that every feature in DAS/2.0 has a unique _absolute_ URI. Most IDs can be treated as relative URIs but not absolute URIs, and referring to relative URIs is not particularly useful outside their context.
Furthermore technically not all arbitrary ID strings can actually be relative URIs either. I thought this was mostly a theoretical issue until my Trellis/Ivy DAS1-->DAS2 proxy choked on such a case on only the third DAS1 data source I was testing, http://www.ebi.ac.uk/das-srv/genomicdas/das/batman_CD4. It returns features that derive their IDs from their genomic location, like "21:26029715,26029814". Which can't be any form of URI, because according to the URI syntax spec <http://tools.ietf.org/html/rfc3986> the appearance of the colon before any forward slash means the "21" should be treated as the URI scheme, but the scheme can't have a digit as the first character. This isn't just a rare instance either -- I count at least sixteen data sources like this (probably more) on ProServer servers for the latest human genome assembly alone. On a side note, I'm not sure if these IDs are legal DAS1.53 feature IDs either, since many of them will not be unique within their DAS server, and depeding on how you interpret the 1.53 spec the colon may not be a legal ID character. The Trellis/Ivy proxy now deals with these cases, but checking each ID to see if it's a legal URI, and figuring out what to do if it's not, is definitely adding some performance overhead to the proxy. This also points to the need for better validation of server responses, preferably as enhancements to the validation that the DAS1 registry already does. I doubt if the current DAS2 validator would catch these kinds of things either. I'll chime in with my opinion on the other issues you raise in another email... Gregg On Wed, Oct 29, 2008 at 12:04 PM, Andy Jenkinson <[EMAIL PROTECTED]>wrote: > The difference between an ID and a URI is not so great, any ID can be a URI > if we refer to the URN definition. _______________________________________________ DAS mailing list [email protected] http://lists.open-bio.org/mailman/listinfo/das
