[DAS] maxbins in DAS1.6?

Tue Sep 15 16:56:16 UTC 2009

On 15 Sep 2009, at 16:35, Jonathan Warren wrote:

> I agree with Andy on both these (we talked about versioning before).
> The version numbers really have no meaning at the moment (no web  
> pages anywhere actually explain what a different version means) and  
> don't seem to be used at all in data sources ( I'm guessing people  
> end up just copying the version numbers from examples given.
>
> I've always had an issue with the commands like this http://www.ebi.ac.uk/das-srv/genomicdas/das/eqtl_rat_cis_fat 
>  not being a valid das command as it's the most natural request for  
> a person new to das to make. So giving it a specific purpose and  
> response is a good idea.
>
> My only concern is how to handle these if we start using the power  
> of multiple query_uri s per das source (inherited from DAS2, which  
> we have started to talk about, rather than the das1 style where all  
> urls have a root) as currently there is no "root" url specified in  
> the DAS2 spec in the sources document...?? So this would have to be  
> specified as another capability? or you could infer it from the  
> features command, but obviously not the sources cmd!!!

My take on this is that the root URI identifies the source. In a  
conceptual sense the definition of a source is merely a combination of  
commands acting on a common set of data. It is not really important  
where that information comes from (a registry, a server, a flat  
file...) because a server by itself does not really mean anything. So  
the URI http://www.ebi.ac.uk/das-srv/genomicdas/das/eqtl_rat_cis_fat  
is not actually meaningful, even less so given it is not even a  
resolvable URL.

The query URI system inherited from DAS/2 has the potential to allow  
the commands to be served from different locations on the web. It is  
not something we have needed up to now (all query URIs start with the  
same path), and does add confusion but I can see it being used for  
stylesheets. For example a "sequence ontology stylesheet" served from  
a single location.

But the biggest reason to have it is because of the registry. The  
registry assigns its own root URIs for a DAS source (e.g. DS_1234),  
which means it is necessary to provide another URI used to actually  
query it. Since we already have a way of doing it in the sources  
document, I don't really want to change it now. It seems we might as  
well just embrace the extra flexibility and merely describe it better.

> On 15 Sep 2009, at 15:47, Andy Jenkinson wrote:
>
>> On 15 Sep 2009, at 15:19, Thomas Down wrote:
>>> Capabilities are stated in the sources document:
>>> <CAPABILITY type="das1:maxbins" />
>>>
>>> Ah, interesting.  I'd seen that, of course, but hadn't explicitly  
>>> linked this with the idea of capabilities as listed in the X-DAS- 
>>> Capabilities header (although of course it makes a lot more sense  
>>> to have one set of capability metadata, rather than two!). There  
>>> are a couple of issues here:
>>>
>>>           1. The SOURCES examples all say "das command" in the  
>>> type attribute of the CAPABILITY element, whereas many of the  
>>> capabilities don't actually map to commands.  I notice that the  
>>> latest DAS1.6 draft does give an example to clarify this.
>>>
>>>           2. X-DAS-Capabilities entries are versioned whereas  
>>> SOURCES capabilities aren't, which makes them look rather  
>>> different. (and I note that the 1.6 spec is bumping up the version  
>>> numbers on some of the existing capabilities...)
>>>
>>> How about versioning capabilities in SOURCES, e.g.:
>>>
>>>        <CAPABILITY type="features" version="1.1" query_uri="http://noranti.derkholm.net/das/mydata/features 
>>> " />
>>>        <CAPABILITY type="maxbins" version="1.0" />
>>>
>>> Assume any missing version attributes are "1.0" and everything  
>>> should be backwards compatible.
>>
>> Indeed I did increment the version, just because it seemed the  
>> right thing to do. However as far as I am aware these per- 
>> capability versions are totally superfluous when taken in context  
>> with the X-DAS-Version header, i.e. we do NOT want to make it  
>> possible to implement DAS 1.6 and features 1.0, for example. This  
>> could create a whole world of pain!
>>
>> IMO the per-capability version is unnecessary and confusing.  
>> ProServer does use it internally, but that can be easily changed.  
>> Getting rid of it would make the spec less confusing, but will of  
>> course break things that depend on the current format (if there are  
>> any).
>>
>> What do others think?
>>
>>> The only snag is that right now you have to parse all sources.  
>>> Technically both the registry and proserver allow you do do:
>>> http://www.ebi.ac.uk/das-srv/genomicdas/das/sources/eqtl_rat_cis_fat
>>>
>>> But IIRC I didn't include this in the spec to keep things simple.
>>>
>>> If this isn't specified yet, how about allowing:
>>>
>>>            http://www.ebi.ac.uk/das-srv/genomicdas/das/eqtl_rat_cis_fat/sources
>>>
>>> ?
>>>
>>> Then it's possible to stick with the model of passing a single URI  
>>> around to refer to a "DAS datasource", and stick a command on the  
>>> end of it to get the data you're after.
>>
>> Well, the reason we didn't use this format is simply that it  
>> doesn't "read" well, if only because "sources" is plural. What  
>> would perhaps make sense, and which would allow for quickly  
>> 'pinging' a source for other similar uses, is to use this URL format:
>> http://www.ebi.ac.uk/das-srv/genomicdas/das/eqtl_rat_cis_fat
>>
>> Again, this is what seems most 'sensible' to me but I am happy to  
>> go with the consensus.
>> _______________________________________________
>> DAS mailing list
>> DAS at lists.open-bio.org
>> http://lists.open-bio.org/mailman/listinfo/das
>
> Jonathan Warren
> Senior Developer and DAS coordinator
> jw12 at sanger.ac.uk
> Ext: 2314
> Telephone: 01223 492314
>
>
>
>
>
>
>
> -- 
> The Wellcome Trust Sanger Institute is operated by Genome  
> ResearchLimited, a charity registered in England with number 1021457  
> and acompany registered in England with number 2742969, whose  
> registeredoffice is 215 Euston Road, London, NW1 2BE.