[DAS] Dalliance: a new genome DAS client

Thomas Down thomas.a.down at gmail.com
Tue Aug 3 21:28:40 UTC 2010

Jonathan's written a nice summary here:


But briefly...  it's the "official" way to work around the same-origin
policy (by default, browsers only allow unsigned javascript to trigger HTTP
requests to the server from which it was originally downloaded).  The
specification is here:


(Please don't be too alarmed by the datestamp!  The core parts have been
stable for > a year now, and it's well supported by Mozilla, WebKit, and --
via a slightly different API -- Internet Explorer).

If you're running a public server and want it to be CORS accessible, all
that is needed is to emit the header:

          Access-Control-Allow-Origin: *

...and you're done.

(If you're running password-protected DAS servers, or DAS servers hosting
sensitive information behind a firewall, you might want a slightly more
sophisticated CORS implementation.  Happy to discuss if anyone is


On Tue, Aug 3, 2010 at 10:21 PM, Lincoln Stein <lincoln.stein at gmail.com>wrote:

> Someone give me a quick summary of CORS support. I want to make sure that
> GBrowse exports DAS 1.53 with CORS (is it just the registry metadata, or
> something new?)
> Lincoln
> On Tue, Aug 3, 2010 at 4:52 PM, Jonathan Warren <jw12 at sanger.ac.uk> wrote:
>> This is very cool - I had a look the other day. Was wondering why some
>> sources could be attached and some can't....
>> Best browser experience yet by far I'd say.
>> No problems about adding CORS support - for the record I'm very happy to
>> implement new capabilities testing and other suggestions to the registry
>> from anyone who cares to drop me a line. Especially if it's going to enhance
>> and promote the use of the registry :)
>> On 3 Aug 2010, at 20:41, Thomas Down wrote:
>>  As some of you already know, I've been experimenting recently with a
>>> web-based DAS client for genomic data.  It's still in
>>> a unashamedly prototypical state (in particular, some of the popups and
>>> configuration stuff is outright clunky, and we know it!), but we're
>>> starting
>>> to find it quite useful, and would be interested to receive more
>>> feedback.
>>> So if you're curious, you can try it here:
>>>              http://www.biodalliance.org/human/ncbi36/
>>> It's a fully-fledged DAS/1.53 client (with a few bits of DAS/1.6, and
>>> hopefully rather more coming soon), but has one major caveat: since it's
>>> pure Javascript code running in your web browser, there are limitations
>>> to
>>> which servers it can connect to.  Specifically, it will only work with
>>> DAS
>>> servers that implement the W3C cross-origin resource sharing model (which
>>> has been discussed on this list before, but drop me a line if you've got
>>> any
>>> questions).  What does this mean in practice?  If you're adding
>>> datasources
>>> from the registry, things are simple because Dalliance will only allow
>>> you
>>> to add CORS-enabled sources (a huge thanks to Jonathan Warren for adding
>>> some support for this in the registry).  If you run your own DAS servers
>>> and
>>> don't list them in the registry, you'll need to check for CORS
>>> compatibility
>>> yourself.  The latest versions of Proserver and Dazzle should both be
>>> okay.
>>> All comments, suggestions, and bug reports are welcome!
>>>                  Thomas Down.
>>> _______________________________________________
>>> DAS mailing list
>>> DAS at lists.open-bio.org
>>> http://lists.open-bio.org/mailman/listinfo/das
>> Jonathan Warren
>> Senior Developer and DAS coordinator
>> blog: http://biodasman.wordpress.com/
>> 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._______________________________________________
>> DAS mailing list
>> DAS at lists.open-bio.org
>> http://lists.open-bio.org/mailman/listinfo/das
> --
> Lincoln D. Stein
> Director, Informatics and Biocomputing Platform
> Ontario Institute for Cancer Research
> 101 College St., Suite 800
> Toronto, ON, Canada M5G0A3
> 416 673-8514
> Assistant: Renata Musa <Renata.Musa at oicr.on.ca>

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