[ckan-discuss] [nathan at webr3.org: Please allow JS access to Ontologies and LOD]

[William Waites]

This came up in the context of linked data but would seem a good
idea for the CKAN API as well -- are there any JavaScript clients
out there? Just a one-line change to the apache config... No
code changes at all.

Thoughts?
-w

----- Forwarded message from Nathan <nathan at webr3.org> -----

Date: Sat, 23 Oct 2010 00:04:09 +0100
From: Nathan <nathan at webr3.org>
Subject: Please allow JS access to Ontologies and LOD
To: Linked Data community <public-lod at w3.org>, 
 Semantic Web <semantic-web at w3.org>
CC: foaf-protocols <foaf-protocols at lists.foaf-project.org>

Hi All,

Currently nearly all the web of linked data is blocked from access via 
client side scripts (javascript) due to CORS [1] being implemented in 
the major browsers.

Whilst this is important for all data, there are many of you reading 
this who have it in your power to expose huge chunks of the RDF on the 
web to JS clients, if you manage any of the common ontologies or 
anything in the LOD cloud diagram, please do take a few minutes from 
your day to expose the single http header needed.

Long story short, to allow js clients to access our "open" data we need 
to add one small HTTP Response header which will allow HEAD/GET and POST 
requests - the header is:
  Access-Control-Allow-Origin "*"

This is both XMLHttpRequest (W3C) and XDomainRequest (Microsoft) 
compatible and supported by all the major browser vendors.

Instructions for common servers follow:

If you're on Apache then you can send this header by simply adding the 
following line to a .htaccess file in the dir you want to expose 
(probably site-root):
  Header add Access-Control-Allow-Origin "*"

For NGINX:
  add_header Access-Control-Allow-Origin "*";
see: http://wiki.nginx.org/NginxHttpHeadersModule

For IIS see:
  http://technet.microsoft.com/en-us/library/cc753133(WS.10).aspx

In PHP you add the following line before any output has been sent from 
the server with:
  header("Access-Control-Allow-Origin", "*");

For anything else you'll need to check the relevant docs I'm afraid.

Best & TIA,

Nathan

[1] http://dev.w3.org/2006/waf/access-control/


----- End forwarded message -----