Fix No 'Access-Control-Allow-Origin' error or provide better warning #31
Description
As mentioned during the public launch, some feeds cannot be accessed by the DCAT validator because of:
XMLHttpRequest cannot load ... No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'http://validator.dcat.be' is therefore not allowed access.
For which the DCAT validator will show the warning:
The URI you have entered is not valid.
I think it is possible to solve this error (see e.g. this Stack Overflow thread, where e.g. jsonp is suggested).
If that is not feasible I would provide another error message, such as:
The server at the URI you have entered is blocking access to the content.
That way, it is more clear that the user hasn't made a typo (i.e. the URI is valid), but that it has something to do beyond their control.