RFC for DALI-1.0

[Douglas Tody]

On Thu, 14 Mar 2013, Markus Demleitner wrote:
>
> A second major point would be that from the current document I'm
> still not sure whether I'm supposed to return my VOTable error
> documents with a 200 or a 400/500/some other error code.  I believe
> the Sao Paulo agreement was current DAL behaviour (returning 200 if
> you can even if the server's on fire) would be legal and might be
> mandatory); I won't veto that, but I'd like to repeat my strong
> dislike for this kind of weirdness ("everything's ok, but here's an
> error message for you...").

I think that we should continue to distinguish between errors in the
transport protocol (HTTP error codes), and errors in the DAL service
functionality.  Hence returning a HTTP 200 status if things are OK at
the HTTP level should be permitted if not mandatory for services which
return a VOTable status document.  If we were to start returning HTTP
error codes for service logical errors then it is likely that somewhere
in the HTTP transport layers the error would be caught and the transport
would break, failing to return the VOTable status document to the higher
level client code.

Anyway, it seemed to me that the current draft supports this
distinction, which is already used successfully in our current DAL
services (and should not be changed without a compelling reason), hence
is ok as written.

 	- Doug