Re: Need for error messages?

Hi Ivan,

>> For example, an 'error-profile-not-available' event handler might
>> choose to abort processing completely, whilst a
>> 'warning-prefix-not-defined' handler might be used in only in an
>> editing scenario, as a way to give authors some feedback as they work.
>>
>
> The problem with this approach is that it does not properly work in a distiller setting. If I issue
> a request to distill an RDFa content, I expect a graph back. Events is then a kind of an
> out-of-bands mechanism that does not fit well into the model. That is why I really prefer to
> base this on graphs...

I think what you want is still possible:

1. Your distiller would be a wrapper around an RDFa parser.

2. The parser would fire events at various points according to the
spec -- parsing begins, parsing ends, profile loading started, profile
loading completed, profile failed to load, prefix not found, and so
on. (Events are something that I want to add to the RDFa DOM API
anyway, and have discussed a little with Benjamin and Manu. But until
I saw your suggestions, I had only been thinking of general things
such as 'parsing complete'.)

3. Your distiller would have event handlers registered on the parser,
and the handlers would implement whatever you decide is the
appropriate course of action: you might abort processing on an error,
and return an error message; you might create your 'error graph' as
you describe; if a profile fails to load you may decide to load a
cached version, or try a completely different server, based on a
lookup. And so on.

So I'm thinking that from the point of view of the specifications we
should be considering providing hooks out of the parser, so that
applications that use a parser can decide what they want to do with
the knowledge that something has gone wrong (or right). By providing
these hooks we allow for all sorts of courses of action, including the
one that you describe.

Regards,

Mark

--
Mark Birbeck, webBackplane

mark.birbeck@webBackplane.com

http://webBackplane.com/mark-birbeck

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Received on Friday, 30 April 2010 11:01:02 UTC