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Re: SHOULD use POST for expensive queries?

From: Seaborne, Andy <andy.seaborne@hp.com>
Date: Wed, 18 Jan 2006 15:26:36 +0000
Message-ID: <43CE5E2C.60708@hp.com>
To: Kendall Clark <kendall@monkeyfist.com>
CC: dawg mailing list <public-rdf-dawg@w3.org>

Kendall Clark wrote:
> Folks,
> Mark Baker suggests [1] that we should add a SHOULD requirement that  
> queryHttpPost binding should be used "where the cost of processing  
> the query may be prohibitive". I don't really agree with this, since  
> there's no way to no statically which are the expensive and which are  
> the cheap queries. Even very sophisticated query analysis can't tell  
> you which RDF datasets are expensive to assemble.

Very true.  It's not just the query that determines whether it will be 
expensive - it's the dataset as well (and the sever load).

[I confess I don't see why POST is better than GET for expensive operations 
except that timeouts are not at the mercy of caches as well.]

> And, further, I don't know of any way to programmatically redirect  
> expensive GETs to POSTs (you can send a Location: header to the POST  
> endpoint, if it's different from the GET endpoint, but I don't think  
> that *really* suffices; alternately, we could define a WSDL fault,  
> UsePost, but that seems an awful kludge), and I don't really see the  
> *point* of doing so either, since if the query is too expensive, it's  
> too expensive, whether it comes in via GET or POST.
> Mark retorts [2] that the "safety" of GET includes expensive  
> operations, citing some message from Roy Fielding, but I think the  
> message undercuts Mark's use of it, since it's very clearly about  
> implementations of services, not about the semantics of their  
> interfaces.
> Pat +1'd the proposal, but that was before further discussion, so I'm  
> not certain where he would be now. I'm opposed to the inclusion that  
> Baker suggests, for the reasons I've stated, but I will leave it to  
> the WG to decide.

SHOULD language (meaning "carefully weigh the situation before choosing a 
different course") is acceptable if that reflects good web practice; not 
having the text on the grounds that you believe that there isn't anything 
sufficiently SPARQL related is also acceptable.

> Cheers,
> Kendall Clark
> [1] http://lists.w3.org/Archives/Public/public-rdf-dawg-comments/ 
> 2006Jan/0094.html
> [2] http://lists.w3.org/Archives/Public/public-rdf-dawg-comments/ 
> 2006Jan/0111.html

Received on Wednesday, 18 January 2006 15:26:47 UTC

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