Re: query language

On 9/10/14 12:09 PM, Ryan McDonough wrote:
> If your SLAs and predictable performance matter, I'd be reluctant to 
> offer a service that allowed arbitrary queries to be issued against 
> it. To clarify adhoc, I am referring to the equivalent of being able 
> to issue something like a random SQL query to my service. That's not 
> to say I don't want users to not query my data, but rather I want to 
> control what they can query. For example, HTML forms allows me to 
> control what data sets a consumer can query and the types of 
> operations I want to allow on that resource. I can more predictably 
> determine my SLAs and loads because I'm controlling the data access 
> patterns.
>
> HTSQL (http://htsql.org/) is probably a better example of what I'm 
> getting at. I could create a hypermedia control that generates a query 
> like so:
>
> http://demo.htsql.org/define($avg_credits%20:=%20avg(course.credits))%0A%20.course%7Btitle,%20credits%7D?credits%3E$avg_credits 
> <http://demo.htsql.org/define%28$avg_credits%20:=%20avg%28course.credits%29%29%0A%20.course%7Btitle,%20credits%7D?credits%3E$avg_credits>
>
> If I do that, it could be considered RESTful. But where it starts to 
> violate REST constraints is making the client responsible for 
> constricting links. And requiring the client to have specialized 
> knowledge of how to format these special URIs. Because HTSQL, as well 
> as OData and RQL, have specific URI conventions to issue queries to 
> the server without being instructed by the server as to how to format 
> those URLs, violates a few constraints. To me the violate a lot of Dr. 
> Fielding's clarifications:
>
> http://roy.gbiv.com/untangled/2008/rest-apis-must-be-hypertext-driven
>
> Specifically, the 1st, 4th, and last bullet points. Ignoring the  REST 
> constraints, I now loose predicability because clients can issue query 
> work loads that I may not be able to handle. And more importantly, you 
> now have a client/server coupling because the server can't just 
> interpret HTTP URLs, but now needs specialized parsers for HTSQL URLs, 
> or OData URLs, etc. in order to satisfy the request.
>
> Like I said, if I want to offer adhoc query capability, I'd stand up a 
> SPARQL endpoint, likely on different hardware, so that it does not 
> complete with the SLAs of my primary system. But that's just my opinion.
>
> Ryan-

+10000....


[1] http://linkeddata.uriburner.com/c/9G36GVL -- follow-your-nose from 
here in regards to Tickets, Web Tickets, SLAs, and enforcement rules & 
policies (in RDF) for protecting Web Services (SPARQL or any other kind 
of service).

-- 
Regards,

Kingsley Idehen 
Founder & CEO
OpenLink Software
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