[oslc-core] missing oslc query functionality
Nick Crossley
ncrossley at us.ibm.com
Tue Jul 17 13:49:31 EDT 2012
Just to be quite clear, are you still talking about a provider or domain
specific extension to the query language?
I think the bar for extending the query language required by OSLC Core
should be very high.
Nick.
From: Joe Ross/Austin/IBM at IBMUS
To: Arthur Ryman <ryman at ca.ibm.com>,
Cc: oslc-core at open-services.net
Date: 07/17/2012 10:36 AM
Subject: Re: [oslc-core] missing oslc query functionality
Sent by: oslc-core-bounces at open-services.net
Well a unary "not" operator has more general applicability than a binary
"never" operator. For example, someone could say
oslc.where=not :topping in [:bacon,:cheese]
or
oslc.where=not :num < 5
note that this is not the same as oslc.where=:num >= 5 if num is
multivalued
If we are extending the syntax, seems that adding "not" will be more
useful.
================================================
Joe Ross/Austin/IBM, joeross at us.ibm.com
Tivoli Autonomic Computing & Component Technologies
512-286-8311, T/L 363-8311
From: Arthur Ryman/Toronto/IBM at IBMCA
To: Joe Ross/Austin/IBM at IBMUS,
Cc: oslc-core at open-services.net
Date: 07/17/2012 12:20 PM
Subject: Re: [oslc-core] missing oslc query functionality
Joe,
How about using "never" instead of "not", like so?
oslc.where=:topping never :bacon
Using "never" suggests we are looking at all the property values.
Regards,
___________________________________________________________________________
Arthur Ryman
DE, Chief Architect, Reporting &
Portfolio Strategy and Management
IBM Software, Rational
Toronto Lab | +1-905-413-3077 (office) |
+1-416-939-5063 (mobile)
From: Joe Ross/Austin/IBM at IBMUS
To: Arthur Ryman/Toronto/IBM at IBMCA
Cc: oslc-core at open-services.net
Date: 07/17/2012 11:02 AM
Subject: Re: [oslc-core] missing oslc query functionality
Yes, that is the answer I would want. However, != operator would not give
me that, since all three pizzas have a topping that is not bacon.
So, I think we would need the following:
oslc.where=not :topping=:bacon
this would return all resources except those that have bacon (pizza-1 and
pizza-2, but not pizza-3).
Joe
================================================
Joe Ross/Austin/IBM, joeross at us.ibm.com
Tivoli Autonomic Computing & Component Technologies
512-286-8311, T/L 363-8311
From: Arthur Ryman/Toronto/IBM at IBMCA
To: Joe Ross/Austin/IBM at IBMUS,
Cc: oslc-core at open-services.net
Date: 07/17/2012 09:30 AM
Subject: Re: [oslc-core] missing oslc query functionality
Joe,
Just so I understand, for #1 you only want to return resources in which the
specified property value never appears?
Suppose we have the following member resources:
:pizza-1 :topping :pepperoni , :olives, :mushrooms .
:pizza-2 :topping :cheese, :olives, :onion .
:pizza-3 :topping :bacon, :cheese, :mushrooms.
Then the query oslc.where=:topping!=:bacon would return :pizza-1, :pizza-2.
Regards,
___________________________________________________________________________
Arthur Ryman
DE, Chief Architect, Reporting &
Portfolio Strategy and Management
IBM Software, Rational
Toronto Lab | +1-905-413-3077 (office) |
+1-416-939-5063 (mobile)
From: Joe Ross/Austin/IBM at IBMUS
To: Arthur Ryman <ryman at ca.ibm.com>
Cc: oslc-core at open-services.net
Date: 07/13/2012 10:30 AM
Subject: Re: [oslc-core] missing oslc query functionality
Thanks, Arthur. So, it sounds like these were intentional simplifications,
and we could implement our own extensions or SPARQL if we want.
> 1. Correct. What semantics do you want for multi-value properties? Are
you
> looking for the existence of one value that does not equal the given
> value?
In this particular case we are looking for resources that don't have a
particular value for a multi-valued property. If we were simply looking for
the existence of a value that doesn't equal the give value, I think !=
would handle that.
> 2. Correct. However, you could approximate this effect by comparing the
> property to a value that you are sure does not exist. e.g. if ex:estimate
> is always non-negative, then ex:estimate > -1 would return resource that
> had any value for ex:estimate.
That is actually how we are doing it now . Using != with a value we know
won't ever exist.
Joe
================================================
Joe Ross/Austin/IBM, joeross at us.ibm.com
Tivoli Autonomic Computing & Component Technologies
512-286-8311, T/L 363-8311
Arthur Ryman <ryman at ca.ibm.com> wrote on 07/13/2012 09:11:06 AM:
> From: Arthur Ryman <ryman at ca.ibm.com>
> To: Joe Ross/Austin/IBM at IBMUS,
> Cc: oslc-core at open-services.net, oslc-core-bounces at open-services.net
> Date: 07/13/2012 09:11 AM
> Subject: Re: [oslc-core] missing oslc query functionality
>
> Joe,
>
> The query language was scoped to be simple to implement. It is not
> intended to be a fully general query language. For more complex
> requirements, services can implement a standard query language. SPARQL is
> recommended.
>
> 1. Correct. What semantics do you want for multi-value properties? Are
you
> looking for the existence of one value that does not equal the given
> value?
>
> 2. Correct. However, you could approximate this effect by comparing the
> property to a value that you are sure does not exist. e.g. if ex:estimate
> is always non-negative, then ex:estimate > -1 would return resource that
> had any value for ex:estimate.
>
> Regards,
>
___________________________________________________________________________
>
> Arthur Ryman
>
> DE, Chief Architect, Reporting &
> Portfolio Strategy and Management
> IBM Software, Rational
>
> Toronto Lab | +1-905-413-3077 (office) | +1-416-939-5063 (mobile)
>
>
>
>
>
> From:
> Joe Ross <joeross at us.ibm.com>
> To:
> oslc-core at open-services.net
> Date:
> 07/12/2012 06:39 PM
> Subject:
> [oslc-core] missing oslc query functionality
> Sent by:
> oslc-core-bounces at open-services.net
>
>
>
> We've had a couple of scenarios that don't seem to be addressable using
> the OSLC core 2.0 query syntax:
>
> 1. Finding all resources that don't have a particular value for a
> property.
> The != operator won't work for this, because in the case of multi-valued
> properties, records will be returned as long as there is a value that is
> not equal, even if there is also a value that is equal. This would
require
> a unary "not" logical operator.
>
> 2. Finding all resources that have any value for a particular property
> (matching on predicate, regardless of value).
> This is probably would probably be best handled by a unary "exists"
> operator, or support for wildcard as the value in oslc.where clauses.
> Currently the grammar seems to only allow for wildcard for the predicate.
>
> So, am I correct in this assessment? If so, was this omission intentional
> (and if so what was the reason), or an oversight?
>
> ================================================
> Joe Ross/Austin/IBM, joeross at us.ibm.com
> Tivoli Autonomic Computing & Component Technologies
> 512-286-8311, T/L 363-8311_______________________________________________
> Oslc-Core mailing list
> Oslc-Core at open-services.net
> http://open-services.net/mailman/listinfo/oslc-core_open-services.net
>
>
>
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