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Re: Agent Sub-Types

From: Reza B'Far <reza.bfar@oracle.com>
Date: Mon, 18 Jul 2011 11:49:09 -0700
Message-ID: <4E248025.1010402@oracle.com>
To: public-prov-wg@w3.org
Paolo -

In the case of "Trust", I think your solution works and it solves the problem.  
There was another thread where someone suggested (I don't remember who now, 
sorry) the same thing for system vs. human (this is the user-agent vs. agent vs. 
etc.) discussion.  In that case, it doesn't work.

So, here are my thoughts on your email:

 1. Thanks for the solution of "Trust" being an attribute of some sort.  This
    will work.  Either you and/or I should send out a separate email as proposal
    to see what the greater group thinks.
 2. On profiles, I also responded to this, I'm very weary of profiles.  There
    are lots of standards with profiles that have flopped.  At least my strong
    preference is to be as specific as possible in the model and would rather
    risk being wrong on the specific versus generic side given examples like
    HTML, etc. where standards are more successful in gaining adoption when
    erring on the side of specific.  I also realize we don't want to venture too
    far in there, but I think you get my point.

There is also another question that has come up that I do not find an answer to 
that I believe is crucial to be answered in order for more concrete definition 
on entities:

Does the provenance of an entity begin beyond its physical origination?

I'd like to get a binary answer from the perspective of this working group.  All 
the materials that I have studied regarding provenance in the past indicates a 
"Yes" to above so I had assumed (perhaps incorrectly) that the answer is "Yes".  
But I think it's crucial we answer this question and document it on the wiki.


On 7/18/11 10:50 AM, Paolo Missier wrote:
> Reza,
>
> it's worth trying to make progress on this as we are in the process of editing 
> a document draft.
>
> I can see the dilemma:
> - the less you specify in the model, the more you risk incompatibilities as 
> different implementations make their own choices to fill the gaps;
> - but by adding specific extensions to the top-level concepts in the model, 
> you risk to make those choices arbitrary.
>
> But in this specific instance, I believe that "trusted" is one specific 
> qualification of "Agent" that does not belong to the model, rather it belongs 
> to applications that use the model (i.e., to /assess some measure of trust/).
>   But I see your need for a "placeholder" where I can assert something about 
> how trust for Agents. This is fine: let Trusted not be a sub-class of Agent, 
> but let "Trust properties" can be properties of Agent. Would that be a 
> problem?  Any application that knows about trust would fill in into those 
> properties.
>
> To repeat my proposal, I see Agent as a Role that any first-class entity in 
> the model can take on when it is involved in relations that concern activities.
>
> The general lesson I see from this thread is that we urgently need to discuss 
> how principled extension mechanisms ("profiles") make it into our proposal.
>
> atb -Paolo
>
>
> On 7/14/11 10:06 PM, Reza B'Far wrote:
>> Ok.  At this point, I'm resigning to the fact that I'm in the minority.  
>> However, just look at HTML as a data point:
>>
>> They could have made <p></p> and <div></div> tags into the same generic tag 
>> with an attribute (or attributes).  I would argue that they made the right 
>> decision(s) in the strong types they created, though not all were perfect 
>> decisions (e.g. <blink>).  That "strongly encouraged" all the implementers of 
>> browsers to define rendering of a paragraph in a specific way (and different 
>> from <div) which is more loose).  The core issue is compatibility.  If you 
>> make something generic and provide only soft guidelines for extensions, you 
>> end up with compatibility issues when product implementers build their 
>> products because they will do whatever they can within the specification to 
>> differentiate their products.  Ignoring that fact risks success of a standard 
>> once implemented.
>>
>> But, I end with my original statement that I'll drop the topic.
>>
>> On 7/14/11 1:57 PM, Daniel Garijo wrote:
>>> Hi Reza, all,
>>> I agree with you in that subtyping is very important from an implementer 
>>> persepctive.
>>> However I think that the model discussed in the model TF is supposed to be 
>>> generic,
>>> and once we have it, the test cases TF can develop some profiles subtyping 
>>> all the
>>> generic concepts, showing examples of how it would be extended in different 
>>> domains.
>>> Thus, developers could use these profiles as reference for other extensions.
>>> Best,
>>> Daniel
>>>
>>> 2011/7/14 Reza B'Far <reza.bfar@oracle.com <mailto:reza.bfar@oracle.com>>
>>>
>>>     I agree that it's the right thing to do to keep trust definition out of
>>>     the scope of WG.  However, if the group is saying that defining touch
>>>     points to the tangent layers, per your own references, is also out of
>>>     scope, then I warn that there is a fundamental problem for product
>>>     implementers.  If you want to exclude all aspects of trust including any
>>>     think like the ability to embed something else via a URI or something
>>>     like that to a trust mechanism, then you'll have compatibility issues
>>>     from different product vendors.  If you want to do that knowingly, it's
>>>     fine and I'll drop the thread, but if you disagree and think that
>>>     exclusion of trust doesn't cause fundamental incompatibility, we can
>>>     continue thread and I can provide more details on why this is the case.
>>>
>>>     So, my point from the beginning is that without subtyping, things are
>>>     too generic to be able to import and export things about entities
>>>     between different systems.  And I believe a primary use-case for usage
>>>     of the model is import/export between different implementations.
>>>
>
Received on Monday, 18 July 2011 18:49:56 GMT

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