Re: [soa-rm-ra] quick poll on identifier and description

[Francis McCabe <frankmccabe@mac.com>]

Ken
  The key property is uniquely resolving a resource from a given  
identifier. So that we can use pointer comparison to know that two  
resources are the same ... but, in the open world assumption (sic), if  
two pointers are different, we do *not* know for certain that the  
things they identify are different! (Blame OWL)

  Not all resources need to have descriptions. The key for a resource  
is to have an identifier and an owner. We can model this by using  
cardinalities in UML.
  So, a description which itself has no description can still be a  
resource.

frank



On Nov 14, 2007, at 5:59 PM, Ken Laskey wrote:

> Frank,
>
> There may not be a single identifier (argh! for figuring out when  
> two references point to the same thing) but a known identifier  
> should resolve uniquely.  I don't think having identifier in  
> Description and Identifier in Resource makes sense unless we somehow  
> justify how the two are different.
>
> Now, when is there a limit in Description being a Resource?  Well,  
> obviously somewhere along the way you have a Description, which  
> although considered a Resource, does not have a description of  
> itself.  How does this show up in the UML?  It appears an override  
> of the parent class, and I believe that is possible but don't  
> remember how.  Otherwise, Description sure looks and feels like a  
> Resource.
>
> Ken
>
> On Nov 14, 2007, at 6:01 PM, Francis McCabe wrote:
>
>> Ken
>>
>>  I think that there is not likely to be a single identifier, nor is  
>> there a 'standard' way of getting from a resource to its identifier.
>>
>>  I notice that the original diagram (and yours) had arrows on the  
>> associations; including a navigability from resources to  
>> identifiers. On reflection, I am not sure that that is correct.
>>
>> Frank
>>
>> On Nov 14, 2007, at 12:52 PM, Ken Laskey wrote:
>>
>>> Today's discussion talked about description being a resource and a  
>>> resource having an identifier, so description has an identifier.
>>>
>>> In the most recent (general) Description diagram (sent out in an  
>>> email 10/16), Resource has a Description and Identifiers are a  
>>> component of Description.
>>>
>>> Which is our preference?
>>>
>>> I'm thinking of something like the following diagram
>>>
>>> <pastedGraphic.png>
>>>
>>> where Resource has both a Description and an Identifier, the  
>>> Description of a Resource has a reference to that Identifier (so  
>>> you unambiguously know what is being described), and Description  
>>> being a subclass of Resource thus has its own Identifier. (Ignore  
>>> the ' on Resource and Identifier.)
>>>
>>> Note, a version of this also needs to show up as an artifact  
>>> diagram.
>>>
>>> Your vote?
>>>
>>> Ken
>>>
>>>
>>> ------------------------------------------------------------------------------------------
>>> Ken Laskey
>>> MITRE Corporation, M/S H305     phone:  703-983-7934
>>> 7515 Colshire Drive                        fax:        703-983-1379
>>> McLean VA 22102-7508
>>>
>>
>
> -----------------------------------------------------------------------------
> Ken Laskey
> MITRE Corporation, M/S H305      phone: 703-983-7934
> 7151 Colshire Drive                         fax:       703-983-1379
> McLean VA 22102-7508
>
>
>
>