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

[Ken Laskey <klaskey@mitre.org>]

So besides a Description, what Resource would not have a description?  I'm not saying it's a capital offense not to have a description, just that it seems to apply to everything else.

Ken

On Nov 14, 2007, at 9:07 PM, Francis McCabe wrote:

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

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Ken Laskey

MITRE Corporation, M/S H305     phone:  703-983-7934

7515 Colshire Drive                        fax:        703-983-1379

McLean VA 22102-7508

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Ken Laskey

MITRE Corporation, M/S H305      phone: 703-983-7934

7151 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

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