[cap-talk] Objects and Facets

[Jed at Webstart]

At 08:31 AM 8/8/2006, Norman Hardy wrote:
>I grant the following points made in the mail below (and previously).
>
>In the context of David's description of the up-down counter,
>"component" makes sense as a noun for what I would call an object.
>It becomes a component of the app that calls the counter creator.
>
>In my model with several facets to the same object I must explain how
>the implementation of such an object distinguishes via which facet a
>message arrived. This is unnecessary in your model.

I'm not sure how much I want to get involved in this level of discussion
(see "soap box"), but it seems to me the issues with regard to
distinguishing facets are essentially the same in either model -
whether you call the facets distinct functions or capabilities.

>In our descriptions of specific functionalities, we need a name for
>the site of the state.
>You would say 'component', I would say 'object'. I grant that
>'component' suits the case at hand.

What's better about "component" in this case?  Are you suggesting
that an integer 'object' is discordant in some sense?  If so then I
fear we've restricted the 'object' notion further than I feel helpful.

>We may or may not need a name for the unique thing designated by a
>capability.
>In your adequate description of the counter below, you could have
>said that 3 capabilities were returned.
>Then 'facet' would be unneeded.

Or it could be used to note that the three capabilities referred to
the same mutable state?  Doesn't this level of discussion seem
unnecessarily picky to you (both)?

>I don't know whether you can
>generally avoid the term.
>Both of our descriptions need additionally to specify that the three
>returned capabilities provide the only access to the state.
>(I would bundle such security requirements with the specifications.)
>I don't know whether some style of description can cover this
>implicitly.

I'm not sure whether it would even be appropriate to do so.  What about
the server itself?  Are you arguing that it doesn't have access to these
services?  What about the owner of the system?  Suppose new capabilities
are created that provide the same permission?  Are the old capabilities
any less "capabilities" because there are new means to these ends?

Are you trying to work inside a formal system where you can
place constraints on what states can result?  E.g. you know
where an 'object' was created, where the capabilities to it were
returned and communicated and you want to be able to make
statements about what can and cannot happen to the object?

>We both abuse terminology when we say 'increment an integer' but that
>is not germane to the current issue.

I certainly hope not!

--Jed http://www.webstart.com/jed/