[cap-talk] Definition of "authority"? Got it right?

[Kevin Reid]

On Jan 22, 2008, at 10:44, Mark Miller wrote:
> On Jan 21, 2008 10:21 PM, Jed Donnelley <capability at webstart.com>  
> wrote:
>>  What bothers me about this definition set is that, at least for  
>> object capability systems, it seems to somewhat trivialize the  
>> notion of a "permission".  Permissions are always the same.  They  
>> only provide communication.
>
> In all ocap systems of which I'm aware, both language and OS, the  
> kernel does provide some object types primitively -- such as an  
> indexable read/write data container of some sort. E provides  
> FlexLists. The KeyKOS line provides segments and nodes.

This doesn't seem to fit to me.

In E, a FlexList (whether or not it is implemented primitively [1]),  
or any other possibly primitive object, is *used* via the same  
operation, the call ("communicate"), as every other object; at the  
level at which these would be considered different permissions, it  
would be equally reasonable to consider various types of user-defined  
objects different permissions.


[1] E-on-CL's FlexLists are E objects; however, they use a similarly  
primitive mutable array type internally.

-- 
Kevin Reid                            <http://homepage.mac.com/kpreid/>