[tech2]

Maybe? I guess the difference is that with a capability object model (or similar arrangement) the _only_ way the application has to interact with the outside world is via those objects/handles it's been granted. There's no risk of escape because they only have access to the handles the process has been provided.

It's almost the opposite of a permission model in some ways, permission models restrict access to a global array of functionality where capability models allow access only to what's been provided.

[rbanffy]

Sorry. I was joking. It feels like you are giving applications small fragments of the user.

[tech2]

Sorry, I appreciate the joke (really :) ) but I also worry that people keep trying to add the concept of "users" or an existing role or permissions model into capability-based systems when they're unnecessary.

You could maybe model or emulate a user in a capability system by providing the login's session manager an object with read/write access to the configured "user" directory, read and execute access to an applications collection, and full access to the root window. From there, when the user starts a new application it's given an object with access to a window created for it (by calling "createWindow" on the root window object, so it can't even do something like enumerate other windows or whatever), and whichever other requirements were configured as part of its install.

It's capabilities all the way down with no "user" involved.