[cap-talk] Capability-based Projects - theory vs. practice

[Mark Miller]

On 8/3/07, Jed Donnelley <capability at webstart.com> wrote:
> I was hoping you'd challenge the lack of persistence (better term
> than durability I guess?) for E MarkM.  That allows me to ask
> (or try to ask) what persistence means in the language context.

> For the language context (e.g. E) is there a similar
> notion?  Maybe this question isn't well enough formed
> to be answered, but please give it a try if you understand
> what I am getting at.  Can you show me, for example, how
> actions in E can result in shared access of an object
> between two "users" that persists after a system restart?

Hi Jed, I'm going to give you a long reading list.

Chapter 17 of my thesis, especially section 17.4.

My rough draft on Data-E serialization at
<http://erights.org/data/serial/jhu-paper/>.

In the E source distribution, the file
src/esrc/scripts/persist-echat.e does exactly what you ask for above.

Reading this example first is currently the best way to understand E's
persistence API, called the timeMachine, whose source is in
src/esrc/org/erights/e/extern/persist/makeTimeMachineAuthor.emaker.
The API is messy, but at least it is somewhat documented.


> Is something required at the OS level to make such
> persistent object sharing work?

The file system must usually survive restarts ;).

-- 
Text by me above is hereby placed in the public domain

    Cheers,
    --MarkM