Re: For the AdaOS folks

["Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>]

On Mon, 03 Jan 2005 11:36:34 -0500, Warren W. Gay VE3WWG wrote:

> Dmitry A. Kazakov wrote:
> 
>> On Sun, 02 Jan 2005 17:04:29 -0500, Warren W. Gay VE3WWG wrote:
>>>Dmitry A. Kazakov wrote:
>>>>On Sat, 01 Jan 2005 19:31:56 -0500, Warren W. Gay VE3WWG wrote:
>>>And how do your identify your GNAT object? At the end of the day,
>>>you still have to grapple with "names" and "identities". Only
>>>the details change.
>> 
>> The "detail" is that you identify not some GNAT installation file #1534,
>> but GNAT. GNAT itself is easy to find, 
> 
> Is it? What if you 2 or 3 versions of it?  There is an interesting
> situation now with windows as well, since you can have a cygwin
> version in addition to the usual gnat-3.15p type of release.

OK, these will be different objects. An application should probably be a
factory object of its versions. So you will ask GNAT factory: give me an
instance of GNAT with the parameters so and so.

>> its components are not. They may
>> vary from version to version. It is GNAT's responsibility to know them, not
>> of GNAT user.
> 
> If I want to install a binding, I need to know where GNAT has installed
> its bindings (like win32). The registry makes this a trivial thing to
> do (I know, because I have used it).

Nowhere. It is installed and available.

>>>So just how do you expect to identify what piece of software
>>>you want to know about, without using a name (or identity if
>>>you prefer)? OO doesn't do away with this requirement.
>> 
>> ADT allows to organize it in a proper way. We are using types to forget
>> about bytes. In OSes we are still using "bytes" = files.
> 
> You haven't answered how you are going to identify your
> object. This doesn't explain it away.

The same way you identify objects in your program:

declare
   GNAT_Installation : Application_Type'Class :=
      Get (Local_Machine, "GNAT");
begin
   ...

>> It is a
>> key in some associative array. To "dereference" it you have to switch to
>> supervisor mode. Then you have to check it, because somebody could mess
>> with its value etc. It is very inefficient. You have to do all this even if
>> you call a function of a protected object, which could be safely performed
>> in user-mode. BTW, the very notion of user-mode is also of old procedural
>> fashion. A protected object is passive. You should be able to access it in
>> any "mode". But when you want to queue to its entry or to call its
>> procedure, only then you have to switch the context to make the object data
>> available to write. It is not kernel business anymore.
> 
> But if you were to replace the file descriptor with an object that
> implements the equivalent of a v-node, you wouldn't be able to do
> this in "user mode".

Your application may have read-only mapping to the public parts of the
descriptor.

>> Your RPC services is another model. They are monitors. These can be exposed
>> in API as tasks to have rendezvous with. 
> 
> Or they could be simple procedure/function calls in Ada. It is merely
> a point of presentation.

You cannot make a conditional or timed call to a procedure. You cannot
requeue to a procedure. Why not to use the advantages Ada gives?

>> Again OO/ADT could bring great
>> advantages here. Imagine extensible tasks. Presently, if you have some
>> sequence of actions to be performed on one service, you have to care about
>> locking, serializing, then you implement it as separate inefficient RPCs to
>> the server. Service extensions would be sort of stored procedures in DB
>> terms.
> 
> Again, you can package it any way you like already. Just wrap it
> in the trimmings you want.

Turing completeness...

>> This new OS will not
>> become a breakthrough. It will be a stable decent OS, but who needs that?
> 
> Firewalls for one.

Huh, firewalls only exist because of that crippled, buggy, unsafe OSes!
 
>> See what happened with VMS? The only way to kill the Windows/UNIX monster
>> to offer something really revolutionary.
> 
> I am not on any quest for world domination, though I don't
> discourage others from trying to do so ;-)

Seriously, I do think that Windows/UNIX impact on history of humankind is
yet to estimate. But it is another story...

-- 
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de