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Re: Objects, processes, and encapsulation


>How can they argue that "encapsulation is still vulnerable to client
>requests"?  There's no way a client can impact the (encapsulated) state
>of a server - the client has to get the server to do that.  If the server
>refuses to listen to the client, there's nothing the client can do about
>it!  Process state is invulnerable - only the process itself can change it.
>If my server (process) always guarantees service to clients (e.g. it fair
>ALTs or FIFOs them), then it never refuses requests - but, in that case,
>I have deliberately programmed such "vulnerability" (a strange word for
>this context).  It's still in full control of its response though - not
>the client!
All that I meant was that these guys might claim that, in order to 
provide services, you still have to respond to a request by executing a 
procedure (which might be just one line, removing any purpose to capsule) 
with access to local state. (Don't shoot me, I'm just trying to play 
devil's advocate.) And that the _all-important_ difference is that you 
can decide if/when/how you respond next time.

>>> Better go read Meyer's book I suppose ...
>> Once read, it remains useful for standing on to reach high places.
>I don't like heights.
Door jam, barricade, prop, ...


Dr. Ian Robert East

Room T2.10, Turing Building                      0 (44) 1865 484529
School of Computing and Mathematical Sciences
Oxford Brookes University
Wheatley Campus
Oxford OX33 1HX                                ireast@xxxxxxxxxxxxx

2001/2 Term 1 Consultation hours:
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