著者: W B Hacker 日付: To: exim users 題目: Re: [exim] Defining "Virtual"
Jakob Hirsch wrote: > Quoting W B Hacker:
>
>> ... domain
> ...
>> ...servers, services, or whatever.
>> Where is the 'virtual'?
>
> Thinking of the historical meaning of a domain, where hosts in a network
> are something like host.section.example.net, a
> mail-/web-/$anyservice-server handling (*.)example.net (and probably
> other domains) does not really contain contain the whole domain. I'd say
> it's more like a proxy (with some added functionality) or a wrapper.
>>From the outside, you don't know (and shouldn't care) if
> some.host.example.org is real or ... virtual, yes.
That is still in the flawed (semantics) area.
> Virtual doesn't mean
> that it doesn't exist. It just means there's something, but it may be
> something else than it looks like.
That's a better one...
> The extra layer handling the
> virtuality makes its usage transparent.
> Think of virtual memory: You don't know which real memory location you
> are accessing, but you will surely access real memory (even if your data
> has to be swapped in before to the location).
>
ACK - but here again, there is 'real' memory of one of more speed/acess type
classes. Historically, tape and punched card storage 'near-line' or off-line
memory, and a hard drive is 'rotating' memory. None of it is a 'lie'.
The 'virtual memory' usage should probably have been called 'virtual core' when
it first appeared and we might not have gotten into this fuzzball.
;-)
But - as has been said - not much point in expecting anyone to change.
"Man invented language to satisfy his deep need to complain." - Anon