[MUD-Dev] Persistant storage.... My current idea.

J C Lawrence claw at under.engr.sgi.com
Tue Apr 7 09:56:36 New Zealand Standard Time 1998

On Fri, 3 Apr 1998 17:41:06 PST8PDT 
Ben Greear<greear at cyberhighway.net> wrote:

> On Fri, 3 Apr 1998, J C Lawrence wrote:

>> Really?  Does this mean that objects migrate between servers?
>> Think this thru:

> Yes, objects will migrate, probably through a 'gate' or some other
> transport mechanism.  The servers will do handoff of IO as smoothly
> as possible....

>> Object A is defined on Server X.
>> A inherits from objects Q, R, S, and T, also defined on X.
>> You now move A to server Y.
>> Do Q, R, S and T, __and__ all their other children follow?
>> What about all the objects that remain on X that inherit from those
>> objects too?

> Ummm, not sure I understand this.  It makes no sense to me.  My idea
> is thus: You have a space ship, with cargo, and various objects on
> board.  You go through a 'gate' to another server (solar system).
> Every object within the ship leaves the previous one and joins the
> latter.  The java classes of course do not move, and in fact are
> found on ever server.

You are going to require that the class heirarchy on all servers match 
perfectly?  If you don't then you have the problem of an object
attempting to move to a server which may not have an indentical
supporting class heirarchy.

This also makes the possibility of free user programming more
difficult.  How are you going to maintain synchronisation of class
heirarchies across servers as new classes are created or old classes
are maintained?  

Are you preapared to require that all descendants of a class must be
compliant with the latest version of that class, or are you going to
have some sort of class versioning where instances are bound to a
particular version of a defined class?

Re-read the above in the light of different servers not having
identical class heirarchies -- it should make sense.  

Note: It is possible to move or replicate class heirarchies between
servers, its just not trivial.
>> Do you merely make copies of A, Q, R, S, and T, on Y, and leave the
>> originals on X?

> No copies, in this world there is only one of everything (as in RL).

Yet there may be multiple instances of a given class no?

>> ADSL has not quite reached my part of the SF Bay area (its close),
>> but that's $180 for 384Kbps symmetrical (it varies slightly
>> depending on who you pick for your CLEC: PacBell, Covad, or
>> NorthPoint).  IDSL (which I'd be more likely to go for), has yet to
>> establish a firm pricing model here alas.

> Here in phoenix: around $40 a month for a cable modem, around 1 Mbps
> average it seems..both ways!

Note that all cable modems are not equal.  Some use the cable fdor
down trafic only, with a standard asynch modem for the up-traffic.
Others are bidirectional on the cable, but are also massively
asymetrical (I've seen as high as a 20:1 ratio between in and out
bandwidth).  Lastly, for the bidirectional modems, in almost all cases
you share your bandwidth with the other subscribers on the local loop,
and some cable companies have been known to be stupid enough to use a
/16 subnet...

Cable modems are not necessarily that great.  Check your local
providers implementation.

J C Lawrence                               Internet: claw at null.net
(Contractor)                               Internet: coder at ibm.net
---------(*)                     Internet: claw at under.engr.sgi.com
...Honourary Member of Clan McFud -- Teamer's Avenging Monolith...

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