Time travel and Logging

[Jon A. Lambert]

On 27 Dec 97 at 15:48, Ola Fosheim Gr=B0stad wrote:
> coder at ibm.net wrote:
> >>Ola wrote:
> >  As mentioned earlier I log everything.  Be careful of that word "log"=
. 
> >This does not mean that I create text files which record past doings, b=
ut
> >that I log DB activity amd the event sequences such that any prior poin=
t
> >in time for that BD can be created __exactly__ as it was then, with the
> >addition that that point in time can be rolled forward thru time such t=
hat
> >__exactly__ the same things as ahppened back then, now happen again.
> 
> (From a norwegian legal POV "access" and "neccessity" are the
> keywords, the nature of the storage doesn't matter.)
>

I think what JCL is describing is just that, database logging.  
Many RDBs and ODBs perform logging.  I'm quite certain it's legal in most
countries to run a communications server off of DB2 or Oracle.

In some mud implementations it may be certainly necessary to log 
conversation. For instance conversation may cause state changes in mud 
objects (NPC reactions, auditory events to open doors, activation of 
equipment, etc.).

> >From a CS POV logging is a fascinating principle, because, as you
> mention, it preserves the timeline.  I made a prototype environment
> for case handling a while back that used this for determining whether a
> case had followed the rules or not.  The system also provided a set of
> legal actions which were determined by parsing the history (log) of the
> case.  (Used extended RE.)
> 
> Are you doing this in your system?
>

I would doubt his logs are human readable, no?   The interesting potential
side-effect of backwards time travel does pose some technical problems.
For instance, the observing object originally took no part in the 
original events.  The replay mechanism would have to account for this
and add the observing object to all the local event chains.  I wonder how
or whether perception of the character would be translated into the
viewing object.  For instance, would a character notice a hidden/invisible=
 
character that he hadn't noticed when he passed through a location
a few days earlier?  Or would he, by observing as a third party, generate =
a 
new chance to detect this or see it automatically?  I would also assume
that the replay engine(s) would be a separate state machine of it's
own separate from the 'real' mud and that time travel events wouldn't
be logged. 

> >  Want to see exactly what happened on Main St yesterday at 16:03?  Jus=
t
> >go to that location on Main St, walk back thru time to 16:05, and then
> >resume normal time flow.  You'll see everything that happened there,
> >exactly as it happened, exactly as if you had been standing there at th=
e
> >time (except that you won't be affected by anything).
> 
> Ok, but on what level is this observation done?
> 
> I split concepts into at least 3 levels:
> 
> - World level 
> - Room level ("field of view" if the system doesn't involve rooms)
> - Avatar level
> 
> For instance, is it possible to observe actions that take place on the
> avatar level? ("you feel hungry" etc)
 
That's interesting.  I would guess that events that are "internalized" 
or avatar events would not be observable by a third party time traveller. =
 
Whose avatar events would they be observing in any event?  I suppose
'tell' (the traditional implementation) as well as person to person
telepathy would also be unobservable to the typical time traveler.

--
Jon A. Lambert
"Everything that deceives may be said to enchant" - Plato