reference another stack

Rob Cozens rcozens at pon.net
Sun Jan 12 11:07:01 EST 2003


>  >What kind of  strategy could one use to insure that any changes
>>made to the stack appear on the server, even if someone else is
>  >using the stack at the same moment?
>
>[snip]
>I don't think there's a good way to create an ideal solution for this,
>though - you'd need to handle all the usual problems of a database system
>(what to do about collisions where two people are trying to save at the
>same time; how to deal with the situation where someone's made changes to
>their copy since the previous save-and-reload).

Howard, Jeanne, et al:

If Howard needs what he specified--a way for multiple users to update 
the SAME stack "simultaneously"--I can't help.

However if the EFFECT of multiple updates to the same stack will do, 
it should be possible using two stacks and IPC (eg: Apple Events, 
Process commands).

* Create two stacks: one to hold the data and one to display it.
* Script IPC handlers in the display stack to request data from the data stack.
* Script IPC handlers in the data stack to process IPC requests from 
display stacks and send them the requested data.
* Run the data stack as a network server ONLY, with each user running 
the display stack.

Note that in this scenario Jeanne's concerns are moot:  Though it 
appears several users are "simultaneously" updating the data stack, 
in actuality the data stack is only updated by the server app 
processing each user's request(s) in the order it was received; so 
there can be no collision and individual users CANNOT actually change 
the data directly...only by requesting changes of the server app. 
About the only thing else needed for true multi-user support is a 
mechanism for user locking/unlocking of records.

Anyone interested in working on an open-source IPC project for 
Revolution should contact group leader, Jan Schenkel 
<janschenkel at yahoo.com>.
-- 

Rob Cozens
CCW, Serendipity Software Company
http://www.oenolog.com/who.htm

"And I, which was two fooles, do so grow three;
Who are a little wise, the best fooles bee."

from "The Triple Foole" by John Donne (1572-1631)



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