Persistence (was: Hello)
Aaron J Reichow
reic0024 at d.umn.edu
Fri Apr 25 18:19:28 UTC 2003
On Fri, 25 Apr 2003, Ned Konz wrote:
> On Friday 25 April 2003 08:25 am, I wrote:
> > > - What is the best way to save data, e.g. like the notes in a
> > > pda? In a collaborative setting? Is there any work on database
> > > connectivity?
> > The easiest way to save chunks of connected data is probably using
> > ImageSegments.
> Not necessarily (I'm just waking up). You can use the SmartRefStream
> perhaps a bit easier.
This is how the Faure PDA project saves its data. It will save
automatically when you quit Squeak, and load and install it when you start
the image again- with no need to save the image itself, meaning that the
image could be flashed on the PDA's ROM. This approach isn't neccesarily
the best, because it only saves when you quit. If the machine froze and
you had to reset, you'd lose all the changes you made in that session.
One could easily add a button for doing a save of the PDA data whenever
during the session, or at fixed intervals of time or new data, but writing
to a SmartRefStream is relatively slow and intrusive.
To make up for this, my PDA project, Dynapad, stores everything in an
object database. I am using Magma. Data is saved onto disk/RAM/Flash
cards as it is added, and losing power on the PDA randomly isn't a big
deal. Magma is how the notes taken on the PDA stored along with all other
data, including applications. The database is configured such that a
complete rebuild is possible in the case of a reboot. Magma performs
pretty well, even!
Aaron Reichow :: UMD ACM Pres :: http://www.d.umn.edu/~reic0024/
"the profit system follows the path of least resistance and following the path
of least resistance is what makes a river crooked." :: u. utah phillips
More information about the Squeak-dev