Hi,
I think that's the way to go too. Data handled by a database system (wich
MI is not), and geometric objects and functions in a GIS (wich ACCESS -by
example- is not).
BTW I sent a prototype of ACCESS to MI linker that'll do just that, to
people on this list, to write down a documentation (I haven't got the time,
and it'd be better written by a native english speaker ...), it should be
put on the FTP site in a few weeks.
Anyhow, this way of working with data makes me feel like 'I want more', and
it's tempting to fill out some gaps I found in MI. It's easy to store point
data, to rebuild a point map 'on the fly'. I've done it with polylines too,
to allow an intelligent drawing at different scales (to produce easier to
read maps), or to produce schematics maps (I've done this for bus lines :
no need to draw all stops in a town when you're looking at inter regional
travel ...).
Now I'd like to store z data as well (for points/lines/polylines and
regions), but I feel like reinvinting the wheel, and more and more like
stepping on MI -should be- work ...
Any advice, anyone done this ?
Eric Maranne
EMI Informatiques
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+4 42 80 06 22 22 GMT +1
[EMAIL PROTECTED]
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GIS MapInfo - VRML Integration
-----Message d'origine-----
De: Exa-Min [SMTP:[EMAIL PROTECTED]]
Date: mardi 7 septembre 1999 12:08
A: [EMAIL PROTECTED]
Cc: [EMAIL PROTECTED]
Objet: RE: MI How to handle multi-user in Mapbasic apps?
I think Chris summed it up but there are some work arounds .....
MapInfo holds a copy of each table in local memory, so it is better suited
to handling multi-user concurrency at the table level than on the record
level (which would better suite your requirement). Spatialware relies on
ORACLE and the Spatialware toplogy manager to resolve concurrency issues at
save time.
As most of our multi-user problems relate to attribute data, we step around
the issue by maintaining the reference data in a database (eg
Access/ORACLE) and editing attributes through database forms. We avoid
directly opening an Access database in MapInfo in favour of ODBC. As long
as you hold the database ID in MapInfo you can do two way hot-linking
between MapInfo and the database forms. Even humble MS Access handle the
concurrency issues quite well.
For point data we regard the database copy as the primary copy. You can use
ODBC linked tables and the MapInfo "create points" function to build a
temporary tab file for each user. That lets your handle the concurrency in
the MapBasic app - and decide whether to update the x/y in the primary
database record where a user edits the location of a point or creates a new
point.
MapInfo handles multiple readers quite well but multi user editing of the
geometry component for polylines and regions can be a challenge - and might
still be a challenge even if MapInfo did record level locking, given
implicit relationship between adjacent graphical elements.
... Ken Moule
>Chris Perry wrote....
>
>I think you will probably find that MapInfo is really going to leave the
>multi-user stuff to other software and then just use and ODBC or OCI link
to
>that system. The Oracle 8i Spatial and MapInfo Spatial Extender Cartridge
>(ie. SpatialWare) easily handles the multi-user stuff. Even an ODBC link
to
>an Access database for attribute data handles multi-user OK.
>
Davie wrote...
>From my perspective as a database geek, seems like the MI folk could use
some expensive consulting <grin> re: what is common practice among
multi-user applications. I appreciate that it would be "hard", especially
for the graphical (i.e., obj) parts of a layer, but it's important.
The multi-user issue is a big one for my firm, where we often have 3-4
engineers trying to work on maps, databases and hydraulic models during
project crunch times. We usually just make copies, and agree which one is
the "live" one. Too error prone for my taste, also it works only because
most people are just referencing the maps, not trying to update or add to
them by that point in the project.
Exa-Min Resource Industry Consultants
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PO Box 12020, Elizabeth Street Q 4002
AUSTRALIA
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