[GRASS5] web grass

John Preston jpreston at uwimona.edu.jm
Thu Jun 7 14:39:32 EDT 2001


Hi all,
Just to add my 2 cents worth.

Glynn Clements wrote concerning what Joan M Friedman wrote:

> One piece of advice: a web interface will need to take great care to
> validate all user-supplied input before passing it to GRASS.
> Otherwise, the end result would be highly vulnerable to malicious use.

I have written a web-based interface to GRASS that allows users to perform
predefined GIS application tasks. The user is interacting with a GIS
application
so the mapsets, and other data are selected for different users and they only

see what they need to for the particular application.

> However, there are potential issues with concurrent execution. A
> number of commands use "static" data stored within the "mapset", e.g.
> the current region. You would either have to have a pool of user ids (each
> with their own
> mapset), or you would have to serialize operations so that no two
> requests can operate concurrently.

My implimentation allocates preloaded monitors to logged in users and handles

their deallocation after users are finished with them. All the users session
data
are stored independantly so that concurrent operations are possible.

> Hopefully these kinds of problems will be eliminated in future
> releases (e.g. they currently prevent a user from running multiple
> sessions concurrently). However, they won't be fixed for the 5.0.0
> release, which is currently the main priority.

The system as put together runs as an addon to 4.3. While it has some
limitations
(and a few bugs) and uses a patch for d.mon,
I think it shows that a web interface to GRASS
is a nice tool to allow GRASS to be used by non-technical users
(who are probably the majority). The web address
for my test system called SIVS (Spatial Information Viewing System)
is
    "http://196.3.4.220:8000/jdb/icens.sivs?class=gis"
and you can login using username "guest" and password "icens".





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