Subject Re: [IBO] limiting concurrent users
Author Geoff Worboys
> As I am about to deliver a nice little software running
> over interbase, I am now in the situation where I have
> to limit the number of concurrent users logged into some
> tables (but not all the tables).

Users do not "logon" to individual tables - databases yes, but not

I think the best you can hope to achieve is to build something into
your client application that logs access details when a form is
openned, and clears when a form is closed. Of course this will mean
problems when the application aborts or the connection fails for some
reason - since the logged access information will not be cleared.
Perhaps the client app will need to do some sort of "keep alive"
processing so that old access details can be cleared when no updates
have been received for a period of time.

Of course you also have the difficulty that IB does not know (or care)
about what client application is used to access the data. So people
can avoid the restrictions by using some other application to access
the data. I implement a basic form of client application restriction
by hashing the users passwords - so that the password they login with
is not the same as that received by IB, the user never knows what
their real password is. (This is not perfect since it relies on the
users not knowing what the hashing algorithm is.)

Without better support at the server there is not much more that you
can do.

Geoff Worboys
Telesis Computing