Invalid SID error with large number of processes

[ismir.kamili]

I previously purchased the DBExpress driver for ORACLE from CoreLab.
I develop a CGI application using Delphi 7 that connects to ORACLE through DBExpress. The application works fine when small amount of users accessed it. But when more users accessed the application (there could be about 200 instances of the CGI process at the same time), the application failed to connect to the ORACLE and got the message 'Invalid SID'.

Is the problem caused by the ORACLE itself or from the connection library or even from the weakness of the DBExpress architecture ? For your information, my ORACLE has been fully licensed. Any suggestion for the problem ? Or may be I should buy another license from CoreLab / Devart for such application ?

Regards

[Plash]

Please specify whether you are using the driver in the Direct mode (without OCI).

If so, try to use the driver in the OCI mode. This mode can be more stable.

[ismir.kamili]

I don't really understand how to put the driver in OCI mode or direct mode. Could you please give me the information ? Is it done by setting the parameters property ? Which is the default mode, OCI or direct ? I think I'm using the default mode (cause I did not make any settings related to it)

[Plash]

This can be done by selecting an approprite driver: Oracle (Core Lab) or Oracle Direct (Core Lab).