constantUsersPerSec and reachRps and webservice


I am new to gatling and I want to use gatling to make a performance test of a java webservice.

I want to know if my java webservice can support 200 transactions per second during 30 minutes.

I see in the gatling documentation that there are two solutions constantUsersPerSec and reachRps.

Can you tell me if I must use constantUsersPerSec (with the value 200 during 30 minutes ) or reachRps (with the value 200 and holdFor(30 minute)) to stress my webservice ?

Thanks in advance,

Best Regards,