simulation set up

Hi Gatling Experts

With the sample of the simulation following we inject one user at once :

class BasicSimulation extends Simulation {

val httpConf = http
.baseURL(“http://computer-database.gatling.io”)
.userAgentHeader(“Mozilla/5.0 (Windows NT 5.1; rv:31.0) Gecko/20100101 Firefox/31.0”)

val scn = scenario(“BasicSimulation”)
.exec(http(“request_1”)
.get("/"))
.pause(5)

setUp(scn.inject(atOnceUsers(1))).protocols(httpConf)
}

But if I want to inject 20 users with a rate of 1 users every 3 seconds and hold this load for 10 minutes and with the same scenario I want to add 30 users with a rate of 1 users every 3 seconds (therefore we have a total of 50 users) and hold this load for 10 minutes.

How can I write that simulation setup ?

Thanks a lot

Viet Minh