new application benchmark

hi, Guys:

  We have just built a customer ordering application which use oracle as backend DB system, our goal is allow 1000 concurrent connections and transactions, here are the questions, I want ask your experts:

1. how can we do the simulatation and benchmark for 1000 concurrent connections? is there any tools we can use?
2. How can we tell the current hardware can handle the 1000 concurrent connections? if it cann't then what we need more?

                                                    Thanks.