File access from a .war

[M S]

Hi,

I have a web service that is supposed to generate prime numbers. I store the latest generated prime number in a file called prime.txt. So for example, if the program is run and generated 3, 3 will be stored in prime.txt and next time it will generate 5. If there is no prime.txt, the program will generate 1 and try to create prime.txt.

My problem is that my web service application does not seem to be able to read/write a file. Any ideas on how this should be done? Notice that the prime.txt must be able to saved for the duration of the web service's lifetime.

Regards