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ColdFusion, Random Numbers, and Time

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ColdFusion, Random Numbers, and Time

· Java Zone
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A while ago I logged a bug I had discovered with ColdFusion REST services. I had created a simple REST service that returned a random number between one and one hundred. Nothing too complex, right? But then I noticed something odd. If I called the REST service with a cfhttp call twice, I got the same number back. I had discovered - I thought - a serious caching issue with REST services. Turns out I was wrong.

If you read the comments for the bug, you will see one in particular that stands out:

I assume this is one of the engineers, although I don't know. It makes sense - kinda - but I certainly didn't know this and I'm willing to bet most folks aren't aware of this either. As a long time computer programmer, I have a vague idea of the intricacies of random number generation. Apparently it involves quantum states, time travel, and zombie kittens.

The person helping out on the comment thread suggested using IBMSecureRandom as an algorithm for the randRange, but according to the docs this is only supported on WebSphere. I used SHA1PRNG and it worked immediately.

 

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