Thanks for the response. I do have control of the code for both applications. The perl code is not sleeping forever - it is a full application.

I'm happy to continue to pass the actual information through a file. What I want to do is simply notify the Perl app that new data is in the file, and then the Perl app would read the file as it normally does. The goal is to reduce that potential 200ms latency by an order of magnitude.

I was hoping there might be some simplier method then setting up socket communication just to generate an interrupt :-) but if you think thats the best fit for what I'm doing I'll look into it.

Thanks!