I am using Nagios for an energy efficiency project and workload balancing is a crucial aspect of the project. I am interested in how I can retrieve historical data from Nagios (e.g. CPU load for the past 10 minutes, memory usage for a process) and trends (e.g. CPU load increasing, decreasing). I am a beginner in regard to Nagios so any information about this subject would be helpful.
I am not interested in displaying the information in a graphical manner, I would like to use it in a custom application (Does Nagios have an interface -- web-service based or something else -- trough which to extract such data?).