OpenNMS: enterprise-grade network monitoring platform
OpenNMS [1] is an enterprise-grade network monitoring platform developed under the open source software model. It consists of a community-supported, open-source project as well as an organization offering commercial services, training and support.
The full featured monitoring solution is written in Java and is released under GNU Public License. I used to use Nagios, but OpenNMS seems to be a Nagios killer. At least it is worth taking a deep breath. Get an impression on your own and try out the demo (username:demo password:demo).
In the current stable release technology preview series 1.7.0, OpenNMS uses the Spring Framework (WP: Spring Framework) 2.5 and a RESTful Interface was added.
