You can monitor all sorts of things through NSClient: https://docs.nsclient.org/manual/index.html
In XI we suggest NSClient .3.9, but it has a serious bug with PROCSTATE. Our fallback is .4.3, but it too has issues. I generally suggest people use one of those two, or use .4.4 if they need PROCSTATE and .4.3 isn't working for them. .5 is much more advanced, but we have not done extensive testing with it.
Also, just so it's clear going forward, are you actually looking to develop a plugin? You posted in the development section. If you are looking to develop, you should look at http://nagios-plugins.org/doc/guidelines.html