Nagios Plugin to check memory consumption

For some reason the Nagios package in Debian / Ubuntu does not provide a plugin to check the memory consumption so I built a simple script to do that. It ignores swap space (since if your machine starts swapping you’re lost anyway) and caches (it’s nice to have memory available for caches but this isn’t really required). That way only the real memory consumption is checked and if that passes a certain threshold you can rest assured that you’re in for trouble.


Iterating over nested objects in a Spring form

Spring 3 allows for wonderfully simply forms and automatic binding of form values back to the command object. However if your command object has further nested objects that you want to make editable from the form as well things get a little tricky. In that case you can’t just use a standard JSTL forEach loop as this will not allow you to build the path to the nested object correctly. The trick is to use the varStatus attribute to keep track of the index.


Unit Testing a Spring @Controller

Thanks to Spring’s new MVC Annotations (@Controller, @RequestMapping, @RequestParam etc.) unit testing a Spring controller is now easier than ever before. Still, I had a hard time figuring out how to do this since most of your controller methods will not take a ServletRequest as input. Instead they use a form-backing / command object, a BindingResult and maybe a ModelMap. In a web environment Spring takes care of filling the command object and validation results however in a unit test you will have to do this yourself.

Following is the basic outline for writing such a test.


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