Let’s capitalize on the Yun Arduino new features to create an electronic “guard dog", which allows you to watch your stuff, a hidden corner of the backyard or our car silently laying in the garden. Here we wanted to face a small project, but one you would not be able to do with old Arduino boards. Connect a webcam, being able to display images on a web browser and activate actions if "something" or "someone" moves into the field that we want to hold on check. After an event trigger we could be alerted by Twitter, reusing the example proposed, or by e-mail, or even with the lightening of a notification LED. As previously said on this blog, Arduino YUN forces you to pay attention to the software architecture and the general design that you want to accomplish. Especially to breaking the app into modules and defining the interaction and communication between them is key. The application is based on an existing infrastructure, consisting of the operating system [...]