This paper presents a thesis about a language and an execution model for the detection of situations aimed at reducing the complexity of active applications. This work has been motivated by the observation that in many cases, there is a gap between current tools that enable to react to a single event (following the ECA: Event – condition – action paradigm), and the reality, in which a single event may not require any reaction, however the reaction should be given to patterns over the event history. The concept of situation presented in this paper, extends the concept of composite event, in its expressive power, flexibility, and usability. This paper motivates the work, surveys other efforts in this are, and presents preliminary ideas for both the language and the execution model.