In this paper, we propose and develop MECA, a common middleware infrastructure for data collection from mobile devices in an efficient, exible, and scalable manner. It provides a high level abstraction of phenomenon such that applications can express diverse data needs in a declarative fashion. MECA coordinates the data collection and primitive processing activities, so that data can be shared among applications. It addresses the inefficiency issues in the current vertical integration approach. We showcase the benefits of MECA by means of a disaster management application. Copyright is held by the International World Wide Web Conference Committee (IW3C2).