The aim of this chapter is to describe and optimize the specifications of signal processing systems, aimed at extracting in real time valuable information out of large-scale decentralized datasets. A first section will explain the motivations and stakes and describe key characteristics and challenges of stream mining applications. We then formalize an analytical framework which will be used to describe and optimize distributed stream mining knowledge extraction from large scale streams. In stream mining applications, classifiers are organized into a connected topology mapped onto a distributed infrastructure. We will study linear chains and optimise the ordering of the classifiers to increase accuracy of classification and minimise delay. We then present a decentralized decision framework for joint topology construction and local classifier configuration. In many cases, accuracy of classifiers are not known beforehand. In the last section, we look at how to learn online the classifiers characteristics without increasing computation overhead. Stream mining is an active field of research, at the crossing of various disciplines, including multimedia signal processing, distributed systems, machine learning etc. As such, we will indicate several areas for future research and development.