Ambient systems are populated by autonomous devices interconnected to one another that supply a variety of functionality that is eventually used by the users. One of the biggest challenges in this research area is to establish automatic mechanisms to compose, in a dynamic way, services on demand. The objective of the composition is to satisfy user needs combining the existing services, when there is not a service in the environment that can perform it. The aim of this research work is, firstly, to have a look at and analyze the state of the art regarding service composition in ubiquitous environments and, secondly, to propose a set of properties and characteristics that can be applied to this type of systems to allow their classification and ultimately their scientific comparison.