: This paper summarizes how an algebra for mobile systems, the -calculus, can be applied as unified formal foundation to service oriented architectures (SOA). The concepts accounted are orchestrations including data and processes, as well as choreographies consisting of interacting processes. Since SOAs incorporate agile binding of interaction partners, static process structures as found in Petri nets are not sufficient for completely representing orchestrations and choreographies. The -calculus, in contrast, inherently supports link passing mobility required for agile interacting processes.