This paper reports on a new formal approach for the decentralized orchestration of service oriented processes. We focus on the dynamic binding (discovery and use) of services following a decentralized approach. We investigate synchronization issues of a process being executed on different computing entities. We propose formal techniques that insures the synchronization of distributed activities in the presence of decentralized and dynamic service bindings. Precisely, our contribution consists of two different techniques that prevent concurrent service bindings. The latter are characterized by additional operations implemented by orchestrated services.