The CHOReOS project aims to develop techniques for sustaining large-scale, decentralized service compositions over dynamic networks. It focuses on revisiting choreography-centric service-oriented architectures with an integrated development process. The project will create abstractions and models to reason about composition, interaction protocols, and choreography evolution at ultra-large scales. It will also develop a service-oriented middleware and governance/validation support to enable dynamic choreography-centric development and deployment of scalable and adaptable choreographies. The project is a 3-year European program with a consortium of 7 industrial and 8 academic partners working on representative use cases.