In recent years, service-oriented systems are becoming increasingly complex, with growing size and heterogeneity. Developing and deploying such large-scale systems present several challenges, such as reliability, reproducibility, handling failures on infrastructure, scaling deployment time as composition size grows, coordinating deployment among multiple organizations, dependency management, and supporting requirements of adaptable systems. However, many organizations still rely on manual deployment processes, which imposes difficulties in overcoming such challenges. In this paper, we propose a flexible and extensible middleware solution that addresses the challenges present in the large-scale deployment of service compositions. The CHOReOS Enactment Engine is a robust middleware infrastructure to automate the deployment of large-scale service compositions. We describe the middleware architecture and implementation and then present experimental results demonstrating the feasibility of our approach.