Web services describe a standardized way of integrating Web-based applications. In recent days, with the advancement of cloud computing, web services play pivoting roles towards meeting complex business objectives on a large scale. However, engineering dynamic web services is a complex task as they can be added, modified and deleted on the fly and even without any prior notification. Executing a large scale business process using dynamic web services is very challenging. This paper proposes an execution machine, called Web Service Dynamic Execution Machine (WSDE machine), which works in the execution layer of the three layered architecture for web service dynamics [23]. The proposed machine is capable of executing business processes having both deterministic and non-deterministic flows, where the related web services are represented using a graph-based semantic based formal model. The generic nature of the WSDE machine is useful in improving performance, scalability and maintainability of large scale web service based information systems. In this paper, the proposed WSDE machine is also illustrated with a suitable case study.