A business process displays complexity as a result of multiple interactions of its internal components and interaction between the process and its environment. To manage complexity and foster flexibility of business process management (BPM), we present the DCAR architecture for developing complex BPM systems, which includes decomposition of complex processes (D); coordination of interactive activities (C); awareness of dynamic environments (A); and resource selection and coordination (R). On the other hand, computing technologies, such as object-oriented programming, component-based development, agent-oriented computing, and service-oriented architecture have been applied in modeling and developing complex systems. However, there is considerable ambiguity involved in differentiating between these overlapping technologies and their use in developing BPM systems. No explicit linkage has been established between the requirement of complex BPM and the supporting technologies. In this study, we use the DCAR architecture as the foundation to identify the BPM requirements for employing technologies in developing BPM systems. Based on an examination of the both sides (BPM requirements and supporting technologies), we present a clear picture of business process complexity with a systemic approach for developing complex BPM systems by using appropriate computing technologies.