This paper introduces an integrated modeling approach that has been used to design and implement the ColNet platform. ColNet is the result of creating an integrated system, supporting distributed business processes design and execution in a Collaborative Network (CN) belonging to an Open Ecosystem (VBE). The work has been carried out as a part of the FP7 REMPLANET European Project, which aims at providing methods and tools for better decision-making in non-hierarchical collaborative networks. The functional alignment of Open Service Ecosystems, Collaborative Networks and Services Entities lifecycles is adopted as main functional requirements for the platform design and implementation while, at the same time, they raise an integrated modeling need. Both constitute the underlying approach followed when designing and implementing ColNet and are briefly described here.