Business process management systems play a central role in supporting the business operations of medium and large organizations. This paper analyses the properties current business enterprise systems and proposes a new application type called Open Business Enterprise System. A new open system architecture called Business Workflow System is proposed. This architecture combines the instruments for flexible data management, business process management and integration into a flexible system able to manage modern business operations. The architecture was validated by implementing it into the DocuMentor platform used by major companies in Romania and US. These implementations offered the necessary data to create and refine an enterprise integration methodology called DMCPI. The final section of the paper presents the concepts, stages and techniques employed by the methodology.