Modern organizations need to understand and constantly improve their business processes (BPs) in order to make successful business decisions. This paper describes an integration model for building a Business Process Management Application (BPMA) and connecting the BPMA with legacy systems based on Service-Oriented Architecture (SOA). A BPMA is an application developed to support a BP performed by legacy application/s. A combination of multiple BPMAs provides support for multiple BPs and forms a BPM solution. The presented model is characterized by a simple co-dependence of the BPMA and the existing systems, minimal changes to the legacy applications and a maximal utilization of the existing functionalities. It enables the existing applications to function independently from the BPMA and simplifies the business data used in the BPMA. An extensive evaluation of the model was undertaken by experts from the BPM area. Its feasibility is demonstrated on a real-life business use case scenario.