Increasingly, organisations are using a Service-Oriented Architecture (SOA) as an approach to Enterprise Application Integration (EAI), which is required for the automation of business processes. This paper presents an architecture development process which guides the transition from business models to a service-based software architecture. The process is supported by business reference models and patterns. Firstly, the business process models are enhanced with domain model elements, application architecture elements and business-level patterns. Afterwards, business reference models and patterns are exploited for identification of software services and their dependencies. The subsequent activities are focused on the transformation of the enhanced business processes toward a service-based architecture that solves the application integration problem.