Service-oriented architecture (SOA) is currently the predominant software integration framework. Web services provide the predominant platform for SOA. SOA as an integration architecture solution supports a range of application scenarios. We present a solution for the integration of business information systems based on SOA and Web services. We discuss maintainability requirements in relation to information-specific integration and architecture aspects. A template-based approach based on modular and declarative transformation rules and architectural styles and patterns defines our solution to the maintainability problem of integration architectures.