Recently, large-scale enterprise information systems are commonly based on the multi-tiered middleware or frameworks to support such requirements as functional reuse, heterogeneous system resources, and multiple platforms. However, these multi-tiered or distributed multi-platform architecture incurs the interoperability issue of the components and metadata among the middleware. This paper introduces the Simple Object Application Framework (SOAF) which supports heterogeneous resources and platform-independent component-based development, with the abstract programming style of the object-oriented frameworks and the XML-SOAP based component persistence mechanism.