Abstract: The paper presents ”Any Input XML Output” (AIXO), a general and flexible software architecture for wrappers. The architecture has been designed to present data sources as collections of XML documents. The use of XSLT as extraction language permits extensive reuse of standards, tools and knowledge. A prototype developed in Java has been effectively proven in several case studies. The tool has also been successfully integrated as a wrapper service into BioAgent, a mobile agent middleware specialized for use in the molecular biology domain.