Two disparate systems might agree to interact via XML formats. This means that whenever there is an outgoing communication, the system's data structure needs to be converted to XML; while in the case of incoming messages, it needs to be converted to a data structure understood by the system. How do we do this? Spring provides first-class support to deal with XML via its OXM (Object-to-XML) framework. Marshalling and unmarshalling is done by classes—org.springframework.oxm.Marshaller and org.springframework.oxm.Unmarshaller, respectively. Marshaller converts an Object to an XML stream, while unmarshaller converts an XML stream to Object. Spring's Object/XML Mapping support provides several implementations supporting marshalling and unmarshalling using JAXB, Castor, and JiBX among others. Spring Integration abstracts it further and provides many out-of-the-box components, which help to deal with the XML payload. A few of them are marshalling transformer, unmarshalling...