Message Transformers play a very important role in enabling the loose-coupling of Message Producers and Message Consumers. Rather than requiring every Message-producing component to know what type is expected by the next consumer, Transformers can be added between those components. Generic transformers, such as one that converts a String to an XML Document, are also highly reusable.

For some systems, it may be best to provide a Canonical Data Model, but Spring Integration's general philosophy is not to require any particular format. Rather, for maximum flexibility, Spring Integration aims to provide the simplest possible model for extension. As with the other endpoint types, the use of declarative configuration in XML and/or Annotations enables simple POJOs to be adapted for the role of Message Transformers. These configuration options will be described below.

	Note
	For the same reason of maximizing flexibility, Spring does not require XML-based Message payloads. Nevertheless, the framework does provide some convenient Transformers for dealing with XML-based payloads if that is indeed the right choice for your application. For more information on those transformers, see Chapter 26, Dealing with XML Payloads.