Transformation represents a change to the format or representation of a message's content. The representation of a message is the Java contract used to access the underlying content. For example, java.lang.String and org.example.MyFancyObject. The format of a message refers to the actual structure of the data itself. Examples of data formats include XML, JSON, CSV, and EDI. Here is an example of message content in XML format:

<MyBook>
  <Chapter1>
  <Chapter2>
</MyBook>

You can also represent XML in Java as a String. For example:

String content = "<MyBook>...";

Transformation plays an important role in connecting service consumers and providers, as the format and representation of message content can be quite different between the two. For example, a SOAP gateway binding is likely use a different representation and format for messages than a service offered by a Java Bean. In order to route services from the SOAP gateway to the Bean providing the service, the format and representation of the SOAP message needs to change. Implementing the transformation logic directly in the consumer or provider pollutes the service logic and can lead to tight coupling. SwitchYard allows you to declare the transformation logic outside the service logic and inject into the mediation layer at runtime.