9.3. Message Composition
9.3.1. Message Composers
A MessageComposer composes or decomposes a native binding message to or from SwitchYard's canonical message. It does so in three steps:
- Construct a new target message instance.
- Copy the content of the message.
- Delegate the header/property mapping to a ContextMapper.
A SOAPMessageComposer and CamelMessageComposer are included with SwitchYard. These implementations are used by their associated bindings but you can override these with your own implementations.
9.3.2. Create a Custom Message Composer
Procedure 9.2. Create a Custom Message Composer
- Implement the
org.switchyard.component.common.composer.MessageComposerinterface:public interface MessageComposer<T> { ContextMapper<T> getContextMapper(); MessageComposer<T> setContextMapper(ContextMapper<T> contextMapper); Message compose(T source, Exchange exchange, boolean create) throws Exception; public T decompose(Exchange exchange, T target) throws Exception; } - Specify your implementation in your
switchyard.xmlfile:<binding.xyz ...> <messageComposer class="com.example.MyMessageComposer"/> </binding.xyz>
9.3.3. Custom Message Composer Properties
- The
getContextMapper()andsetContextMapper()methods are bean properties. If you extend BaseMessageComposer, both properties are implemented for you. - Your
compose()method needs to take the data from the passed-in source native message and compose a SwitchYard Message based on the specified Exchange. The create parameter determines whether or not we ask the Exchange to create a new Message, or use the existing one. - Your
decompose()method needs to take the data from the SwitchYard Message in the specified Exchange and "decompose it" into the target native message.
