Appendix B. Component and transformer annotations quick reference

As introduced in section 6.1.4, Mule offers Java code-level annotations that can be used on components, transformers, and other classes loaded by Mule. These annotations cover a whole range of functionality. Table B.1 provides you with a quick reference for these annotations.

Table B.1. Annotations reference

Annotation	Description	Type	Module
@ContainsTransformer-Methods	Signals that a class contains transformer methods.	Method	annotations
@Transformer	Used to create a Mule transformer from a class method.	Method	annotations
@Schedule	Schedules a method for execution using either a simple frequency or cron expression.	Method	quartz
@IntegrationBean	A dependency injector annotation used to inject an iBean such as Facebook or Amazon S3 into your component.	Field	ibeans
@MockIntegrationBean	Similar to the @IntegrationBean annotation, this one can be used in tests to create a mock instance of an iBean that’s good for testing the bean without actually making requests to the external service.	Field	ibeans
@Lookup	Dependency injection annotation used to retrieve objects from the registry.	Field, parameter	annotations
@Payload	A parameter injection annotation that can be used on component entry points and transformer methods defined using the @Transformer annotation, this annotation controls how the current message payload is passed into a method by performing automatic transformation of the message payload to match the annotated parameter type.	Parameter	annotations
@InboundHeaders	Used on component entry points and transformer methods, this annotation controls how the current message inbound headers are passed into a method. The annotation supports Map, List, single headers, and wildcards.	Parameter	annotations
@OutboundHeaders	Used on component entry points and transformer methods, this annotation controls how the current message outbound headers are passed into a method. Users can write to this Map to attach headers to the outgoing message.	Parameter	annotations
@InboundAttachments	Used on component entry points and transformer methods, this annotation controls how the current message inbound attachments are passed into a method. The annotation supports Map, List, single headers, and wildcards.	Parameter	annotations
@OutboundAttachments	Used on component entry points and transformer methods, this annotation controls how the current message outbound attachments are passed into a method. Users can write to this Map to attach attachments to the outgoing message.	Parameter	annotations
@Xpath	This annotation can be used to execute an XPath expression on the message payload with the result being passed into the method.	Parameter	xml
@Groovy	This annotation can be used to execute a Groovy expression on the message payload with the result being passed into the method.	Parameter	scripting
@Mule	A parameter injection annotation that can be used on component entry points and transformer methods, this annotation can be used to execute a Mule expression.	Parameter	annotations
@Function	A parameter injection annotation expression on the message payload with the result being passed into the method, this annotation exposes a common set of functions used in Mule such as a counter, UUID generator, date and timestamps, etc.	Parameter	annotations

Most annotations are provided in the mule-module-annotations module, but some come from other modules. Be sure to have the necessary modules on your classpath if you’re not deploying on Mule standalone.