Package io.fluxcapacitor.javaclient.tracking.handling

Annotation Interface HandleMessage

@Documented @Retention(RUNTIME) @Target(ANNOTATION_TYPE) public @interface HandleMessage
Meta-annotation used to declare that an annotation marks a method as a message handler for a specific MessageType.

This annotation is not applied to handler methods directly, but is used as a meta-annotation on other handler annotations such as HandleEvent, HandleCommand, or HandleQuery. It defines the message semantics and optional constraints on the payload types that can be handled.

The value() element specifies the MessageType this handler annotation corresponds to (e.g., EVENT, COMMAND, QUERY).

The allowedClasses() element can be used to restrict which payload types are valid for handler methods annotated with the derived annotation. This is particularly useful when a single handler method is intended to handle multiple related message types (e.g., a common base class or interface).

See Also:

  • Required Element Summary

    Required Elements
    Modifier and Type
    Required Element
    Description
    MessageType
    value
    The type of message this handler annotation is intended to process.

  • Optional Element Summary

    Optional Elements
    Modifier and Type
    Optional Element
    Description
    Class<?>[]
    allowedClasses
    Optional list of payload types that are allowed for handler methods using this annotation.

  • Element Details

    • value

      MessageType value
      The type of message this handler annotation is intended to process. This determines how the framework routes and dispatches the message to handlers.
      Returns:
      the message type (e.g., EVENT, COMMAND, QUERY)

    • allowedClasses

      Class<?>[] allowedClasses
      Optional list of payload types that are allowed for handler methods using this annotation.

      If empty (default), any payload type is accepted. If one or more classes are specified, the handler method will only be considered for messages whose payload type is assignable to one of the specified classes.

      Note that handler methods may still filter the payload type of messages they handle using their method parameters. This allows fine-grained control even when allowedClasses is left broad or empty.

      Returns:
      array of permitted payload classes for the handler. If empty, any payload type is accepted.
      Default:
      {}