org.eclipse.microprofile.faulttolerance

Annotation Type Fallback

@Documented
 @Retention(value=RUNTIME)
 @Target(value=METHOD)
 @Inherited
 @InterceptorBinding
public @interface Fallback

The fallback annotation to define the fallback handler class so that a failure can be handled properly. The criteria are as follows:

1. If value is specified, use FallbackHandler.handle(ExecutionContext) on the specified handler to execute the fallback.
2. If fallbackMethod is specified, invoke the method specified by the fallbackMethod on the same class.
3. If both are specified, the FaultToleranceDefinitionException must be thrown.

When a method returns and the fallback policy is present, the following rules are applied:

1. If the method returns normally (doesn't throw), the result is simply returned.
2. Otherwise, if the thrown object is assignable to any value in the skipOn() parameter, the thrown object will be rethrown.
3. Otherwise, if the thrown object is assignable to any value in the applyOn() parameter, the fallback policy, detailed above, will be applied.
4. Otherwise the thrown object will be rethrown.

If a method throws a Throwable which is not an Error or Exception, non-portable behavior results.

Author:

Emily Jiang

See Also:

value(), fallbackMethod(), applyOn(), skipOn()

Optional Element Summary

Optional Elements

Modifier and Type	Optional Element and Description
Class<? extends Throwable>[]	applyOn The list of exception types which should trigger Fallback
String	fallbackMethod Specify the method name to fallback to.
Class<? extends Throwable>[]	skipOn The list of exception types which should not trigger Fallback
Class<? extends FallbackHandler<?>>	value Specify the fallback class to be used.

Element Detail

value

public abstract Class<? extends FallbackHandler<?>> value

Specify the fallback class to be used. A new instance of the fallback class is returned. The instance is unmanaged. The type parameter of the fallback class must be assignable to the return type of the annotated method. Otherwise, FaultToleranceDefinitionException occurs.

Returns:

the fallback class

Default:

org.eclipse.microprofile.faulttolerance.Fallback.DEFAULT.class

fallbackMethod

public abstract String fallbackMethod

Specify the method name to fallback to. This method belongs to the same class as the method to fallback. The method must have the exact same arguments as the method being annotated. The method return type must be assignable to the return type of the method the fallback is for. Otherwise, FaultToleranceDefinitionException must be thrown.

Returns:

the local method to fallback to

Default:

""

applyOn

public abstract Class<? extends Throwable>[] applyOn

The list of exception types which should trigger Fallback

Note that if a method throws a Throwable which is not an Error or Exception, non-portable behavior results.

Returns:

the exception types which should trigger Fallback

Default:

java.lang.Throwable.class

skipOn

public abstract Class<? extends Throwable>[] skipOn

The list of exception types which should not trigger Fallback

This list takes priority over the types listed in applyOn()

Note that if a method throws a Throwable which is not an Error or Exception, non-portable behavior results.

Returns:

the exception types which should not trigger Fallback

Default:

{}