org.apache.nifi.processor

Interface SchedulingContext

All Superinterfaces:

ProcessContext

public interface SchedulingContext
extends ProcessContext

Method Summary

Methods

Modifier and Type	Method and Description
void	leaseControllerService(String identifier) Indicates to the framework that the Controller Service with the given identifier will be used by this Processor.

Methods inherited from interface org.apache.nifi.processor.ProcessContext

decrypt, encrypt, getAnnotationData, getAvailableRelationships, getControllerServiceLookup, getMaxConcurrentTasks, getProperties, getProperty, getProperty, newPropertyValue, yield

Method Detail

leaseControllerService

void leaseControllerService(String identifier)

Indicates to the framework that the Controller Service with the given identifier will be used by this Processor. This will prevent any Data Flow Manager from disabling the Controller Service while this Processor is still running.

Generally, a Controller Service is accessed by indicating in a PropertyDescriptor that the PropertyDescriptor identifies a Controller Service via the identifiesControllerService(Class) method and then calling ProcessContext.getProperty(PropertyDescriptor).asControllerService(Class). In this case, it is not necessary to lease the Controller Service, as the Framework will handle this.

There are, however, cases in which a Controller Service must be accessed in a different way, via the ControllerServiceLookup (accessed via ProcessContext.getControllerServiceLookup()). In this case, the Controller Service that is obtained from the ControllerServiceLookup can be disabled by a Data Flow Manager while it is still in use by a Processor, causing IllegalStateException to be thrown whenever the Processor attempts to interact with the service. This method provides a mechanism by which a Processor is able to indicate that the Controller Service with the given identifier should not be disabled while this Processor is running.

For any Controller Service that is leased by calling this method, the lease will automatically be terminated, allowing the Controller Service to be disabled, whenever the Processor is stopped.

Parameters:

identifier -

Throws:

IllegalArgumentException - if no Controller Service exists with the given identifier