org.apache.nifi.lookup

Interface LookupService<T>

All Superinterfaces:

ConfigurableComponent, ControllerService

All Known Subinterfaces:

RecordLookupService, StringLookupService

public interface LookupService<T>
extends ControllerService

Method Summary

Modifier and Type	Method and Description
Set<String>	getRequiredKeys() Many Lookup Services will require a specific set of information be passed in to the lookup(Map) method.
Class<?>	getValueType()
Optional<T>	lookup(Map<String,Object> coordinates) Looks up a value that corresponds to the given map of information, referred to as lookup coordinates
default Optional<T>	lookup(Map<String,Object> coordinates, Map<String,String> context) Looks up a value that corresponds to the given map, coordinates.

Methods inherited from interface org.apache.nifi.controller.ControllerService

initialize

Methods inherited from interface org.apache.nifi.components.ConfigurableComponent

getIdentifier, getPropertyDescriptor, getPropertyDescriptors, onPropertyModified, validate

Method Detail

lookup

Optional<T> lookup(Map<String,Object> coordinates)
            throws LookupFailureException

Looks up a value that corresponds to the given map of information, referred to as lookup coordinates

Parameters:

coordinates - a Map of key/value pairs that indicate the information that should be looked up

Returns:

a value that corresponds to the given coordinates

Throws:

LookupFailureException - if unable to lookup a value for the given coordinates

lookup

default Optional<T> lookup(Map<String,Object> coordinates,
                           Map<String,String> context)
                    throws LookupFailureException

Looks up a value that corresponds to the given map, coordinates. Additional contextual information will also be passed into the map labeled context from sources such as flowfile attributes.

Parameters:

coordinates - a Map of key/value pairs that indicate the information that should be looked up

context - a Map of additional information

Returns:

a value that corresponds to the given coordinates

Throws:

LookupFailureException - if unable to lookup a value for the given coordinates

getValueType

Class<?> getValueType()

Returns:

the Class that represents the type of value that will be returned by lookup(Map)

getRequiredKeys

Set<String> getRequiredKeys()

Many Lookup Services will require a specific set of information be passed in to the lookup(Map) method. This method will return the Set of keys that must be present in the map that is passed to lookup(Map) in order for the lookup to succeed.

Returns:

the keys that must be present in the map passed to lookup(Map) in order to the lookup to succeed, or an empty set if no specific keys are required.