org.apache.nifi.registry

Interface VariableRegistry

All Known Subinterfaces:

ComponentVariableRegistry

public interface VariableRegistry

Provides a registry of variables available for use by various components and extension points. This enables components to reference variable names rather than explicit values which can make configurations of those components more portable.

Field Summary

Fields

Modifier and Type	Field and Description
static VariableRegistry	EMPTY_REGISTRY Returns an empty registry which can be used as a more intentional null value.
static VariableRegistry	ENVIRONMENT_SYSTEM_REGISTRY Provides a registry containing all environment variables and system properties.

Method Summary

Modifier and Type	Method and Description
default VariableDescriptor	getVariableKey(String name) Returns the VariableDescriptor for the given key name if it exists.
Map<VariableDescriptor,String>	getVariableMap() Provides access to a map of variable key/value pairs.
default String	getVariableValue(String name) Gets the variable value
default String	getVariableValue(VariableDescriptor descriptor) Gets the variable value

Field Detail

EMPTY_REGISTRY

static final VariableRegistry EMPTY_REGISTRY

Returns an empty registry which can be used as a more intentional null value.

ENVIRONMENT_SYSTEM_REGISTRY

static final VariableRegistry ENVIRONMENT_SYSTEM_REGISTRY

Provides a registry containing all environment variables and system properties. System properties receive precedence.

Method Detail

getVariableMap

Map<VariableDescriptor,String> getVariableMap()

Provides access to a map of variable key/value pairs. For variables considered to be sensitive care must be taken to ensure their values are protected whenever stored or exposed.

Returns:

An immutable map of all variables in the registry

getVariableKey

default VariableDescriptor getVariableKey(String name)

Returns the VariableDescriptor for the given key name if it exists.

Parameters:

name - the string name of the VariableDescriptor to lookup.

Returns:

the variable descriptor registered for this name if it exists; null otherwise

getVariableValue

default String getVariableValue(String name)

Gets the variable value

Parameters:

name - the string name of the VariableDescriptor that is the key of the value to lookup.

Returns:

the value associated with the given variable name if found; null otherwise

getVariableValue

default String getVariableValue(VariableDescriptor descriptor)

Gets the variable value

Parameters:

descriptor - the descriptor for which to lookup the variable value.

Returns:

the variable value if the given descriptor is equivalent to one of the entries in the registry; null otherwise