org.apache.nifi.parameter.ParameterProvider Maven / Gradle / Ivy
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.nifi.parameter;
import org.apache.nifi.annotation.lifecycle.OnConfigurationRestored;
import org.apache.nifi.components.ConfigurableComponent;
import org.apache.nifi.controller.ConfigurationContext;
import org.apache.nifi.reporting.InitializationException;
import java.io.IOException;
import java.util.List;
/**
* Defines a provider that is responsible for fetching from an external source Parameters with
* which a ParameterContext can be populated.
*
*
* ParameterProviders are discovered following Java's
* ServiceLoader pattern. As a result, all implementations must
* follow these rules:
*
*
* - The implementation must implement this interface.
* - The implementation must have a file named
* org.apache.nifi.parameter.ParameterProvider located within the jar's
*
META-INF/services directory. This file contains a list of
* fully-qualified class names of all ParameterProviders in the jar,
* one-per-line.
* - The implementation must support a default constructor.
*
*
*
*
* All implementations of this interface must be thread-safe.
*
*
*
* Parameter Providers may choose to annotate a method with the
* {@link OnConfigurationRestored @OnConfigurationRestored} annotation. If this is done, that method
* will be invoked after all properties have been set for the ParameterProvider and
* before its parameters are fetched.
*
*/
public interface ParameterProvider extends ConfigurableComponent {
/**
* Provides the Parameter Provider with access to objects that may be of use
* throughout the life of the provider
*
* @param config of initialization context
* @throws org.apache.nifi.reporting.InitializationException if unable to init
*/
void initialize(ParameterProviderInitializationContext config) throws InitializationException;
/**
* Fetches named groups of parameters from an external source.
*
* Any referencing Parameter Context will only receive the Parameters from a group if the Parameter Context name matches
* the group name (ignoring case) and the reference sensitivity matches the group sensitivity.
*
* If group name is null, all referencing Parameter Contexts will receive the Parameters in that group,
* regardless of their name.
*
* If more than one ProvidedParameterGroup matches a given ParameterContext, all parameters from these groups will be
* applied. However, if any parameters among these matching groups have the same name but different value, the framework
* will throw a RuntimeException
*
* @param context The ConfigurationContextfor the provider
* @return A list of fetched Parameter groups. The framework will set the sensitivity appropriately based on how the ParameterProvider
* is referenced in a ParameterContext.
* @throws IOException if there is an I/O problem while fetching the Parameters
*/
List fetchParameters(ConfigurationContext context) throws IOException;
}