PluginContext.java

/*
 * Copyright © 2015 Cask Data, Inc.
 *
 * Licensed 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 co.cask.cdap.api.plugin;

import co.cask.cdap.api.annotation.Beta;

/**
 * Provides access to plugin context when a program is executing.
 */
@Beta
public interface PluginContext {

  /**
   * Gets the {@link PluginProperties} associated with the given plugin id.
   *
   * @param pluginId the unique identifier provide when declaring plugin usage in the program.
   * @return the {@link PluginProperties}.
   * @throws IllegalArgumentException if pluginId is not found
   * @throws UnsupportedOperationException if the program does not support plugin
   */
  PluginProperties getPluginProperties(String pluginId);

  /**
   * Loads and returns a plugin class as specified by the given plugin id.
   *
   * @param pluginId the unique identifier provide when declaring plugin usage in the program.
   * @param <T> the class type of the plugin
   * @return the resulting plugin {@link Class}.
   * @throws IllegalArgumentException if pluginId is not found
   * @throws UnsupportedOperationException if the program does not support plugin
   */
  <T> Class<T> loadPluginClass(String pluginId);

  /**
   * Creates a new instance of a plugin. The instance returned will have the {@link PluginConfig} setup with
   * {@link PluginProperties} provided at the time when the
   * {@link PluginConfigurer#usePlugin(String, String, String, PluginProperties)} was called during the
   * program configuration time.
   *
   * @param pluginId the unique identifier provide when declaring plugin usage in the program.
   * @param <T> the class type of the plugin
   * @return A new instance of the plugin being specified by the arguments
   *
   * @throws InstantiationException if failed create a new instance
   * @throws IllegalArgumentException if pluginId is not found
   * @throws UnsupportedOperationException if the program does not support plugin
   */
  <T> T newPluginInstance(String pluginId) throws InstantiationException;
}