content: /*
   * 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.asterix.common.api;
  
  import java.util.List;
  
  import org.apache.hyracks.algebricks.common.utils.Pair;
  import org.apache.hyracks.api.application.IServiceContext;
  
  /**
   * an interface for an extension that provides a mechanism to override system behaviour
   * or add new features
   */
  public interface IExtension {
  
      enum ExtensionKind {
          /**
           * Extends Query translator
           */
          STATEMENT_EXECUTOR,
          /**
           * Extends Metadata
           */
          METADATA,
          /**
           * Extends Language Syntax and Algebric Operations
           */
          LANG,
          /**
           * Extends Recovery Capabilities
           */
          RECOVERY
      }
  
      /**
       * @return Unique Id for the extension (used for lookup operations)
       */
      ExtensionId getId();
  
      /**
       * Configures the extension with configuration parameters.
       * This method is called on system boot
       *
       * @param args
       * @param serviceCtx
       */
      void configure(List<Pair<String, String>> args, IServiceContext serviceCtx);
  
      /**
       * @return The extension point implemented by this extension
       */
      ExtensionKind getExtensionKind();
  }
  