/*
 * 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;

/**
 * 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
    }

    /**
     * @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
     */
    void configure(List<Pair<String, String>> args);

    /**
     * @return The extension point implemented by this extension
     */
    ExtensionKind getExtensionKind();
}
