FileStorage.java

/**
 * Copyright 2016 Hortonworks.
 *
 * 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 com.hortonworks.registries.common.util;

import java.io.IOException;
import java.io.InputStream;
import java.util.Map;

/**
 * Interface abstracting the upload and download of files (like parser jars, split/join or custom processor jars or any other files) for IoTaS.
 * IoTaS will provide a default file system based implementation which can be swapped by another implementation using fileStorageConfiguration
 * property in the iotas.yaml
 */
public interface FileStorage {

    String DEFAULT_DIR = "/tmp/iotas-files";

    /**
     * The file storage can be initialized with a set of key/value pairs.
     *
     * @param config the config specific to implementation
     */
    void init(Map<String, String> config);

    /**
     * Uploads the content from given {@code InputStream} to the configured storage with the given {@code name } as identifier which can
     * be used later for {@link #downloadFile(String)} or {@link #deleteFile(String)}.
     *
     * @param inputStream stream to read the file content from
     * @param name        identifier of the file to be used later to retrieve
     *                    using {@link #downloadFile(String)}
     * @throws java.io.IOException if any IO error occurs
     */
    String uploadFile(InputStream inputStream, String name) throws IOException;

    /**
     * Returns {@link InputStream} of file for the given name.
     *
     * @param name identifier of the file to be downloaded that was first
     *             passed during {@link #uploadFile(InputStream, String)}
     * @return InputStream representing the file
     * @throws java.io.IOException if any IO error occurs
     */
    InputStream downloadFile(String name) throws IOException;

    /**
     * Deletes the stored file for given {@code name}.
     *
     * @param name identifier of the file to be deleted that was
     *             passed during {@link #uploadFile(InputStream, String)}
     * @return {@code true} if the file is deleted, {@code false} if the file could not be deleted
     * @throws IOException if any IO error occurs
     */
    boolean deleteFile(String name) throws IOException;

}