| /* |
| * 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.jackrabbit.oak.api; |
| |
| import java.io.InputStream; |
| |
| import javax.annotation.CheckForNull; |
| import javax.annotation.Nonnull; |
| |
| /** |
| * Immutable representation of a binary value of finite length. |
| * <p> |
| * Two blobs are considered equal in terms of {@link Object#equals(Object)} |
| * if they contain the same sequences of bytes. Implementations can optimize |
| * the equality checks by using strong hash codes or other similar means as |
| * long as they comply with the above definition of equality. |
| * <p> |
| * Due to their nature blobs should not be used as keys in hash tables. |
| * To highlight that and to ensure semantic correctness of the equality |
| * contract across different blob implementations, the {@link Object#hashCode()} |
| * method of all blob instances should return zero. |
| */ |
| public interface Blob { |
| |
| /** |
| * Returns a new stream for this blob. The streams returned from |
| * multiple calls to this method are byte wise equals. That is, |
| * subsequent calls to {@link java.io.InputStream#read() read} |
| * return the same sequence of bytes as long as neither call throws |
| * an exception. |
| * |
| * @return a new stream for this blob |
| */ |
| @Nonnull |
| InputStream getNewStream(); |
| |
| /** |
| * Returns the length of this blob or -1 if unknown. |
| * |
| * @return the length of this blob. |
| */ |
| long length(); |
| |
| /** |
| * Returns a secure reference to this blob, or {@code null} if such |
| * a reference is not available. |
| * |
| * @see <a href="https://issues.apache.org/jira/browse/OAK-834">OAK-834</a> |
| * @return binary reference, or {@code null} |
| */ |
| @CheckForNull |
| String getReference(); |
| |
| /** |
| * A unique identifier of the content of this value. Usually this is a |
| * message digest of the content (a cryptographically secure one-way hash). |
| * This allows to avoid processing large binary values multiple times. |
| * <p> |
| * This method returns null if the identifier is unknown. The identifier may |
| * not always be available, for example if the value has not yet been saved |
| * or processed. Once an identifier is available, it will never change |
| * because values are immutable. |
| * <p> |
| * If two values have the same identifier, the content of the value is |
| * guaranteed to be the same. However it is not guaranteed that two values |
| * with the same content will return the same identifier. |
| * <p> |
| * The identifier is opaque, meaning it can have any format and size. |
| * |
| * @return the unique identifier or null |
| */ |
| @CheckForNull |
| String getContentIdentity(); |
| } |