001 /** 002 * Licensed to the Apache Software Foundation (ASF) under one or more 003 * contributor license agreements. See the NOTICE file distributed with 004 * this work for additional information regarding copyright ownership. 005 * The ASF licenses this file to You under the Apache License, Version 2.0 006 * (the "License"); you may not use this file except in compliance with 007 * the License. You may obtain a copy of the License at 008 * 009 * http://www.apache.org/licenses/LICENSE-2.0 010 * 011 * Unless required by applicable law or agreed to in writing, software 012 * distributed under the License is distributed on an "AS IS" BASIS, 013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 014 * See the License for the specific language governing permissions and 015 * limitations under the License. 016 */ 017 package org.apache.camel; 018 019 import java.io.IOException; 020 import java.io.OutputStream; 021 022 /** 023 * Tagging interface to indicate that a type is capable of caching the underlying data stream. 024 * <p/> 025 * This is a useful feature for avoiding message re-readability issues. 026 * This interface is mainly used by the {@link org.apache.camel.processor.interceptor.StreamCachingInterceptor} 027 * for determining if/how to wrap a stream-based message. 028 * 029 * @version 030 */ 031 public interface StreamCache { 032 033 long DEFAULT_SPOOL_THRESHOLD = 128 * 1024; 034 035 /** 036 * Resets the StreamCache for a new stream consumption. 037 */ 038 void reset(); 039 040 /** 041 * Writes the stream to the given output 042 * 043 * @param os the destination to write to 044 * @throws java.io.IOException is thrown if write fails 045 */ 046 void writeTo(OutputStream os) throws IOException; 047 048 /** 049 * Whether this {@link StreamCache} is in memory only or 050 * spooled to persistent storage such as files. 051 */ 052 boolean inMemory(); 053 054 /** 055 * Gets the length of the cached stream. 056 * <p/> 057 * The implementation may return <tt>0</tt> in cases where the length 058 * cannot be computed, or if the implementation does not support this. 059 * 060 * @return number of bytes in the cache. 061 */ 062 long length(); 063 064 }