001/*
002 * Copyright 2002-2019 the original author or authors.
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License");
005 * you may not use this file except in compliance with the License.
006 * You may obtain a copy of the License at
007 *
008 *      https://www.apache.org/licenses/LICENSE-2.0
009 *
010 * Unless required by applicable law or agreed to in writing, software
011 * distributed under the License is distributed on an "AS IS" BASIS,
012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 * See the License for the specific language governing permissions and
014 * limitations under the License.
015 */
016package org.springframework.messaging.rsocket;
017
018import java.util.Map;
019
020import io.rsocket.Payload;
021
022import org.springframework.core.codec.DecodingException;
023import org.springframework.util.MimeType;
024
025/**
026 * Strategy to extract a map of value(s) from {@link Payload} metadata, which
027 * could be composite metadata with multiple entries. Each metadata entry
028 * is decoded based on its {@code MimeType} and a name is assigned to the decoded
029 * value. The resulting name-value pairs can be added to the headers of a
030 * {@link org.springframework.messaging.Message Message}.
031 *
032 * @author Rossen Stoyanchev
033 * @since 5.2
034 * @see MetadataExtractorRegistry
035 */
036public interface MetadataExtractor {
037
038        /**
039         * The key to assign to the extracted "route" of the payload.
040         */
041        String ROUTE_KEY = "route";
042
043
044        /**
045         * Extract a map of values from the given {@link Payload} metadata.
046         * The Payload "route", if present, should be saved under {@link #ROUTE_KEY}.
047         * @param payload the payload whose metadata should be read
048         * @param metadataMimeType the metadata MimeType for the connection.
049         * @return name values pairs extracted from the metadata
050         * @throws DecodingException if the metadata cannot be decoded
051         * @throws IllegalArgumentException if routing metadata cannot be decoded
052         */
053        Map<String, Object> extract(Payload payload, MimeType metadataMimeType);
054
055}