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 */
017package org.apache.camel.spi;
018
019import org.apache.camel.CamelContext;
020import org.apache.camel.CamelContextAware;
021import org.apache.camel.Message;
022import org.apache.camel.support.service.ServiceSupport;
023
024/**
025 * <a href="http://camel.apache.org/transformer.html">Transformer</a>
026 * performs message transformation according to the declared data type.
027 * {@link org.apache.camel.processor.ContractAdvice} looks for a required Transformer and apply if
028 * input/output type declared on a route is different from current message type.
029 *  
030 * @see {@link org.apache.camel.processor.ContractAdvice}
031 * {@link DataType} {@link org.apache.camel.model.InputTypeDefinition} {@link org.apache.camel.model.OutputTypeDefinition}
032 */
033public abstract class Transformer extends ServiceSupport implements CamelContextAware {
034
035    private CamelContext camelContext;
036    private String model;
037    private DataType from;
038    private DataType to;
039
040    /**
041     * Perform data transformation with specified from/to type.
042     *
043     * @param message message to apply transformation
044     * @param from 'from' data type
045     * @param to 'to' data type
046     */
047    public abstract void transform(Message message, DataType from, DataType to) throws Exception;
048
049    /**
050     * Get a data model which is supported by this transformer.
051     */
052    public String getModel() {
053        return model;
054    }
055
056    /**
057     * Get 'from' data type.
058     */
059    public DataType getFrom() {
060        return from;
061    }
062
063    /**
064     * Get 'to' data type.
065     */
066    public DataType getTo() {
067        return to;
068    }
069
070    /**
071     * Set data model.
072     *
073     * @param model data model
074     */
075    public Transformer setModel(String model) {
076        this.model = model;
077        return this;
078    }
079
080    /**
081     * Set 'from' data type.
082     *
083     * @param from 'from' data type
084     */
085    public Transformer setFrom(String from) {
086        this.from = new DataType(from);
087        return this;
088    }
089
090    /**
091     * Set 'to' data type.
092     *
093     * @param to 'to' data type
094     */
095    public Transformer setTo(String to) {
096        this.to = new DataType(to);
097        return this;
098    }
099
100    @Override
101    public CamelContext getCamelContext() {
102        return this.camelContext;
103    }
104
105    @Override
106    public void setCamelContext(CamelContext context) {
107        this.camelContext = context;
108    }
109
110    @Override
111    public String toString() {
112        return String.format("%s[scheme='%s', from='%s', to='%s']", this.getClass().getSimpleName(), model, from, to);
113    }
114
115    @Override
116    protected void doStart() throws Exception {
117        // no-op
118    }
119
120    @Override
121    protected void doStop() throws Exception {
122        // no-op
123    }
124}