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.activemq.transport.mqtt;
018    
019    import java.io.DataInput;
020    import java.io.DataInputStream;
021    import java.io.DataOutput;
022    import java.io.DataOutputStream;
023    import java.io.IOException;
024    
025    import org.apache.activemq.util.ByteArrayInputStream;
026    import org.apache.activemq.util.ByteArrayOutputStream;
027    import org.apache.activemq.util.ByteSequence;
028    import org.apache.activemq.wireformat.WireFormat;
029    import org.fusesource.hawtbuf.Buffer;
030    import org.fusesource.mqtt.codec.MQTTFrame;
031    
032    /**
033     * Implements marshalling and unmarsalling the <a
034     * href="http://mqtt.org/">MQTT</a> protocol.
035     */
036    public class MQTTWireFormat implements WireFormat {
037    
038    
039        static final int MAX_MESSAGE_LENGTH = 1024 * 1024 * 256;
040    
041        private boolean encodingEnabled = false;
042        private int version = 1;
043    
044        public ByteSequence marshal(Object command) throws IOException {
045            ByteArrayOutputStream baos = new ByteArrayOutputStream();
046            DataOutputStream dos = new DataOutputStream(baos);
047            marshal(command, dos);
048            dos.close();
049            return baos.toByteSequence();
050        }
051    
052        public Object unmarshal(ByteSequence packet) throws IOException {
053            ByteArrayInputStream stream = new ByteArrayInputStream(packet);
054            DataInputStream dis = new DataInputStream(stream);
055            return unmarshal(dis);
056        }
057    
058        public void marshal(Object command, DataOutput dataOut) throws IOException {
059            MQTTFrame frame = (MQTTFrame) command;
060            dataOut.write(frame.header());
061    
062            int remaining = 0;
063            for (Buffer buffer : frame.buffers) {
064                remaining += buffer.length;
065            }
066            do {
067                byte digit = (byte) (remaining & 0x7F);
068                remaining >>>= 7;
069                if (remaining > 0) {
070                    digit |= 0x80;
071                }
072                dataOut.write(digit);
073            } while (remaining > 0);
074            for (Buffer buffer : frame.buffers) {
075                dataOut.write(buffer.data, buffer.offset, buffer.length);
076            }
077        }
078    
079        public Object unmarshal(DataInput dataIn) throws IOException {
080            byte header = dataIn.readByte();
081    
082            byte digit;
083            int multiplier = 1;
084            int length = 0;
085            do {
086                digit = dataIn.readByte();
087                length += (digit & 0x7F) * multiplier;
088                multiplier <<= 7;
089            }
090            while ((digit & 0x80) != 0);
091    
092            if (length >= 0) {
093                if (length > MAX_MESSAGE_LENGTH) {
094                    throw new IOException("The maximum message length was exceeded");
095                }
096    
097                if (length > 0) {
098                    byte[] data = new byte[length];
099                    dataIn.readFully(data);
100                    Buffer body = new Buffer(data);
101                    return new MQTTFrame(body).header(header);
102                } else {
103                    return new MQTTFrame().header(header);
104                }
105            }
106            return null;
107        }
108    
109        /**
110         * @param the version of the wire format
111         */
112        public void setVersion(int version) {
113            this.version = version;
114        }
115    
116        /**
117         * @return the version of the wire format
118         */
119        public int getVersion() {
120            return this.version;
121        }
122    
123    
124    }