001/**
002The contents of this file are subject to the Mozilla Public License Version 1.1 
003(the "License"); you may not use this file except in compliance with the License. 
004You may obtain a copy of the License at http://www.mozilla.org/MPL/ 
005Software distributed under the License is distributed on an "AS IS" basis, 
006WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License for the 
007specific language governing rights and limitations under the License. 
008
009The Original Code is "MinLLPReader.java".  Description: 
010"Title:        HL7Reader
011  Description:  A buffered reader specifically designed for use in reading
012                HL7 ASCII strings" 
013
014The Initial Developer of the Original Code is University Health Network. Copyright (C) 
0152001.  All Rights Reserved. 
016
017Contributor(s): ______________________________________. 
018
019Alternatively, the contents of this file may be used under the terms of the 
020GNU General Public License (the  ?GPL?), in which case the provisions of the GPL are 
021applicable instead of those above.  If you wish to allow use of your version of this 
022file only under the terms of the GPL and not to allow others to use your version 
023of this file under the MPL, indicate your decision by deleting  the provisions above 
024and replace  them with the notice and other provisions required by the GPL License.  
025If you do not delete the provisions above, a recipient may use your version of 
026this file under either the MPL or the GPL. 
027
028*/
029
030package ca.uhn.hl7v2.llp;
031
032import java.io.BufferedReader;
033import java.io.IOException;
034import java.io.InputStream;
035import java.io.InputStreamReader;
036import java.net.Socket;
037import java.net.SocketException;
038import java.net.SocketTimeoutException;
039import java.nio.charset.Charset;
040
041import org.slf4j.Logger;
042import org.slf4j.LoggerFactory;
043
044/**
045 * Title:        HL7Reader
046 * Description:  A buffered reader specifically designed for use in reading
047 *               HL7 ASCII strings. This class assumes that the minimal lower
048 *               layer protocol is being used.
049 * Copyright:    Copyright (c) 2001
050 * Company:      University Health Network
051 * @author       Damian Horton (damian.horton@uhn.on.ca); mods by Bryan Tripp
052 */
053
054public class MinLLPReader implements HL7Reader
055{
056    
057    /**
058     *<p>
059     * System property: If a value is set for this property, the value
060     * is interpreted as a character set, and this characterset is 
061     * used. A possible example is "UTF-8" if you are receiving messages
062     * from a system that transmits in UTF-8.
063     * </p>
064     * <p>
065     * If the system property is set to a value of "default" (in other words, a
066     * string containing only the word default), then the platform default
067     * is used.
068     * </p>
069     * <p>
070     * If the system property is not set, US-ASCII encoding is used.
071     * </p>
072     */
073    public static final String CHARSET_KEY = "ca.uhn.hl7v2.llp.charset";
074
075    private static final Logger log = LoggerFactory.getLogger(MinLLPReader.class);
076    
077    private BufferedReader myReader;
078
079        private Charset charset;
080
081    /**
082     * Character indicating the termination of an HL7 message
083     */
084    public static final char END_MESSAGE = '\u001c'; 
085    
086    /**
087     * character indicating the start of an HL7 message
088     */
089    public static final char START_MESSAGE = '\u000b';
090    
091    /**
092     * The final character of a message: a carriage return. NB: This is per the minimal lower layer protocol.
093     */
094    public static final char LAST_CHARACTER = 13;
095
096    /** Creates a MinLLPReader with no setup - setInputStream must be set later. 
097    */
098    public MinLLPReader() 
099    {
100    }
101    
102    /** Creates a MinLLPReader which reads from the given InputStream. The stream
103     *  is assumed to be an ASCII bit stream.
104     */
105    public MinLLPReader(InputStream in) throws IOException
106    {
107        setInputStream(in);
108    }
109
110    /** Creates a MinLLPReader which reads from the given InputStream. The stream
111     *  is assumed to be an ASCII bit stream.
112     */
113    public MinLLPReader(InputStream in, Charset theCharset) throws IOException
114    {
115        charset = theCharset;
116        setInputStream(in);
117    }
118
119    /**
120     * Sets the InputStream from which to read messages.  The InputStream must be set 
121     * before any calls to <code>getMessage()</code>.
122     */
123    public synchronized void setInputStream(InputStream in) throws IOException 
124    {
125        if (charset != null) {
126            myReader = new BufferedReader(new InputStreamReader(in, charset));
127        } else { 
128                String charsetString = System.getProperty(CHARSET_KEY, "US-ASCII");
129                if (charsetString.equals("default")) {
130                    myReader = new BufferedReader(new InputStreamReader(in));
131                } else {
132                    myReader = new BufferedReader(new InputStreamReader(in, charsetString));
133                }
134        }
135    }
136
137    /** Calls the same method in the underlying BufferedReader. */
138    /**private int read(char[] parm1, int parm2, int parm3) throws java.io.IOException
139    {
140        return myReader.read(parm1, parm2, parm3);
141    }*/
142
143    /** Reads an HL7 encoded message from this Reader's InputStream.
144        @return The message, in string format, without the lower level
145        protocol delimeters. Returns null if a -1 is received on the initial
146         read.
147     */
148    public synchronized String getMessage() throws LLPException, IOException 
149    {
150        StringBuilder s_buffer = new StringBuilder();
151
152        boolean end_of_message = false;
153                        
154            int c;
155            try {
156                c = myReader.read();  
157            } catch (SocketTimeoutException e) {
158                log.debug("SocketTimeoutException on read() attempt.");
159                return null;               
160            } catch (SocketException e) {
161                log.info("SocketException on read() attempt.  Socket appears to have been closed: " + e.getMessage());
162                throw e;
163            }
164
165            //trying to read when there is no data (stream may have been closed at other end)
166            if (c == -1) {
167                log.info("End of input stream reached.");
168                throw new SocketException("End of input stream reached."); 
169            }
170            LowerLayerProtocol.logCharacterReceived(c);
171
172            if (c != START_MESSAGE)
173            {
174                throw new LLPException("Message violates the "+
175                    "minimal lower layer protocol: no start of message indicator "+
176                    "received. Received: " + c);
177            }
178
179            while (! end_of_message)
180            {
181                c = myReader.read();
182
183                if (c == -1)
184                {
185                    throw new LLPException("Message violates the "+
186                        "minimal lower protocol: message terminated without "+
187                        "a terminating character.");
188                }
189                LowerLayerProtocol.logCharacterReceived(c);
190                
191                if (c == END_MESSAGE)
192                {
193                    //subsequent character should be a carriage return
194                    c = myReader.read();
195                    if (c >= 0) LowerLayerProtocol.logCharacterReceived(c);
196                    if (c != LAST_CHARACTER)
197                    {
198                        throw new LLPException("Message "+
199                            "violates the minimal lower layer protocol: "+
200                            "message terminator not followed by a return "+
201                            "character.");
202                    }
203                    end_of_message = true;
204                }
205                else
206                {
207                //the character wasn't the end of message, append it to the message
208                    s_buffer.append((char) c);
209                }
210            } //end while
211
212        return s_buffer.toString();
213    }
214
215    /** Test driver for the program. Bounces a message off of an echo socket,
216     *  and ascertaines whether or not this class works.
217     */
218    public static void main(String args[]) {
219        Socket s = null;
220        try {
221            s = new Socket("142.224.51.2", 7);
222
223            HL7Reader in = new MinLLPReader(s.getInputStream());
224            HL7Writer out = new MinLLPWriter(s.getOutputStream());
225
226            out.writeMessage("Some message.");
227            System.out.println("wrote");
228            String str = in.getMessage();
229            System.out.println("read");
230
231            System.out.println(str);
232        } catch (Exception e) {
233            System.out.println(e);
234        } finally {
235                if (s != null) {
236                        try {
237                                        s.close();
238                                } catch (IOException e) {
239                    // empty
240                                }
241                }
242        }
243    }
244
245    /** 
246     * Closes the underlying BufferedReader.
247     */
248    public synchronized void close() throws java.io.IOException
249    {
250        myReader.close();
251    }
252    
253        
254}
255