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1   /**
2   The contents of this file are subject to the Mozilla Public License Version 1.1 
3   (the "License"); you may not use this file except in compliance with the License. 
4   You may obtain a copy of the License at http://www.mozilla.org/MPL/ 
5   Software distributed under the License is distributed on an "AS IS" basis, 
6   WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License for the 
7   specific language governing rights and limitations under the License. 
8   
9   The Original Code is "MinLLPReader.java".  Description: 
10  "Title:        HL7Reader
11    Description:  A buffered reader specifically designed for use in reading
12                  HL7 ASCII strings" 
13  
14  The Initial Developer of the Original Code is University Health Network. Copyright (C) 
15  2001.  All Rights Reserved. 
16  
17  Contributor(s): ______________________________________. 
18  
19  Alternatively, the contents of this file may be used under the terms of the 
20  GNU General Public License (the  �GPL�), in which case the provisions of the GPL are 
21  applicable instead of those above.  If you wish to allow use of your version of this 
22  file only under the terms of the GPL and not to allow others to use your version 
23  of this file under the MPL, indicate your decision by deleting  the provisions above 
24  and replace  them with the notice and other provisions required by the GPL License.  
25  If you do not delete the provisions above, a recipient may use your version of 
26  this file under either the MPL or the GPL. 
27  
28  */
29  
30  package ca.uhn.hl7v2.llp;
31  
32  import java.io.BufferedReader;
33  import java.io.IOException;
34  import java.io.InputStream;
35  import java.io.InputStreamReader;
36  import java.net.Socket;
37  import java.net.SocketException;
38  import java.net.SocketTimeoutException;
39  import java.nio.charset.Charset;
40  
41  import org.slf4j.Logger;
42  import org.slf4j.LoggerFactory;
43  
44  /**
45   * Title:        HL7Reader
46   * Description:  A buffered reader specifically designed for use in reading
47   *               HL7 ASCII strings. This class assumes that the minimal lower
48   *               layer protocol is being used.
49   * Copyright:    Copyright (c) 2001
50   * Company:      University Health Network
51   * @author       Damian Horton (damian.horton@uhn.on.ca); mods by Bryan Tripp
52   */
53  
54  public class MinLLPReader implements HL7Reader
55  {
56      
57      /**
58       *<p>
59       * System property: If a value is set for this property, the value
60       * is interpreted as a character set, and this characterset is 
61       * used. A possible example is "UTF-8" if you are receiving messages
62       * from a system that transmits in UTF-8.
63       * </p>
64       * <p>
65       * If the system property is set to a value of "default" (in other words, a
66       * string containing only the word default), then the platform default
67       * is used.
68       * </p>
69       * <p>
70       * If the system property is not set, US-ASCII encoding is used.
71       * </p>
72       */
73      public static final String CHARSET_KEY = "ca.uhn.hl7v2.llp.charset";
74  
75      private static final Logger log = LoggerFactory.getLogger(MinLLPReader.class);
76      
77      private BufferedReader myReader;
78  
79  	private Charset charset;
80  
81      /**
82       * Character indicating the termination of an HL7 message
83       */
84      public static final char END_MESSAGE = '\u001c'; 
85      
86      /**
87       * character indicating the start of an HL7 message
88       */
89      public static final char START_MESSAGE = '\u000b';
90      
91      /**
92       * The final character of a message: a carriage return. NB: This is per the minimal lower layer protocol.
93       */
94      public static final char LAST_CHARACTER = 13;
95  
96      /** Creates a MinLLPReader with no setup - setInputStream must be set later. 
97      */
98      public MinLLPReader() 
99      {
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