001 /**
002 The 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.
004 You may obtain a copy of the License at http://www.mozilla.org/MPL/
005 Software distributed under the License is distributed on an "AS IS" basis,
006 WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License for the
007 specific language governing rights and limitations under the License.
008
009 The 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
014 The Initial Developer of the Original Code is University Health Network. Copyright (C)
015 2001. All Rights Reserved.
016
017 Contributor(s): ______________________________________.
018
019 Alternatively, the contents of this file may be used under the terms of the
020 GNU General Public License (the �GPL�), in which case the provisions of the GPL are
021 applicable instead of those above. If you wish to allow use of your version of this
022 file only under the terms of the GPL and not to allow others to use your version
023 of this file under the MPL, indicate your decision by deleting the provisions above
024 and replace them with the notice and other provisions required by the GPL License.
025 If you do not delete the provisions above, a recipient may use your version of
026 this file under either the MPL or the GPL.
027
028 */
029
030 package ca.uhn.hl7v2.llp;
031
032 import java.io.BufferedReader;
033 import java.io.IOException;
034 import java.io.InputStream;
035 import java.io.InputStreamReader;
036 import java.net.Socket;
037 import java.net.SocketException;
038 import java.net.SocketTimeoutException;
039 import java.nio.charset.Charset;
040
041 import org.slf4j.Logger;
042 import 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
054 public 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 StringBuffer s_buffer = new StringBuffer();
151
152 boolean end_of_message = false;
153
154 int c = 0;
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 {
220 try
221 {
222 Socket s = new Socket("142.224.51.2", 7);
223
224 HL7Reader in = new MinLLPReader(s.getInputStream());
225 HL7Writer out = new MinLLPWriter(s.getOutputStream());
226
227 out.writeMessage("Some message.");
228 System.out.println("wrote");
229 String str = in.getMessage();
230 System.out.println("read");
231
232 System.out.println(str);
233 }
234 catch (Exception e)
235 {
236 System.out.println(e);
237 }
238 }
239
240 /**
241 * Closes the underlying BufferedReader.
242 */
243 public synchronized void close() throws java.io.IOException
244 {
245 myReader.close();
246 }
247
248
249 }
250