1 | /*
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2 | * Licensed to the Apache Software Foundation (ASF) under one or more
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3 | * contributor license agreements. See the NOTICE file distributed with
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4 | * this work for additional information regarding copyright ownership.
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5 | * The ASF licenses this file to You under the Apache License, Version 2.0
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6 | * (the "License"); you may not use this file except in compliance with
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7 | * the License. You may obtain a copy of the License at
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8 | *
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9 | * http://www.apache.org/licenses/LICENSE-2.0
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10 | *
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11 | * Unless required by applicable law or agreed to in writing, software
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12 | * distributed under the License is distributed on an "AS IS" BASIS,
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13 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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14 | * See the License for the specific language governing permissions and
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15 | * limitations under the License.
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16 | */
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17 |
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18 | #ifndef _LOG4CXX_NET_XML_SOCKET_APPENDER_H
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19 | #define _LOG4CXX_NET_XML_SOCKET_APPENDER_H
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20 |
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21 | #include <log4cxx/net/socketappenderskeleton.h>
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22 | #include <log4cxx/helpers/writer.h>
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23 |
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24 | namespace log4cxx
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25 | {
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26 | namespace net
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27 | {
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28 |
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29 | /**
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30 | Sends {@link log4cxx::spi::LoggingEvent LoggingEvent} objects in XML format
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31 | to a remote a log server, usually a XMLSocketNode.
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32 |
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33 | <p>The XMLSocketAppender has the following properties:
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34 |
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35 | - If sent to a XMLSocketNode, remote logging
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36 | is non-intrusive as far as the log event is concerned. In other
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37 | words, the event will be logged with the same time stamp, {@link
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38 | NDC NDC}, location info as if it were logged locally by
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39 | the client.
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40 |
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41 | - XMLSocketAppenders use exclusively an XMLLayout. They ship an
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42 | XML stream representing a {@link spi::LoggingEvent LoggingEvent} object
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43 | to the server side.
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44 |
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45 | - Remote logging uses the TCP protocol. Consequently, if
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46 | the server is reachable, then log events will eventually arrive
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47 | at the server.
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48 |
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49 | - If the remote server is down, the logging requests are
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50 | simply dropped. However, if and when the server comes back up,
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51 | then event transmission is resumed transparently. This
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52 | transparent reconneciton is performed by a <em>connector</em>
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53 | thread which periodically attempts to connect to the server.
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54 |
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55 | - Logging events are automatically <em>buffered</em> by the
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56 | native TCP implementation. This means that if the link to server
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57 | is slow but still faster than the rate of (log) event production
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58 | by the client, the client will not be affected by the slow
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59 | network connection. However, if the network connection is slower
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60 | then the rate of event production, then the client can only
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61 | progress at the network rate. In particular, if the network link
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62 | to the the server is down, the client will be blocked.
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63 | @n @n On the other hand, if the network link is up, but the server
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64 | is down, the client will not be blocked when making log requests
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65 | but the log events will be lost due to server unavailability.
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66 |
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67 | - Even if an <code>XMLSocketAppender</code> is no longer
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68 | attached to any logger, it will not be destroyed in
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69 | the presence of a connector thread. A connector thread exists
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70 | only if the connection to the server is down. To avoid this
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71 | destruction problem, you should #close the the
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72 | <code>XMLSocketAppender</code> explicitly. See also next item.
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73 | @n @n Long lived applications which create/destroy many
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74 | <code>XMLSocketAppender</code> instances should be aware of this
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75 | destruction problem. Most other applications can safely
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76 | ignore it.
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77 |
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78 | - If the application hosting the <code>XMLSocketAppender</code>
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79 | exits before the <code>XMLSocketAppender</code> is closed either
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80 | explicitly or subsequent to destruction, then there might
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81 | be untransmitted data in the pipe which might be lost.
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82 | @n @n To avoid lost data, it is usually sufficient to
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83 | #close the <code>XMLSocketAppender</code> either explicitly or by
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84 | calling the LogManager#shutdown method
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85 | before exiting the application.
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86 | */
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87 |
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88 | class LOG4CXX_EXPORT XMLSocketAppender : public SocketAppenderSkeleton
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89 | {
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90 | public:
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91 | /**
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92 | The default port number of remote logging server (4560).
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93 | */
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94 | static int DEFAULT_PORT;
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95 |
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96 | /**
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97 | The default reconnection delay (30000 milliseconds or 30 seconds).
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98 | */
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99 | static int DEFAULT_RECONNECTION_DELAY;
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100 |
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101 | /**
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102 | An event XML stream cannot exceed 1024 bytes.
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103 | */
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104 | static const int MAX_EVENT_LEN;
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105 |
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106 | DECLARE_LOG4CXX_OBJECT(XMLSocketAppender)
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107 | BEGIN_LOG4CXX_CAST_MAP()
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108 | LOG4CXX_CAST_ENTRY(XMLSocketAppender)
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109 | LOG4CXX_CAST_ENTRY_CHAIN(AppenderSkeleton)
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110 | END_LOG4CXX_CAST_MAP()
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111 |
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112 | XMLSocketAppender();
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113 | ~XMLSocketAppender();
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114 |
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115 | /**
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116 | Connects to remote server at <code>address</code> and <code>port</code>.
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117 | */
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118 | XMLSocketAppender(helpers::InetAddressPtr address, int port);
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119 |
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120 | /**
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121 | Connects to remote server at <code>host</code> and <code>port</code>.
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122 | */
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123 | XMLSocketAppender(const LogString& host, int port);
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124 |
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125 |
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126 | protected:
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127 | virtual void setSocket(log4cxx::helpers::SocketPtr& socket, log4cxx::helpers::Pool& p);
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128 |
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129 | virtual void cleanUp(log4cxx::helpers::Pool& p);
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130 |
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131 | virtual int getDefaultDelay() const;
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132 |
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133 | virtual int getDefaultPort() const;
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134 |
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135 | void append(const spi::LoggingEventPtr& event, log4cxx::helpers::Pool& pool);
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136 |
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137 | private:
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138 | log4cxx::helpers::WriterPtr writer;
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139 | // prevent copy and assignment statements
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140 | XMLSocketAppender(const XMLSocketAppender&);
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141 | XMLSocketAppender& operator=(const XMLSocketAppender&);
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142 | }; // class XMLSocketAppender
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143 |
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144 | LOG4CXX_PTR_DEF(XMLSocketAppender);
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145 |
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146 | } // namespace net
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147 | } // namespace log4cxx
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148 |
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149 | #endif // _LOG4CXX_NET_XML_SOCKET_APPENDER_H
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150 |
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