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| 32 | <td align="right" valign="center"><img src="logo32.png" align="right" width="64" height="32" border="0"></td></tr></table><h1 align=center>QSocketNotifier Class Reference</h1>
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| 33 |
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| 34 | <p>The QSocketNotifier class provides support for socket callbacks.
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| 35 | <a href="#details">More...</a>
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| 36 | <p><tt>#include <<a href="qsocketnotifier-h.html">qsocketnotifier.h</a>></tt>
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| 37 | <p>Inherits <a href="qobject.html">QObject</a>.
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| 38 | <p><a href="qsocketnotifier-members.html">List of all member functions.</a>
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| 39 | <h2>Public Members</h2>
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| 40 | <ul>
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| 41 | <li class=fn>enum <a href="#Type-enum"><b>Type</b></a> { Read, Write, Exception }</li>
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| 42 | <li class=fn><a href="#QSocketNotifier"><b>QSocketNotifier</b></a> ( int socket, Type type, QObject * parent = 0, const char * name = 0 )</li>
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| 43 | <li class=fn><a href="#~QSocketNotifier"><b>~QSocketNotifier</b></a> ()</li>
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| 44 | <li class=fn>int <a href="#socket"><b>socket</b></a> () const</li>
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| 45 | <li class=fn>Type <a href="#type"><b>type</b></a> () const</li>
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| 46 | <li class=fn>bool <a href="#isEnabled"><b>isEnabled</b></a> () const</li>
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| 47 | <li class=fn>virtual void <a href="#setEnabled"><b>setEnabled</b></a> ( bool enable )</li>
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| 48 | </ul>
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| 49 | <h2>Signals</h2>
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| 50 | <ul>
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| 51 | <li class=fn>void <a href="#activated"><b>activated</b></a> ( int socket )</li>
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| 52 | </ul>
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| 53 | <hr><a name="details"></a><h2>Detailed Description</h2>
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| 54 |
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| 55 |
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| 56 | The QSocketNotifier class provides support for socket callbacks.
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| 57 | <p>
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| 58 | <p> This class makes it possible to write asynchronous socket-based
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| 59 | code in Qt. Using synchronous socket operations blocks the
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| 60 | program, which is clearly not acceptable for an event-driven GUI
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| 61 | program.
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| 62 | <p> Once you have opened a non-blocking socket (whether for TCP, UDP,
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| 63 | a UNIX-domain socket, or any other protocol family your operating
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| 64 | system supports), you can create a socket notifier to monitor the
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| 65 | socket. Then you connect the <a href="#activated">activated</a>() signal to the slot you
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| 66 | want to be called when a socket event occurs.
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| 67 | <p> Note for Windows users: the socket passed to QSocketNotifier will
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| 68 | become non-blocking, even if it was created as a blocking socket.
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| 69 | <p> There are three types of socket notifiers (read, write and
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| 70 | exception); you must specify one of these in the constructor.
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| 71 | <p> The type specifies when the activated() signal is to be emitted:
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| 72 | <ol type=1>
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| 73 | <li> QSocketNotifier::Read - There is data to be read (socket read event).
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| 74 | <li> QSocketNotifier::Write - Data can be written (socket write event).
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| 75 | <li> QSocketNofifier::Exception - An exception has occurred (socket
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| 76 | exception event). We recommend against using this.
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| 77 | </ol>
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| 78 | <p> For example, if you need to monitor both reads and writes for the
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| 79 | same socket you must create two socket notifiers.
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| 80 | <p> For read notifiers it makes little sense to connect the
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| 81 | activated() signal to more than one slot because the data can be
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| 82 | read from the socket only once.
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| 83 | <p> Also observe that if you do not read all the available data when
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| 84 | the read notifier fires, it fires again and again.
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| 85 | <p> For write notifiers, immediately disable the notifier after the
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| 86 | <a href="#activated">activated</a>() signal has been received and you have sent the data to
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| 87 | be written on the socket. When you have more data to be written,
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| 88 | enable it again to get a new activated() signal. The exception is
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| 89 | if the socket data writing operation (send() or equivalent) fails
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| 90 | with a "would block" error, which means that some buffer is full
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| 91 | and you must wait before sending more data. In that case you do
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| 92 | not need to disable and re-enable the write notifier; it will fire
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| 93 | again as soon as the system allows more data to be sent.
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| 94 | <p> The behavior of a write notifier that is left in enabled state
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| 95 | after having emitting the first activated() signal (and no "would
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| 96 | block" error has occurred) is undefined. Depending on the
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| 97 | operating system, it may fire on every pass of the event loop or
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| 98 | not at all.
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| 99 | <p> If you need a time-out for your sockets you can use either <a href="qobject.html#startTimer">timer events</a> or the <a href="qtimer.html">QTimer</a> class.
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| 100 | <p> Socket action is detected in the <a href="qapplication.html#exec">main
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| 101 | event loop</a> of Qt. The X11 version of Qt has a single UNIX
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| 102 | select() call that incorporates all socket notifiers and the X
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| 103 | socket.
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| 104 | <p> Note that on XFree86 for OS/2, select() works only in the thread
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| 105 | in which main() is running; you should therefore use that thread
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| 106 | for GUI operations.
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| 107 | <p> <p>See also <a href="qsocket.html">QSocket</a>, <a href="qserversocket.html">QServerSocket</a>, <a href="qsocketdevice.html">QSocketDevice</a>, <a href="qfile.html#handle">QFile::handle</a>(), and <a href="io.html">Input/Output and Networking</a>.
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| 108 |
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| 109 | <hr><h2>Member Type Documentation</h2>
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| 110 | <h3 class=fn><a name="Type-enum"></a>QSocketNotifier::Type</h3>
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| 111 |
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| 112 | <ul>
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| 113 | <li><tt>QSocketNotifier::Read</tt>
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| 114 | <li><tt>QSocketNotifier::Write</tt>
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| 115 | <li><tt>QSocketNotifier::Exception</tt>
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| 116 | </ul>
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| 117 | <hr><h2>Member Function Documentation</h2>
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| 118 | <h3 class=fn><a name="QSocketNotifier"></a>QSocketNotifier::QSocketNotifier ( int socket, <a href="qsocketnotifier.html#Type-enum">Type</a> type, <a href="qobject.html">QObject</a> * parent = 0, const char * name = 0 )
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| 119 | </h3>
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| 120 | Constructs a socket notifier called <em>name</em>, with the parent, <em>parent</em>. It watches <em>socket</em> for <em>type</em> events, and enables it.
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| 121 | <p> It is generally advisable to explicitly enable or disable the
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| 122 | socket notifier, especially for write notifiers.
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| 123 | <p> <p>See also <a href="#setEnabled">setEnabled</a>() and <a href="#isEnabled">isEnabled</a>().
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| 124 |
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| 125 | <h3 class=fn><a name="~QSocketNotifier"></a>QSocketNotifier::~QSocketNotifier ()
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| 126 | </h3>
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| 127 | Destroys the socket notifier.
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| 128 |
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| 129 | <h3 class=fn>void <a name="activated"></a>QSocketNotifier::activated ( int socket )<tt> [signal]</tt>
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| 130 | </h3>
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| 131 |
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| 132 | <p> This signal is emitted under certain conditions specified by the
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| 133 | notifier <a href="#type">type</a>():
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| 134 | <ol type=1>
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| 135 | <li> QSocketNotifier::Read - There is data to be read (socket read event).
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| 136 | <li> QSocketNotifier::Write - Data can be written (socket write event).
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| 137 | <li> QSocketNofifier::Exception - An exception has occurred (socket
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| 138 | exception event).
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| 139 | </ol>
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| 140 | <p> The <em>socket</em> argument is the <a href="#socket">socket</a> identifier.
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| 141 | <p> <p>See also <a href="#type">type</a>() and <a href="#socket">socket</a>().
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| 142 |
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| 143 | <h3 class=fn>bool <a name="isEnabled"></a>QSocketNotifier::isEnabled () const
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| 144 | </h3>
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| 145 |
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| 146 | <p> Returns TRUE if the notifier is enabled; otherwise returns FALSE.
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| 147 | <p> <p>See also <a href="#setEnabled">setEnabled</a>().
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| 148 |
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| 149 | <h3 class=fn>void <a name="setEnabled"></a>QSocketNotifier::setEnabled ( bool enable )<tt> [virtual]</tt>
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| 150 | </h3>
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| 151 | Enables the notifier if <em>enable</em> is TRUE or disables it if <em>enable</em> is FALSE.
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| 152 | <p> The notifier is enabled by default.
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| 153 | <p> If the notifier is enabled, it emits the <a href="#activated">activated</a>() signal
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| 154 | whenever a socket event corresponding to its <a href="#type">type</a> occurs. If it is disabled, it ignores socket events
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| 155 | (the same effect as not creating the socket notifier).
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| 156 | <p> Write notifiers should normally be disabled immediately after the
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| 157 | activated() signal has been emitted; see discussion of write
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| 158 | notifiers in the <a href="#details">class description</a> above.
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| 159 | <p> <p>See also <a href="#isEnabled">isEnabled</a>() and <a href="#activated">activated</a>().
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| 160 |
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| 161 | <h3 class=fn>int <a name="socket"></a>QSocketNotifier::socket () const
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| 162 | </h3>
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| 163 |
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| 164 | <p> Returns the socket identifier specified to the constructor.
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| 165 | <p> <p>See also <a href="#type">type</a>().
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| 166 |
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| 167 | <h3 class=fn><a href="qsocketnotifier.html#Type-enum">Type</a> <a name="type"></a>QSocketNotifier::type () const
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| 168 | </h3>
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| 169 |
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| 170 | <p> Returns the socket event type specified to the constructor: <a href="#Type-enum">QSocketNotifier::Read</a>, <a href="#Type-enum">QSocketNotifier::Write</a>, or <a href="#Type-enum">QSocketNotifier::Exception</a>.
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| 171 | <p> <p>See also <a href="#socket">socket</a>().
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| 172 |
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| 173 | <!-- eof -->
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| 174 | <hr><p>
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| 175 | This file is part of the <a href="index.html">Qt toolkit</a>.
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| 176 | Copyright © 1995-2007
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| 177 | <a href="http://www.trolltech.com/">Trolltech</a>. All Rights Reserved.<p><address><hr><div align=center>
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| 178 | <table width=100% cellspacing=0 border=0><tr>
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| 179 | <td>Copyright © 2007
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| 180 | <a href="troll.html">Trolltech</a><td align=center><a href="trademarks.html">Trademarks</a>
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| 181 | <td align=right><div align=right>Qt 3.3.8</div>
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| 182 | </table></div></address></body>
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| 183 | </html>
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