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  7.   <title>QtService Class Reference</title>

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  14. <td width="1">&nbsp;&nbsp;</td><td class="postheader" valign="center"><a href="index.html"><font color="#004faf">Home</font></a></td>

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  15. </tr></table><h1 class="title">QtService Class Reference</h1>

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  16. <p>The QtService is a convenient template class that allows you to create a service for a particular application type. <a href="#details">More...</a></p>

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  17. <pre> #include &lt;QtService&gt;</pre><p>Inherits <a href="qtservicebase.html">QtServiceBase</a>.</p>

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  18. <ul>

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  19. <li><a href="qtservice-members.html">List of all members, including inherited members</a></li>

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  20. </ul>

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  21. <a name="public-functions"></a>

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  22. <h3>Public Functions</h3>

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  23. <ul>

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  24. <li><div class="fn"></div><b><a href="qtservice.html#QtService">QtService</a></b> ( int <i>argc</i>, char ** <i>argv</i>, const QString &amp; <i>name</i> )</li>

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  25. <li><div class="fn"></div><b><a href="qtservice.html#dtor.QtService">~QtService</a></b> ()</li>

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  26. </ul>

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  27. <ul>

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  28. <li><div class="fn"></div>9 public functions inherited from <a href="qtservicebase.html#public-functions">QtServiceBase</a></li>

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  29. </ul>

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  30. <a name="protected-functions"></a>

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  31. <h3>Protected Functions</h3>

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  32. <ul>

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  33. <li><div class="fn"></div>Application * <b><a href="qtservice.html#application">application</a></b> () const</li>

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  34. </ul>

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  35. <ul>

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  36. <li><div class="fn"></div>7 protected functions inherited from <a href="qtservicebase.html#protected-functions">QtServiceBase</a></li>

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  37. </ul>

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  38. <h3>Additional Inherited Members</h3>

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  39. <ul>

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  40. <li><div class="fn"></div>1 static public member inherited from <a href="qtservicebase.html#static-public-members">QtServiceBase</a></li>

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  41. </ul>

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  42. <a name="details"></a>

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  43. <hr />

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  44. <h2>Detailed Description</h2>

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  45. <p>The QtService is a convenient template class that allows you to create a service for a particular application type.</p>

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  46. <p>A Windows service or Unix daemon (a &quot;service&quot;), is a program that runs &quot;in the background&quot; independently of whether a user is logged in or not. A service is often set up to start when the machine boots up, and will typically run continuously as long as the machine is on.</p>

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  47. <p>Services are usually non-interactive console applications. User interaction, if required, is usually implemented in a separate, normal GUI application that communicates with the service through an IPC channel. For simple communication, <a href="qtservicecontroller.html#sendCommand">QtServiceController::sendCommand</a>() and <a href="qtservicebase.html#processCommand">QtService::processCommand</a>() may be used, possibly in combination with a shared settings file. For more complex, interactive communication, a custom IPC channel should be used, e.g&#x2e; based on Qt's networking classes. (In certain circumstances, a service may provide a GUI itself, ref. the &quot;interactive&quot; example documentation).</p>

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  48. <p><b>Note:</b> On Unix systems, this class relies on facilities provided by the <a href="http://qt.nokia.com/doc/4.5/qtnetwork.html">QtNetwork</a> module, provided as part of the Qt Open Source Edition and certain <a href="http://qt.nokia.com/doc/4.5/commercialeditions.html">Qt Commercial Editions</a>.</p>

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  49. <p>The QtService class functionality is inherited from <a href="qtservicebase.html">QtServiceBase</a>, but in addition the QtService class binds an instance of <a href="qtservicebase.html">QtServiceBase</a> with an application type.</p>

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  50. <p>Typically, you will create a service by subclassing the QtService template class. For example:</p>

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  51. <pre> class MyService : public QtService&lt;QApplication&gt;

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  52.  {

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  53.  public:

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  54.      MyService(int argc, char **argv);

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  55.      ~MyService();

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  57.  protected:

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  58.      void start();

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  59.      void stop();

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  60.      void pause();

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  61.      void resume();

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  62.      void processCommand(int code);

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  63.  };</pre>

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  64. <p>The application type can be <a href="http://qt.nokia.com/doc/4.5/qcoreapplication.html">QCoreApplication</a> for services without GUI, <a href="http://qt.nokia.com/doc/4.5/qapplication.html">QApplication</a> for services with GUI or you can use your own custom application type.</p>

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  65. <p>You must reimplement the <a href="qtservicebase.html#start">QtServiceBase::start</a>() function to perform the service's work. Usually you create some main object on the heap which is the heart of your service.</p>

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  66. <p>In addition, you might want to reimplement the <a href="qtservicebase.html#pause">QtServiceBase::pause</a>(), <a href="qtservicebase.html#processCommand">QtServiceBase::processCommand</a>(), <a href="qtservicebase.html#resume">QtServiceBase::resume</a>() and <a href="qtservicebase.html#stop">QtServiceBase::stop</a>() to intervene the service's process on controller requests. You can control any given service using an instance of the <a href="qtservicecontroller.html">QtServiceController</a> class which also allows you to control services from separate applications. The mentioned functions are all virtual and won't do anything unless they are reimplemented.</p>

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  67. <p>Your custom service is typically instantiated in the application's main function. Then the main function will call your service's <a href="qtservicebase.html#exec">exec</a>() function, and return the result of that call. For example:</p>

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  68. <pre>     int main(int argc, char **argv)

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  69.      {

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  70.          MyService service(argc, argv);

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  71.          return service.exec();

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  72.      }</pre>

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  73. <p>When the <a href="qtservicebase.html#exec">exec</a>() function is called, it will parse the <a href="qtservicebase.html#servicespecificarguments">service specific arguments</a> passed in <tt>argv</tt>, perform the required actions, and exit.</p>

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  74. <p>If none of the arguments is recognized as service specific, <a href="qtservicebase.html#exec">exec</a>() will first call the <a href="qtservicebase.html#createApplication">createApplication</a>() function, then <a href="qtservicebase.html#executeApplication">executeApplication</a>() and finally the <a href="qtservicebase.html#start">start</a>() function. In the end, <a href="qtservicebase.html#exec">exec</a>() returns while the service continues in its own process waiting for commands from the service controller.</p>

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  75. <p>See also <a href="qtservicebase.html">QtServiceBase</a> and <a href="qtservicecontroller.html">QtServiceController</a>.</p>

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  76. <hr />

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  77. <h2>Member Function Documentation</h2>

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  78. <h3 class="fn"><a name="QtService"></a>QtService::QtService ( int <i>argc</i>, char ** <i>argv</i>, const <a href="http://qt.nokia.com/doc/4.5/qstring.html">QString</a> &amp; <i>name</i> )</h3>

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  79. <p>Constructs a <a href="qtservice.html">QtService</a> object called <i>name</i>. The <i>argc</i> and <i>argv</i> parameters are parsed after the <a href="qtservicebase.html#exec">exec</a>() function has been called. Then they are passed to the application's constructor.</p>

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  80. <p>There can only be one <a href="qtservice.html">QtService</a> object in a process.</p>

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  81. <p>See also <a href="qtservicebase.html#QtServiceBase">QtServiceBase</a>().</p>

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  82. <h3 class="fn"><a name="dtor.QtService"></a>QtService::~QtService ()</h3>

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  83. <p>Destroys the service object.</p>

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  84. <h3 class="fn"><a name="application"></a>Application * QtService::application () const&nbsp;&nbsp;<tt> [protected]</tt></h3>

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  85. <p>Returns a pointer to the application object.</p>

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