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Separate Thread for the Service</p>  
  
<p class=BodyText> You can  
use the service's built-in service thread for simple services. For other types  
of services, you probably want to spawn a separate thread to execute the  
service's code. Whether or not you do this depends largely on what the service  
does. If, for example, the service is expected to handle multiple client  
requests, then you may want a separate thread for each client request. </p>  
  
<p class=BodyText> &nbsp; </p>  
  
<p class=BodyText> You  
should also use a separate thread for your service if your service performs  
lengthy startup tasks. The SCM allows two minutes for a service to start. The  
SCM instructs the service to start and then waits for a response from the  
service. If the response doesn't come back within two minutes, NT assumes that  
the service is hung and kills the service process. If your startup tasks will  
take longer than two minutes, you should spawn a separate thread to perform the  
startup tasks. This frees the service thread to handle service requests from  
the SCM. </p>  
  
<p class=BodyText> &nbsp; </p>  
  
<p class=BodyText> Figures  
5 and 6 show a modified beep service called BeepSrvcThread. This version of the  
beep services uses a separate thread to handle the service's code. </p>  
  
<p class=BodyText> &nbsp; </p>  
  
<p class=Code><span class=Code><span Class=CodeGrn>#ifndef  
BeepServiceThreadUH</span></span></p>  
  
<p class=Code><span class=Code><span Class=CodeGrn>#define  
BeepServiceThreadUH</span></span></p>  
  
<p class=Code><span class=Code>&nbsp; </span></p>  
  
<p class=Code><span class=Code><span Class=CodeGrn>#include  
&lt;SysUtils.hpp&gt; </span></span></p>  
  
<p class=Code><span class=Code><span Class=CodeGrn>#include  
&lt;Classes.hpp&gt; </span></span></p>  
  
<p class=Code><span class=Code><span Class=CodeGrn>#include  
&lt;SvcMgr.hpp&gt; </span></span></p>  
  
<p class=Code><span class=Code>&nbsp; </span></p>  
  
<p class=Code><span class=Code><b>class</b>  
TBeepThread : <b>public</b> TThread {</span></p>  
  
<p class=Code><span class=Code>&nbsp;&nbsp;<b> public</b>:</span></p>  
  
<p class=Code><span class=Code>&nbsp;&nbsp;&nbsp;&nbsp;<b> virtual</b>  
<b>__fastcall</b> <b>void</b> Execute();</span></p>  
  
<p class=Code><span class=Code>&nbsp;&nbsp;&nbsp;&nbsp;<b> __fastcall</b>  
TBeepThread(<b>bool</b> CreateSuspended); </span></p>  
  
<p class=Code><span class=Code>};</span></p>  
  
<p class=Code><span class=Code>&nbsp; </span></p>  
  
<p class=Code><span class=Code><b>class</b>  
TBeepServiceThread : <b>public</b> TService</span></p>  
  
<p class=Code><span class=Code>{</span></p>  
  
<p class=Code><span class=Code><b>__published</b>:&nbsp;&nbsp;&nbsp;&nbsp;<i> <span Class=CodeBlue>// IDE-managed Components</span></i></span></p>  
  
<p class=Code><span class=Code>&nbsp;&nbsp;<b> void</b>  
<b>__fastcall</b> BeepServiceThreadStart(</span></p>  
  
<p class=Code><span class=Code>&nbsp;&nbsp;&nbsp;&nbsp;TService *Sender, <b>bool</b> &amp;Started); </span></p>  
  
<p class=Code><span class=Code>&nbsp;&nbsp;<b> void</b>  
<b>__fastcall</b> BeepServiceThreadStop(</span></p>  
  
<p class=Code><span class=Code>&nbsp;&nbsp;&nbsp;&nbsp;TService *Sender, <b>bool</b> &amp;Stopped); </span></p>  
  
<p class=Code><span class=Code>&nbsp;&nbsp;<b> void</b>  
<b>__fastcall</b> BeepServiceThreadPause(</span></p>  
  
<p class=Code><span class=Code>&nbsp;&nbsp;&nbsp;&nbsp;TService *Sender, <b>bool</b> &amp;Paused); </span></p>  
  
<p class=Code><span class=Code>&nbsp;&nbsp;<b> void</b>  
<b>__fastcall</b>  
BeepServiceThreadContinue(</span></p>  
  
<p class=Code><span class=Code>&nbsp;&nbsp;&nbsp;&nbsp;TService *Sender, <b>bool</b> &amp;Continued); </span></p>  
  
<p class=Code><span class=Code><b>private</b>:&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<i> <span Class=CodeBlue>// User declarations</span></i></span></p>  
  
<p class=Code><span class=Code>&nbsp;&nbsp;TBeepThread* BeepThread; </span></p>  
  
<p class=Code><span class=Code><b>public</b>:&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<i> <span Class=CodeBlue>// User declarations</span></i></span></p>  
  
<p class=Code><span class=Code>&nbsp;&nbsp;<b> __fastcall</b>  
TBeepServiceThread(TComponent* Owner); </span></p>  
  
<p class=Code><span class=Code>&nbsp;&nbsp;PServiceController <b>__fastcall</b> GetServiceController(<b>void</b>);</span></p>  
  
<p class=Code><span class=Code>&nbsp;&nbsp;<b> friend</b>  
<b>void</b> <b>__stdcall</b> ServiceController(<b>unsigned</b>  
CtrlCode); </span></p>  
  
<p class=Code><span class=Code>};</span></p>  
  
<p class=Code><span class=Code>&nbsp; </span></p>  
  
<p class=Code><span class=Code><b>extern</b>  
PACKAGE TBeepServiceThread *BeepServiceThread; </span></p>  
  
<p class=Code><span class=Code>&nbsp; </span></p>  
  
<p class=Code><span class=Code><span Class=CodeGrn>#endif</span></span></p>  
  
<p class=Captions><b>Figure  
5:</b> The header for  
the BeepSrvcThread program. </p>  
  
<p class=BodyText> &nbsp; </p>  
  
<p class=Code><span class=Code><span Class=CodeGrn>#include  
&quot;BeepServiceThreadU.h&quot; </span></span></p>  
  
<p class=Code><span class=Code>&nbsp; </span></p>  
  
<p class=Code><span class=Code><span Class=CodeGrn>#pragma  
package(smart_init) </span></span></p>  
  
<p class=Code><span class=Code><span Class=CodeGrn>#pragma  
resource &quot;*.dfm&quot; </span></span></p>  
  
<p class=Code><span class=Code>&nbsp; </span></p>  
  
<p class=Code><span class=Code>TBeepServiceThread  
*BeepServiceThread; </span></p>  
  
<p class=Code><span class=Code>&nbsp; </span></p>  
  
<p class=Code><span class=Code><i><span Class=CodeBlue>// TBeepThread implementation</span></i></span></p>  
  
<p class=Code><span class=Code><b>__fastcall</b>  
TBeepThread::TBeepThread(<b>bool</b>  
CreateSuspended) </span></p>  
  
<p class=Code><span class=Code>&nbsp;: TThread(CreateSuspended) </span></p>  
  
<p class=Code><span class=Code>{</span></p>  
  
<p class=Code><span class=Code>}</span></p>  
  
<p class=Code><span class=Code>&nbsp; </span></p>  
  
<p class=Code><span class=Code><b>void</b> <b  
style='mso-bidi-font-weight:normal'>__fastcall</b> TBeepThread::Execute()</span></p>  
  
<p class=Code><span class=Code>{</span></p>  
  
<p class=Code><span class=Code>&nbsp;&nbsp;<b> while</b>  
(!Terminated) {</span></p>  
  
<p class=Code><span class=Code>&nbsp;&nbsp;&nbsp;&nbsp;MessageBeep(0); </span></p>  
  
<p class=Code><span class=Code>&nbsp;&nbsp;&nbsp;&nbsp;Sleep(1000); </span></p>  
  
<p class=Code><span class=Code>&nbsp;&nbsp;} </span></p>  
  
<p class=Code><span class=Code>}</span></p>  
  
<p class=Code><span class=Code>&nbsp; </span></p>  
  
<p class=Code><span class=Code><i><span Class=CodeBlue>// TBeepServiceThread implementation</span></i></span></p>  
  
<p class=Code><span class=Code><b>__fastcall</b>  
TBeepServiceThread::TBeepServiceThread(TComponent* Owner) </span></p>  
  
<p class=Code><span class=Code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;: TService(Owner) </span></p>  
  
<p class=Code><span class=Code>{</span></p>  
  
<p class=Code><span class=Code>}</span></p>  
  
<p class=Code><span class=Code>&nbsp; </span></p>  
  
<p class=Code><span class=Code>PServiceController  
<b>__fastcall</b></span></p>  
  
<p class=Code><span class=Code>&nbsp;&nbsp;TBeepServiceThread::GetServiceController(<b  
style='mso-bidi-font-weight:normal'>void</b>)</span></p>  
  
<p class=Code><span class=Code>{</span></p>  
  
<p class=Code><span class=Code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<b> return</b>  
(PServiceController) ServiceController; </span></p>  
  
<p class=Code><span class=Code>}</span></p>  
  
<p class=Code><span class=Code>&nbsp; </span></p>  
  
<p class=Code><span class=Code><b>void</b> <b  
style='mso-bidi-font-weight:normal'>__stdcall</b> ServiceController(<b  
style='mso-bidi-font-weight:normal'>unsigned</b> CtrlCode) </span></p>  
  
<p class=Code><span class=Code>{</span></p>  
  
<p class=Code><span class=Code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;BeepServiceThread-&gt;Controller(CtrlCode); </span></p>  
  
<p class=Code><span class=Code>}</span></p>  
  
<p class=Code><span class=Code>&nbsp; </span></p>  
  
<p class=Code><span class=Code><b>void</b> <b  
style='mso-bidi-font-weight:normal'>__fastcall</b> TBeepServiceThread::BeepServiceThreadStart(</span></p>  
  
<p class=Code><span class=Code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;TService *Sender, <b>bool</b> &amp;Started) </span></p>  
  
<p class=Code><span class=Code>{</span></p>  
  
<p class=Code><span class=Code>&nbsp;&nbsp;BeepThread = <b>new</b> TBeepThread(<b>false</b>);</span></p>  
  
<p class=Code><span class=Code>&nbsp;&nbsp;Started = <b>true</b>;</span></p>  
  
<p class=Code><span class=Code>}</span></p>  
  
<p class=Code><span class=Code>&nbsp; </span></p>  
  
<p class=Code><span class=Code><b>void</b> <b  
style='mso-bidi-font-weight:normal'>__fastcall</b>  
TBeepServiceThread::BeepServiceThreadStop(</span></p>  
  
<p class=Code><span class=Code>&nbsp;&nbsp;TService *Sender, <b>bool</b> &amp;Stopped)&lt;$I~services;threads&gt;&lt;$I~threads;services&gt;&lt;$I~Windows  
NT;services;threads&gt;&lt;$I~BeepService program  
example;threads&gt;&lt;$I~Windows NT;services;BeepService program example&gt; </span></p>  
  
<p class=Code><span class=Code>{</span></p>  
  
<p class=Code><span class=Code>&nbsp;&nbsp;BeepThread-&gt;Terminate();</span></p>  
  
<p class=Code><span class=Code>&nbsp;&nbsp;Stopped = <b>true</b>;</span></p>  
  
<p class=Code><span class=Code>}</span></p>  
  
<p class=Code><span class=Code><b>void</b> <b  
style='mso-bidi-font-weight:normal'>__fastcall</b>  
TBeepServiceThread::BeepServiceThreadPause(</span></p>  
  
<p class=Code><span class=Code>&nbsp;&nbsp; TService *Sender, <b>bool</b>  
&amp;Paused) </span></p>  
  
<p class=Code><span class=Code>{</span></p>  
  
<p class=Code><span class=Code>&nbsp;&nbsp;BeepThread-&gt;Suspend();</span></p>  
  
<p class=Code><span class=Code>&nbsp;&nbsp;Paused = <b>true</b>;</span></p>  
  
<p class=Code><span class=Code>}</span></p>  
  
<p class=Code><span class=Code>&nbsp; </span></p>  
  
<p class=Code><span class=Code><b>void</b> <b  
style='mso-bidi-font-weight:normal'>__fastcall</b>  
TBeepServiceThread::BeepServiceThreadContinue(</span></p>  
  
<p class=Code><span class=Code>&nbsp;&nbsp;TService *Sender, <b>bool</b> &amp;Continued) </span></p>  
  
<p class=Code><span class=Code>{</span></p>  
  
<p class=Code><span class=Code>&nbsp;&nbsp;BeepThread-&gt;Resume();</span></p>  
  
<p class=Code><span class=Code>&nbsp;&nbsp;Continued = <b>true</b>;</span></p>  
  
<p class=Code><span class=Code>}</span></p>  
  
<p class=Captions><b>Figure  
6: </b>The source code  
for the BeepSrvcThread program. </p>  
  
<p class=BodyText> &nbsp; </p>  
  
<p class=BodyText> There  
are two important differences between this service and the BeepService program  
presented earlier: </p>  
  
<p class=BodyText> 1) &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;  
This  
service does not use the service's <i>OnExecute</i>  
event. </p>  
  
<p class=BodyText> 2) &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;  
This  
service provides event handlers for the <i>OnStart</i>,  
<i>OnStop</i>, <i>OnPause</i>, and <i>OnContinue</i>  
events. </p>  
  
<p class=BodyText> &nbsp; </p>  
  
<p class=BodyText> Since I  
am not using the service's built-in service thread, I must take responsibility  
for specifically starting, stopping, suspending, and resuming my thread when  
the SCM sends the start, stop, pause, or continue requests. For example, the <i  
style='mso-bidi-font-style:normal'>OnPause</i> and <i>OnContinue</i> event handlers look like Figure 7. </p>  
  
<p class=BodyText> &nbsp; </p>  
  
<p class=Code><span class=Code><b>void</b> <b  
style='mso-bidi-font-weight:normal'>__fastcall</b>  
TBeepServiceThread::BeepServiceThreadPause(</span></p>  
  
<p class=Code><span class=Code>&nbsp;&nbsp;TService *Sender, <b>bool</b> &amp;Paused) </span></p>  
  
<p class=Code><span class=Code>{</span></p>  
  
<p class=Code><span class=Code>&nbsp;&nbsp;BeepThread-&gt;Suspend();</span></p>  
  
<p class=Code><span class=Code>&nbsp;&nbsp;Paused = <b>true</b>;</span></p>  
  
<p class=Code><span class=Code>}</span></p>