If you want to have an external timer run on the application to give the application a 'tic' that can be used to stimulate automatic actions within the web page, there are a few methods.

One method is to install a WTimer somewhere within the application and use it to drive signal events. The difficulty, however, with these timers is that they place a load on both the web-browser and the network connection as the WTimer is actually running within the web-browser, and must send events back to the server through the network. This can generate oddities in the UI experience.

Another method is to fire a separate thread that imposes a simple delay and then calls-back in to the application to stimulate timer 'tic' events.

Difference between thread timer and browser timer: Timer in Thread Timer in Browser Button in Browser
--------------- ---------------- -----------------
thread Browser Browser
Timer (sleep) Timer (sleep) Button (click)
App (wake) Network Network
event() Internet Internet
Network Network
Service Service
App (wake) App (wake)
event() event()

190   std::thread thread( Rtm::AppBase::tic_handler, this );
191   thread.detach();
192
193 } // endvoid Rtm::AppBase::init( )
194
195 void Rtm::AppBase::tic_handler( Rtm::AppBase * app ) // this is a static function
196 {
197   /*
198   ** If there is no app-pointer, then quit.
199   **
200   */
201   if( !app )
202     return;
203
204   /*
205   ** This task just runs forever, sleeping for a bit, and then
206   **  waking the app.
207   **
208   */
209   while( true )
210   {
211     /*
212     ** Sleep this thread for just one second
213     **  before doing anything
214     **
215     */
216     std::this_thread::sleep_for( std::chrono::seconds(1) );
217
218     /*
219     ** If the application has already quit, then there's nothing to do.
220     **
221     */
222     if( app-> hasQuit() )
223       return;
224
225     /*
226     ** Acquire an application lock.  If the application is busy handling
227     **  some user interaction, this call will block until that other
228     **  task has completed.
229     **
230     */
231     Wt::WApplication::UpdateLock lock( app );
232
233     /*
234     ** If we could not get a lock, then quit.  If we could not get a lock,
235     **  then it sort of implies that the application was being destroyed.
236     **  In that case, we don't want to do anything more anyhow, so we just
237     **  quit.
238     **
239     */
240     if( !lock )
241       return;
242
243     /*
244     ** Make the tic happen
245     **
246     */
247     app-> tic();
248
249     /*
250     ** After everything has fired, trigger an update.
251     **
252     */
253     app-> triggerUpdate();
254
255   } // endwhile( true )
256
257 } // endvoid Rtm::AppBase::tic_handler( Rtm::AppBase * app )
258
2024 void AdminWidget::hold_me()
2025 {
2026   for( int i = 0; i < 10; i++ )
2027   {
2028     std::cout << __FILE__ << ":" << __LINE__ << " holding... " << i << std::endl;
2029
2030     std::this_thread::sleep_for( std::chrono::seconds(1) );
2031   }
2032
2033   std::cout << __FILE__ << ":" << __LINE__ << " held." << std::endl;
2034
2035 }
2036
AppBase.cpp:198 0
[2020-Jul-08 08:45:25.400] AppBase.cpp:298 logs/Admin(1)/2020-07-08.log Admin(1) buildSite logon ip:71.170.246.90 w:1920 h:1080
[2020-Jul-08 13:45:26.471] 26022 [/staff2 tg4JC7kUmbwSwunn] [warning] "WApplication: WApplication::addMetaHeader() with no effect"
AppBase.cpp:198 1
[2020-Jul-08 13:45:27.406] 26022 [/staff2 tg4JC7kUmbwSwunn] [error] "Wt: decodeSignal(): signal 'orp26iu.render' not exposed"
AppBase.cpp:198 2
AppBase.cpp:198 3
AppBase.cpp:198 4
AppBase.cpp:198 5
src/AppStaff.cpp:2028 holding... 0
src/AppStaff.cpp:2028 holding... 1
src/AppStaff.cpp:2028 holding... 2
src/AppStaff.cpp:2028 holding... 3
src/AppStaff.cpp:2028 holding... 4
src/AppStaff.cpp:2028 holding... 5
src/AppStaff.cpp:2028 holding... 6
src/AppStaff.cpp:2028 holding... 7
src/AppStaff.cpp:2028 holding... 8
src/AppStaff.cpp:2028 holding... 9
src/AppStaff.cpp:2033 held.
AppBase.cpp:198 6
AppBase.cpp:198 7
AppBase.cpp:198 8
AppBase.cpp:198 9
^Csleep for 1