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| {{Template:I18n/Language Navigation Bar|Development/Tutorials/Session Management}}
| | This tutorial was updated and moved to https://develop.kde.org/docs/features/session-managment/ |
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| {{Under Construction}}
| | [[Category:MovedDevelop]] |
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| ==About KDE and X11 session management==
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| KDE supports the legacy X11R4 and ICCCM session
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| management protocols. Legacy applications that define the <tt>WM_COMMAND</tt>
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| property or support the <tt>WM_SAVE_YOURSELF</tt> protocol will be restarted
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| with the specified command. The window geometries will be restored on a best
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| effort basis.
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| Since version 2.0, KDE also supports and uses the standard X11R6
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| session management protocol XSMP. The official documentation of the
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| standard can be download from the X Consortium's FTP server
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| [http://stuff.mit.edu/afs/sipb/contrib/doc/X11/hardcopy/SM/xsmp.PS.gz ftp.x.org].
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| Unlike these legacy protocols, the new X11R6 session management gives a
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| chance to save application dependent settings when you log out. A text
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| editor, for instance, would save the names of the loaded files and would
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| reload them when you log in again. Another major advantage of the new
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| protocol is the support for a clean and safe logout procedure even if the
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| users decides not to restore the session next time. The protocol gives
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| applications the possibility to interact with the user in case they are in
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| danger to lose some data, and to cancel the shutdown process if necessary.
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| ==Further Reading==
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| An introductive overview of session management functionality and
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| the Qt API for it is available from [http://doc.trolltech.com/4.4/session.html doc.trolltech.com].
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| In KDE, the classes [http://api.kde.org/4.x-api/kdelibs-apidocs/kdeui/html/classKApplication.html KApplication]
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| and [http://api.kde.org/4.x-api/kdelibs-apidocs/kdeui/html/classKMainWindow.html KMainWindow]
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| hide all the ugly details from the programmer. Basically, a
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| [http://api.kde.org/4.x-api/kdelibs-apidocs/kdeui/html/classKApplication.html KApplication] manages a
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| [http://api.kde.org/4.x-api/kdelibs-apidocs/kdecore/html/classKConfig.html KConfig] configuration object
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| [http://api.kde.org/4.x-api/kdelibs-apidocs/kdeui/html/classKApplication.html#8f88369c240d6d90a04d29b2761989d9 sessionConfig()]
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| for you, that your application can utilize to store session specific data.
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| Please read the respective class documentation, especially the one of
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| [http://api.kde.org/4.x-api/kdelibs-apidocs/kdeui/html/classKMainWindow.html KMainWindow], for a detailed interface description. With the advanced
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| functionality in [http://api.kde.org/4.x-api/kdelibs-apidocs/kdeui/html/classKMainWindow.html KMainWindow], it's really just a matter of a few lines to get even a multi-window application to retains its state between
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| different user sessions.
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| ==Implementing session management in your application==
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| Here's just a brief overview how things are done. Again, see the
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| respective class documentation for details.
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| ===Add session management support to your main() function===
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| ====For one kind of toplevel widget====
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| If your client has only one kind of toplevel widgets (which should be pretty usual) then you should use the RESTORE-macro for backwards compatibility with 3.1 and 3.0 branches.
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| Imagine you have an
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| application with a main window MyWindow inherited from
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| [http://api.kde.org/4.x-api/kdelibs-apidocs/kdeui/html/classKMainWindow.html KMainWindow] (or from
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| [http://api.kde.org/4.x-api/kdelibs-apidocs/kdeui/html/classKXmlGuiWindow.html KXmlGuiWindow], which inherits from
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| [http://api.kde.org/4.x-api/kdelibs-apidocs/kdeui/html/classKMainWindow.html KMainWindow]). In your main() function, you would then create/restore the
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| application windows with something like:
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| <code cppqt>
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| KApplication app;
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| if ( kapp->isSessionRestored() ) {
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| RESTORE( MyWindow )
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| } else {
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| // create default application as usual
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| // for example:
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| MyWindow* window = new MyWindow();
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| window->show();
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| }
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| return app.exec();
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| </code>
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| ====For several kinds of toplevel widget====
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| It is also possible to
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| restore different types of toplevel windows within one application. In
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| that case, the RESTORE macro is too primitive. If you have more than one
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| kind of toplevel widget (each derived from [http://api.kde.org/4.x-api/kdelibs-apidocs/kdeui/html/classKMainWindow.html KMainWindow], of course), you
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| can use the templated kRestoreMainWindows global functions:
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| <code cppqt>
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| KApplication app;
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| if ( kapp->isSessionRestored() ) {
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| kRestoreMainWindows< childMW1, childMW2, childMW3 >();
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| } else {
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| // create default application as usual
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| // for example:
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| childMW1* window1 = new childMW1();
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| childMW2* window2 = new childMW2();
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| childMW3* window3 = new childMW3();
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| window1->show();
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| window2->show();
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| window3->show();
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| }
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| return app.exec();
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| </code>
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| Currently, these functions are provided for up to three template arguments.
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| ===Reimplement some virtual functions of KMainWindow===
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| You reimplement the store/restore handlers in MyWindow to save and
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| restore all additional settings. For a text editor, that would be the
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| loaded files, for example:
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| <code cppqt>
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| void MyWindow::saveProperties( KConfig* )
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| {
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| // save properties here
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| }
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| void MyWindow::readProperties( KConfig* )
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| {
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| // read properties here
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| }
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| </code>
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| Note that standard settings like window sizes, toolbar settings
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| etc. are automatically handled.
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| ==Appendix: Architecture of the KDE session manager==
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| The session management server in KDE is called '''ksmserver''' and it is
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| part of the '''kdebase''' package. The server interacts with the KDE window
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| manager '''kwin''' to save and restore the window geometries and to perform
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| legacy session management. To make session management work, '''ksmserver'''
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| has to be started as last process of the X login procedure. This happens
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| automatically at the end of the '''startkde''' script.
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| [[Category:Programming]]
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| [[Category:Tutorial]]
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| [[Category:FAQs]] | |
