appmotor/doc/mainpage.dox

/*! \mainpage Applauncherd Usage

\section intro Introduction

Invoker (front-end binary) and applauncherd (daemon) are tools that helps applications launch faster and save memory via shared resources. This is achieved by preloading a set of dynamically linked libraries and caching stuff
(MComponentCache, MDeclarativeCache). There's a also a possibility to configure an application-specific splash screen, which is shown before the application is started. Also a single-instance support is provided to allow only one instance of an application at a time. 

This documentation describes the idea behind this functionality and how to utilize it.

\section contents Contents

- \ref howdoesitwork "How does it work?"

- How to enable boosted startup for different types of applications: 
  - \ref qmlboost "QML"
  - \ref qtboost "Qt"
  - \ref libmeegotouchboost "MeeGo Touch"
  - \ref eboost "Generic booster for all applications"

- \ref splash "How to enable splash screen for the application"

- \ref singleinstance "How to enable single instance support for the application"

- \ref debug "How to debug boosted applications"

- \ref dbus "How to use applauncherd with D-Bus"

- \ref aegis "Aegis platform security and applauncherd"

- \ref limitations "Limitations and known issues"

- \ref invokerparameters "Advanced invoker command line parameters"

- \ref customboosters "How to write custom boosters"

- \ref technical "Technical overview"

\page compilinglinking Compiling and linking your application

Binaries intended to be run with applauncherd should be compiled with -fPIC option
to produce position independent code. In order to produce a position independent
executable, -pie option and -rdynamic options can be used in linking. This allows
the result to be executed both traditionally and with the launcher.

To improve linking and loading times of shared object libraries the size of dynamic
export table it is encouraged to hide the unnecessary symbols from the resulting
binary by using -fvisibility=hidden and -fvisibility-inlines-hidden flags as well.

\section changestocode Changes to the code

With -fvisibility=hidden you must make sure that the symbol for main() is
exported, because otherwise the launcher is not able to find the entry point
for your application. This can be done like this (MeeGo Touch):

\code
  #include <MExport>

  M_EXPORT int main(int argc, char **argv)
  {
  ...
  }
\endcode

or like this (Qt):

\code
  #include <QtCore/QtGlobal>
  
  Q_DECL_EXPORT int main(int argc, char **argv)
  {
  ...
  }
\endcode

or like this (generic way with gcc):

\code
  extern "C" __attribute__ ((__visibility__("default"))) int main(int argc, char **argv)
  {
  ...
  }
\endcode

\section buildconfiguration Build configuration

These instructions describe how to build your application so that it
can be launched using applauncherd. Only Debian packaging is considered,
you have to creatively apply the instructions if you are doing RPM packaging.

\li \subpage usingqmake "Using QMake"
\li \subpage usingcmake "Using cmake"
\li \subpage usingpkgconfig "Using pkg-config"

\page usingqmake  Using QMake

  If you are using QMake, making your application boostable is just a
  matter of adding a suitable configuration option.

  For MeeGo Touch applications, install the libmeegotouch-dev package. If you
  are creating Debian packages, your application must build-depend on
  libmeegotouch-dev to build correctly. Add the following line in your .pro
  file (the meegotouch-boostable configuration option includes the meegotouch
  option so you should not specify it explicitly):

\verbatim
    CONFIG += meegotouch-boostable
\endverbatim

  For Qt Declarative (QML) applications, and plain Qt applications, the configuration 
  option is provided by the applauncherd-dev package. Again, a build dependency is 
  required for correct building of Debian packages. The configuration options are:

\verbatim
    CONFIG += qdeclarative-boostable
\endverbatim
\verbatim
    CONFIG += qt-boostable
\endverbatim

  If you want to use pkg-config directly for some reason (like getting
  error messages), you can add explicit pkg-config calls in the appropriate
  flags. 

  For MeeGo Touch, the flags are:

\verbatim
    QMAKE_CXXFLAGS += `pkg-config --cflags meegotouch-boostable`
    QMAKE_LFLAGS += `pkg-config --libs meegotouch-boostable`
\endverbatim

  For Qt Declarative, the flags are:

\verbatim
    QMAKE_CXXFLAGS += `pkg-config --cflags qdeclarative-boostable`
    QMAKE_LFLAGS += `pkg-config --libs qdeclarative-boostable`
\endverbatim

  For plain Qt, the flags are:

\verbatim
    QMAKE_CXXFLAGS += `pkg-config --cflags qt-boostable`
    QMAKE_LFLAGS += `pkg-config --libs qt-boostable`
\endverbatim

  You can also manually set the options in your .pro file like this:

\verbatim
    QMAKE_CXXFLAGS += -fPIC -fvisibility=hidden -fvisibility-inlines-hidden
    QMAKE_LFLAGS += -pie -rdynamic
\endverbatim

  Note that in this case you have to update the flags manually if there are any
  changes in the required flags.

\page usingcmake Using CMake

  You can utilize pkg-config in CMake by including FindPkgConfig in CMakeLists.txt:

\verbatim
  include(FindPkgConfig) 
\endverbatim

  To get Debian packages built correctly, make the package build-depend on libmeegotouch-dev 
  for MeeGo Touch applications, and on applauncherd-dev for other cases. To obtain the 
  compiler and linker flags, add the following lines in CMakeLists.txt.

  For MeeGo Touch applications:

\verbatim
  pkg_check_modules(MEEGOTOUCH_BOOSTABLE REQUIRED meegotouch-boostable)
  add_definitions(${MEEGOTOUCH_BOOSTABLE_CFLAGS})
  link_libraries(${MEEGOTOUCH_BOOSTABLE_LDFLAGS})
\endverbatim

  For Qt Declarative applications:

\verbatim
  pkg_check_modules(QDECLARATIVE_BOOSTABLE REQUIRED qdeclarative-boostable)
  add_definitions(${QDECLARATIVE_BOOSTABLE_CFLAGS})
  link_libraries(${QDECLARATIVE_BOOSTABLE_LDFLAGS})
\endverbatim

  For plain Qt applications:

\verbatim
  pkg_check_modules(QT_BOOSTABLE REQUIRED qt-boostable)
  add_definitions(${QT_BOOSTABLE_CFLAGS})
  link_libraries(${QT_BOOSTABLE_LDFLAGS})
\endverbatim
  
  If you do not want to use pkg-config for some reason, you can manually add the
  compiler and linker flags like this:

\verbatim
  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fPIC -fvisibility=hidden -fvisibility-inlines-hidden")
  set(CMAKE_EXE_LINKER_FLAGS "-pie -rdynamic")
\endverbatim
  
  Again, this requires you to update the flags if something changes.

\page usingpkgconfig Automatic settings with pkg-config (any build system)

  To get Debian packages built correctly, make the package build-depend on libmeegotouch-dev 
  for MeeGo Touch applications, and on applauncherd-dev for other cases. The correct 
  flags can be automatically obtained with one of:

\verbatim
    pkg-config --cflags meegotouch-boostable
    pkg-config --libs meegotouch-boostable
\endverbatim

\verbatim
    pkg-config --cflags qdeclarative-boostable
    pkg-config --libs qdeclarative-boostable
\endverbatim

\verbatim
    pkg-config --cflags qt-boostable
    pkg-config --libs qt-boostable
\endverbatim

\page invoker Launching your application using invoker

The application to be launched must be "invoked" using the invoker executable.
Invoker then sends the application data, essentially arguments and environment, 
to the launcher daemon via a socket connection. The launched application will
see its real binary name in its argv[0].

The invoker can also provide

\li \subpage splash "A splash screen"

\li \subpage singleinstance "Single instance behavior"

\section commandline Launch from the command-line

Use one of the following invoker options to identify what kind of application
you are launching. In these examples --type=m is used.

   \li \c --type=m           MeeGo Touch applications
   \li \c --type=d           Qt Declarative applications
   \li \c --type=qt          Qt applications and everything else (see section 7). 

Here is a launch example for a MeeGo Touch application:

\verbatim
  /usr/bin/invoker --type=m <application_name>
\endverbatim

\page usingboosters Using boosters

The booster processes can speed up application startup by doing some
application independent initialization beforehand. This section
documents the use of the qdeclarativebooster (QML booster), see the MeeGo Touch
documentation for boosting MeeGo Touch applications similarly.

\section changesqml Changes to code with QML booster

The application cannot directly instantiate QApplication and
QDeclarativeView. Instead of writing e.g.

\verbatim
      QApplication app;
      QDeclarativeView view;
\endverbatim

you need to pick up instances of QApplication and QDeclarativeView from a cache:

\verbatim
     QApplication *app = MDeclarativeCache::qApplication(argc, argv);
     QDeclarativeView *window = MDeclarativeCache::qDeclarativeView();
\endverbatim

See the MDeclarativeCache documentation for details.

\page starting Starting applauncherd

Applauncherd is usually started by UpStart (Harmattan) or uxlaunch (MeeGo) at boot,
but it can be also started manually in scratchbox or in the device by the /usr/bin/applauncherd
script. Applauncherd does not daemonize itself by default. If daemonizing is
wanted, use --daemon command-line parameter.

\section bootmode Boot mode

There is a special boot mode that can be used to speed up device boots when
applauncherd is used. 

In boot mode, no booster caches are initialized and the booster respawn delay is 
set to zero to ensure quick booster restarts after launches.

The boot mode is activated by starting applauncherd with --boot-mode. Normal mode
can be entered again by sending SIGUSR1 Unix signal to the launcher.

Boot mode can be activated also by sending SIGUSR2 Unix signal to the launcher.

\section debuginfo Debug info

Applauncherd logs to syslog.
Additional debug messages and logging also to stdout can be enabled with --debug.

\page dependencies Package Dependencies

Applications using the launcher must depend on the applauncherd package.

\page otherboosters Other boosters

Warning: behavior of these boosters is subject to change.

Qt booster is a no-operation booster. It can be used by calling 
invoker --type=qt. Qt booster requires only that main() is exported
with M_EXPORT (or Q_DECL_EXPORT).
Any MeeGo Touch boostable application can be launched with this booster 
type as well, but it results in a slower start-up because of empty cache.


\page commandlineparams Command line parameters

All parameters are listed by:

\verbatim
invoker --help
\endverbatim

\verbatim
applauncherd --help
\endverbatim

\page moreinformation More information

See MeeGo Touch documentation for fast application startup.

*/