Library: Util
Package: Application
Header: Poco/Util/Application.h
The Application class implements the main subsystem in a process. The application class is responsible for initializing all its subsystems.
Subclasses can and should override the following virtual methods:
The application's main logic should be implemented in the main() method.
There may be at most one instance of the Application class in a process.
The Application class maintains a LayeredConfiguration (available via the config() member function) consisting of:
The Application class sets a few default properties in its configuration. These are:
If loadConfiguration() has never been called, application.configDir will be equal to application.dir.
The POCO_APP_MAIN macro can be used to implement main(argc, argv). If POCO has been built with POCO_WIN32_UTF8, POCO_APP_MAIN supports Unicode command line arguments.
Direct Base Classes: Subsystem
All Base Classes: Poco::RefCountedObject, Subsystem
Known Derived Classes: ServerApplication
Member Functions: addSubsystem, commandName, config, defineOptions, findFile, getSubsystem, handleOption, init, initialize, initialized, instance, loadConfiguration, logger, main, name, options, reinitialize, run, setLogger, setUnixOptions, startTime, stopOptionsProcessing, uninitialize, uptime
Inherited Functions: defineOptions, duplicate, initialize, name, referenceCount, reinitialize, release, uninitialize
PRIO_APPLICATION = - 100
PRIO_DEFAULT = 0
PRIO_SYSTEM = 100
Commonly used exit status codes. Based on the definitions in the 4.3BSD <sysexits.h> header file.
EXIT_OK = 0
successful termination
EXIT_USAGE = 64
command line usage error
EXIT_DATAERR = 65
data format error
EXIT_NOINPUT = 66
cannot open input
EXIT_NOUSER = 67
addressee unknown
EXIT_NOHOST = 68
host name unknown
EXIT_UNAVAILABLE = 69
service unavailable
EXIT_SOFTWARE = 70
internal software error
EXIT_OSERR = 71
system error (e.g., can't fork)
EXIT_OSFILE = 72
critical OS file missing
EXIT_CANTCREAT = 73
can't create (user) output file
EXIT_IOERR = 74
input/output error
EXIT_TEMPFAIL = 75
temp failure; user is invited to retry
EXIT_PROTOCOL = 76
remote error in protocol
EXIT_NOPERM = 77
permission denied
EXIT_CONFIG = 78
configuration error
Application();
Creates the Application.
Application(
int argc,
char * argv[]
);
Creates the Application and calls init(argc, argv).
~Application();
Destroys the Application and deletes all registered subsystems.
void addSubsystem(
Subsystem * pSubsystem
);
Adds a new subsystem to the application. The application immediately takes ownership of it, so that a call in the form
Application::instance().addSubsystem(new MySubsystem);
is okay.
std::string commandName() const;
Returns the command name used to invoke the application.
LayeredConfiguration & config() const;
Returns the application's configuration.
template < class C > C & getSubsystem() const;
Returns a reference to the subsystem of the class given as template argument.
Throws a NotFoundException if such a subsystem has not been registered.
void init(
int argc,
char * argv[]
);
Processes the application's command line arguments and sets the application's properties (e.g., "application.path", "application.name", etc.).
Note that as of release 1.3.7, init() no longer calls initialize(). This is now called from run().
void init(
int argc,
wchar_t * argv[]
);
Processes the application's command line arguments and sets the application's properties (e.g., "application.path", "application.name", etc.).
Note that as of release 1.3.7, init() no longer calls initialize(). This is now called from run().
This Windows-specific version of init is used for passing Unicode command line arguments from wmain().
void init(
const std::vector < std::string > & args
);
Processes the application's command line arguments and sets the application's properties (e.g., "application.path", "application.name", etc.).
Note that as of release 1.3.7, init() no longer calls initialize(). This is now called from run().
bool initialized() const;
Returns true if and only if the application is in initialized state (that means, has been initialized but not yet uninitialized).
static Application & instance();
Returns a reference to the Application singleton.
Throws a NullPointerException if no Application instance exists.
int loadConfiguration(
int priority = PRIO_DEFAULT
);
Loads configuration information from a default location.
The configuration(s) will be added to the application's LayeredConfiguration with the given priority.
The configuration file(s) must be located in the same directory as the executable or a parent directory of it, and must have the same base name as the executable, with one of the following extensions: .properties, .ini or .xml.
The .properties file, if it exists, is loaded first, followed by the .ini file and the .xml file.
If the application is built in debug mode (the _DEBUG preprocessor macro is defined) and the base name of the appication executable ends with a 'd', a config file without the 'd' ending its base name is also found.
Example: Given the application "SampleAppd.exe", built in debug mode. Then loadConfiguration() will automatically find a configuration file named "SampleApp.properties" if it exists and if "SampleAppd.properties" cannot be found.
Returns the number of configuration files loaded, which may be zero.
This method must not be called before init(argc, argv) has been called.
void loadConfiguration(
const std::string & path,
int priority = PRIO_DEFAULT
);
Loads configuration information from the file specified by the given path. The file type is determined by the file extension. The following extensions are supported:
Extensions are not case sensitive.
The configuration will be added to the application's LayeredConfiguration with the given priority.
Poco::Logger & logger() const;
Returns the application's logger.
Before the logging subsystem has been initialized, the application's logger is "ApplicationStartup", which is connected to a ConsoleChannel.
After the logging subsystem has been initialized, which usually happens as the first action in Application::initialize(), the application's logger is the one specified by the "application.logger" configuration property. If that property is not specified, the logger is "Application".
const char * name() const;
See also: Poco::Util::Subsystem::name()
const OptionSet & options() const;
Returns the application's option set.
virtual int run();
Runs the application by performing additional initializations and calling the main() method.
First calls initialize(), then calls main(), and finally calls uninitialize(). The latter will be called even if main() throws an exception. If initialize() throws an exception, main() will not be called and the exception will be propagated to the caller.
void setUnixOptions(
bool flag
);
Specify whether command line option handling is Unix-style (flag == true; default) or Windows/OpenVMS-style (flag == false).
This member function should be called from the constructor of a subclass to be effective.
const Poco::Timestamp & startTime() const;
Returns the application start time (UTC).
void stopOptionsProcessing();
If called from an option callback, stops all further options processing.
If called, the following options on the command line will not be processed, and required options will not be checked.
This is useful, for example, if an option for displaying help information has been encountered and no other things besides displaying help shall be done.
Poco::Timespan uptime() const;
Returns the application uptime.
virtual void defineOptions(
OptionSet & options
);
Called before command line processing begins. If a subclass wants to support command line arguments, it must override this method. The default implementation does not define any options itself, but calls defineOptions() on all registered subsystems.
Overriding implementations should call the base class implementation.
See also: Poco::Util::Subsystem::defineOptions()
bool findFile(
Poco::Path & path
) const;
Searches for the file in path in the application directory.
If path is absolute, the method immediately returns true and leaves path unchanged.
If path is relative, searches for the file in the application directory and in all subsequent parent directories. Returns true and stores the absolute path to the file in path if the file could be found. Returns false and leaves path unchanged otherwise.
virtual void handleOption(
const std::string & name,
const std::string & value
);
Called when the option with the given name is encountered during command line arguments processing.
The default implementation does option validation, bindings and callback handling.
Overriding implementations must call the base class implementation.
void init();
Common initialization code.
void initialize(
Application & self
);
Initializes the application and all registered subsystems. Subsystems are always initialized in the exact same order in which they have been registered.
Overriding implementations must call the base class implementation.
See also: Poco::Util::Subsystem::initialize()
virtual int main(
const std::vector < std::string > & args
);
The application's main logic.
Unprocessed command line arguments are passed in args. Note that all original command line arguments are available via the properties application.argc and application.argv[<n>].
Returns an exit code which should be one of the values from the ExitCode enumeration.
void reinitialize(
Application & self
);
Re-nitializes the application and all registered subsystems. Subsystems are always reinitialized in the exact same order in which they have been registered.
Overriding implementations must call the base class implementation.
See also: Poco::Util::Subsystem::reinitialize()
void setLogger(
Poco::Logger & logger
);
Sets the logger used by the application.
void uninitialize();
Uninitializes the application and all registered subsystems. Subsystems are always uninitialized in reverse order in which they have been initialized.
Overriding implementations must call the base class implementation.
See also: Poco::Util::Subsystem::uninitialize()