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dbus-1-tqt/tqdbusobject.h

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/* qdbusobject.h DBUS service object interface
*
* Copyright (C) 2005-2007 Kevin Krammer <kevin.krammer@gmx.at>
*
* Licensed under the Academic Free License version 2.1
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
* USA.
*
*/
#ifndef TQDBUSOBJECT_H
#define TQDBUSOBJECT_H
/**
* @page dbusservice Providing services over D-Bus
*
* Contents:
* - @ref dbusservice-introduction
* - @ref dbusservice-example
* - @ref dbusservice-requestname
* - @ref dbusservice-registerobjects
* - @ref dbusservice-interfaces
*
* @section dbusservice-introduction Introduction
*
* The TQt3 bindings do not support autogeneration of service objects yet. In
* order to provide interfaces over D-Bus, an application has to implement the
* TQT_DBusObjectBase interface and register an instance of the resulting class
* with the TQT_DBusConnection.
*
* @section dbusservice-example A simple D-Bus client example
*
* @code
* #include <dbus/tqdbusconnection.h>;
* #include <dbus/tqdbusobject.h>;
*
* class TQStringList;
*
* class TestService : public TQT_DBusObjectBase
* {
* public:
* TestService(const TQT_DBusConnection& connection);
* virtual ~TestService();
*
* protected:
* virtual bool handleMethodCall(const TQT_DBusMessage& message);
*
* private:
* TQT_DBusConnection m_connection;
*
* private:
* TQStringList sortStrings(const TQStringList& list);
* };
* @endcode
* @code
*
* #include <tqstringlist.h>;
*
* #include <dbus/tqdbuserror.h>;
* #include <dbus/tqdbusmessage.h>;
*
* TestService::TestService(const TQT_DBusConnection& connection) : m_connection(connection)
* {
* m_connection.registerObject("/ListSorter", this);
* }
*
* TestService::~TestService()
* {
* m_connection.unregisterObject("/ListSorter");
* }
*
* // return false to let D-Bus send a standard error message that the method is unknown
*
* bool TestService::handleMethod(const TQT_DBusMessage& message)
* {
* if (message.interface() != "org.example.Sort") return false;
*
* if (message.member() == "Strings")
* {
* // check parameters
*
* if (message.count() != 1 || message[0].type() != TQT_DBusData::List)
* {
* // method signature not what we expected
*
* TQT_DBusError error = TQT_DBusError::stdInvalidArgs(
* "Expected one argument of type array of string");
*
* TQT_DBusMessage reply = TQT_DBusMessage::methodError(message, error);
*
* // send error
*
* m_connection.send(reply);
*
* // tell D-Bus we did handle the call
*
* return true;
* }
*
* // call implementation
*
* TQStringList result = sortStrings(message[0].toTQStringList());
*
* // prepare reply
*
* TQT_DBusMessage reply = TQT_DBusMessage::methodReply(message);
*
* reply << TQT_DBusData::fromList(result);
*
* // send reply
*
* m_connection.send(reply);
*
* // tell D-Bus we did handle the call
*
* return true;
* }
*
* return false;
* }
*
* TQStringList TestService::sortStrings(const TQStringList& list)
* {
* TQStringList result = list;
*
* result.sort();
*
* return result;
* }
* @endcode
* @code
* int main(int argc, char** argv)
* {
* TQApplication app(argc, argv, false);
*
* TQT_DBusConnection connection = TQT_DBusConnection::sessionBus();
* if (!connection.isConnected())
* qFatal("Cannot connect to session bus");
*
* // try to get a specific service name
* if (!connection.requestName("org.example.SortService"))
* {
* qWarning("Requesting name 'org.example.SortService' failed. "
* "Will only be addressable through unique name '%s'",
* connection.uniqueName().local8Bit().data());
* }
* else
* {
* qDebug("Requesting name 'org.example.SortService' successfull");
* }
*
* TestService service(connection);
*
* return app.exec();
* }
* @endcode
*
* @section dbusservice-requestname Requesting service name
*
* When an application connects to D-Bus it gets a unique name generated by
* the bus daemon.
*
* However, an application providing service will often want to be reachable
* under a fixed name, like a webserver being reachable through a domain name
* independent from its actual IP address.
* See section @ref dbusconventions-servicename for details on service names.
*
* In order to get such a specific name an application has to request it
* using TQT_DBusConnection::requestName()
*
* The example above request @c "org.example.SortService" but continues with
* the default unique name in the case some other application is currently
* owning that name.
*
* @section dbusservice-registerobjects Registering objects
*
* To make service objects available to other applications on the same
* bus the application has to register the objects instances with the
* connection to the bus using TQT_DBusConnection::registerObject()
*
* Registering means to specify an object path where the object will be
* located, i.e. how it can be unambiguously be addressed in method calls.
* See section @ref dbusconventions-objectpath for details on object paths.
*
* If the applications has introspectable objects it is recommended to
* register an introspectable root object, i.e. using @c "/" as the path, so
* other applications have a common place to start asking for introspection
* data.
*
* In the example above a service object providing sorting services on lists is
* registered on the path @c "/ListSorter"
*
* @section dbusservice-interfaces Service interfaces
*
* D-Bus methods and signals of a service object a grouped into interfaces.
*
* See section @ref dbusconventions-interfacename for details on interface
* naming.
*
* An object can implement any number of interfaces, for example the interface
* for the functionality it wants to provide and a D-Bus standard interface like
* @c "org.freedesktop.DBus.Introspectable" for providing an XML description of
* all its interfaces.
*
*
* The service object of the example above implements just one interface
* @c "org.example.Sort" and its handleMethodCall() explicitly checks all
* received messages and rejects any messsage not sent to this particular
* interface by returning @c false and thus telling the D-Bus layer to
* generate a standard error response.
*
* Multiple interfaces can of course be directly implemented in one C++ class,
* however it might sometimes be wise to delegate calls for different
* interfaces to different implementations:
* @code
* class Interface1 : public TQT_DBusObjectBase
* {
* public:
* Interface1(const TQT_DBusConnection&);
*
* protected:
* virtual bool handleMethodCall(const TQT_DBusMessage&);
* };
*
* class Interface2 : public TQT_DBusObjectBase
* {
* public:
* Interface2(const TQT_DBusConnection&);
*
* protected:
* virtual bool handleMethodCall(const TQT_DBusMessage&);
* };
*
* class MultiInterfaceService : public TQT_DBusObjectBase
* {
* public:
* MultiInterfaceService(const TQT_DBusConnection&);
*
* protected:
* virtual bool handleMethodCall(const TQT_DBusMessage&);
*
* private:
* TQMap<TQString, TQT_DBusObjectBase*> m_interfaces;
* };
*
* MultiInterfaceService::MultiInterfaceService(const TQT_DBusConnection& connection)
* {
* m_interfaces.insert("org.example.Interface1", new Interface1(connection));
* m_interfaces.insert("org.example.Interface2", new Interface2(connection));
* }
*
* bool MultiInterfaceService::handleMethodCall(const TQT_DBusMessage& message)
* {
* // delegate call to its interface handler
* TQT_DBusObjectBase* handler = m_interfaces[message.interface()];
* if (handler != 0)
* return delegateMethodCall->(message, handler);
* else
* return false; // no such interface
* }
* @endcode
*/
/**
* @include example-service.h
* @example example-service.cpp
*/
#include "tqdbusmacros.h"
class TQT_DBusMessage;
/**
* @brief Base interface for D-Bus service objects
*
* In order to register a service object with the TQT_DBusConnection it needs to
* implement the interface specified by this class.
*
* The connection will forward all method calls that have a path equivalent
* to the path the service object was registered with to the object's
* handleMethodCall() method. See TQT_DBusConnection::registerObject()
*
* If for some reason, e.g. the call is not meant for this interface, or the
* method is unknown, the implementation can just return @c false and the
* connection will handle the rest.
*
* See section @ref dbusservice for documentation on how to use TQT_DBusObjectBase
*/
class TQDBUS_EXPORT TQT_DBusObjectBase
{
friend class TQT_DBusConnectionPrivate;
public:
/**
* @brief Destroys the object
*/
virtual ~TQT_DBusObjectBase() {}
protected:
/**
* @brief Method call entry point
*
* This method has to be implemented to handle method calls sent to the
* service object.
* An object implementation can handle all its interfaces in one class or
* again forward the method call to interface implementators.
*
* If for some reason, e.g. the call is not meant for this interface, or
* the method is unknown, the implementation can just return @c false and
* the connection will handle the rest.
*
* If an error occurs during the method call, e.g. the number of parameters
* or their types are not what would be expected, the service object
* should reply with a TQT_DBusMessage of type TQT_DBusMessage::ErrorMessage
* which in turn should include the D-Bus error describing the problem.
* See TQT_DBusConnection::send() for sending reply messages.
*
* See TQT_DBusMessage::methodError() and TQT_DBusMessage::methodReply() on
* how to create suitable reply messages for the given method call.
*
* @param message the method call to handle
*
* @return @c true if the message can be handled independent if handling
* resulted in an error. In this case implementations should an
* error reply. Returns @c false only if interface or method are
* unknown
*/
virtual bool handleMethodCall(const TQT_DBusMessage& message) = 0;
/**
* @brief Delegate a method call to another object
*
* When a service object is built as a collection of separated interface
* class instances, i.e. each interface of the object is implemented in
* its own TQT_DBusObjectBase subclass and the main object just wanst to pass
* on the method calls to the respective interface implementations, it
* can do so by calling this base class method.
*
* Since it is a method of the base class, it can call the otherwise
* protected handleMethodCall() of the interface implementor.
*
* See @ref dbusservice-interfaces for an example.
*
* @param message the method call to delegate
* @param delegate the object which should handle the call instead
*
* @return @c true if the message can be handled independent if handling
* resulted in an error. In this case implementations should an
* error reply. Returns @c false only if interface or method are
* unknown
*
*/
bool delegateMethodCall(const TQT_DBusMessage& message, TQT_DBusObjectBase* delegate)
{
return delegate->handleMethodCall(message);
}
};
#endif