TDE DBus Tutorial
Revision as of 18:19, 5 August 2018 by imported>Deloptes (→Test the service with proxy client)
Introduction
I want to put down a summary of my experience with auto-generated interfaces and their use in TDE.
I hope it will save many time for playing, copy/pasting "strange" code or just head ache.
Here are two examples to show the use of DBus proxy and DBus interface.
Additional information can be found in the documentation of package dbus-1-tqt, but I spent almost 2 days until magic combination of following steps came out.
Create DBus Interface
To create a DBus interface we need first a definition of the interface. More information on the interface type and signatures can be found in official dbus tutorial
The definition of the interface is a xml file. We take as example a file describing "org.example.Service" that has one method "ListSorter". The generated code will automatically include the Introspection interface and we will see how we can create a service to handle both interfaces.
<!DOCTYPE node PUBLIC "-//freedesktop//DTD D-BUS Object Introspection 1.0//EN"
"http://www.freedesktop.org/standards/dbus/1.0/introspect.dtd">
<node name="/org/example/Service">
<interface name="org.example.Service">
<method name="ListSorter">
<arg name="input" type="as" direction="in" />
<arg name="output" type="as" direction="out" />
</method>
</interface>
</node>
Generate the code
To generate the TQt C++ classes use dbusxml2qt3 (Note: [1])
$ dbusxml2qt3 sortexample.xml
ClassGenerator: processing interface 'org.example.Service'
Generating org.freedesktop.DBus.Introspectable on demand
in the second step generate the proxy with unique namespace to fit your application
$/usr/bin/dbusxml2qt3 sortexample.xml -p -N MyNameSpace::Proxy
the result is
$ ls -1
introspectableinterface.cpp
introspectableinterface.h
org_example_servicenode.cpp
org_example_servicenode.h
serviceinterface.cpp
serviceinterface.h
serviceproxy.cpp
serviceproxy.h
sortexample.xml
We have to correct few errors introduced by the generator
- <*>node.cpp file missing "interface" in the include
// interface classes includes
#include "serviceinterface.h"
- <*>proxy.cpp you need to add whatever your proxy is called .moc at the end
#include "serviceproxy.moc"
// End of File
Implement the Service
Now we can create our own service using the interface from step one, or create our own proxy from step two
testservice.h
#include <tqdbusconnection.h>
#include <tqdbusobject.h>
#include <tqmap.h>
#include "serviceinterface.h"
#include "org_example_servicenode.h"
class Interface1 : public org::example::Service
{
public:
Interface1(TQT_DBusConnection&);
virtual ~Interface1();
protected: // implement methods
virtual bool ListSorter(const TQStringList& input, TQStringList& output, TQT_DBusError& error);
protected: // implement sending replies
virtual void handleMethodReply(const TQT_DBusMessage& reply);
private:
TQT_DBusConnection *m_connection;
};
class MultiInterfaceService : public org_example_Service
{
public:
MultiInterfaceService(TQT_DBusConnection&);
~MultiInterfaceService();
protected:
virtual TQT_DBusObjectBase* createInterface(const TQString&);
private:
TQMap<TQString, TQT_DBusObjectBase*> m_interfaces;
TQT_DBusConnection m_connection;
};
testservice.cpp
#include "testservice.h"
#include <kdebug.h>
// TQt includes
#include <tqdom.h>
#include <tqstring.h>
#include <tqstringlist.h>
#include <tqdbuserror.h>
#include <tqdbusmessage.h>
#include <tqdbusdatalist.h>
Interface1::Interface1(TQT_DBusConnection &conn)
: m_connection(&conn)
{
kdDebug() << k_funcinfo << endl;
}
Interface1::~Interface1(){
kdDebug() << k_funcinfo << endl;
}
void Interface1::handleMethodReply(const TQT_DBusMessage& reply) {
kdDebug() << k_funcinfo << endl;
// do something
m_connection->send(reply);
}
bool Interface1::ListSorter(const TQStringList& input, TQStringList& output, TQT_DBusError& error) {
kdDebug() << k_funcinfo << endl;
output = input;
output.sort();
return true;
}
MultiInterfaceService::MultiInterfaceService(TQT_DBusConnection &connection )
: org_example_Service(), m_connection(connection)
{
kdDebug() << k_funcinfo << endl;
m_interfaces.insert("org.freedesktop.DBus.Introspectable", this);
m_interfaces.insert("org.example.Service", new Interface1(m_connection));
registerObject(m_connection,"/");
}
MultiInterfaceService::~MultiInterfaceService(){
kdDebug() << k_funcinfo << endl;
}
TQT_DBusObjectBase* MultiInterfaceService::createInterface(const TQString& interfaceName)
{
kdDebug() << k_funcinfo << endl;
kdDebug() << "Interface Name: " << interfaceName << endl;
return (TQT_DBusObjectBase*) m_interfaces[interfaceName];
}
tqdbusexample.cpp
#include "testservice.h"
#include <tqapplication.h>
#include <tqdbusconnection.h>
int main(int argc, char** argv)
{
TQApplication app(argc, argv, false);
TQT_DBusConnection connection = TQT_DBusConnection::sessionBus();
// TQT_DBusConnection connection = TQT_DBusConnection::systemBus();
if (!connection.isConnected())
tqFatal("Cannot connect to session bus");
// try to get a specific service name
if (!connection.requestName("org.example.Service"))
{
tqWarning("Requesting name 'org.example.Service' failed. "
"Will only be addressable through unique name '%s'",
connection.uniqueName().local8Bit().data());
}
else
{
tqDebug("Requesting name 'org.example.Service' successfull");
}
MultiInterfaceService service(connection);
return app.exec();
}
buildtqdbusexample.sh
/usr/bin/g++ -g -O2 -fstack-protector-strong -Wformat -Werror=format-security -Wdate-time \
-D_FORTIFY_SOURCE=2 -DQT_NO_ASCII_CAST -DQT_CLEAN_NAMESPACE -DQT_NO_STL -DQT_NO_COMPAT \
-DQT_NO_TRANSLATION -DQT_THREAD_SUPPORT -D_REENTRANT -include tqt.h -I/usr/include/tqt3 \
-I/opt/trinity/include/ -I/usr/include/dbus-1-tqt -I/usr/include/tqt -I -DQT_NO_ASCII_CAST \
-DQT_CLEAN_NAMESPACE -DQT_NO_STL -DQT_NO_COMPAT -DQT_NO_TRANSLATION -DQT_THREAD_SUPPORT \
-D_REENTRANT -include tqt.h -g -Wl,-z,relro tqdbusexample.cpp testservice.cpp \
org_example_servicenode.cpp introspectableinterface.cpp serviceinterface.cpp \
-o tqdbusexample -ldbus-1-tqt \
/opt/trinity/lib/libtdeparts.so.2.1.0 /opt/trinity/lib/libtdeio.so.14.0.0 \
/opt/trinity/lib/libtdecore.so.14.0.0 -ltqt -ltqt-mt -lXrender -lX11 -lc \
/usr/lib/x86_64-linux-gnu/libz.so -lidn -lXcomposite -lICE -lSM -lutil -lr -lacl -lattr -ltqui
Using a Proxy
We will use the service from our first example and implement a proxy to utilize the service.
tqdbusproxy.cpp
#include <tqstringlist.h>
#include <tqdbusconnection.h>
#include "serviceproxy.h"
int main(int argc, char** argv)
{
TQT_DBusConnection connection = TQT_DBusConnection::sessionBus();
// TQT_DBusConnection connection = TQT_DBusConnection::systemBus();
if (!connection.isConnected())
tqFatal("Cannot connect to session bus");
MyNameSpace::Proxy::Service serviceProxy("org.example.Service", "/");
serviceProxy.setConnection(connection);
TQStringList list;
list << "D" << "C" << "B" << "A";
tqWarning("OUTPUT BEFORE SORT");
for (TQStringList::iterator it= list.begin(); it != list.end(); ++it) {
tqWarning("\t%s",(*it).utf8().data());
}
TQStringList data;
TQT_DBusError error;
if (!serviceProxy.ListSorter(list,data,error)) {
tqFatal("'org.example.Service.ListSorter' failed. ");
}
else {
tqWarning("OUTPUT AFTER SORT");
for (TQStringList::iterator it = data.begin(); it != data.end(); ++it) {
tqWarning("\t%s",(*it).utf8().data());
}
}
return 0;
}
buildtqdbusproxy.sh
/usr/bin/g++ -g -O2 -fstack-protector-strong -Wformat -Werror=format-security -Wdate-time \
-D_FORTIFY_SOURCE=2 -DQT_NO_ASCII_CAST -DQT_CLEAN_NAMESPACE -DQT_NO_STL -DQT_NO_COMPAT \
-DQT_NO_TRANSLATION -DQT_THREAD_SUPPORT -D_REENTRANT -include tqt.h -I/usr/include/tqt3 \
-I/opt/trinity/include/ -I/usr/include/dbus-1-tqt -I/usr/include/tqt -I -DQT_NO_ASCII_CAST \
-DQT_CLEAN_NAMESPACE -DQT_NO_STL -DQT_NO_COMPAT -DQT_NO_TRANSLATION -DQT_THREAD_SUPPORT \
-D_REENTRANT -include tqt.h -g -Wl,-z,relro tqdbusproxy.cpp serviceproxy.cpp \
-o tqdbusproxy -ldbus-1-tqt \
/opt/trinity/lib/libtdeparts.so.2.1.0 /opt/trinity/lib/libtdeio.so.14.0.0 \
/opt/trinity/lib/libtdecore.so.14.0.0 -ltqt -ltqt-mt -lXrender -lX11 -lc \
/usr/lib/x86_64-linux-gnu/libz.so -lidn -lXcomposite -lICE -lSM -lutil -lr -lacl -lattr -ltqui
Try it
Start the service
./tqdbusexample
Test the service from command line
$ dbus-send --print-reply --session --dest=org.example.Service / org.example.Service.ListSorter array:string:"B","A","C"
method return time=1533488709.968425 sender=:1.352 -> destination=:1.355 serial=8 reply_serial=2
array [
string "A"
string "B"
string "C"
]
Test the service with proxy client
./tqdbusproxy
OUTPUT BEFORE SORT
D
C
B
A
OUTPUT AFTER SORT
A
B
C
D