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| <article id="index"> |
| <articleinfo> |
| <title>D-Bus Tutorial</title> |
| <releaseinfo>Version 0.5.0</releaseinfo> |
| <date>20 August 2006</date> |
| <authorgroup> |
| <author> |
| <firstname>Havoc</firstname> |
| <surname>Pennington</surname> |
| <affiliation> |
| <orgname>Red Hat, Inc.</orgname> |
| <address><email>hp@pobox.com</email></address> |
| </affiliation> |
| </author> |
| <author> |
| <firstname>David</firstname> |
| <surname>Wheeler</surname> |
| </author> |
| <author> |
| <firstname>John</firstname> |
| <surname>Palmieri</surname> |
| <affiliation> |
| <orgname>Red Hat, Inc.</orgname> |
| <address><email>johnp@redhat.com</email></address> |
| </affiliation> |
| </author> |
| <author> |
| <firstname>Colin</firstname> |
| <surname>Walters</surname> |
| <affiliation> |
| <orgname>Red Hat, Inc.</orgname> |
| <address><email>walters@redhat.com</email></address> |
| </affiliation> |
| </author> |
| </authorgroup> |
| </articleinfo> |
| |
| <sect1 id="meta"> |
| <title>Tutorial Work In Progress</title> |
| |
| <para> |
| This tutorial is not complete; it probably contains some useful information, but |
| also has plenty of gaps. Right now, you'll also need to refer to the D-Bus specification, |
| Doxygen reference documentation, and look at some examples of how other apps use D-Bus. |
| </para> |
| |
| <para> |
| Enhancing the tutorial is definitely encouraged - send your patches or suggestions to the |
| mailing list. If you create a D-Bus binding, please add a section to the tutorial for your |
| binding, if only a short section with a couple of examples. |
| </para> |
| |
| </sect1> |
| |
| <sect1 id="whatis"> |
| <title>What is D-Bus?</title> |
| <para> |
| D-Bus is a system for <firstterm>interprocess communication</firstterm> |
| (IPC). Architecturally, it has several layers: |
| |
| <itemizedlist> |
| <listitem> |
| <para> |
| A library, <firstterm>libdbus</firstterm>, that allows two |
| applications to connect to each other and exchange messages. |
| </para> |
| </listitem> |
| <listitem> |
| <para> |
| A <firstterm>message bus daemon</firstterm> executable, built on |
| libdbus, that multiple applications can connect to. The daemon can |
| route messages from one application to zero or more other |
| applications. |
| </para> |
| </listitem> |
| <listitem> |
| <para> |
| <firstterm>Wrapper libraries</firstterm> or <firstterm>bindings</firstterm> |
| based on particular application frameworks. For example, libdbus-glib and |
| libdbus-qt. There are also bindings to languages such as |
| Python. These wrapper libraries are the API most people should use, |
| as they simplify the details of D-Bus programming. libdbus is |
| intended to be a low-level backend for the higher level bindings. |
| Much of the libdbus API is only useful for binding implementation. |
| </para> |
| </listitem> |
| </itemizedlist> |
| </para> |
| |
| <para> |
| libdbus only supports one-to-one connections, just like a raw network |
| socket. However, rather than sending byte streams over the connection, you |
| send <firstterm>messages</firstterm>. Messages have a header identifying |
| the kind of message, and a body containing a data payload. libdbus also |
| abstracts the exact transport used (sockets vs. whatever else), and |
| handles details such as authentication. |
| </para> |
| |
| <para> |
| The message bus daemon forms the hub of a wheel. Each spoke of the wheel |
| is a one-to-one connection to an application using libdbus. An |
| application sends a message to the bus daemon over its spoke, and the bus |
| daemon forwards the message to other connected applications as |
| appropriate. Think of the daemon as a router. |
| </para> |
| |
| <para> |
| The bus daemon has multiple instances on a typical computer. The |
| first instance is a machine-global singleton, that is, a system daemon |
| similar to sendmail or Apache. This instance has heavy security |
| restrictions on what messages it will accept, and is used for systemwide |
| communication. The other instances are created one per user login session. |
| These instances allow applications in the user's session to communicate |
| with one another. |
| </para> |
| |
| <para> |
| The systemwide and per-user daemons are separate. Normal within-session |
| IPC does not involve the systemwide message bus process and vice versa. |
| </para> |
| |
| <sect2 id="uses"> |
| <title>D-Bus applications</title> |
| <para> |
| There are many, many technologies in the world that have "Inter-process |
| communication" or "networking" in their stated purpose: <ulink |
| url="http://www.omg.org">CORBA</ulink>, <ulink |
| url="http://www.opengroup.org/dce/">DCE</ulink>, <ulink |
| url="http://www.microsoft.com/com/">DCOM</ulink>, <ulink |
| url="http://developer.kde.org/documentation/library/kdeqt/dcop.html">DCOP</ulink>, <ulink |
| url="http://www.xmlrpc.com">XML-RPC</ulink>, <ulink |
| url="http://www.w3.org/TR/SOAP/">SOAP</ulink>, <ulink |
| url="http://www.mbus.org/">MBUS</ulink>, <ulink |
| url="http://www.zeroc.com/ice.html">Internet Communications Engine (ICE)</ulink>, |
| and probably hundreds more. |
| Each of these is tailored for particular kinds of application. |
| D-Bus is designed for two specific cases: |
| <itemizedlist> |
| <listitem> |
| <para> |
| Communication between desktop applications in the same desktop |
| session; to allow integration of the desktop session as a whole, |
| and address issues of process lifecycle (when do desktop components |
| start and stop running). |
| </para> |
| </listitem> |
| <listitem> |
| <para> |
| Communication between the desktop session and the operating system, |
| where the operating system would typically include the kernel |
| and any system daemons or processes. |
| </para> |
| </listitem> |
| </itemizedlist> |
| </para> |
| <para> |
| For the within-desktop-session use case, the GNOME and KDE desktops |
| have significant previous experience with different IPC solutions |
| such as CORBA and DCOP. D-Bus is built on that experience and |
| carefully tailored to meet the needs of these desktop projects |
| in particular. D-Bus may or may not be appropriate for other |
| applications; the FAQ has some comparisons to other IPC systems. |
| </para> |
| <para> |
| The problem solved by the systemwide or communication-with-the-OS case |
| is explained well by the following text from the Linux Hotplug project: |
| <blockquote> |
| <para> |
| A gap in current Linux support is that policies with any sort of |
| dynamic "interact with user" component aren't currently |
| supported. For example, that's often needed the first time a network |
| adapter or printer is connected, and to determine appropriate places |
| to mount disk drives. It would seem that such actions could be |
| supported for any case where a responsible human can be identified: |
| single user workstations, or any system which is remotely |
| administered. |
| </para> |
| |
| <para> |
| This is a classic "remote sysadmin" problem, where in this case |
| hotplugging needs to deliver an event from one security domain |
| (operating system kernel, in this case) to another (desktop for |
| logged-in user, or remote sysadmin). Any effective response must go |
| the other way: the remote domain taking some action that lets the |
| kernel expose the desired device capabilities. (The action can often |
| be taken asynchronously, for example letting new hardware be idle |
| until a meeting finishes.) At this writing, Linux doesn't have |
| widely adopted solutions to such problems. However, the new D-Bus |
| work may begin to solve that problem. |
| </para> |
| </blockquote> |
| </para> |
| <para> |
| D-Bus may happen to be useful for purposes other than the one it was |
| designed for. Its general properties that distinguish it from |
| other forms of IPC are: |
| <itemizedlist> |
| <listitem> |
| <para> |
| Binary protocol designed to be used asynchronously |
| (similar in spirit to the X Window System protocol). |
| </para> |
| </listitem> |
| <listitem> |
| <para> |
| Stateful, reliable connections held open over time. |
| </para> |
| </listitem> |
| <listitem> |
| <para> |
| The message bus is a daemon, not a "swarm" or |
| distributed architecture. |
| </para> |
| </listitem> |
| <listitem> |
| <para> |
| Many implementation and deployment issues are specified rather |
| than left ambiguous/configurable/pluggable. |
| </para> |
| </listitem> |
| <listitem> |
| <para> |
| Semantics are similar to the existing DCOP system, allowing |
| KDE to adopt it more easily. |
| </para> |
| </listitem> |
| <listitem> |
| <para> |
| Security features to support the systemwide mode of the |
| message bus. |
| </para> |
| </listitem> |
| </itemizedlist> |
| </para> |
| </sect2> |
| </sect1> |
| <sect1 id="concepts"> |
| <title>Concepts</title> |
| <para> |
| Some basic concepts apply no matter what application framework you're |
| using to write a D-Bus application. The exact code you write will be |
| different for GLib vs. Qt vs. Python applications, however. |
| </para> |
| |
| <para> |
| Here is a diagram (<ulink url="diagram.png">png</ulink> <ulink |
| url="diagram.svg">svg</ulink>) that may help you visualize the concepts |
| that follow. |
| </para> |
| |
| <sect2 id="objects"> |
| <title>Native Objects and Object Paths</title> |
| <para> |
| Your programming framework probably defines what an "object" is like; |
| usually with a base class. For example: java.lang.Object, GObject, QObject, |
| python's base Object, or whatever. Let's call this a <firstterm>native object</firstterm>. |
| </para> |
| <para> |
| The low-level D-Bus protocol, and corresponding libdbus API, does not care about native objects. |
| However, it provides a concept called an |
| <firstterm>object path</firstterm>. The idea of an object path is that |
| higher-level bindings can name native object instances, and allow remote applications |
| to refer to them. |
| </para> |
| <para> |
| The object path |
| looks like a filesystem path, for example an object could be |
| named <literal>/org/kde/kspread/sheets/3/cells/4/5</literal>. |
| Human-readable paths are nice, but you are free to create an |
| object named <literal>/com/mycompany/c5yo817y0c1y1c5b</literal> |
| if it makes sense for your application. |
| </para> |
| <para> |
| Namespacing object paths is smart, by starting them with the components |
| of a domain name you own (e.g. <literal>/org/kde</literal>). This |
| keeps different code modules in the same process from stepping |
| on one another's toes. |
| </para> |
| </sect2> |
| |
| <sect2 id="members"> |
| <title>Methods and Signals</title> |
| |
| <para> |
| Each object has <firstterm>members</firstterm>; the two kinds of member |
| are <firstterm>methods</firstterm> and |
| <firstterm>signals</firstterm>. Methods are operations that can be |
| invoked on an object, with optional input (aka arguments or "in |
| parameters") and output (aka return values or "out parameters"). |
| Signals are broadcasts from the object to any interested observers |
| of the object; signals may contain a data payload. |
| </para> |
| |
| <para> |
| Both methods and signals are referred to by name, such as |
| "Frobate" or "OnClicked". |
| </para> |
| |
| </sect2> |
| |
| <sect2 id="interfaces"> |
| <title>Interfaces</title> |
| <para> |
| Each object supports one or more <firstterm>interfaces</firstterm>. |
| Think of an interface as a named group of methods and signals, |
| just as it is in GLib or Qt or Java. Interfaces define the |
| <emphasis>type</emphasis> of an object instance. |
| </para> |
| <para> |
| DBus identifies interfaces with a simple namespaced string, |
| something like <literal>org.freedesktop.Introspectable</literal>. |
| Most bindings will map these interface names directly to |
| the appropriate programming language construct, for example |
| to Java interfaces or C++ pure virtual classes. |
| </para> |
| </sect2> |
| |
| <sect2 id="proxies"> |
| <title>Proxies</title> |
| <para> |
| A <firstterm>proxy object</firstterm> is a convenient native object created to |
| represent a remote object in another process. The low-level DBus API involves manually creating |
| a method call message, sending it, then manually receiving and processing |
| the method reply message. Higher-level bindings provide proxies as an alternative. |
| Proxies look like a normal native object; but when you invoke a method on the proxy |
| object, the binding converts it into a DBus method call message, waits for the reply |
| message, unpacks the return value, and returns it from the native method.. |
| </para> |
| <para> |
| In pseudocode, programming without proxies might look like this: |
| <programlisting> |
| Message message = new Message("/remote/object/path", "MethodName", arg1, arg2); |
| Connection connection = getBusConnection(); |
| connection.send(message); |
| Message reply = connection.waitForReply(message); |
| if (reply.isError()) { |
| |
| } else { |
| Object returnValue = reply.getReturnValue(); |
| } |
| </programlisting> |
| </para> |
| <para> |
| Programming with proxies might look like this: |
| <programlisting> |
| Proxy proxy = new Proxy(getBusConnection(), "/remote/object/path"); |
| Object returnValue = proxy.MethodName(arg1, arg2); |
| </programlisting> |
| </para> |
| </sect2> |
| |
| <sect2 id="bus-names"> |
| <title>Bus Names</title> |
| |
| <para> |
| When each application connects to the bus daemon, the daemon immediately |
| assigns it a name, called the <firstterm>unique connection name</firstterm>. |
| A unique name begins with a ':' (colon) character. These names are never |
| reused during the lifetime of the bus daemon - that is, you know |
| a given name will always refer to the same application. |
| An example of a unique name might be |
| <literal>:34-907</literal>. The numbers after the colon have |
| no meaning other than their uniqueness. |
| </para> |
| |
| <para> |
| When a name is mapped |
| to a particular application's connection, that application is said to |
| <firstterm>own</firstterm> that name. |
| </para> |
| |
| <para> |
| Applications may ask to own additional <firstterm>well-known |
| names</firstterm>. For example, you could write a specification to |
| define a name called <literal>com.mycompany.TextEditor</literal>. |
| Your definition could specify that to own this name, an application |
| should have an object at the path |
| <literal>/com/mycompany/TextFileManager</literal> supporting the |
| interface <literal>org.freedesktop.FileHandler</literal>. |
| </para> |
| |
| <para> |
| Applications could then send messages to this bus name, |
| object, and interface to execute method calls. |
| </para> |
| |
| <para> |
| You could think of the unique names as IP addresses, and the |
| well-known names as domain names. So |
| <literal>com.mycompany.TextEditor</literal> might map to something like |
| <literal>:34-907</literal> just as <literal>mycompany.com</literal> maps |
| to something like <literal>192.168.0.5</literal>. |
| </para> |
| |
| <para> |
| Names have a second important use, other than routing messages. They |
| are used to track lifecycle. When an application exits (or crashes), its |
| connection to the message bus will be closed by the operating system |
| kernel. The message bus then sends out notification messages telling |
| remaining applications that the application's names have lost their |
| owner. By tracking these notifications, your application can reliably |
| monitor the lifetime of other applications. |
| </para> |
| |
| <para> |
| Bus names can also be used to coordinate single-instance applications. |
| If you want to be sure only one |
| <literal>com.mycompany.TextEditor</literal> application is running for |
| example, have the text editor application exit if the bus name already |
| has an owner. |
| </para> |
| |
| </sect2> |
| |
| <sect2 id="addresses"> |
| <title>Addresses</title> |
| |
| <para> |
| Applications using D-Bus are either servers or clients. A server |
| listens for incoming connections; a client connects to a server. Once |
| the connection is established, it is a symmetric flow of messages; the |
| client-server distinction only matters when setting up the |
| connection. |
| </para> |
| |
| <para> |
| If you're using the bus daemon, as you probably are, your application |
| will be a client of the bus daemon. That is, the bus daemon listens |
| for connections and your application initiates a connection to the bus |
| daemon. |
| </para> |
| |
| <para> |
| A D-Bus <firstterm>address</firstterm> specifies where a server will |
| listen, and where a client will connect. For example, the address |
| <literal>unix:path=/tmp/abcdef</literal> specifies that the server will |
| listen on a UNIX domain socket at the path |
| <literal>/tmp/abcdef</literal> and the client will connect to that |
| socket. An address can also specify TCP/IP sockets, or any other |
| transport defined in future iterations of the D-Bus specification. |
| </para> |
| |
| <para> |
| When using D-Bus with a message bus daemon, |
| libdbus automatically discovers the address of the per-session bus |
| daemon by reading an environment variable. It discovers the |
| systemwide bus daemon by checking a well-known UNIX domain socket path |
| (though you can override this address with an environment variable). |
| </para> |
| |
| <para> |
| If you're using D-Bus without a bus daemon, it's up to you to |
| define which application will be the server and which will be |
| the client, and specify a mechanism for them to agree on |
| the server's address. This is an unusual case. |
| </para> |
| |
| </sect2> |
| |
| <sect2 id="bigpicture"> |
| <title>Big Conceptual Picture</title> |
| |
| <para> |
| Pulling all these concepts together, to specify a particular |
| method call on a particular object instance, a number of |
| nested components have to be named: |
| <programlisting> |
| Address -> [Bus Name] -> Path -> Interface -> Method |
| </programlisting> |
| The bus name is in brackets to indicate that it's optional -- you only |
| provide a name to route the method call to the right application |
| when using the bus daemon. If you have a direct connection to another |
| application, bus names aren't used; there's no bus daemon. |
| </para> |
| |
| <para> |
| The interface is also optional, primarily for historical |
| reasons; DCOP does not require specifying the interface, |
| instead simply forbidding duplicate method names |
| on the same object instance. D-Bus will thus let you |
| omit the interface, but if your method name is ambiguous |
| it is undefined which method will be invoked. |
| </para> |
| |
| </sect2> |
| |
| <sect2 id="messages"> |
| <title>Messages - Behind the Scenes</title> |
| <para> |
| D-Bus works by sending messages between processes. If you're using |
| a sufficiently high-level binding, you may never work with messages directly. |
| </para> |
| <para> |
| There are 4 message types: |
| <itemizedlist> |
| <listitem> |
| <para> |
| Method call messages ask to invoke a method |
| on an object. |
| </para> |
| </listitem> |
| <listitem> |
| <para> |
| Method return messages return the results |
| of invoking a method. |
| </para> |
| </listitem> |
| <listitem> |
| <para> |
| Error messages return an exception caused by |
| invoking a method. |
| </para> |
| </listitem> |
| <listitem> |
| <para> |
| Signal messages are notifications that a given signal |
| has been emitted (that an event has occurred). |
| You could also think of these as "event" messages. |
| </para> |
| </listitem> |
| </itemizedlist> |
| </para> |
| <para> |
| A method call maps very simply to messages: you send a method call |
| message, and receive either a method return message or an error message |
| in reply. |
| </para> |
| <para> |
| Each message has a <firstterm>header</firstterm>, including <firstterm>fields</firstterm>, |
| and a <firstterm>body</firstterm>, including <firstterm>arguments</firstterm>. You can think |
| of the header as the routing information for the message, and the body as the payload. |
| Header fields might include the sender bus name, destination bus name, method or signal name, |
| and so forth. One of the header fields is a <firstterm>type signature</firstterm> describing the |
| values found in the body. For example, the letter "i" means "32-bit integer" so the signature |
| "ii" means the payload has two 32-bit integers. |
| </para> |
| </sect2> |
| |
| <sect2 id="callprocedure"> |
| <title>Calling a Method - Behind the Scenes</title> |
| |
| <para> |
| A method call in DBus consists of two messages; a method call message sent from process A to process B, |
| and a matching method reply message sent from process B to process A. Both the call and the reply messages |
| are routed through the bus daemon. The caller includes a different serial number in each call message, and the |
| reply message includes this number to allow the caller to match replies to calls. |
| </para> |
| |
| <para> |
| The call message will contain any arguments to the method. |
| The reply message may indicate an error, or may contain data returned by the method. |
| </para> |
| |
| <para> |
| A method invocation in DBus happens as follows: |
| <itemizedlist> |
| <listitem> |
| <para> |
| The language binding may provide a proxy, such that invoking a method on |
| an in-process object invokes a method on a remote object in another process. If so, the |
| application calls a method on the proxy, and the proxy |
| constructs a method call message to send to the remote process. |
| </para> |
| </listitem> |
| <listitem> |
| <para> |
| For more low-level APIs, the application may construct a method call message itself, without |
| using a proxy. |
| </para> |
| </listitem> |
| <listitem> |
| <para> |
| In either case, the method call message contains: a bus name belonging to the remote process; the name of the method; |
| the arguments to the method; an object path inside the remote process; and optionally the name of the |
| interface that specifies the method. |
| </para> |
| </listitem> |
| <listitem> |
| <para> |
| The method call message is sent to the bus daemon. |
| </para> |
| </listitem> |
| <listitem> |
| <para> |
| The bus daemon looks at the destination bus name. If a process owns that name, |
| the bus daemon forwards the method call to that process. Otherwise, the bus daemon |
| creates an error message and sends it back as the reply to the method call message. |
| </para> |
| </listitem> |
| <listitem> |
| <para> |
| The receiving process unpacks the method call message. In a simple low-level API situation, it |
| may immediately run the method and send a method reply message to the bus daemon. |
| When using a high-level binding API, the binding might examine the object path, interface, |
| and method name, and convert the method call message into an invocation of a method on |
| a native object (GObject, java.lang.Object, QObject, etc.), then convert the return |
| value from the native method into a method reply message. |
| </para> |
| </listitem> |
| <listitem> |
| <para> |
| The bus daemon receives the method reply message and sends it to the process that |
| made the method call. |
| </para> |
| </listitem> |
| <listitem> |
| <para> |
| The process that made the method call looks at the method reply and makes use of any |
| return values included in the reply. The reply may also indicate that an error occurred. |
| When using a binding, the method reply message may be converted into the return value of |
| of a proxy method, or into an exception. |
| </para> |
| </listitem> |
| </itemizedlist> |
| </para> |
| |
| <para> |
| The bus daemon never reorders messages. That is, if you send two method call messages to the same recipient, |
| they will be received in the order they were sent. The recipient is not required to reply to the calls |
| in order, however; for example, it may process each method call in a separate thread, and return reply messages |
| in an undefined order depending on when the threads complete. Method calls have a unique serial |
| number used by the method caller to match reply messages to call messages. |
| </para> |
| |
| </sect2> |
| |
| <sect2 id="signalprocedure"> |
| <title>Emitting a Signal - Behind the Scenes</title> |
| |
| <para> |
| A signal in DBus consists of a single message, sent by one process to any number of other processes. |
| That is, a signal is a unidirectional broadcast. The signal may contain arguments (a data payload), but |
| because it is a broadcast, it never has a "return value." Contrast this with a method call |
| (see <xref linkend="callprocedure"/>) where the method call message has a matching method reply message. |
| </para> |
| |
| <para> |
| The emitter (aka sender) of a signal has no knowledge of the signal recipients. Recipients register |
| with the bus daemon to receive signals based on "match rules" - these rules would typically include the sender and |
| the signal name. The bus daemon sends each signal only to recipients who have expressed interest in that |
| signal. |
| </para> |
| |
| <para> |
| A signal in DBus happens as follows: |
| <itemizedlist> |
| <listitem> |
| <para> |
| A signal message is created and sent to the bus daemon. When using the low-level API this may be |
| done manually, with certain bindings it may be done for you by the binding when a native object |
| emits a native signal or event. |
| </para> |
| </listitem> |
| <listitem> |
| <para> |
| The signal message contains the name of the interface that specifies the signal; |
| the name of the signal; the bus name of the process sending the signal; and |
| any arguments |
| </para> |
| </listitem> |
| <listitem> |
| <para> |
| Any process on the message bus can register "match rules" indicating which signals it |
| is interested in. The bus has a list of registered match rules. |
| </para> |
| </listitem> |
| <listitem> |
| <para> |
| The bus daemon examines the signal and determines which processes are interested in it. |
| It sends the signal message to these processes. |
| </para> |
| </listitem> |
| <listitem> |
| <para> |
| Each process receiving the signal decides what to do with it; if using a binding, |
| the binding may choose to emit a native signal on a proxy object. If using the |
| low-level API, the process may just look at the signal sender and name and decide |
| what to do based on that. |
| </para> |
| </listitem> |
| </itemizedlist> |
| </para> |
| |
| </sect2> |
| |
| <sect2 id="introspection"> |
| <title>Introspection</title> |
| |
| <para> |
| D-Bus objects may support the interface <literal>org.freedesktop.DBus.Introspectable</literal>. |
| This interface has one method <literal>Introspect</literal> which takes no arguments and returns |
| an XML string. The XML string describes the interfaces, methods, and signals of the object. |
| See the D-Bus specification for more details on this introspection format. |
| </para> |
| |
| </sect2> |
| |
| </sect1> |
| |
| <sect1 id="glib-client"> |
| <title>GLib APIs</title> |
| <para> |
| The recommended GLib API for D-Bus is GDBus, which has been |
| distributed with GLib since version 2.26. It is not documented here. |
| See <ulink url="https://developer.gnome.org/gio/stable/gdbus-convenience.html">the |
| GLib documentation</ulink> for details of how to use GDBus. |
| </para> |
| |
| <para> |
| An older API, dbus-glib, also exists. It is deprecated and should |
| not be used in new code. Whenever possible, porting existing code |
| from dbus-glib to GDBus is also recommended. |
| </para> |
| </sect1> |
| |
| <sect1 id="python-client"> |
| <title>Python API</title> |
| <para> |
| The Python API, dbus-python, is now documented separately in |
| <ulink url="http://dbus.freedesktop.org/doc/dbus-python/doc/tutorial.html">the dbus-python tutorial</ulink> (also available in doc/tutorial.txt, |
| and doc/tutorial.html if built with python-docutils, in the dbus-python |
| source distribution). |
| </para> |
| </sect1> |
| |
| <sect1 id="qt-client"> |
| <title>Qt API</title> |
| <para> |
| The Qt binding for libdbus, QtDBus, has been distributed with Qt |
| since version 4.2. It is not documented here. See |
| <ulink url="http://qt-project.org/doc/qt-5/qtdbus-index.html">the Qt |
| documentation</ulink> for details of how to use QtDBus. |
| </para> |
| </sect1> |
| </article> |