@c @setchapternewpage odd
@c %**end of header
+@syncodeindex vr cp
+@syncodeindex fn cp
+
@copying
-Copyright @copyright{} 2007, 2008, 2009, 2010, 2011 Free Software Foundation, Inc.
+Copyright @copyright{} 2007-2012 Free Software Foundation, Inc.
@quotation
Permission is granted to copy, distribute and/or modify this document
is included in the section entitled ``GNU Free Documentation License''.
(a) The FSF's Back-Cover Text is: ``You have the freedom to copy and
-modify this GNU manual. Buying copies from the FSF supports it in
-developing GNU and promoting software freedom.''
+modify this GNU manual.''
@end quotation
@end copying
* Asynchronous Methods:: Calling methods non-blocking.
* Receiving Method Calls:: Offering own methods.
* Signals:: Sending and receiving signals.
+* Alternative Buses:: Alternative buses and environments.
* Errors and Events:: Errors and events.
+* Index:: Index including concepts, functions, variables.
+
* GNU Free Documentation License:: The license for this documentation.
@end menu
@cindex inspection
@menu
+* Version:: Determining the D-Bus version.
* Bus names:: Discovering D-Bus names.
* Introspection:: Knowing the details of D-Bus services.
* Nodes and Interfaces:: Detecting object paths and interfaces.
@end menu
+@node Version
+@section D-Bus version.
+
+D-Bus has evolved over the years. New features have been added with
+new D-Bus versions. There are two variables, which allow to determine
+the used D-Bus version.
+
+@defvar dbus-compiled-version
+This variable, a string, determines the version of D-Bus Emacs is
+compiled against. If it cannot be determined the value is @code{nil}.
+@end defvar
+
+@defvar dbus-runtime-version
+The other D-Bus version to be checked is the version of D-Bus Emacs
+runs with. This string can be different from @code{dbus-compiled-version}.
+It is also @code{nil}, if it cannot be determined at runtime.
+@end defvar
+
+
@node Bus names
@section Bus names.
registered names. Internally they use the basic interface
@samp{org.freedesktop.DBus}, which is supported by all objects of a bus.
-@defun dbus-list-activatable-names
-This function returns the D-Bus service names, which can be activated.
-An activatable service is described in a service registration file.
-Under GNU/Linux, such files are located at
-@file{/usr/share/dbus-1/services/}.
+@defun dbus-list-activatable-names &optional bus
+This function returns the D-Bus service names, which can be activated
+for @var{bus}. It must be either the symbol @code{:system} (the
+default) or the symbol @code{:session}. An activatable service is
+described in a service registration file. Under GNU/Linux, such files
+are located at @file{/usr/share/dbus-1/system-services/} (for the
+@code{:system} bus) or @file{/usr/share/dbus-1/services/}. An
+activatable service is not necessarily registered at @var{bus} at already.
The result is a list of strings, which is @code{nil} when there are no
-activatable service names at all.
+activatable service names at all. Example:
+
+@lisp
+;; Check, whether the document viewer can be accessed via D-Bus.
+(member "org.gnome.evince.Daemon"
+ (dbus-list-activatable-names :session))
+@end lisp
@end defun
@defun dbus-list-names bus
@end defun
@defun dbus-list-known-names bus
-Retrieves all services which correspond to a known name in @var{bus}.
+Retrieves all registered services which correspond to a known name in @var{bus}.
A service has a known name if it doesn't start with @samp{:}. The
result is a list of strings, which is @code{nil} when there are no
known names at all.
@code{method}, @code{signal}, and @code{property} elements. Unlike
properties, which can change their values during lifetime of a D-Bus
object, annotations are static. Often they are used for code
-generators of D-Bus langugae bindings. Example:
+generators of D-Bus language bindings. Example:
@example
<annotation name="de.berlios.Pinot.GetStatistics" value="pinotDBus"/>
@result{} "/org/freedesktop/SystemToolsBackends/UsersConfig"
@end lisp
-If @var{object} has no @var{attribute}, the function returns nil.
+If @var{object} has no @var{attribute}, the function returns
+@code{nil}.
@end defun
@node Methods and Signal
@section Applying the functionality.
-Methods and signals are the communicatione means to D-Bus. The
+Methods and signals are the communication means to D-Bus. The
following functions return their specifications.
@defun dbus-introspect-get-method-names bus service path interface
That is, properties can be retrieved and changed during lifetime of an
element.
+A generalized interface is
+@samp{org.freedesktop.DBus.Objectmanager}@footnote{See
+@uref{http://dbus.freedesktop.org/doc/dbus-specification.html#standard-interfaces-objectmanager}},
+which returns objects, their interfaces and properties for a given
+service in just one call.
+
Annotations, on the other hand, are static values for an element.
Often, they are used to instruct generators, how to generate code from
the interface for a given language binding.
@defun dbus-get-property bus service path interface property
This function returns the value of @var{property} of @var{interface}.
It will be checked at @var{bus}, @var{service}, @var{path}. The
-result can be any valid D-Bus value, or nil if there is no
+result can be any valid D-Bus value, or @code{nil} if there is no
@var{property}. Example:
@lisp
@end lisp
@end defun
+@defun dbus-get-all-managed-objects bus service path
+This functions returns all objects at @var{bus}, @var{service},
+@var{path}, and the children of @var{path}. The result is a list of
+objects. Every object is a cons of an existing path name, and the
+list of available interface objects. An interface object is another
+cons, which car is the interface name, and the cdr is the list of
+properties as returned by @code{dbus-get-all-properties} for that path
+and interface. Example:
+
+@lisp
+(dbus-get-all-managed-objects
+ :session "org.gnome.SettingsDaemon" "/")
+
+@result{} (("/org/gnome/SettingsDaemon/MediaKeys"
+ ("org.gnome.SettingsDaemon.MediaKeys")
+ ("org.freedesktop.DBus.Peer")
+ ("org.freedesktop.DBus.Introspectable")
+ ("org.freedesktop.DBus.Properties")
+ ("org.freedesktop.DBus.ObjectManager"))
+ ("/org/gnome/SettingsDaemon/Power"
+ ("org.gnome.SettingsDaemon.Power.Keyboard")
+ ("org.gnome.SettingsDaemon.Power.Screen")
+ ("org.gnome.SettingsDaemon.Power"
+ ("Icon" . ". GThemedIcon battery-full-charged-symbolic ")
+ ("Tooltip" . "Laptop battery is charged"))
+ ("org.freedesktop.DBus.Peer")
+ ("org.freedesktop.DBus.Introspectable")
+ ("org.freedesktop.DBus.Properties")
+ ("org.freedesktop.DBus.ObjectManager"))
+ @dots{})
+@end lisp
+
+If possible, @samp{org.freedesktop.DBus.ObjectManager.GetManagedObjects}
+is used for retrieving the information. Otherwise, the information
+is collected via @samp{org.freedesktop.DBus.Introspectable.Introspect}
+and @samp{org.freedesktop.DBus.Properties.GetAll}, which is slow.
+
+An overview of all existing object paths, their interfaces and
+properties could be retrieved by the following code:
+
+@lisp
+(with-current-buffer (switch-to-buffer "*objectmanager*")
+ (erase-buffer)
+ (let (result)
+ (dolist (service (dbus-list-known-names :session) result)
+ (message "%s" service)
+ (add-to-list
+ 'result
+ (cons service
+ (dbus-get-all-managed-objects :session service "/"))))
+ (insert (message "%s" (pp result)))
+ (redisplay t)))
+@end lisp
+@end defun
+
@defun dbus-introspect-get-annotation-names bus service path interface &optional name
Return a list of all annotation names as list of strings. If
@var{name} is @code{nil}, the annotations are children of
applied, when the corresponding D-Bus message is created:
@example
-@multitable {@code{t} and @code{nil}} {@expansion{}} {DBUS_TYPE_BOOLEAN}
+@multitable {negative integer} {@expansion{}} {DBUS_TYPE_BOOLEAN}
@item Lisp type @tab @tab D-Bus type
@item
@item @code{t} and @code{nil} @tab @expansion{} @tab DBUS_TYPE_BOOLEAN
-@item number @tab @expansion{} @tab DBUS_TYPE_UINT32
-@item integer @tab @expansion{} @tab DBUS_TYPE_INT32
+@item natural number @tab @expansion{} @tab DBUS_TYPE_UINT32
+@item negative integer @tab @expansion{} @tab DBUS_TYPE_INT32
@item float @tab @expansion{} @tab DBUS_TYPE_DOUBLE
@item string @tab @expansion{} @tab DBUS_TYPE_STRING
@item list @tab @expansion{} @tab DBUS_TYPE_ARRAY
@end example
Other Lisp objects, like symbols or hash tables, are not accepted as
-input parameter.
+input parameters.
If it is necessary to use another D-Bus type, a corresponding type
-symbol can be preceeded to the corresponding Lisp object. Basic D-Bus
+symbol can be prepended to the corresponding Lisp object. Basic D-Bus
types are represented by the type symbols @code{:byte},
@code{:boolean}, @code{:int16}, @code{:uint16}, @code{:int32},
@code{:uint32}, @code{:int64}, @code{:uint64}, @code{:double},
-@code{:string}, @code{:object-path} and @code{:signature}.
+@code{:string}, @code{:object-path}, @code{:signature} and
+@code{:unix-fd}.
@noindent
Example:
@lisp
-(dbus-call-method @dots{} @var{NUMBER} @var{STRING})
+(dbus-call-method @dots{} @var{NAT-NUMBER} @var{STRING})
@end lisp
is equivalent to
@lisp
-(dbus-call-method @dots{} :uint32 @var{NUMBER} :string @var{STRING})
+(dbus-call-method @dots{} :uint32 @var{NAT-NUMBER} :string @var{STRING})
@end lisp
but different to
@lisp
-(dbus-call-method @dots{} :int32 @var{NUMBER} :signature @var{STRING})
+(dbus-call-method @dots{} :int32 @var{NAT-NUMBER} :signature @var{STRING})
@end lisp
The value for a byte D-Bus type can be any integer in the range 0
@code{:byte ?x} is equal to @code{:byte ?\M-x}, but it is not equal to
@code{:byte ?\C-x} or @code{:byte ?\M-\C-x}.
+Signed and unsigned integer D-Bus types expect a corresponding integer
+value. If the value does not fit Emacs's integer range, it is also
+possible to use an equivalent floating point number.
+
A D-Bus compound type is always represented as a list. The @sc{car}
of this list can be the type symbol @code{:array}, @code{:variant},
@code{:struct} or @code{:dict-entry}, which would result in a
objects.
@example
-@multitable {DBUS_TYPE_OBJECT_PATH} {@expansion{}} {@code{t} or @code{nil}}
+@multitable {DBUS_TYPE_OBJECT_PATH} {@expansion{}} {natural number or float}
@item D-Bus type @tab @tab Lisp type
@item
@item DBUS_TYPE_BOOLEAN @tab @expansion{} @tab @code{t} or @code{nil}
-@item DBUS_TYPE_BYTE @tab @expansion{} @tab number
-@item DBUS_TYPE_UINT16 @tab @expansion{} @tab number
-@item DBUS_TYPE_INT16 @tab @expansion{} @tab number
-@item DBUS_TYPE_UINT32 @tab @expansion{} @tab number or float
-@item DBUS_TYPE_INT32 @tab @expansion{} @tab number or float
-@item DBUS_TYPE_UINT64 @tab @expansion{} @tab number or float
-@item DBUS_TYPE_INT64 @tab @expansion{} @tab number or float
+@item DBUS_TYPE_BYTE @tab @expansion{} @tab natural number
+@item DBUS_TYPE_UINT16 @tab @expansion{} @tab natural number
+@item DBUS_TYPE_INT16 @tab @expansion{} @tab integer
+@item DBUS_TYPE_UINT32 @tab @expansion{} @tab natural number or float
+@item DBUS_TYPE_UNIX_FD @tab @expansion{} @tab natural number or float
+@item DBUS_TYPE_INT32 @tab @expansion{} @tab integer or float
+@item DBUS_TYPE_UINT64 @tab @expansion{} @tab natural number or float
+@item DBUS_TYPE_INT64 @tab @expansion{} @tab integer or float
@item DBUS_TYPE_DOUBLE @tab @expansion{} @tab float
@item DBUS_TYPE_STRING @tab @expansion{} @tab string
@item DBUS_TYPE_OBJECT_PATH @tab @expansion{} @tab string
@end example
A float object in case of @code{DBUS_TYPE_UINT32},
-@code{DBUS_TYPE_INT32}, @code{DBUS_TYPE_UINT64} and
-@code{DBUS_TYPE_INT6432} is returned, when the C value exceeds the
-Emacs number size range.
+@code{DBUS_TYPE_INT32}, @code{DBUS_TYPE_UINT64},
+@code{DBUS_TYPE_INT64} and @code{DBUS_TYPE_UNIX_FD} is returned, when
+the C value exceeds the Emacs number size range.
The resulting list of the last 4 D-Bus compound types contains as
elements the elements of the D-Bus container, mapped according to the
(@var{BOOL} stands here for either @code{nil} or @code{t}):
@lisp
-(@var{NUMBER} ((@var{STRING} @var{BOOL} @var{BOOL}) (@var{STRING} @var{BOOL} @var{BOOL}) @dots{}))
+(@var{INTEGER} ((@var{STRING} @var{BOOL} @var{BOOL}) (@var{STRING} @var{BOOL} @var{BOOL}) @dots{}))
@end lisp
@defun dbus-byte-array-to-string byte-array
@end lisp
@end defun
-@defun dbus-call-method-non-blocking bus service path interface method &optional :timeout timeout &rest args
-Call @var{method} on the D-Bus @var{bus}, but don't block the event queue.
-This is necessary for communicating to registered D-Bus methods,
-which are running in the same Emacs process.
-
-The arguments are the same as in @code{dbus-call-method}. Example:
-
-@lisp
-(dbus-call-method-non-blocking
- :system "org.freedesktop.Hal"
- "/org/freedesktop/Hal/devices/computer"
- "org.freedesktop.Hal.Device" "GetPropertyString"
- "system.kernel.machine")
-
-@result{} "i686"
-@end lisp
-@end defun
-
@node Asynchronous Methods
@chapter Calling methods non-blocking.
They are converted into D-Bus types as described in @ref{Type
Conversion}.
-Unless @var{handler} is @code{nil}, the function returns a key into
+If @var{handler} is a Lisp function, the function returns a key into
the hash table @code{dbus-registered-objects-table}. The
corresponding entry in the hash table is removed, when the return
message has been arrived, and @var{handler} is called. Example:
"org.freedesktop.Hal.Device" "GetPropertyString" 'message
"system.kernel.machine")
-@result{} (:system 2)
+@result{} (:serial :system 2)
@print{} i686
@end lisp
@cindex method calls, returning
@cindex returning method calls
-Emacs can also offer own methods, which can be called by other
-applications. These methods could be an implementation of an
-interface of a well known service, like @samp{org.freedesktop.TextEditor}.
+In order to register methods on the D-Bus, Emacs has to request a well
+known name on the D-Bus under which it will be available for other
+clients. Names on the D-Bus can be registered and unregistered using
+the following functions:
+
+@defun dbus-register-service bus service &rest flags
+Register the known name @var{service} on D-Bus @var{bus}.
+
+@var{bus} is either the symbol @code{:system} or the symbol
+@code{:session}.
+
+@var{service} is the service name to be registered on the D-Bus. It
+must be a known name.
+
+@var{flags} is a subset of the following keywords:
+
+@itemize
+@item @code{:allow-replacement}: Allow another service to become the primary
+owner if requested.
+
+@item @code{:replace-existing}: Request to replace the current primary owner.
+
+@item @code{:do-not-queue}: If we can not become the primary owner do not
+place us in the queue.
+@end itemize
+
+One of the following keywords is returned:
+
+@itemize
+
+@item @code{:primary-owner}: We have become the primary owner of the name
+@var{service}.
+
+@item @code{:in-queue}: We could not become the primary owner and
+have been placed in the queue.
+
+@item @code{:exists}: We already are in the queue.
+
+@item @code{:already-owner}: We already are the primary
+owner.
+@end itemize
+@end defun
+
+@defun dbus-unregister-service bus service
+Unregister all objects from D-Bus @var{bus}, registered by Emacs for
+@var{service}.
+
+@var{bus} is either the symbol @code{:system} or the symbol
+@code{:session}.
+
+@var{service} is the D-Bus service name of the D-Bus. It must be a
+known name. Emacs releases its association to @var{service} from
+D-Bus.
+
+One of the following keywords is returned:
+
+@itemize
+@item @code{:released}: We successfully released the name @var{service}.
+@item @code{:non-existent}: The name @var{service} does not exist on the bus.
+@item @code{:not-owner}: We are not an owner of the name @var{service}.
+@end itemize
+@end defun
+
+When a name has been chosen, Emacs can offer own methods, which can be
+called by other applications. These methods could be an
+implementation of an interface of a well known service, like
+@samp{org.freedesktop.TextEditor}.
It could be also an implementation of an own interface. In this case,
the service name must be @samp{org.gnu.Emacs}. The object path shall
-begin with @samp{/org/gnu/Emacs/@strong{Application}/}, and the
+begin with @samp{/org/gnu/Emacs/@strong{Application}}, and the
interface name shall be @code{org.gnu.Emacs.@strong{Application}}.
@samp{@strong{Application}} is the name of the application which
provides the interface.
@deffn Constant dbus-service-emacs
-The well known service name of Emacs.
+The well known service name @samp{org.gnu.Emacs} of Emacs.
@end deffn
@deffn Constant dbus-path-emacs
-The object path head "/org/gnu/Emacs" used by Emacs. All object
-paths, used by offered methods or signals, shall start with this
-string.
+The object path namespace @samp{/org/gnu/Emacs} used by Emacs.
+@end deffn
+
+@deffn Constant dbus-interface-emacs
+The interface namespace @code{org.gnu.Emacs} used by Emacs.
@end deffn
-@defun dbus-register-method bus service path interface method handler
+@defun dbus-register-method bus service path interface method handler dont-register-service
With this function, an application registers @var{method} on the D-Bus
@var{bus}.
@code{:session}.
@var{service} is the D-Bus service name of the D-Bus object
-@var{method} is registered for. It must be a known name.
+@var{method} is registered for. It must be a known name (See
+discussion of @var{dont-register-service} below).
-@var{path} is the D-Bus object path @var{service} is
-registered.
+@var{path} is the D-Bus object path @var{service} is registered (See
+discussion of @var{dont-register-service} below).
@var{interface} is the interface offered by @var{service}. It must
provide @var{method}.
In case @var{handler} shall return a reply message with an empty
argument list, @var{handler} must return the symbol @code{:ignore}.
+When @var{dont-register-service} is non-@code{nil}, the known name
+@var{service} is not registered. This means that other D-Bus clients
+have no way of noticing the newly registered method. When interfaces
+are constructed incrementally by adding single methods or properties
+at a time, @var{dont-register-service} can be used to prevent other
+clients from discovering the still incomplete interface.
+
The default D-Bus timeout when waiting for a message reply is 25
seconds. This value could be even smaller, depending on the calling
client. Therefore, @var{handler} shall not last longer than
"org.freedesktop.TextEditor" "OpenFile"
'my-dbus-method-handler)
-@result{} ((:session "org.freedesktop.TextEditor" "OpenFile")
+@result{} ((:method :session "org.freedesktop.TextEditor" "OpenFile")
("org.freedesktop.TextEditor" "/org/freedesktop/TextEditor"
my-dbus-method-handler))
@end lisp
@end example
@end defun
-@defun dbus-register-property bus service path interface property access value
+@defun dbus-register-property bus service path interface property access value &optional emits-signal dont-register-service
With this function, an application declares a @var{property} on the D-Bus
@var{bus}.
@var{service} is the D-Bus service name of the D-Bus. It must be a
known name.
-@var{path} is the D-Bus object path @var{service} is
-registered.
+@var{path} is the D-Bus object path @var{service} is registered (See
+discussion of @var{dont-register-service} below).
@var{interface} is the name of the interface used at @var{path},
@var{property} is the name of the property of @var{interface}.
The interface @samp{org.freedesktop.DBus.Properties} is added to
@var{path}, including a default handler for the @samp{Get},
-@samp{GetAll} and @samp{Set} methods of this interface. Example:
+@samp{GetAll} and @samp{Set} methods of this interface. When
+@var{emits-signal} is non-@code{nil}, the signal
+@samp{PropertiesChanged} is sent when the property is changed by
+@code{dbus-set-property}.
+
+When @var{dont-register-service} is non-@code{nil}, the known name
+@var{service} is not registered. This means that other D-Bus clients
+have no way of noticing the newly registered method. When interfaces
+are constructed incrementally by adding single methods or properties
+at a time, @var{dont-register-service} can be used to prevent other
+clients from discovering the still incomplete interface.
+
+@noindent Example:
@lisp
(dbus-register-property
:session "org.freedesktop.TextEditor" "/org/freedesktop/TextEditor"
"org.freedesktop.TextEditor" "name" :read "GNU Emacs")
-@result{} ((:session "org.freedesktop.TextEditor" "name")
+@result{} ((:property :session "org.freedesktop.TextEditor" "name")
("org.freedesktop.TextEditor" "/org/freedesktop/TextEditor"))
(dbus-register-property
:session "org.freedesktop.TextEditor" "/org/freedesktop/TextEditor"
- "org.freedesktop.TextEditor" "version" :readwrite emacs-version)
+ "org.freedesktop.TextEditor" "version" :readwrite emacs-version t)
-@result{} ((:session "org.freedesktop.TextEditor" "version")
+@result{} ((:property :session "org.freedesktop.TextEditor" "version")
("org.freedesktop.TextEditor" "/org/freedesktop/TextEditor"))
@end lisp
to the service from D-Bus.
@end defun
-@defun dbus-unregister-service bus service
-Unregister all objects from D-Bus @var{bus}, registered by Emacs for
-@var{service}.
-
-@var{bus} is either the symbol @code{:system} or the symbol
-@code{:session}.
-
-@var{service} is the D-Bus service name of the D-Bus. It must be a
-known name. Emacs releases its association to @var{service} from
-D-Bus.
-@end defun
-
@node Signals
@chapter Sending and receiving signals.
@cindex signals
-Signals are broadcast messages. They carry input parameters, which
-are received by all objects which have registered for such a signal.
+Signals are one way messages. They carry input parameters, which are
+received by all objects which have registered for such a signal.
@defun dbus-send-signal bus service path interface signal &rest args
This function is similar to @code{dbus-call-method}. The difference
either the symbol @code{:system} or the symbol @code{:session}. It
doesn't matter whether another object has registered for @var{signal}.
-@var{service} is the D-Bus service name of the object the signal is
-emitted from. @var{path} is the corresponding D-Bus object path,
-@var{service} is registered at. @var{interface} is an interface
-offered by @var{service}. It must provide @var{signal}.
+Signals can be unicast or broadcast messages. For broadcast messages,
+@var{service} must be @code{nil}. Otherwise, @var{service} is the
+D-Bus service name the signal is sent to as unicast
+message.@footnote{For backward compatibility, a broadcast message is
+also emitted if @var{service} is the known or unique name Emacs is
+registered at D-Bus @var{bus}.} @var{path} is the D-Bus object path
+@var{signal} is sent from. @var{interface} is an interface available
+at @var{path}. It must provide @var{signal}.
All other arguments args are passed to @var{signal} as arguments.
They are converted into D-Bus types as described in @ref{Type
@lisp
(dbus-send-signal
- :session dbus-service-emacs dbus-path-emacs
- (concat dbus-service-emacs ".FileManager") "FileModified"
+ :session nil dbus-path-emacs
+ (concat dbus-interface-emacs ".FileManager") "FileModified"
"/home/albinus/.emacs")
@end lisp
@end defun
@defun dbus-register-signal bus service path interface signal handler &rest args
-With this function, an application registers for @var{signal} on the
-D-Bus @var{bus}.
+With this function, an application registers for a signal on the D-Bus
+@var{bus}.
@var{bus} is either the symbol @code{:system} or the symbol
@code{:session}.
@var{service} is the D-Bus service name used by the sending D-Bus
object. It can be either a known name or the unique name of the D-Bus
-object sending the signal. In case of a unique name, signals won't be
-received any longer once the object owning this unique name has
-disappeared, and a new queued object has replaced it.
-
-When @var{service} is @code{nil}, related signals from all D-Bus
-objects shall be accepted.
+object sending the signal. A known name will be mapped onto the
+unique name of the object, owning @var{service} at registration time.
+When the corresponding D-Bus object disappears, signals won't be
+received any longer.
@var{path} is the corresponding D-Bus object path, @var{service} is
-registered at. It can also be @code{nil} if the path name of incoming
-signals shall not be checked.
+registered at. @var{interface} is an interface offered by
+@var{service}. It must provide @var{signal}.
-@var{interface} is an interface offered by @var{service}. It must
-provide @var{signal}.
+@var{service}, @var{path}, @var{interface} and @var{signal} can be
+@code{nil}. This is interpreted as a wildcard for the respective
+argument.
@var{handler} is a Lisp function to be called when the @var{signal} is
received. It must accept as arguments the output parameters
@var{signal} is sending.
-All other arguments @var{args}, if specified, must be strings. They
-stand for the respective arguments of @var{signal} in their order, and
-are used for filtering as well. A @code{nil} argument might be used
-to preserve the order.
+The remaining arguments @var{args} can be keywords or keyword string
+pairs.@footnote{For backward compatibility, the arguments @var{args}
+can also be just strings. They stand for the respective arguments of
+@var{signal} in their order, and are used for filtering as well. A
+@code{nil} argument might be used to preserve the order.} The meaning
+is as follows:
+
+@itemize
+@item @code{:argN} @var{string}:@*
+@code{:pathN} @var{string}:@*
+This stands for the Nth argument of the signal. @code{:pathN}
+arguments can be used for object path wildcard matches as specified by
+D-Bus, while an @code{:argN} argument requires an exact match.
+
+@item @code{:arg-namespace} @var{string}:@*
+Register for the signals, which first argument defines the service or
+interface namespace @var{string}.
+
+@item @code{:path-namespace} @var{string}:@*
+Register for the object path namespace @var{string}. All signals sent
+from an object path, which has @var{string} as the preceding string,
+are matched. This requires @var{path} to be @code{nil}.
+
+@item @code{:eavesdrop}:@*
+Register for unicast signals which are not directed to the D-Bus
+object Emacs is registered at D-Bus BUS, if the security policy of BUS
+allows this. Otherwise, this argument is ignored.
+@end itemize
@code{dbus-register-signal} returns a Lisp object, which can be used
as argument in @code{dbus-unregister-object} for removing the
"org.freedesktop.Hal.Manager" "DeviceAdded"
'my-dbus-signal-handler)
-@result{} ((:system "org.freedesktop.Hal.Manager" "DeviceAdded")
+@result{} ((:signal :system "org.freedesktop.Hal.Manager" "DeviceAdded")
("org.freedesktop.Hal" "/org/freedesktop/Hal/Manager"
my-signal-handler))
@end lisp
single string argument therefore. Plugging an USB device to your
machine, when registered for signal @samp{DeviceAdded}, will show you
which objects the GNU/Linux @code{hal} daemon adds.
+
+Some of the match rules have been added to a later version of D-Bus.
+In order to test the availability of such features, you could register
+for a dummy signal, and check the result:
+
+@lisp
+(dbus-ignore-errors
+ (dbus-register-signal
+ :system nil nil nil nil 'ignore :path-namespace "/invalid/path"))
+
+@result{} nil
+@end lisp
+@end defun
+
+
+@node Alternative Buses
+@chapter Alternative buses and environments.
+@cindex bus names
+@cindex UNIX domain socket
+@cindex TCP/IP socket
+
+Until now, we have spoken about the system and the session buses,
+which are the default buses to be connected to. However, it is
+possible to connect to any bus, from which the address is known. This
+is a UNIX domain or TCP/IP socket. Everywhere, where a @var{bus} is
+mentioned as argument of a function (the symbol @code{:system} or the
+symbol @code{:session}), this address can be used instead. The
+connection to this bus must be initialized first.
+
+@defun dbus-init-bus bus &optional private
+Establish the connection to D-Bus @var{bus}.
+
+@var{bus} can be either the symbol @code{:system} or the symbol
+@code{:session}, or it can be a string denoting the address of the
+corresponding bus. For the system and session buses, this function
+is called when loading @file{dbus.el}, there is no need to call it
+again.
+
+The function returns a number, which counts the connections this Emacs
+session has established to the @var{bus} under the same unique name
+(see @code{dbus-get-unique-name}). It depends on the libraries Emacs
+is linked with, and on the environment Emacs is running. For example,
+if Emacs is linked with the gtk toolkit, and it runs in a GTK-aware
+environment like Gnome, another connection might already be
+established.
+
+When @var{private} is non-@code{nil}, a new connection is established
+instead of reusing an existing one. It results in a new unique name
+at the bus. This can be used, if it is necessary to distinguish from
+another connection used in the same Emacs process, like the one
+established by GTK+. It should be used with care for at least the
+@code{:system} and @code{:session} buses, because other Emacs Lisp
+packages might already use this connection to those buses.
+
+Example: You initialize a connection to the AT-SPI bus on your host:
+
+@lisp
+(setq my-bus
+ (dbus-call-method
+ :session "org.a11y.Bus" "/org/a11y/bus"
+ "org.a11y.Bus" "GetAddress"))
+
+@result{} "unix:abstract=/tmp/dbus-2yzWHOCdSD,guid=a490dd26625870ca1298b6e10000fd7f"
+
+;; If Emacs is built with gtk support, and you run in a GTK enabled
+;; environment (like a GNOME session), the initialization reuses the
+;; connection established by GTK's atk bindings.
+(dbus-init-bus my-bus)
+
+@result{} 2
+
+(dbus-get-unique-name my-bus)
+
+@result{} ":1.19"
+
+;; Open a new connection to the same bus. This obsoletes the
+;; previous one.
+(dbus-init-bus my-bus 'private)
+
+@result{} 1
+
+(dbus-get-unique-name my-bus)
+
+@result{} ":1.20"
+@end lisp
+
+D-Bus addresses can specify different transport. A possible address
+could be based on TCP/IP sockets, see next example. However, it
+depends on the bus daemon configuration, which transport is supported.
+@end defun
+
+@defun dbus-setenv bus variable value
+Set the value of the @var{bus} environment variable @var{variable} to
+@var{value}.
+
+@var{bus} is either a Lisp symbol, @code{:system} or @code{:session},
+or a string denoting the bus address. Both @var{variable} and
+@var{value} should be strings.
+
+Normally, services inherit the environment of the bus daemon. This
+function adds to or modifies that environment when activating services.
+
+Some bus instances, such as @code{:system}, may disable setting the
+environment. In such cases, or if this feature is not available in
+older D-Bus versions, a @code{dbus-error} error is raised.
+
+As an example, it might be desirable to start X11 enabled services on
+a remote host's bus on the same X11 server the local Emacs is
+running. This could be achieved by
+
+@lisp
+(setq my-bus "unix:host=example.gnu.org,port=4711")
+
+@result{} "unix:host=example.gnu.org,port=4711"
+
+(dbus-init-bus my-bus)
+
+@result{} 1
+
+(dbus-setenv my-bus "DISPLAY" (getenv "DISPLAY"))
+
+@result{} nil
+@end lisp
@end defun
@node Errors and Events
@chapter Errors and events.
+@cindex debugging
@cindex errors
@cindex events
+The internal actions can be traced by running in a debug mode.
+
+@defvar dbus-debug
+If this variable is non-@code{nil}, D-Bus specific debug messages are raised.
+@end defvar
+
Input parameters of @code{dbus-call-method},
-@code{dbus-call-method-non-blocking},
-@code{dbus-call-method-asynchronously}, and
+@code{dbus-call-method-asynchronously}, @code{dbus-send-signal},
+@code{dbus-register-method}, @code{dbus-register-property} and
@code{dbus-register-signal} are checked for correct D-Bus types. If
there is a type mismatch, the Lisp error @code{wrong-type-argument}
@code{D-Bus ARG} is raised.
@defspec dbus-ignore-errors forms@dots{}
This executes @var{forms} exactly like a @code{progn}, except that
@code{dbus-error} errors are ignored during the @var{forms}. These
-errors can be made visible when variable @code{dbus-debug} is set to
-@code{t}.
+errors can be made visible when @code{dbus-debug} is set to @code{t}.
@end defspec
Incoming D-Bus messages are handled as Emacs events, see @pxref{Misc
@defun dbus-event-message-type event
Returns the message type of the corresponding D-Bus message. The
-result is a number.
+result is a natural number.
@end defun
@defun dbus-event-serial-number event
Returns the serial number of the corresponding D-Bus message.
-The result is a number.
+The result is a natural number.
@end defun
@defun dbus-event-service-name event
setting the variable @code{dbus-debug} to @code{t}. They can also be
handled by a hook function.
-@defvar dbus-event-error-hooks
+@defvar dbus-event-error-functions
This hook variable keeps a list of functions, which are called when a
D-Bus error happens in the event handler. Every function must accept
-two arguments, the event and the error variable catched in
+two arguments, the event and the error variable caught in
@code{condition-case} by @code{dbus-error}.
Such functions can be used the adapt the error signal to be raised.
@lisp
(defun my-dbus-event-error-handler (event error)
- (when (string-equal (concat dbus-service-emacs ".FileManager")
+ (when (string-equal (concat dbus-interface-emacs ".FileManager")
(dbus-event-interface-name event))
(message "my-dbus-event-error-handler: %S %S" event error)
(signal 'file-error (cdr error))))
-(add-hook 'dbus-event-error-hooks 'my-dbus-event-error-handler)
+(add-hook 'dbus-event-error-functions 'my-dbus-event-error-handler)
@end lisp
@end defvar
whether a given D-Bus error is related to them.
+@node Index
+@unnumbered Index
+
+@printindex cp
+
+
@node GNU Free Documentation License
@appendix GNU Free Documentation License
@include doclicense.texi
@bye
-
-@ignore
- arch-tag: 2eeec19d-0caf-44e0-a193-329d7f9951d8
-@end ignore
HCoop / bpt / emacs.git / blobdiff