This is ../../info/dbus, produced by makeinfo version 4.11 from
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Copyright (C) 2007, 2008, 2009, 2010 Free Software Foundation, Inc.
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document under the terms of the GNU Free Documentation License,
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Foundation; with no Invariant Sections, with the Front-Cover texts
being "A GNU Manual", and with the Back-Cover Texts as in (a)
below. A copy of the license 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."
INFO-DIR-SECTION Emacs
START-INFO-DIR-ENTRY
* D-Bus: (dbus). Using D-Bus in Emacs.
END-INFO-DIR-ENTRY
File: dbus, Node: Top, Next: Overview, Prev: (dir), Up: (dir)
D-Bus integration in Emacs
**************************
This manual documents an API for usage of D-Bus in Emacs. D-Bus is a
message bus system, a simple way for applications to talk to one
another. An overview of D-Bus can be found at
`http://dbus.freedesktop.org/'.
Copyright (C) 2007, 2008, 2009, 2010 Free Software Foundation, Inc.
Permission is granted to copy, distribute and/or modify this
document under the terms of the GNU Free Documentation License,
Version 1.3 or any later version published by the Free Software
Foundation; with no Invariant Sections, with the Front-Cover texts
being "A GNU Manual", and with the Back-Cover Texts as in (a)
below. A copy of the license 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."
* Menu:
* Overview:: An overview of D-Bus.
* Inspection:: Inspection of D-Bus services.
* Type Conversion:: Mapping Lisp types and D-Bus types.
* Synchronous Methods:: Calling methods in a blocking way.
* Asynchronous Methods:: Calling methods non-blocking.
* Receiving Method Calls:: Offering own methods.
* Signals:: Sending and receiving signals.
* Errors and Events:: Errors and events.
* GNU Free Documentation License:: The license for this documentation.
File: dbus, Node: Overview, Next: Inspection, Prev: Top, Up: Top
1 An overview of D-Bus
**********************
D-Bus is an inter-process communication mechanism for applications
residing on the same host. The communication is based on "messages".
Data in the messages is carried in a structured way, it is not just a
byte stream.
The communication is connection oriented to two kinds of message
buses: a so called "system bus", and a "session bus". On a given
machine, there is always one single system bus for miscellaneous
system-wide communication, like changing of hardware configuration. On
the other hand, the session bus is always related to a single user's
session.
Every client application, which is connected to a bus, registers
under a "unique name" at the bus. This name is used for identifying the
client application. Such a unique name starts always with a colon, and
looks like `:1.42'.
Additionally, a client application can register itself to a so called
"known name", which is a series of identifiers separated by dots, as in
`org.gnu.Emacs'. If several applications register to the same known
name, these registrations are queued, and only the first application
which has registered for the known name is reachable via this name. If
this application disconnects from the bus, the next queued unique name
becomes the owner of this known name.
An application can install one or several objects under its name.
Such objects are identified by an "object path", which looks similar to
paths in a filesystem. An example of such an object path could be
`/org/gnu/Emacs/'.
Applications might send a request to an object, that means sending a
message with some data as input parameters, and receiving a message
from that object with the result of this message, the output
parameters. Such a request is called "method" in D-Bus.
The other form of communication are "signals". The underlying
message is emitted from an object and will be received by all other
applications which have registered for such a signal.
All methods and signals an object supports are called "interface" of
the object. Interfaces are specified under a hierarchical name in
D-Bus; an object can support several interfaces. Such an interface
name could be `org.gnu.Emacs.TextEditor' or `org.gnu.Emacs.FileManager'.
File: dbus, Node: Inspection, Next: Type Conversion, Prev: Overview, Up: Top
2 Inspection of D-Bus services.
*******************************
* Menu:
* Bus names:: Discovering D-Bus names.
* Introspection:: Knowing the details of D-Bus services.
* Nodes and Interfaces:: Detecting object paths and interfaces.
* Methods and Signal:: Applying the functionality.
* Properties and Annotations:: What else to know about interfaces.
* Arguments and Signatures:: The final details.
File: dbus, Node: Bus names, Next: Introspection, Up: Inspection
2.1 Bus names.
==============
There are several basic functions which inspect the buses for
registered names. Internally they use the basic interface
`org.freedesktop.DBus', which is supported by all objects of a bus.
-- Function: 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
`/usr/share/dbus-1/services/'.
The result is a list of strings, which is `nil' when there are no
activatable service names at all.
-- Function: dbus-list-names bus
All service names, which are registered at D-Bus BUS, are
returned. The result is a list of strings, which is `nil' when
there are no registered service names at all. Well known names are
strings like `org.freedesktop.DBus'. Names starting with `:' are
unique names for services.
BUS must be either the symbol `:system' or the symbol `:session'.
-- Function: dbus-list-known-names bus
Retrieves all services which correspond to a known name in BUS. A
service has a known name if it doesn't start with `:'. The result
is a list of strings, which is `nil' when there are no known names
at all.
BUS must be either the symbol `:system' or the symbol `:session'.
-- Function: dbus-list-queued-owners bus service
For a given service, registered at D-Bus BUS under the name
SERVICE, all queued unique names are returned. The result is a
list of strings, or `nil' when there are no queued names for
SERVICE at all.
BUS must be either the symbol `:system' or the symbol `:session'.
SERVICE must be a known service name as string.
-- Function: dbus-get-name-owner bus service
For a given service, registered at D-Bus BUS under the name
SERVICE, the unique name of the name owner is returned. The
result is a string, or `nil' when there exist no name owner of
SERVICE.
BUS must be either the symbol `:system' or the symbol `:session'.
SERVICE must be a known service name as string.
-- Function: dbus-ping bus service &optional timeout
Check whether the service name SERVICE is registered at D-Bus BUS.
SERVICE might not have been started yet, it is autostarted if
possible. The result is either `t' or `nil'.
BUS must be either the symbol `:system' or the symbol `:session'.
SERVICE must be a string. TIMEOUT, a nonnegative integer,
specifies the maximum number of milliseconds `dbus-ping' must
return. The default value is 25,000. Example:
(message
"%s screensaver on board."
(cond
((dbus-ping :session "org.gnome.ScreenSaver" 100) "Gnome")
((dbus-ping :session "org.freedesktop.ScreenSaver" 100) "KDE")
(t "No")))
If it shall be checked whether SERVICE is already running without
autostarting it, one shall apply
(member service (dbus-list-known-names bus))
-- Function: dbus-get-unique-name bus
The unique name, under which Emacs is registered at D-Bus BUS, is
returned as string.
BUS must be either the symbol `:system' or the symbol `:session'.
File: dbus, Node: Introspection, Next: Nodes and Interfaces, Prev: Bus names, Up: Inspection
2.2 Knowing the details of D-Bus services.
==========================================
D-Bus services publish their interfaces. This can be retrieved and
analyzed during runtime, in order to understand the used implementation.
The resulting introspection data are in XML format. The root
introspection element is always a `node' element. It might have a
`name' attribute, which denotes the (absolute) object path an interface
is introspected.
The root `node' element may have `node' and `interface' children. A
child `node' element must have a `name' attribute, this case it is the
relative object path to the root `node' element.
An `interface' element has just one attribute, `name', which is the
full name of that interface. The default interface
`org.freedesktop.DBus.Introspectable' is always present. Example:
...
...
...
...
Children of an `interface' element can be `method', `signal' and
`property' elements. A `method' element stands for a D-Bus method of
the surrounding interface. The element itself has a `name' attribute,
showing the method name. Children elements `arg' stand for the
arguments of a method. Example:
`arg' elements can have the attributes `name', `type' and
`direction'. The `name' attribute is optional. The `type' attribute
stands for the "signature" of the argument in D-Bus. For a discussion
of D-Bus types and their Lisp representation see *note Type
Conversion::.(1) The `direction' attribute of an `arg' element can be
only `in' or `out'; in case it is omitted, it defaults to `in'.
A `signal' element of an `interface' has a similar structure. The
`direction' attribute of an `arg' child element can be only `out' here;
which is also the default value. Example:
A `property' element has no `arg' child element. It just has the
attributes `name', `type' and `access', which are all mandatory. The
`access' attribute allows the values `readwrite', `read', and `write'.
Example:
`annotation' elements can be children of `interface', `method',
`signal', and `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:
Annotations have just `name' and `value' attributes, both must be
strings.
-- Function: dbus-introspect bus service path
This function returns all interfaces and sub-nodes of SERVICE,
registered at object path PATH at bus BUS.
BUS must be either the symbol `:system' or the symbol `:session'.
SERVICE must be a known service name, and PATH must be a valid
object path. The last two parameters are strings. The result,
the introspection data, is a string in XML format. Example:
(dbus-introspect
:system "org.freedesktop.Hal"
"/org/freedesktop/Hal/devices/computer")
=> "
...
...
"
This example informs us, that the service `org.freedesktop.Hal' at
object path `/org/freedesktop/Hal/devices/computer' offers the
interface `org.freedesktop.Hal.Device' (and 2 other interfaces not
documented here). This interface contains the method
`GetAllProperties', which needs no input parameters, but returns
as output parameter an array of dictionary entries (key-value
pairs). Every dictionary entry has a string as key, and a variant
as value.
The interface offers also a signal, which returns 2 parameters: an
integer, and an array consisting of elements which are a struct of
a string and 2 boolean values.(2)
-- Function: dbus-introspect-xml bus service path
This function has the same intention as function
`dbus-introspect'. The returned value is a parsed XML tree, which
can be used for further analysis. Example:
(dbus-introspect-xml
:session "org.freedesktop.xesam.searcher"
"/org/freedesktop/xesam/searcher/main")
=> (node ((name . "/org/freedesktop/xesam/searcher/main"))
(interface ((name . "org.freedesktop.xesam.Search"))
(method ((name . "GetHitData"))
(arg ((name . "search") (type . "s") (direction . "in")))
(arg ((name . "hit_ids") (type . "au") (direction . "in")))
(arg ((name . "fields") (type . "as") (direction . "in")))
(arg ((name . "hit_data") (type . "aav") (direction . "out")))
)
...
(signal ((name . "HitsAdded"))
(arg ((name . "search") (type . "s")))
(arg ((name . "count") (type . "u")))
)
)
...
)
-- Function: dbus-introspect-get-attribute object attribute
It returns the ATTRIBUTE value of a D-Bus introspection OBJECT.
OBJECT can be every subtree of a parsed XML tree as retrieved with
`dbus-introspect-xml'. ATTRIBUTE must be a string according to
the attribute names in the D-Bus specification. Example:
(dbus-introspect-get-attribute
(dbus-introspect-xml :system "org.freedesktop.SystemToolsBackends"
"/org/freedesktop/SystemToolsBackends/UsersConfig")
"name")
=> "/org/freedesktop/SystemToolsBackends/UsersConfig"
If OBJECT has no ATTRIBUTE, the function returns nil.
---------- Footnotes ----------
(1) D-Bus signatures are explained in the D-Bus specification
`http://dbus.freedesktop.org/doc/dbus-specification.html#message-protocol-signatures'.
(2) The interfaces of the service `org.freedesktop.Hal' are
described at
`http://people.freedesktop.org/~david/hal-spec/hal-spec.html#interfaces'.
File: dbus, Node: Nodes and Interfaces, Next: Methods and Signal, Prev: Introspection, Up: Inspection
2.3 Detecting object paths and interfaces.
==========================================
The first elements, to be introspected for a D-Bus object, are further
object paths and interfaces.
-- Function: dbus-introspect-get-node-names bus service path
All node names of SERVICE in D-Bus BUS at object path PATH are
returned as list of strings. Example:
(dbus-introspect-get-node-names
:session "org.gnome.seahorse" "/org/gnome/seahorse")
=> ("crypto" "keys")
The node names stand for further object paths of the D-Bus
SERVICE, relative to PATH. In the example,
`/org/gnome/seahorse/crypto' and `/org/gnome/seahorse/keys' are
also object paths of the D-Bus service `org.gnome.seahorse'.
-- Function: dbus-introspect-get-all-nodes bus service path
This function returns all node names of SERVICE in D-Bus BUS at
object path PATH. It returns a list of strings with all object
paths of SERVICE, starting at PATH. Example:
(dbus-introspect-get-all-nodes :session "org.gnome.seahorse" "/")
=> ("/" "/org" "/org/gnome" "/org/gnome/seahorse"
"/org/gnome/seahorse/crypto"
"/org/gnome/seahorse/keys"
"/org/gnome/seahorse/keys/openpgp"
"/org/gnome/seahorse/keys/openpgp/local"
"/org/gnome/seahorse/keys/openssh"
"/org/gnome/seahorse/keys/openssh/local")
-- Function: dbus-introspect-get-interface-names bus service path
There will be returned a list strings of all interface names of
SERVICE in D-Bus BUS at object path PATH. This list will contain
the default interface `org.freedesktop.DBus.Introspectable'.
Another default interface is `org.freedesktop.DBus.Properties'.
If present, `interface' elements can also have `property'
children. Example:
(dbus-introspect-get-interface-names
:system "org.freedesktop.Hal"
"/org/freedesktop/Hal/devices/computer")
=> ("org.freedesktop.DBus.Introspectable"
"org.freedesktop.Hal.Device"
"org.freedesktop.Hal.Device.SystemPowerManagement"
"org.freedesktop.Hal.Device.CPUFreq")
-- Function: dbus-introspect-get-interface bus service path interface
Return INTERFACE of SERVICE in D-Bus BUS at object path PATH. The
return value is an XML element. INTERFACE must be a string,
element of the list returned by
`dbus-introspect-get-interface-names'. Example:
(dbus-introspect-get-interface
:session "org.freedesktop.xesam.searcher"
"/org/freedesktop/xesam/searcher/main"
"org.freedesktop.xesam.Search")
=> (interface ((name . "org.freedesktop.xesam.Search"))
(method ((name . "GetHitData"))
(arg ((name . "search") (type . "s") (direction . "in")))
(arg ((name . "hit_ids") (type . "au") (direction . "in")))
(arg ((name . "fields") (type . "as") (direction . "in")))
(arg ((name . "hit_data") (type . "aav") (direction . "out")))
)
...
(signal ((name . "HitsAdded"))
(arg ((name . "search") (type . "s")))
(arg ((name . "count") (type . "u")))
)
)
With these functions, it is possible to retrieve all introspection data
from a running system:
(with-current-buffer (switch-to-buffer "*introspect*")
(erase-buffer)
(dolist (service (dbus-list-known-names :session))
(dolist (path (dbus-introspect-get-all-nodes :session service "/"))
;; We want to introspect only elements, which have more than
;; the default interface "org.freedesktop.DBus.Introspectable".
(when (delete
"org.freedesktop.DBus.Introspectable"
(dbus-introspect-get-interface-names :session service path))
(insert (message "\nservice: \"%s\" path: \"%s\"\n" service path)
(dbus-introspect :session service path))
(redisplay t)))))
File: dbus, Node: Methods and Signal, Next: Properties and Annotations, Prev: Nodes and Interfaces, Up: Inspection
2.4 Applying the functionality.
===============================
Methods and signals are the communicatione means to D-Bus. The
following functions return their specifications.
-- Function: dbus-introspect-get-method-names bus service path
interface
Return a list of strings of all method names of INTERFACE of
SERVICE in D-Bus BUS at object path PATH. Example:
(dbus-introspect-get-method-names
:session "org.freedesktop.xesam.searcher"
"/org/freedesktop/xesam/searcher/main"
"org.freedesktop.xesam.Search")
=> ("GetState" "StartSearch" "GetHitCount" "GetHits" "NewSession"
"CloseSession" "GetHitData" "SetProperty" "NewSearch"
"GetProperty" "CloseSearch")
-- Function: dbus-introspect-get-method bus service path interface
method
This function returns METHOD of INTERFACE as XML element. It must
be located at SERVICE in D-Bus BUS at object path PATH. METHOD
must be a string, element of the list returned by
`dbus-introspect-get-method-names'. Example:
(dbus-introspect-get-method
:session "org.freedesktop.xesam.searcher"
"/org/freedesktop/xesam/searcher/main"
"org.freedesktop.xesam.Search" "GetHitData")
=> (method ((name . "GetHitData"))
(arg ((name . "search") (type . "s") (direction . "in")))
(arg ((name . "hit_ids") (type . "au") (direction . "in")))
(arg ((name . "fields") (type . "as") (direction . "in")))
(arg ((name . "hit_data") (type . "aav") (direction . "out")))
)
-- Function: dbus-introspect-get-signal-names bus service path
interface
Return a list of strings of all signal names of INTERFACE of
SERVICE in D-Bus BUS at object path PATH. Example:
(dbus-introspect-get-signal-names
:session "org.freedesktop.xesam.searcher"
"/org/freedesktop/xesam/searcher/main"
"org.freedesktop.xesam.Search")
=> ("StateChanged" "SearchDone" "HitsModified"
"HitsRemoved" "HitsAdded")
-- Function: dbus-introspect-get-signal bus service path interface
signal
This function returns SIGNAL of INTERFACE as XML element. It must
be located at SERVICE in D-Bus BUS at object path PATH. SIGNAL
must be a string, element of the list returned by
`dbus-introspect-get-signal-names'. Example:
(dbus-introspect-get-signal
:session "org.freedesktop.xesam.searcher"
"/org/freedesktop/xesam/searcher/main"
"org.freedesktop.xesam.Search" "HitsAdded")
=> (signal ((name . "HitsAdded"))
(arg ((name . "search") (type . "s")))
(arg ((name . "count") (type . "u")))
)
File: dbus, Node: Properties and Annotations, Next: Arguments and Signatures, Prev: Methods and Signal, Up: Inspection
2.5 What else to know about interfaces.
=======================================
Interfaces can have properties. These can be exposed via the
`org.freedesktop.DBus.Properties' interface(1). That is, properties
can be retrieved and changed during lifetime of an element.
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.
-- Function: dbus-introspect-get-property-names bus service path
interface
Return a list of strings with all property names of INTERFACE of
SERVICE in D-Bus BUS at object path PATH. Example:
(dbus-introspect-get-property-names
:session "org.kde.kded" "/modules/networkstatus"
"org.kde.Solid.Networking.Client")
=> ("Status")
If an interface declares properties, the corresponding element
supports also the `org.freedesktop.DBus.Properties' interface.
-- Function: dbus-introspect-get-property bus service path interface
property
This function returns PROPERTY of INTERFACE as XML element. It
must be located at SERVICE in D-Bus BUS at object path PATH.
PROPERTY must be a string, element of the list returned by
`dbus-introspect-get-property-names'.
A PROPERTY value can be retrieved by the function
`dbus-introspect-get-attribute'. Example:
(dbus-introspect-get-property
:session "org.kde.kded" "/modules/networkstatus"
"org.kde.Solid.Networking.Client" "Status")
=> (property ((access . "read") (type . "u") (name . "Status")))
(dbus-introspect-get-attribute
(dbus-introspect-get-property
:session "org.kde.kded" "/modules/networkstatus"
"org.kde.Solid.Networking.Client" "Status")
"access")
=> "read"
-- Function: dbus-get-property bus service path interface property
This function returns the value of PROPERTY of INTERFACE. It will
be checked at BUS, SERVICE, PATH. The result can be any valid
D-Bus value, or nil if there is no PROPERTY. Example:
(dbus-get-property
:session "org.kde.kded" "/modules/networkstatus"
"org.kde.Solid.Networking.Client" "Status")
=> 4
-- Function: dbus-set-property bus service path interface property
value
Set value of PROPERTY of INTERFACE to VALUE. It will be checked
at BUS, SERVICE, PATH. When the value has been set successful,
the result is VALUE. Otherwise, `nil' is returned. Example:
(dbus-set-property
:session "org.kde.kaccess" "/MainApplication"
"com.trolltech.Qt.QApplication" "doubleClickInterval" 500)
=> 500
-- Function: dbus-get-all-properties bus service path interface
This function returns all properties of INTERFACE. It will be
checked at BUS, SERVICE, PATH. The result is a list of cons.
Every cons contains the name of the property, and its value. If
there are no properties, `nil' is returned. Example:
(dbus-get-all-properties
:session "org.kde.kaccess" "/MainApplication"
"com.trolltech.Qt.QApplication")
=> (("cursorFlashTime" . 1000) ("doubleClickInterval" . 500)
("keyboardInputInterval" . 400) ("wheelScrollLines" . 3)
("globalStrut" 0 0) ("startDragTime" . 500)
("startDragDistance" . 4) ("quitOnLastWindowClosed" . t)
("styleSheet" . ""))
-- Function: dbus-introspect-get-annotation-names bus service path
interface &optional name
Return a list of all annotation names as list of strings. If NAME
is `nil', the annotations are children of INTERFACE, otherwise
NAME must be a `method', `signal', or `property' XML element,
where the annotations belong to. Example:
(dbus-introspect-get-annotation-names
:session "de.berlios.Pinot" "/de/berlios/Pinot"
"de.berlios.Pinot" "GetStatistics")
=> ("de.berlios.Pinot.GetStatistics")
Default annotation names(2) are
`org.freedesktop.DBus.Deprecated'
Whether or not the entity is deprecated; defaults to `nil'
`org.freedesktop.DBus.GLib.CSymbol'
The C symbol; may be used for `methods' and `interfaces'
`org.freedesktop.DBus.Method.NoReply'
If set, don't expect a reply to the `method' call; defaults
to `nil'
-- Function: dbus-introspect-get-annotation bus service path interface
name annotation
Return annotation ANNOTATION as XML object. If NAME is `nil',
ANNOTATION is a child of INTERFACE, otherwise NAME must be the
name of a `method', `signal', or `property' XML element, where the
ANNOTATION belongs to.
An attribute value can be retrieved by
`dbus-introspect-get-attribute'. Example:
(dbus-introspect-get-annotation
:session "de.berlios.Pinot" "/de/berlios/Pinot"
"de.berlios.Pinot" "GetStatistics"
"de.berlios.Pinot.GetStatistics")
=> (annotation ((name . "de.berlios.Pinot.GetStatistics")
(value . "pinotDBus")))
(dbus-introspect-get-attribute
(dbus-introspect-get-annotation
:session "de.berlios.Pinot" "/de/berlios/Pinot"
"de.berlios.Pinot" "GetStatistics"
"de.berlios.Pinot.GetStatistics")
"value")
=> "pinotDBus"
---------- Footnotes ----------
(1) See
`http://dbus.freedesktop.org/doc/dbus-specification.html#standard-interfaces-properties'
(2) See
`http://dbus.freedesktop.org/doc/dbus-specification.html#introspection-format'
File: dbus, Node: Arguments and Signatures, Prev: Properties and Annotations, Up: Inspection
2.6 The final details.
======================
Methods and signals have arguments. They are described in the `arg'
XML elements.
-- Function: dbus-introspect-get-argument-names bus service path
interface name
Return a list of all argument names as list of strings. NAME must
be a `method' or `signal' XML element. Example:
(dbus-introspect-get-argument-names
:session "org.freedesktop.xesam.searcher"
"/org/freedesktop/xesam/searcher/main"
"org.freedesktop.xesam.Search" "GetHitData")
=> ("search" "hit_ids" "fields" "hit_data")
Argument names are optional; the function can return `nil'
therefore, even if the method or signal has arguments.
-- Function: dbus-introspect-get-argument bus service path interface
name arg
Return argument ARG as XML object. NAME must be a `method' or
`signal' XML element. Example:
(dbus-introspect-get-argument
:session "org.freedesktop.xesam.searcher"
"/org/freedesktop/xesam/searcher/main"
"org.freedesktop.xesam.Search" "GetHitData" "search")
=> (arg ((name . "search") (type . "s") (direction . "in")))
-- Function: dbus-introspect-get-signature bus service path interface
name &optional direction
Return signature of a `method' or `signal', represented by NAME,
as string.
If NAME is a `method', DIRECTION can be either `in' or `out'. If
DIRECTION is `nil', `in' is assumed.
If NAME is a `signal', and DIRECTION is non-`nil', DIRECTION must
be `out'. Example:
(dbus-introspect-get-signature
:session "org.freedesktop.xesam.searcher"
"/org/freedesktop/xesam/searcher/main"
"org.freedesktop.xesam.Search" "GetHitData" "in")
=> "sauas"
(dbus-introspect-get-signature
:session "org.freedesktop.xesam.searcher"
"/org/freedesktop/xesam/searcher/main"
"org.freedesktop.xesam.Search" "HitsAdded")
=> "su"
File: dbus, Node: Type Conversion, Next: Synchronous Methods, Prev: Inspection, Up: Top
3 Mapping Lisp types and D-Bus types.
*************************************
D-Bus method calls and signals accept usually several arguments as
parameters, either as input parameter, or as output parameter. Every
argument belongs to a D-Bus type.
Such arguments must be mapped between the value encoded as a D-Bus
type, and the corresponding type of Lisp objects. The mapping is
applied Lisp object ==> D-Bus type for input parameters, and D-Bus type
==> Lisp object for output parameters.
3.1 Input parameters.
=====================
Input parameters for D-Bus methods and signals occur as arguments of a
Lisp function call. The following mapping to D-Bus types is applied,
when the corresponding D-Bus message is created:
Lisp type D-Bus type
`t' and `nil' ==> DBUS_TYPE_BOOLEAN
number ==> DBUS_TYPE_UINT32
integer ==> DBUS_TYPE_INT32
float ==> DBUS_TYPE_DOUBLE
string ==> DBUS_TYPE_STRING
list ==> DBUS_TYPE_ARRAY
Other Lisp objects, like symbols or hash tables, are not accepted as
input parameter.
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
types are represented by the type symbols `:byte', `:boolean',
`:int16', `:uint16', `:int32', `:uint32', `:int64', `:uint64',
`:double', `:string', `:object-path' and `:signature'.
Example:
(dbus-call-method ... NUMBER STRING)
is equivalent to
(dbus-call-method ... :uint32 NUMBER :string STRING)
but different to
(dbus-call-method ... :int32 NUMBER :signature STRING)
The value for a byte D-Bus type can be any integer in the range 0
through 255. If a character is used as argument, modifiers represented
outside this range are stripped of. For example, `:byte ?x' is equal
to `:byte ?\M-x', but it is not equal to `:byte ?\C-x' or `:byte
?\M-\C-x'.
A D-Bus compound type is always represented as a list. The CAR of
this list can be the type symbol `:array', `:variant', `:struct' or
`:dict-entry', which would result in a corresponding D-Bus container.
`:array' is optional, because this is the default compound D-Bus type
for a list.
The objects being elements of the list are checked according to the
D-Bus compound type rules.
* An array must contain only elements of the same D-Bus type. It
can be empty.
* A variant must contain only one single element.
* A dictionary entry must be element of an array, and it must
contain only a key-value pair of two elements, with a basic D-Bus
type key.
* There is no restriction for structs.
If an empty array needs an element D-Bus type other than string, it
can contain exactly one element of D-Bus type `:signature'. The value
of this element (a string) is used as the signature of the elements of
this array. Example:
(dbus-call-method
:session "org.freedesktop.Notifications"
"/org/freedesktop/Notifications"
"org.freedesktop.Notifications" "Notify"
"GNU Emacs" ;; Application name.
0 ;; No replacement of other notifications.
"" ;; No icon.
"Notification summary" ;; Summary.
(format ;; Body.
"This is a test notification, raised from %s" (emacs-version))
'(:array) ;; No actions (empty array of strings).
'(:array :signature "{sv}") ;; No hints
;; (empty array of dictionary entries).
:int32 -1) ;; Default timeout.
=> 3
-- Function: dbus-string-to-byte-array string
Sometimes, D-Bus methods require as input parameter an array of
bytes, instead of a string. If it is guaranteed, that STRING is an
UTF8 string, this function performs the conversion. Example:
(dbus-string-to-byte-array "/etc/hosts")
=> (:array :byte 47 :byte 101 :byte 116 :byte 99 :byte 47
:byte 104 :byte 111 :byte 115 :byte 116 :byte 115)
-- Function: dbus-escape-as-identifier string
Escape an arbitrary STRING so it follows the rules for a C
identifier. The escaped string can be used as object path
component, interface element component, bus name component or
member name in D-Bus.
The escaping consists of replacing all non-alphanumerics, and the
first character if it's a digit, with an underscore and two
lower-case hex digits. As a special case, "" is escaped to "_".
Example:
(dbus-escape-as-identifier "0123abc_xyz\x01\xff")
=> "_30123abc_5fxyz_01_ff"
3.2 Output parameters.
======================
Output parameters of D-Bus methods and signals are mapped to Lisp
objects.
D-Bus type Lisp type
DBUS_TYPE_BOOLEAN ==> `t' or `nil'
DBUS_TYPE_BYTE ==> number
DBUS_TYPE_UINT16 ==> number
DBUS_TYPE_INT16 ==> number
DBUS_TYPE_UINT32 ==> number or float
DBUS_TYPE_INT32 ==> number or float
DBUS_TYPE_UINT64 ==> number or float
DBUS_TYPE_INT64 ==> number or float
DBUS_TYPE_DOUBLE ==> float
DBUS_TYPE_STRING ==> string
DBUS_TYPE_OBJECT_PATH ==> string
DBUS_TYPE_SIGNATURE ==> string
DBUS_TYPE_ARRAY ==> list
DBUS_TYPE_VARIANT ==> list
DBUS_TYPE_STRUCT ==> list
DBUS_TYPE_DICT_ENTRY ==> list
A float object in case of `DBUS_TYPE_UINT32', `DBUS_TYPE_INT32',
`DBUS_TYPE_UINT64' and `DBUS_TYPE_INT6432' 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
same rules.
The signal `PropertyModified', discussed as example in *note
Inspection::, would offer as Lisp data the following object (BOOL
stands here for either `nil' or `t'):
(NUMBER ((STRING BOOL BOOL) (STRING BOOL BOOL) ...))
-- Function: dbus-byte-array-to-string byte-array
If a D-Bus method or signal returns an array of bytes, which are
known to represent an UTF8 string, this function converts
BYTE-ARRAY to the corresponding string. Example:
(dbus-byte-array-to-string '(47 101 116 99 47 104 111 115 116 115))
=> "/etc/hosts"
-- Function: dbus-unescape-from-identifier string
Retrieve the original string from the encoded STRING. STRING must
have been coded with `dbus-escape-as-identifier'. Example:
(dbus-unescape-from-identifier "_30123abc_5fxyz_01_ff")
=> "0123abc_xyz^Aÿ"
File: dbus, Node: Synchronous Methods, Next: Asynchronous Methods, Prev: Type Conversion, Up: Top
4 Calling methods in a blocking way.
************************************
Methods can be called synchronously ("blocking") or asynchronously
("non-blocking").
At D-Bus level, a method call consist of two messages: one message
which carries the input parameters to the object owning the method to
be called, and a reply message returning the resulting output
parameters from the object.
-- Function: dbus-call-method bus service path interface method
&optional :timeout timeout &rest args
This function calls METHOD on the D-Bus BUS. BUS is either the
symbol `:system' or the symbol `:session'.
SERVICE is the D-Bus service name to be used. PATH is the D-Bus
object path, SERVICE is registered at. INTERFACE is an interface
offered by SERVICE. It must provide METHOD.
If the parameter `:timeout' is given, the following integer
TIMEOUT specifies the maximum number of milliseconds the method
call must return. The default value is 25,000. If the method call
doesn't return in time, a D-Bus error is raised (*note Errors and
Events::).
All other arguments args are passed to METHOD as arguments. They
are converted into D-Bus types as described in *note Type
Conversion::.
The function returns the resulting values of METHOD as a list of
Lisp objects, according to the type conversion rules described in
*note Type Conversion::. Example:
(dbus-call-method
:session "org.gnome.seahorse" "/org/gnome/seahorse/keys/openpgp"
"org.gnome.seahorse.Keys" "GetKeyField"
"openpgp:657984B8C7A966DD" "simple-name")
=> (t ("Philip R. Zimmermann"))
If the result of the method call is just one value, the converted
Lisp object is returned instead of a list containing this single
Lisp object. Example:
(dbus-call-method
:system "org.freedesktop.Hal"
"/org/freedesktop/Hal/devices/computer"
"org.freedesktop.Hal.Device" "GetPropertyString"
"system.kernel.machine")
=> "i686"
With the `dbus-introspect' function it is possible to explore the
interfaces of `org.freedesktop.Hal' service. It offers the
interfaces `org.freedesktop.Hal.Manager' for the object at the
path `/org/freedesktop/Hal/Manager' as well as the interface
`org.freedesktop.Hal.Device' for all objects prefixed with the
path `/org/freedesktop/Hal/devices'. With the methods
`GetAllDevices' and `GetAllProperties', it is simple to emulate
the `lshal' command on GNU/Linux systems:
(dolist (device
(dbus-call-method
:system "org.freedesktop.Hal"
"/org/freedesktop/Hal/Manager"
"org.freedesktop.Hal.Manager" "GetAllDevices"))
(message "\nudi = %s" device)
(dolist (properties
(dbus-call-method
:system "org.freedesktop.Hal" device
"org.freedesktop.Hal.Device" "GetAllProperties"))
(message " %s = %S"
(car properties) (or (caar (cdr properties)) ""))))
-| "udi = /org/freedesktop/Hal/devices/computer
info.addons = (\"hald-addon-acpi\")
info.bus = \"unknown\"
info.product = \"Computer\"
info.subsystem = \"unknown\"
info.udi = \"/org/freedesktop/Hal/devices/computer\"
linux.sysfs_path_device = \"(none)\"
power_management.acpi.linux.version = \"20051216\"
power_management.can_suspend_to_disk = t
power_management.can_suspend_to_ram = \"\"
power_management.type = \"acpi\"
smbios.bios.release_date = \"11/07/2001\"
system.chassis.manufacturer = \"COMPAL\"
system.chassis.type = \"Notebook\"
system.firmware.release_date = \"03/19/2005\"
..."
-- Function: dbus-call-method-non-blocking bus service path interface
method &optional :timeout timeout &rest args
Call METHOD on the D-Bus 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 `dbus-call-method'. Example:
(dbus-call-method-non-blocking
:system "org.freedesktop.Hal"
"/org/freedesktop/Hal/devices/computer"
"org.freedesktop.Hal.Device" "GetPropertyString"
"system.kernel.machine")
=> "i686"
File: dbus, Node: Asynchronous Methods, Next: Receiving Method Calls, Prev: Synchronous Methods, Up: Top
5 Calling methods non-blocking.
*******************************
-- Function: dbus-call-method-asynchronously bus service path
interface method handler &optional :timeout timeout &rest args
This function calls METHOD on the D-Bus BUS asynchronously. BUS
is either the symbol `:system' or the symbol `:session'.
SERVICE is the D-Bus service name to be used. PATH is the D-Bus
object path, SERVICE is registered at. INTERFACE is an interface
offered by SERVICE. It must provide METHOD.
HANDLER is a Lisp function, which is called when the corresponding
return message has arrived. If HANDLER is `nil', no return
message will be expected.
If the parameter `:timeout' is given, the following integer
TIMEOUT specifies the maximum number of milliseconds a reply
message must arrive. The default value is 25,000. If there is no
reply message in time, a D-Bus error is raised (*note Errors and
Events::).
All other arguments args are passed to METHOD as arguments. They
are converted into D-Bus types as described in *note Type
Conversion::.
Unless HANDLER is `nil', the function returns a key into the hash
table `dbus-registered-objects-table'. The corresponding entry in
the hash table is removed, when the return message has been
arrived, and HANDLER is called. Example:
(dbus-call-method-asynchronously
:system "org.freedesktop.Hal"
"/org/freedesktop/Hal/devices/computer"
"org.freedesktop.Hal.Device" "GetPropertyString" 'message
"system.kernel.machine")
=> (:system 2)
-| i686
File: dbus, Node: Receiving Method Calls, Next: Signals, Prev: Asynchronous Methods, Up: Top
6 Offering own methods.
***********************
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 `org.freedesktop.TextEditor'.
It could be also an implementation of an own interface. In this
case, the service name must be `org.gnu.Emacs'. The object path shall
begin with `/org/gnu/Emacs/*Application*/', and the interface name
shall be `org.gnu.Emacs.*Application*'. `*Application*' is the name of
the application which provides the interface.
-- Constant: dbus-service-emacs
The well known service name of Emacs.
-- 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.
-- Function: dbus-register-method bus service path interface method
handler
With this function, an application registers METHOD on the D-Bus
BUS.
BUS is either the symbol `:system' or the symbol `:session'.
SERVICE is the D-Bus service name of the D-Bus object METHOD is
registered for. It must be a known name.
PATH is the D-Bus object path SERVICE is registered.
INTERFACE is the interface offered by SERVICE. It must provide
METHOD.
HANDLER is a Lisp function to be called when a METHOD call is
received. It must accept as arguments the input arguments of
METHOD. HANDLER should return a list, whose elements are to be
used as arguments for the reply message of METHOD. This list can
be composed like the input parameters in *note Type Conversion::.
If HANDLER wants to return just one Lisp object and it is not a
cons cell, HANDLER can return this object directly, instead of
returning a list containing the object.
In case HANDLER shall return a reply message with an empty
argument list, HANDLER must return the symbol `:ignore'.
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, HANDLER shall not last longer than
absolutely necessary.
`dbus-register-method' returns a Lisp object, which can be used as
argument in `dbus-unregister-object' for removing the registration
for METHOD. Example:
(defun my-dbus-method-handler (filename)
(let (result)
(if (find-file filename)
(setq result '(:boolean t))
(setq result '(:boolean nil)))
result))
=> my-dbus-method-handler
(dbus-register-method
:session "org.freedesktop.TextEditor" "/org/freedesktop/TextEditor"
"org.freedesktop.TextEditor" "OpenFile"
'my-dbus-method-handler)
=> ((:session "org.freedesktop.TextEditor" "OpenFile")
("org.freedesktop.TextEditor" "/org/freedesktop/TextEditor"
my-dbus-method-handler))
If you invoke the method `org.freedesktop.TextEditor.OpenFile'
from another D-Bus application with a filename as parameter, the
file is opened in Emacs, and the method returns either TRUE or
FALSE, indicating the success of the method. As test tool one
could use the command line tool `dbus-send' in a shell:
# dbus-send --session --print-reply \
--dest="org.freedesktop.TextEditor" \
"/org/freedesktop/TextEditor" \
"org.freedesktop.TextEditor.OpenFile" string:"/etc/hosts"
-| method return sender=:1.22 -> dest=:1.23 reply_serial=2
boolean true
You can indicate an error by raising the Emacs signal
`dbus-error'. The handler above could be changed like this:
(defun my-dbus-method-handler (&rest args)
(unless (and (= (length args) 1) (stringp (car args)))
(signal 'dbus-error (list (format "Wrong argument list: %S" args))))
(condition-case err
(find-file (car args))
(error (signal 'dbus-error (cdr err))))
t)
=> my-dbus-method-handler
The test runs then
# dbus-send --session --print-reply \
--dest="org.freedesktop.TextEditor" \
"/org/freedesktop/TextEditor" \
"org.freedesktop.TextEditor.OpenFile" \
string:"/etc/hosts" string:"/etc/passwd"
-| Error org.freedesktop.DBus.Error.Failed:
Wrong argument list: ("/etc/hosts" "/etc/passwd")
-- Function: dbus-register-property bus service path interface
property access value
With this function, an application declares a PROPERTY on the D-Bus
BUS.
BUS is either the symbol `:system' or the symbol `:session'.
SERVICE is the D-Bus service name of the D-Bus. It must be a
known name.
PATH is the D-Bus object path SERVICE is registered.
INTERFACE is the name of the interface used at PATH, PROPERTY is
the name of the property of INTERFACE.
ACCESS indicates, whether the property can be changed by other
services via D-Bus. It must be either the symbol `:read' or
`:readwrite'. VALUE is the initial value of the property, it can
be of any valid type (see `dbus-call-method' for details).
If PROPERTY already exists on PATH, it will be overwritten. For
properties with access type `:read' this is the only way to change
their values. Properties with access type `:readwrite' can be
changed by `dbus-set-property'.
The interface `org.freedesktop.DBus.Properties' is added to PATH,
including a default handler for the `Get', `GetAll' and `Set'
methods of this interface. Example:
(dbus-register-property
:session "org.freedesktop.TextEditor" "/org/freedesktop/TextEditor"
"org.freedesktop.TextEditor" "name" :read "GNU Emacs")
=> ((: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)
=> ((:session "org.freedesktop.TextEditor" "version")
("org.freedesktop.TextEditor" "/org/freedesktop/TextEditor"))
Other D-Bus applications can read the property via the default
methods `org.freedesktop.DBus.Properties.Get' and
`org.freedesktop.DBus.Properties.GetAll'. Testing is also
possible via the command line tool `dbus-send' in a shell:
# dbus-send --session --print-reply \
--dest="org.freedesktop.TextEditor" \
"/org/freedesktop/TextEditor" \
"org.freedesktop.DBus.Properties.GetAll" \
string:"org.freedesktop.TextEditor"
-| method return sender=:1.22 -> dest=:1.23 reply_serial=3
array [
dict entry(
string "name"
variant string "GNU Emacs"
)
dict entry(
string "version"
variant string "23.1.50.5"
)
]
It is also possible, to apply the `dbus-get-property',
`dbus-get-all-properties' and `dbus-set-property' functions (*note
Properties and Annotations::).
(dbus-set-property
:session "org.freedesktop.TextEditor" "/org/freedesktop/TextEditor"
"org.freedesktop.TextEditor" "version" "23.1.50")
=> "23.1.50"
(dbus-get-property
:session "org.freedesktop.TextEditor" "/org/freedesktop/TextEditor"
"org.freedesktop.TextEditor" "version")
=> "23.1.50"
-- Function: dbus-unregister-object object
Unregister OBJECT from the D-Bus. OBJECT must be the result of a
preceding `dbus-register-method', `dbus-register-property' or
`dbus-register-signal' call (*note Signals::). It returns `t' if
OBJECT has been unregistered, `nil' otherwise.
When OBJECT identifies the last method or property, which is
registered for the respective service, Emacs releases its
association to the service from D-Bus.
-- Function: dbus-unregister-service bus service
Unregister all objects from D-Bus BUS, registered by Emacs for
SERVICE.
BUS is either the symbol `:system' or the symbol `:session'.
SERVICE is the D-Bus service name of the D-Bus. It must be a
known name. Emacs releases its association to SERVICE from D-Bus.
File: dbus, Node: Signals, Next: Errors and Events, Prev: Receiving Method Calls, Up: Top
7 Sending and receiving signals.
********************************
Signals are broadcast messages. They carry input parameters, which are
received by all objects which have registered for such a signal.
-- Function: dbus-send-signal bus service path interface signal &rest
args
This function is similar to `dbus-call-method'. The difference
is, that there are no returning output parameters.
The function emits SIGNAL on the D-Bus BUS. BUS is either the
symbol `:system' or the symbol `:session'. It doesn't matter
whether another object has registered for SIGNAL.
SERVICE is the D-Bus service name of the object the signal is
emitted from. PATH is the corresponding D-Bus object path,
SERVICE is registered at. INTERFACE is an interface offered by
SERVICE. It must provide SIGNAL.
All other arguments args are passed to SIGNAL as arguments. They
are converted into D-Bus types as described in *note Type
Conversion::. Example:
(dbus-send-signal
:session dbus-service-emacs dbus-path-emacs
(concat dbus-service-emacs ".FileManager") "FileModified"
"/home/albinus/.emacs")
-- Function: dbus-register-signal bus service path interface signal
handler &rest args
With this function, an application registers for SIGNAL on the
D-Bus BUS.
BUS is either the symbol `:system' or the symbol `:session'.
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 SERVICE is `nil', related signals from all D-Bus objects
shall be accepted.
PATH is the corresponding D-Bus object path, SERVICE is registered
at. It can also be `nil' if the path name of incoming signals
shall not be checked.
INTERFACE is an interface offered by SERVICE. It must provide
SIGNAL.
HANDLER is a Lisp function to be called when the SIGNAL is
received. It must accept as arguments the output parameters
SIGNAL is sending.
All other arguments ARGS, if specified, must be strings. They
stand for the respective arguments of SIGNAL in their order, and
are used for filtering as well. A `nil' argument might be used to
preserve the order.
`dbus-register-signal' returns a Lisp object, which can be used as
argument in `dbus-unregister-object' for removing the registration
for SIGNAL. Example:
(defun my-dbus-signal-handler (device)
(message "Device %s added" device))
=> my-dbus-signal-handler
(dbus-register-signal
:system "org.freedesktop.Hal" "/org/freedesktop/Hal/Manager"
"org.freedesktop.Hal.Manager" "DeviceAdded"
'my-dbus-signal-handler)
=> ((:system "org.freedesktop.Hal.Manager" "DeviceAdded")
("org.freedesktop.Hal" "/org/freedesktop/Hal/Manager"
my-signal-handler))
As we know from the introspection data of interface
`org.freedesktop.Hal.Manager', the signal `DeviceAdded' provides
one single parameter, which is mapped into a Lisp string. The
callback function `my-dbus-signal-handler' must define one single
string argument therefore. Plugging an USB device to your
machine, when registered for signal `DeviceAdded', will show you
which objects the GNU/Linux `hal' daemon adds.
File: dbus, Node: Errors and Events, Next: GNU Free Documentation License, Prev: Signals, Up: Top
8 Errors and events.
********************
Input parameters of `dbus-call-method', `dbus-call-method-non-blocking',
`dbus-call-method-asynchronously', and `dbus-register-signal' are
checked for correct D-Bus types. If there is a type mismatch, the Lisp
error `wrong-type-argument' `D-Bus ARG' is raised.
All errors raised by D-Bus are signaled with the error symbol
`dbus-error'. If possible, error messages from D-Bus are appended to
the `dbus-error'.
-- Special Form: dbus-ignore-errors forms...
This executes FORMS exactly like a `progn', except that
`dbus-error' errors are ignored during the FORMS. These errors
can be made visible when variable `dbus-debug' is set to `t'.
Incoming D-Bus messages are handled as Emacs events, see *note Misc
Events: (elisp)Misc Events. They are retrieved only, when Emacs runs in
interactive mode. The generated event has this form:
(dbus-event BUS TYPE SERIAL SERVICE PATH INTERFACE MEMBER HANDLER
&rest ARGS)
BUS identifies the D-Bus the message is coming from. It is either
the symbol `:system' or the symbol `:session'.
TYPE is the D-Bus message type which has caused the event. It can
be `dbus-message-type-invalid', `dbus-message-type-method-call',
`dbus-message-type-method-return', `dbus-message-type-error', or
`dbus-message-type-signal'. SERIAL is the serial number of the
received D-Bus message.
SERVICE and PATH are the unique name and the object path of the
D-Bus object emitting the message. INTERFACE and MEMBER denote the
message which has been sent.
HANDLER is the callback function which has been registered for this
message (see *note Signals::). When a `dbus-event' event arrives,
HANDLER is called with ARGS as arguments.
In order to inspect the `dbus-event' data, you could extend the
definition of the callback function in *note Signals:::
(defun my-dbus-signal-handler (&rest args)
(message "my-dbus-signal-handler: %S" last-input-event))
There exist convenience functions which could be called inside a
callback function in order to retrieve the information from the event.
-- Function: dbus-event-bus-name event
Returns the bus name EVENT is coming from. The result is either
the symbol `:system' or the symbol `:session'.
-- Function: dbus-event-message-type event
Returns the message type of the corresponding D-Bus message. The
result is a number.
-- Function: dbus-event-serial-number event
Returns the serial number of the corresponding D-Bus message. The
result is a number.
-- Function: dbus-event-service-name event
Returns the unique name of the D-Bus object EVENT is coming from.
-- Function: dbus-event-path-name event
Returns the object path of the D-Bus object EVENT is coming from.
-- Function: dbus-event-interface-name event
Returns the interface name of the D-Bus object EVENT is coming
from.
-- Function: dbus-event-member-name event
Returns the member name of the D-Bus object EVENT is coming from.
It is either a signal name or a method name.
D-Bus errors are not propagated during event handling, because it is
usually not desired. D-Bus errors in events can be made visible by
setting the variable `dbus-debug' to `t'. They can also be handled by
a hook function.
-- Variable: dbus-event-error-hooks
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 `condition-case' by `dbus-error'.
Such functions can be used the adapt the error signal to be raised.
Example:
(defun my-dbus-event-error-handler (event error)
(when (string-equal (concat dbus-service-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)
Hook functions shall take into account, that there might be other
D-Bus applications running. Therefore, they shall check carefully,
whether a given D-Bus error is related to them.
File: dbus, Node: GNU Free Documentation License, Prev: Errors and Events, Up: Top
Appendix A GNU Free Documentation License
*****************************************
Version 1.3, 3 November 2008
Copyright (C) 2000, 2001, 2002, 2007, 2008, 2009 Free Software Foundation, Inc.
`http://fsf.org/'
Everyone is permitted to copy and distribute verbatim copies
of this license document, but changing it is not allowed.
0. PREAMBLE
The purpose of this License is to make a manual, textbook, or other
functional and useful document "free" in the sense of freedom: to
assure everyone the effective freedom to copy and redistribute it,
with or without modifying it, either commercially or
noncommercially. Secondarily, this License preserves for the
author and publisher a way to get credit for their work, while not
being considered responsible for modifications made by others.
This License is a kind of "copyleft", which means that derivative
works of the document must themselves be free in the same sense.
It complements the GNU General Public License, which is a copyleft
license designed for free software.
We have designed this License in order to use it for manuals for
free software, because free software needs free documentation: a
free program should come with manuals providing the same freedoms
that the software does. But this License is not limited to
software manuals; it can be used for any textual work, regardless
of subject matter or whether it is published as a printed book.
We recommend this License principally for works whose purpose is
instruction or reference.
1. APPLICABILITY AND DEFINITIONS
This License applies to any manual or other work, in any medium,
that contains a notice placed by the copyright holder saying it
can be distributed under the terms of this License. Such a notice
grants a world-wide, royalty-free license, unlimited in duration,
to use that work under the conditions stated herein. The
"Document", below, refers to any such manual or work. Any member
of the public is a licensee, and is addressed as "you". You
accept the license if you copy, modify or distribute the work in a
way requiring permission under copyright law.
A "Modified Version" of the Document means any work containing the
Document or a portion of it, either copied verbatim, or with
modifications and/or translated into another language.
A "Secondary Section" is a named appendix or a front-matter section
of the Document that deals exclusively with the relationship of the
publishers or authors of the Document to the Document's overall
subject (or to related matters) and contains nothing that could
fall directly within that overall subject. (Thus, if the Document
is in part a textbook of mathematics, a Secondary Section may not
explain any mathematics.) The relationship could be a matter of
historical connection with the subject or with related matters, or
of legal, commercial, philosophical, ethical or political position
regarding them.
The "Invariant Sections" are certain Secondary Sections whose
titles are designated, as being those of Invariant Sections, in
the notice that says that the Document is released under this
License. If a section does not fit the above definition of
Secondary then it is not allowed to be designated as Invariant.
The Document may contain zero Invariant Sections. If the Document
does not identify any Invariant Sections then there are none.
The "Cover Texts" are certain short passages of text that are
listed, as Front-Cover Texts or Back-Cover Texts, in the notice
that says that the Document is released under this License. A
Front-Cover Text may be at most 5 words, and a Back-Cover Text may
be at most 25 words.
A "Transparent" copy of the Document means a machine-readable copy,
represented in a format whose specification is available to the
general public, that is suitable for revising the document
straightforwardly with generic text editors or (for images
composed of pixels) generic paint programs or (for drawings) some
widely available drawing editor, and that is suitable for input to
text formatters or for automatic translation to a variety of
formats suitable for input to text formatters. A copy made in an
otherwise Transparent file format whose markup, or absence of
markup, has been arranged to thwart or discourage subsequent
modification by readers is not Transparent. An image format is
not Transparent if used for any substantial amount of text. A
copy that is not "Transparent" is called "Opaque".
Examples of suitable formats for Transparent copies include plain
ASCII without markup, Texinfo input format, LaTeX input format,
SGML or XML using a publicly available DTD, and
standard-conforming simple HTML, PostScript or PDF designed for
human modification. Examples of transparent image formats include
PNG, XCF and JPG. Opaque formats include proprietary formats that
can be read and edited only by proprietary word processors, SGML or
XML for which the DTD and/or processing tools are not generally
available, and the machine-generated HTML, PostScript or PDF
produced by some word processors for output purposes only.
The "Title Page" means, for a printed book, the title page itself,
plus such following pages as are needed to hold, legibly, the
material this License requires to appear in the title page. For
works in formats which do not have any title page as such, "Title
Page" means the text near the most prominent appearance of the
work's title, preceding the beginning of the body of the text.
The "publisher" means any person or entity that distributes copies
of the Document to the public.
A section "Entitled XYZ" means a named subunit of the Document
whose title either is precisely XYZ or contains XYZ in parentheses
following text that translates XYZ in another language. (Here XYZ
stands for a specific section name mentioned below, such as
"Acknowledgements", "Dedications", "Endorsements", or "History".)
To "Preserve the Title" of such a section when you modify the
Document means that it remains a section "Entitled XYZ" according
to this definition.
The Document may include Warranty Disclaimers next to the notice
which states that this License applies to the Document. These
Warranty Disclaimers are considered to be included by reference in
this License, but only as regards disclaiming warranties: any other
implication that these Warranty Disclaimers may have is void and
has no effect on the meaning of this License.
2. VERBATIM COPYING
You may copy and distribute the Document in any medium, either
commercially or noncommercially, provided that this License, the
copyright notices, and the license notice saying this License
applies to the Document are reproduced in all copies, and that you
add no other conditions whatsoever to those of this License. You
may not use technical measures to obstruct or control the reading
or further copying of the copies you make or distribute. However,
you may accept compensation in exchange for copies. If you
distribute a large enough number of copies you must also follow
the conditions in section 3.
You may also lend copies, under the same conditions stated above,
and you may publicly display copies.
3. COPYING IN QUANTITY
If you publish printed copies (or copies in media that commonly
have printed covers) of the Document, numbering more than 100, and
the Document's license notice requires Cover Texts, you must
enclose the copies in covers that carry, clearly and legibly, all
these Cover Texts: Front-Cover Texts on the front cover, and
Back-Cover Texts on the back cover. Both covers must also clearly
and legibly identify you as the publisher of these copies. The
front cover must present the full title with all words of the
title equally prominent and visible. You may add other material
on the covers in addition. Copying with changes limited to the
covers, as long as they preserve the title of the Document and
satisfy these conditions, can be treated as verbatim copying in
other respects.
If the required texts for either cover are too voluminous to fit
legibly, you should put the first ones listed (as many as fit
reasonably) on the actual cover, and continue the rest onto
adjacent pages.
If you publish or distribute Opaque copies of the Document
numbering more than 100, you must either include a
machine-readable Transparent copy along with each Opaque copy, or
state in or with each Opaque copy a computer-network location from
which the general network-using public has access to download
using public-standard network protocols a complete Transparent
copy of the Document, free of added material. If you use the
latter option, you must take reasonably prudent steps, when you
begin distribution of Opaque copies in quantity, to ensure that
this Transparent copy will remain thus accessible at the stated
location until at least one year after the last time you
distribute an Opaque copy (directly or through your agents or
retailers) of that edition to the public.
It is requested, but not required, that you contact the authors of
the Document well before redistributing any large number of
copies, to give them a chance to provide you with an updated
version of the Document.
4. MODIFICATIONS
You may copy and distribute a Modified Version of the Document
under the conditions of sections 2 and 3 above, provided that you
release the Modified Version under precisely this License, with
the Modified Version filling the role of the Document, thus
licensing distribution and modification of the Modified Version to
whoever possesses a copy of it. In addition, you must do these
things in the Modified Version:
A. Use in the Title Page (and on the covers, if any) a title
distinct from that of the Document, and from those of
previous versions (which should, if there were any, be listed
in the History section of the Document). You may use the
same title as a previous version if the original publisher of
that version gives permission.
B. List on the Title Page, as authors, one or more persons or
entities responsible for authorship of the modifications in
the Modified Version, together with at least five of the
principal authors of the Document (all of its principal
authors, if it has fewer than five), unless they release you
from this requirement.
C. State on the Title page the name of the publisher of the
Modified Version, as the publisher.
D. Preserve all the copyright notices of the Document.
E. Add an appropriate copyright notice for your modifications
adjacent to the other copyright notices.
F. Include, immediately after the copyright notices, a license
notice giving the public permission to use the Modified
Version under the terms of this License, in the form shown in
the Addendum below.
G. Preserve in that license notice the full lists of Invariant
Sections and required Cover Texts given in the Document's
license notice.
H. Include an unaltered copy of this License.
I. Preserve the section Entitled "History", Preserve its Title,
and add to it an item stating at least the title, year, new
authors, and publisher of the Modified Version as given on
the Title Page. If there is no section Entitled "History" in
the Document, create one stating the title, year, authors,
and publisher of the Document as given on its Title Page,
then add an item describing the Modified Version as stated in
the previous sentence.
J. Preserve the network location, if any, given in the Document
for public access to a Transparent copy of the Document, and
likewise the network locations given in the Document for
previous versions it was based on. These may be placed in
the "History" section. You may omit a network location for a
work that was published at least four years before the
Document itself, or if the original publisher of the version
it refers to gives permission.
K. For any section Entitled "Acknowledgements" or "Dedications",
Preserve the Title of the section, and preserve in the
section all the substance and tone of each of the contributor
acknowledgements and/or dedications given therein.
L. Preserve all the Invariant Sections of the Document,
unaltered in their text and in their titles. Section numbers
or the equivalent are not considered part of the section
titles.
M. Delete any section Entitled "Endorsements". Such a section
may not be included in the Modified Version.
N. Do not retitle any existing section to be Entitled
"Endorsements" or to conflict in title with any Invariant
Section.
O. Preserve any Warranty Disclaimers.
If the Modified Version includes new front-matter sections or
appendices that qualify as Secondary Sections and contain no
material copied from the Document, you may at your option
designate some or all of these sections as invariant. To do this,
add their titles to the list of Invariant Sections in the Modified
Version's license notice. These titles must be distinct from any
other section titles.
You may add a section Entitled "Endorsements", provided it contains
nothing but endorsements of your Modified Version by various
parties--for example, statements of peer review or that the text
has been approved by an organization as the authoritative
definition of a standard.
You may add a passage of up to five words as a Front-Cover Text,
and a passage of up to 25 words as a Back-Cover Text, to the end
of the list of Cover Texts in the Modified Version. Only one
passage of Front-Cover Text and one of Back-Cover Text may be
added by (or through arrangements made by) any one entity. If the
Document already includes a cover text for the same cover,
previously added by you or by arrangement made by the same entity
you are acting on behalf of, you may not add another; but you may
replace the old one, on explicit permission from the previous
publisher that added the old one.
The author(s) and publisher(s) of the Document do not by this
License give permission to use their names for publicity for or to
assert or imply endorsement of any Modified Version.
5. COMBINING DOCUMENTS
You may combine the Document with other documents released under
this License, under the terms defined in section 4 above for
modified versions, provided that you include in the combination
all of the Invariant Sections of all of the original documents,
unmodified, and list them all as Invariant Sections of your
combined work in its license notice, and that you preserve all
their Warranty Disclaimers.
The combined work need only contain one copy of this License, and
multiple identical Invariant Sections may be replaced with a single
copy. If there are multiple Invariant Sections with the same name
but different contents, make the title of each such section unique
by adding at the end of it, in parentheses, the name of the
original author or publisher of that section if known, or else a
unique number. Make the same adjustment to the section titles in
the list of Invariant Sections in the license notice of the
combined work.
In the combination, you must combine any sections Entitled
"History" in the various original documents, forming one section
Entitled "History"; likewise combine any sections Entitled
"Acknowledgements", and any sections Entitled "Dedications". You
must delete all sections Entitled "Endorsements."
6. COLLECTIONS OF DOCUMENTS
You may make a collection consisting of the Document and other
documents released under this License, and replace the individual
copies of this License in the various documents with a single copy
that is included in the collection, provided that you follow the
rules of this License for verbatim copying of each of the
documents in all other respects.
You may extract a single document from such a collection, and
distribute it individually under this License, provided you insert
a copy of this License into the extracted document, and follow
this License in all other respects regarding verbatim copying of
that document.
7. AGGREGATION WITH INDEPENDENT WORKS
A compilation of the Document or its derivatives with other
separate and independent documents or works, in or on a volume of
a storage or distribution medium, is called an "aggregate" if the
copyright resulting from the compilation is not used to limit the
legal rights of the compilation's users beyond what the individual
works permit. When the Document is included in an aggregate, this
License does not apply to the other works in the aggregate which
are not themselves derivative works of the Document.
If the Cover Text requirement of section 3 is applicable to these
copies of the Document, then if the Document is less than one half
of the entire aggregate, the Document's Cover Texts may be placed
on covers that bracket the Document within the aggregate, or the
electronic equivalent of covers if the Document is in electronic
form. Otherwise they must appear on printed covers that bracket
the whole aggregate.
8. TRANSLATION
Translation is considered a kind of modification, so you may
distribute translations of the Document under the terms of section
4. Replacing Invariant Sections with translations requires special
permission from their copyright holders, but you may include
translations of some or all Invariant Sections in addition to the
original versions of these Invariant Sections. You may include a
translation of this License, and all the license notices in the
Document, and any Warranty Disclaimers, provided that you also
include the original English version of this License and the
original versions of those notices and disclaimers. In case of a
disagreement between the translation and the original version of
this License or a notice or disclaimer, the original version will
prevail.
If a section in the Document is Entitled "Acknowledgements",
"Dedications", or "History", the requirement (section 4) to
Preserve its Title (section 1) will typically require changing the
actual title.
9. TERMINATION
You may not copy, modify, sublicense, or distribute the Document
except as expressly provided under this License. Any attempt
otherwise to copy, modify, sublicense, or distribute it is void,
and will automatically terminate your rights under this License.
However, if you cease all violation of this License, then your
license from a particular copyright holder is reinstated (a)
provisionally, unless and until the copyright holder explicitly
and finally terminates your license, and (b) permanently, if the
copyright holder fails to notify you of the violation by some
reasonable means prior to 60 days after the cessation.
Moreover, your license from a particular copyright holder is
reinstated permanently if the copyright holder notifies you of the
violation by some reasonable means, this is the first time you have
received notice of violation of this License (for any work) from
that copyright holder, and you cure the violation prior to 30 days
after your receipt of the notice.
Termination of your rights under this section does not terminate
the licenses of parties who have received copies or rights from
you under this License. If your rights have been terminated and
not permanently reinstated, receipt of a copy of some or all of
the same material does not give you any rights to use it.
10. FUTURE REVISIONS OF THIS LICENSE
The Free Software Foundation may publish new, revised versions of
the GNU Free Documentation License from time to time. Such new
versions will be similar in spirit to the present version, but may
differ in detail to address new problems or concerns. See
`http://www.gnu.org/copyleft/'.
Each version of the License is given a distinguishing version
number. If the Document specifies that a particular numbered
version of this License "or any later version" applies to it, you
have the option of following the terms and conditions either of
that specified version or of any later version that has been
published (not as a draft) by the Free Software Foundation. If
the Document does not specify a version number of this License,
you may choose any version ever published (not as a draft) by the
Free Software Foundation. If the Document specifies that a proxy
can decide which future versions of this License can be used, that
proxy's public statement of acceptance of a version permanently
authorizes you to choose that version for the Document.
11. RELICENSING
"Massive Multiauthor Collaboration Site" (or "MMC Site") means any
World Wide Web server that publishes copyrightable works and also
provides prominent facilities for anybody to edit those works. A
public wiki that anybody can edit is an example of such a server.
A "Massive Multiauthor Collaboration" (or "MMC") contained in the
site means any set of copyrightable works thus published on the MMC
site.
"CC-BY-SA" means the Creative Commons Attribution-Share Alike 3.0
license published by Creative Commons Corporation, a not-for-profit
corporation with a principal place of business in San Francisco,
California, as well as future copyleft versions of that license
published by that same organization.
"Incorporate" means to publish or republish a Document, in whole or
in part, as part of another Document.
An MMC is "eligible for relicensing" if it is licensed under this
License, and if all works that were first published under this
License somewhere other than this MMC, and subsequently
incorporated in whole or in part into the MMC, (1) had no cover
texts or invariant sections, and (2) were thus incorporated prior
to November 1, 2008.
The operator of an MMC Site may republish an MMC contained in the
site under CC-BY-SA on the same site at any time before August 1,
2009, provided the MMC is eligible for relicensing.
ADDENDUM: How to use this License for your documents
====================================================
To use this License in a document you have written, include a copy of
the License in the document and put the following copyright and license
notices just after the title page:
Copyright (C) YEAR YOUR NAME.
Permission is granted to copy, distribute and/or modify this document
under the terms of the GNU Free Documentation License, Version 1.3
or any later version published by the Free Software Foundation;
with no Invariant Sections, no Front-Cover Texts, and no Back-Cover
Texts. A copy of the license is included in the section entitled ``GNU
Free Documentation License''.
If you have Invariant Sections, Front-Cover Texts and Back-Cover
Texts, replace the "with...Texts." line with this:
with the Invariant Sections being LIST THEIR TITLES, with
the Front-Cover Texts being LIST, and with the Back-Cover Texts
being LIST.
If you have Invariant Sections without Cover Texts, or some other
combination of the three, merge those two alternatives to suit the
situation.
If your document contains nontrivial examples of program code, we
recommend releasing these examples in parallel under your choice of
free software license, such as the GNU General Public License, to
permit their use in free software.
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Node: Methods and Signal20967
Node: Properties and Annotations23954
Ref: Properties and Annotations-Footnote-129685
Ref: Properties and Annotations-Footnote-229786
Node: Arguments and Signatures29877
Node: Type Conversion32050
Node: Synchronous Methods38933
Node: Asynchronous Methods43745
Node: Receiving Method Calls45542
Node: Signals54387
Node: Errors and Events58153
Node: GNU Free Documentation License62547
End Tag Table