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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) 2007-2013 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."
* 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.
* 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.
File: dbus.info, Node: Overview, Next: Inspection, 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.info, Node: Inspection, Next: Type Conversion, Prev: Overview, Up: Top
2 Inspection of D-Bus services.
*******************************
* 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.
* Methods and Signal:: Applying the functionality.
* Properties and Annotations:: What else to know about interfaces.
* Arguments and Signatures:: The final details.
File: dbus.info, Node: Version, Next: Bus names, Up: Inspection
2.1 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.
-- Variable: 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 'nil'.
-- Variable: 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
'dbus-compiled-version'. It is also 'nil', if it cannot be
determined at runtime.
File: dbus.info, Node: Bus names, Next: Introspection, Prev: Version, Up: Inspection
2.2 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 &optional bus
This function returns the D-Bus service names, which can be
activated for BUS. It must be either the symbol ':system' (the
default) or the symbol ':session'. An activatable service is
described in a service registration file. Under GNU/Linux, such
files are located at '/usr/share/dbus-1/system-services/' (for the
':system' bus) or '/usr/share/dbus-1/services/'. An activatable
service is not necessarily registered at BUS at already.
The result is a list of strings, which is 'nil' when there are no
activatable service names at all. Example:
;; Check, whether the document viewer can be accessed via D-Bus.
(member "org.gnome.evince.Daemon"
(dbus-list-activatable-names :session))
-- 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 registered 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.info, Node: Introspection, Next: Nodes and Interfaces, Prev: Bus names, Up: Inspection
2.3 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:
<node name="/org/bluez">
<interface name="org.freedesktop.DBus.Introspectable">
...
</interface>
<interface name="org.bluez.Manager">
...
</interface>
<interface name="org.bluez.Database">
...
</interface>
<interface name="org.bluez.Security">
...
</interface>
<node name="service_audio"/>
<node name="service_input"/>
<node name="service_network"/>
<node name="service_serial"/>
</node>
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:
<method name="ResolveHostName">
<arg name="interface" type="i" direction="in"/>
<arg name="protocol" type="i" direction="in"/>
<arg name="name" type="s" direction="in"/>
<arg name="aprotocol" type="i" direction="in"/>
<arg name="flags" type="u" direction="in"/>
<arg name="interface" type="i" direction="out"/>
<arg name="protocol" type="i" direction="out"/>
<arg name="name" type="s" direction="out"/>
<arg name="aprotocol" type="i" direction="out"/>
<arg name="address" type="s" direction="out"/>
<arg name="flags" type="u" direction="out"/>
</method>
'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:
<signal name="StateChanged">
<arg name="state" type="i"/>
<arg name="error" type="s"/>
</signal>
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:
<property name="Status" type="u" direction="read"/>
'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 language bindings.
Example:
<annotation name="de.berlios.Pinot.GetStatistics" value="pinotDBus"/>
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")
=> "<!DOCTYPE node PUBLIC
"-//freedesktop//DTD D-BUS Object Introspection 1.0//EN"
"http://www.freedesktop.org/standards/dbus/1.0/introspect.dtd">
<node>
<interface name="org.freedesktop.Hal.Device">
<method name="GetAllProperties">
<arg name="properties" direction="out" type="a{sv}"/>
</method>
...
<signal name="PropertyModified">
<arg name="num_updates" type="i"/>
<arg name="updates" type="a(sbb)"/>
</signal>
</interface>
...
</node>"
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.info, Node: Nodes and Interfaces, Next: Methods and Signal, Prev: Introspection, Up: Inspection
2.4 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.info, Node: Methods and Signal, Next: Properties and Annotations, Prev: Nodes and Interfaces, Up: Inspection
2.5 Applying the functionality.
===============================
Methods and signals are the communication 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.info, Node: Properties and Annotations, Next: Arguments and Signatures, Prev: Methods and Signal, Up: Inspection
2.6 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.
A generalized interface is 'org.freedesktop.DBus.Objectmanager'(2),
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.
-- 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-get-all-managed-objects bus service path
This functions returns all objects at BUS, SERVICE, PATH, and the
children of 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 'dbus-get-all-properties' for that path and interface.
Example:
(dbus-get-all-managed-objects
:session "org.gnome.SettingsDaemon" "/")
=> (("/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"))
...)
If possible, 'org.freedesktop.DBus.ObjectManager.GetManagedObjects'
is used for retrieving the information. Otherwise, the information
is collected via 'org.freedesktop.DBus.Introspectable.Introspect'
and '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:
(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)))
-- 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(3) 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#standard-interfaces-objectmanager>
(3) See
<http://dbus.freedesktop.org/doc/dbus-specification.html#introspection-format>
File: dbus.info, Node: Arguments and Signatures, Prev: Properties and Annotations, Up: Inspection
2.7 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.info, 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
natural number ==> DBUS_TYPE_UINT32
negative 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 parameters.
If it is necessary to use another D-Bus type, a corresponding type
symbol can be prepended 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', ':signature' and ':unix-fd'.
Example:
(dbus-call-method ... NAT-NUMBER STRING)
is equivalent to
(dbus-call-method ... :uint32 NAT-NUMBER :string STRING)
but different to
(dbus-call-method ... :int32 NAT-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'.
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 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 ==> natural number
DBUS_TYPE_UINT16 ==> natural number
DBUS_TYPE_INT16 ==> integer
DBUS_TYPE_UINT32 ==> natural number or float
DBUS_TYPE_UNIX_FD ==> natural number or float
DBUS_TYPE_INT32 ==> integer or float
DBUS_TYPE_UINT64 ==> natural number or float
DBUS_TYPE_INT64 ==> integer 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', 'DBUS_TYPE_INT64' and '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
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'):
(INTEGER ((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.info, 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\"
..."
File: dbus.info, 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::.
If HANDLER is a Lisp function, 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")
=> (:serial :system 2)
-| i686
File: dbus.info, Node: Receiving Method Calls, Next: Signals, Prev: Asynchronous Methods, Up: Top
6 Offering own methods.
***********************
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:
-- Function: dbus-register-service bus service &rest flags
Register the known name SERVICE on D-Bus BUS.
BUS is either the symbol ':system' or the symbol ':session'.
SERVICE is the service name to be registered on the D-Bus. It must
be a known name.
FLAGS is a subset of the following keywords:
* ':allow-replacement': Allow another service to become the
primary owner if requested.
* ':replace-existing': Request to replace the current primary
owner.
* ':do-not-queue': If we can not become the primary owner do not
place us in the queue.
One of the following keywords is returned:
* ':primary-owner': We have become the primary owner of the name
SERVICE.
* ':in-queue': We could not become the primary owner and have
been placed in the queue.
* ':exists': We already are in the queue.
* ':already-owner': We already are the primary owner.
-- 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.
One of the following keywords is returned:
* ':released': We successfully released the name SERVICE.
* ':non-existent': The name SERVICE does not exist on the bus.
* ':not-owner': We are not an owner of the name SERVICE.
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
'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 'org.gnu.Emacs' of Emacs.
-- Constant: dbus-path-emacs
The object path namespace '/org/gnu/Emacs' used by Emacs.
-- Constant: dbus-interface-emacs
The interface namespace 'org.gnu.Emacs' used by Emacs.
-- Function: dbus-register-method bus service path interface method
handler dont-register-service
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 (See discussion of
DONT-REGISTER-SERVICE below).
PATH is the D-Bus object path SERVICE is registered (See discussion
of DONT-REGISTER-SERVICE below).
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'.
When DONT-REGISTER-SERVICE is non-'nil', the known name 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, 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, 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)
=> ((:method :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 &optional emits-signal dont-register-service
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 (See discussion
of DONT-REGISTER-SERVICE below).
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. When EMITS-SIGNAL is non-'nil', the
signal 'PropertiesChanged' is sent when the property is changed by
'dbus-set-property'.
When DONT-REGISTER-SERVICE is non-'nil', the known name 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, DONT-REGISTER-SERVICE can be used to prevent other clients
from discovering the still incomplete interface.
Example:
(dbus-register-property
:session "org.freedesktop.TextEditor" "/org/freedesktop/TextEditor"
"org.freedesktop.TextEditor" "name" :read "GNU Emacs")
=> ((: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 t)
=> ((:property :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.
File: dbus.info, Node: Signals, Next: Alternative Buses, Prev: Receiving Method Calls, Up: Top
7 Sending and receiving signals.
********************************
Signals are one way 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.
Signals can be unicast or broadcast messages. For broadcast
messages, SERVICE must be 'nil'. Otherwise, SERVICE is the D-Bus
service name the signal is sent to as unicast message.(1) PATH is
the D-Bus object path SIGNAL is sent from. INTERFACE is an
interface available at PATH. 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 nil dbus-path-emacs
(concat dbus-interface-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 a 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. A known name will be mapped onto the
unique name of the object, owning SERVICE at registration time.
When the corresponding D-Bus object disappears, signals won't be
received any longer.
PATH is the corresponding D-Bus object path, SERVICE is registered
at. INTERFACE is an interface offered by SERVICE. It must provide
SIGNAL.
SERVICE, PATH, INTERFACE and SIGNAL can be 'nil'. This is
interpreted as a wildcard for the respective argument.
HANDLER is a Lisp function to be called when the SIGNAL is
received. It must accept as arguments the output parameters SIGNAL
is sending.
The remaining arguments ARGS can be keywords or keyword string
pairs.(2) The meaning is as follows:
* ':argN' STRING:
':pathN' STRING:
This stands for the Nth argument of the signal. ':pathN'
arguments can be used for object path wildcard matches as
specified by D-Bus, while an ':argN' argument requires an
exact match.
* ':arg-namespace' STRING:
Register for the signals, which first argument defines the
service or interface namespace STRING.
* ':path-namespace' STRING:
Register for the object path namespace STRING. All signals
sent from an object path, which has STRING as the preceding
string, are matched. This requires PATH to be 'nil'.
* ':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.
'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)
=> ((:signal :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.
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:
(dbus-ignore-errors
(dbus-register-signal
:system nil nil nil nil 'ignore :path-namespace "/invalid/path"))
=> nil
---------- Footnotes ----------
(1) For backward compatibility, a broadcast message is also emitted
if SERVICE is the known or unique name Emacs is registered at D-Bus BUS.
(2) For backward compatibility, the arguments ARGS can also be just
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.
File: dbus.info, Node: Alternative Buses, Next: Errors and Events, Prev: Signals, Up: Top
8 Alternative buses and environments.
*************************************
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 BUS is mentioned as
argument of a function (the symbol ':system' or the symbol ':session'),
this address can be used instead. The connection to this bus must be
initialized first.
-- Function: dbus-init-bus bus &optional private
Establish the connection to D-Bus BUS.
BUS can be either the symbol ':system' or the symbol ':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 '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 BUS under the same unique name
(see '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 PRIVATE is non-'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
':system' and ':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:
(setq my-bus
(dbus-call-method
:session "org.a11y.Bus" "/org/a11y/bus"
"org.a11y.Bus" "GetAddress"))
=> "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)
=> 2
(dbus-get-unique-name my-bus)
=> ":1.19"
;; Open a new connection to the same bus. This obsoletes the
;; previous one.
(dbus-init-bus my-bus 'private)
=> 1
(dbus-get-unique-name my-bus)
=> ":1.20"
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.
-- Function: dbus-setenv bus variable value
Set the value of the BUS environment variable VARIABLE to VALUE.
BUS is either a Lisp symbol, ':system' or ':session', or a string
denoting the bus address. Both VARIABLE and 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 ':system', may disable setting the
environment. In such cases, or if this feature is not available in
older D-Bus versions, a '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
(setq my-bus "unix:host=example.gnu.org,port=4711")
=> "unix:host=example.gnu.org,port=4711"
(dbus-init-bus my-bus)
=> 1
(dbus-setenv my-bus "DISPLAY" (getenv "DISPLAY"))
=> nil
File: dbus.info, Node: Errors and Events, Next: Index, Prev: Alternative Buses, Up: Top
9 Errors and events.
********************
The internal actions can be traced by running in a debug mode.
-- Variable: dbus-debug
If this variable is non-'nil', D-Bus specific debug messages are
raised.
Input parameters of 'dbus-call-method',
'dbus-call-method-asynchronously', 'dbus-send-signal',
'dbus-register-method', 'dbus-register-property' 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 'dbus-debug' is set to 't'.
Incoming D-Bus messages are handled as Emacs events, see *note
(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 natural number.
-- Function: dbus-event-serial-number event
Returns the serial number of the corresponding D-Bus message. The
result is a natural 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-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 caught 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-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-functions '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.info, Node: Index, Next: GNU Free Documentation License, Prev: Errors and Events, Up: Top
Index
*****
[index]
* Menu:
* asynchronous method calls: Asynchronous Methods.
(line 6)
* bus names: Alternative Buses. (line 6)
* dbus-byte-array-to-string: Type Conversion. (line 165)
* dbus-call-method: Synchronous Methods. (line 14)
* dbus-call-method-asynchronously: Asynchronous Methods.
(line 6)
* dbus-compiled-version: Version. (line 10)
* dbus-debug: Errors and Events. (line 8)
* dbus-escape-as-identifier: Type Conversion. (line 111)
* dbus-event-bus-name: Errors and Events. (line 61)
* dbus-event-error-functions: Errors and Events. (line 92)
* dbus-event-interface-name: Errors and Events. (line 79)
* dbus-event-member-name: Errors and Events. (line 83)
* dbus-event-message-type: Errors and Events. (line 65)
* dbus-event-path-name: Errors and Events. (line 76)
* dbus-event-serial-number: Errors and Events. (line 69)
* dbus-event-service-name: Errors and Events. (line 73)
* dbus-get-all-managed-objects: Properties and Annotations.
(line 95)
* dbus-get-all-properties: Properties and Annotations.
(line 79)
* dbus-get-name-owner: Bus names. (line 52)
* dbus-get-property: Properties and Annotations.
(line 56)
* dbus-get-unique-name: Bus names. (line 82)
* dbus-ignore-errors: Errors and Events. (line 23)
* dbus-init-bus: Alternative Buses. (line 14)
* dbus-interface-emacs: Receiving Method Calls.
(line 74)
* dbus-introspect: Introspection. (line 95)
* dbus-introspect-get-all-nodes: Nodes and Interfaces.
(line 23)
* dbus-introspect-get-annotation: Properties and Annotations.
(line 170)
* dbus-introspect-get-annotation-names: Properties and Annotations.
(line 145)
* dbus-introspect-get-argument: Arguments and Signatures.
(line 24)
* dbus-introspect-get-argument-names: Arguments and Signatures.
(line 9)
* dbus-introspect-get-attribute: Introspection. (line 163)
* dbus-introspect-get-interface: Nodes and Interfaces.
(line 56)
* dbus-introspect-get-interface-names: Nodes and Interfaces.
(line 38)
* dbus-introspect-get-method: Methods and Signal. (line 23)
* dbus-introspect-get-method-names: Methods and Signal. (line 9)
* dbus-introspect-get-node-names: Nodes and Interfaces.
(line 9)
* dbus-introspect-get-property: Properties and Annotations.
(line 32)
* dbus-introspect-get-property-names: Properties and Annotations.
(line 18)
* dbus-introspect-get-signal: Methods and Signal. (line 55)
* dbus-introspect-get-signal-names: Methods and Signal. (line 42)
* dbus-introspect-get-signature: Arguments and Signatures.
(line 36)
* dbus-introspect-xml: Introspection. (line 137)
* dbus-list-activatable-names: Bus names. (line 10)
* dbus-list-known-names: Bus names. (line 35)
* dbus-list-names: Bus names. (line 26)
* dbus-list-queued-owners: Bus names. (line 43)
* dbus-path-emacs: Receiving Method Calls.
(line 71)
* dbus-ping: Bus names. (line 60)
* dbus-register-method: Receiving Method Calls.
(line 77)
* dbus-register-property: Receiving Method Calls.
(line 179)
* dbus-register-service: Receiving Method Calls.
(line 11)
* dbus-register-signal: Signals. (line 33)
* dbus-runtime-version: Version. (line 14)
* dbus-send-signal: Signals. (line 9)
* dbus-service-emacs: Receiving Method Calls.
(line 68)
* dbus-set-property: Properties and Annotations.
(line 67)
* dbus-setenv: Alternative Buses. (line 74)
* dbus-string-to-byte-array: Type Conversion. (line 101)
* dbus-unescape-from-identifier: Type Conversion. (line 174)
* dbus-unregister-object: Receiving Method Calls.
(line 273)
* dbus-unregister-service: Receiving Method Calls.
(line 42)
* debugging: Errors and Events. (line 6)
* errors: Errors and Events. (line 6)
* events: Errors and Events. (line 6)
* inspection: Inspection. (line 6)
* method calls, asynchronous: Asynchronous Methods.
(line 6)
* method calls, returning: Receiving Method Calls.
(line 6)
* method calls, synchronous: Synchronous Methods. (line 6)
* overview: Overview. (line 6)
* returning method calls: Receiving Method Calls.
(line 6)
* signals: Signals. (line 6)
* synchronous method calls: Synchronous Methods. (line 6)
* TCP/IP socket: Alternative Buses. (line 6)
* type conversion: Type Conversion. (line 6)
* UNIX domain socket: Alternative Buses. (line 6)
File: dbus.info, Node: GNU Free Documentation License, Prev: Index, 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
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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
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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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