X-Git-Url: http://git.hcoop.net/bpt/emacs.git/blobdiff_plain/b03f96dc5a6651d1dc84b81b2a15cad6908b9809..55033558b53324f4a63b6887ea50d8a2f235f7aa:/doc/misc/dbus.texi
diff --git a/doc/misc/dbus.texi b/doc/misc/dbus.texi
index 392f9a85da..c012647144 100644
--- a/doc/misc/dbus.texi
+++ b/doc/misc/dbus.texi
@@ -6,25 +6,19 @@
@c %**end of header
@copying
-Copyright @copyright{} 2007, 2008 Free Software Foundation, Inc.
+Copyright @copyright{} 2007, 2008, 2009 Free Software Foundation, Inc.
@quotation
Permission is granted to copy, distribute and/or modify this document
-under the terms of the GNU Free Documentation License, Version 1.2 or
+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'' in the Emacs manual.
-
-(a) The FSF's Back-Cover Text is: ``You have freedom to copy and modify
-this GNU Manual, like GNU software. Copies published by the Free
-Software Foundation raise funds for GNU development.''
-
-This document is part of a collection distributed under the GNU Free
-Documentation License. If you want to distribute this document
-separately from the collection, you can do so by adding a copy of the
-license to the document, as described in section 6 of the license.
+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.''
@end quotation
@end copying
@@ -33,6 +27,7 @@ license to the document, as described in section 6 of the license.
* D-Bus: (dbus). Using D-Bus in Emacs.
@end direntry
+
@node Top, Overview, (dir), (dir)
@top D-Bus integration in Emacs
@@ -47,15 +42,17 @@ be found at @uref{http://dbus.freedesktop.org/}.
@menu
* Overview:: An overview of D-Bus.
-* Inspection:: Inspection of the bus names.
+* 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.
@end menu
+
@node Overview
@chapter An overview of D-Bus
@cindex overview
@@ -107,9 +104,22 @@ name could be @samp{org.gnu.Emacs.TextEditor} or
@node Inspection
-@chapter Inspection of the bus names.
+@chapter Inspection of D-Bus services.
@cindex inspection
+@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.
+@end menu
+
+
+@node Bus names
+@section Bus names.
+
There are several basic functions which inspect the buses for
registered names. Internally they use the basic interface
@samp{org.freedesktop.DBus}, which is supported by all objects of a bus.
@@ -193,16 +203,126 @@ is returned as string.
@code{:session}.
@end defun
+
+@node Introspection
+@section 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 @code{node} element. It might have
+a @code{name} attribute, which denotes the (absolute) object path an
+interface is introspected.
+
+The root @code{node} element may have @code{node} and @code{interface}
+children. A child @code{node} element must have a @code{name}
+attribute, this case it is the relative object path to the root
+@code{node} element.
+
+An @code{interface} element has just one attribute, @code{name}, which
+is the full name of that interface. The default interface
+@samp{org.freedesktop.DBus.Introspectable} is always present. Example:
+
+@example
+
+
+ @dots{}
+
+
+ @dots{}
+
+
+ @dots{}
+
+
+ @dots{}
+
+
+
+
+
+
+@end example
+
+Children of an @code{interface} element can be @code{method},
+@code{signal} and @code{property} elements. A @code{method} element
+stands for a D-Bus method of the surrounding interface. The element
+itself has a @code{name} attribute, showing the method name. Children
+elements @code{arg} stand for the arguments of a method. Example:
+
+@example
+
+
+
+
+
+
+
+
+
+
+
+
+
+@end example
+
+@code{arg} elements can have the attributes @code{name}, @code{type}
+and @code{direction}. The @code{name} attribute is optional. The
+@code{type} attribute stands for the @dfn{signature} of the argument
+in D-Bus. For a discussion of D-Bus types and their Lisp
+representation see @ref{Type Conversion}.@footnote{D-Bus signatures
+are explained in the D-Bus specification
+@uref{http://dbus.freedesktop.org/doc/dbus-specification.html#message-protocol-signatures}.}
+The @code{direction} attribute of an @code{arg} element can be only
+@samp{in} or @samp{out}; in case it is omitted, it defaults to
+@samp{in}.
+
+A @code{signal} element of an @code{interface} has a similar
+structure. The @code{direction} attribute of an @code{arg} child
+element can be only @samp{out} here; which is also the default value.
+Example:
+
+@example
+
+
+
+
+@end example
+
+A @code{property} element has no @code{arg} child
+element. It just has the attributes @code{name}, @code{type} and
+@code{access}, which are all mandatory. The @code{access} attribute
+allows the values @samp{readwrite}, @samp{read}, and @samp{write}.
+Example:
+
+@example
+
+@end example
+
+@code{annotation} elements can be children of @code{interface},
+@code{method}, @code{signal}, and @code{property} elements. Unlike
+properties, which can change their values during lifetime of a D-Bus
+object, annotations are static. Often they are used for code
+generators of D-Bus langugae bindings. Example:
+
+@example
+
+@end example
+
+Annotations have just @code{name} and @code{value} attributes, both
+must be strings.
+
@defun dbus-introspect bus service path
-Objects can publish there interfaces to the D-Bus. This function
-returns all interfaces of @var{service}, registered at object path
-@var{path} at bus @var{bus}.
+This function returns all interfaces and sub-nodes of @var{service},
+registered at object path @var{path} at bus @var{bus}.
@var{bus} must be either the symbol @code{:system} or the symbol
@code{:session}. @var{service} must be a known service name, and
@var{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:
+format. Example:
@lisp
(dbus-introspect
@@ -210,45 +330,506 @@ format. Example:
"/org/freedesktop/Hal/devices/computer")
@result{} "
+ "-//freedesktop//DTD D-BUS Object Introspection 1.0//EN"
+ "http://www.freedesktop.org/standards/dbus/1.0/introspect.dtd">
-
-
-
+
+
+
@dots{}
-
-
-
+
+
+
@dots{}
"
@end lisp
-This example informs us, that the service @code{org.freedesktop.Hal}
-at object path @code{/org/freedesktop/Hal/devices/computer} offers the
-interface @code{org.freedesktop.Hal.Device} (and 2 other interfaces
+This example informs us, that the service @samp{org.freedesktop.Hal}
+at object path @samp{/org/freedesktop/Hal/devices/computer} offers the
+interface @samp{org.freedesktop.Hal.Device} (and 2 other interfaces
not documented here). This interface contains the method
-@code{GetAllProperties}, which needs no input parameters, but returns
+@samp{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.
-
-Such type descriptions are called @dfn{signature} in D-Bus. For a
-discussion of D-Bus types and their Lisp representation see @ref{Type
-Conversion}.@footnote{D-Bus signatures are explained in the D-Bus
-specification
-@uref{http://dbus.freedesktop.org/doc/dbus-specification.html#message-protocol-signatures}.
-The interfaces of the service @code{org.freedesktop.Hal} are described
-at
+string and 2 boolean values.@footnote{ The interfaces of the service
+@samp{org.freedesktop.Hal} are described at
@uref{http://people.freedesktop.org/~david/hal-spec/hal-spec.html#interfaces}.}
@end defun
+@defun dbus-introspect-xml bus service path
+This function has the same intention as function
+@code{dbus-introspect}. The returned value is a parsed XML tree,
+which can be used for further analysis. Example:
+
+@lisp
+(dbus-introspect-xml
+ :session "org.freedesktop.xesam.searcher"
+ "/org/freedesktop/xesam/searcher/main")
+
+@result{} (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")))
+ )
+ @dots{}
+ (signal ((name . "HitsAdded"))
+ (arg ((name . "search") (type . "s")))
+ (arg ((name . "count") (type . "u")))
+ )
+ )
+ @dots{}
+ )
+@end lisp
+@end defun
+
+@defun dbus-introspect-get-attribute object attribute
+It returns the @var{attribute} value of a D-Bus introspection
+@var{object}. @var{object} can be every subtree of a parsed XML tree
+as retrieved with @code{dbus-introspect-xml}. @var{attribute} must be
+a string according to the attribute names in the D-Bus specification.
+Example:
+
+@lisp
+(dbus-introspect-get-attribute
+ (dbus-introspect-xml :system "org.freedesktop.SystemToolsBackends"
+ "/org/freedesktop/SystemToolsBackends/UsersConfig")
+ "name")
+
+@result{} "/org/freedesktop/SystemToolsBackends/UsersConfig"
+@end lisp
+
+If @var{object} has no @var{attribute}, the function returns nil.
+@end defun
+
+
+@node Nodes and Interfaces
+@section Detecting object paths and interfaces.
+
+The first elements, to be introspected for a D-Bus object, are further
+object paths and interfaces.
+
+@defun dbus-introspect-get-node-names bus service path
+All node names of @var{service} in D-Bus @var{bus} at object path
+@var{path} are returned as list of strings. Example:
+
+@lisp
+(dbus-introspect-get-node-names
+ :session "org.gnome.seahorse" "/org/gnome/seahorse")
+
+@result{} ("crypto" "keys")
+@end lisp
+
+The node names stand for further object paths of the D-Bus
+@var{service}, relative to @var{path}. In the example,
+@samp{/org/gnome/seahorse/crypto} and @samp{/org/gnome/seahorse/keys}
+are also object paths of the D-Bus service @samp{org.gnome.seahorse}.
+@end defun
+
+@defun dbus-introspect-get-all-nodes bus service path
+This function returns all node names of @var{service} in D-Bus
+@var{bus} at object path @var{path}. It returns a list of strings
+with all object paths of @var{service}, starting at @var{path}.
+Example:
+
+@lisp
+(dbus-introspect-get-all-nodes :session "org.gnome.seahorse" "/")
+
+@result{} ("/" "/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")
+@end lisp
+@end defun
+
+@defun dbus-introspect-get-interface-names bus service path
+There will be returned a list strings of all interface names of
+@var{service} in D-Bus @var{bus} at object path @var{path}. This list
+will contain the default interface @samp{org.freedesktop.DBus.Introspectable}.
+
+Another default interface is @samp{org.freedesktop.DBus.Properties}.
+If present, @code{interface} elements can also have @code{property}
+children. Example:
+
+@lisp
+(dbus-introspect-get-interface-names
+ :system "org.freedesktop.Hal"
+ "/org/freedesktop/Hal/devices/computer")
+
+@result{} ("org.freedesktop.DBus.Introspectable"
+ "org.freedesktop.Hal.Device"
+ "org.freedesktop.Hal.Device.SystemPowerManagement"
+ "org.freedesktop.Hal.Device.CPUFreq")
+@end lisp
+@end defun
+
+@defun dbus-introspect-get-interface bus service path interface
+Return @var{interface} of @var{service} in D-Bus @var{bus} at object
+path @var{path}. The return value is an XML element. @var{interface}
+must be a string, element of the list returned by
+@code{dbus-introspect-get-interface-names}. Example:
+
+@lisp
+(dbus-introspect-get-interface
+ :session "org.freedesktop.xesam.searcher"
+ "/org/freedesktop/xesam/searcher/main"
+ "org.freedesktop.xesam.Search")
+
+@result{} (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")))
+ )
+ @dots{}
+ (signal ((name . "HitsAdded"))
+ (arg ((name . "search") (type . "s")))
+ (arg ((name . "count") (type . "u")))
+ )
+ )
+@end lisp
+@end defun
+
+@noindent
+With these functions, it is possible to retrieve all introspection
+data from a running system:
+
+@lisp
+(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)))))
+@end lisp
+
+
+@node Methods and Signal
+@section Applying the functionality.
+
+Methods and signals are the communicatione means to D-Bus. The
+following functions return their specifications.
+
+@defun dbus-introspect-get-method-names bus service path interface
+Return a list of strings of all method names of @var{interface} of
+@var{service} in D-Bus @var{bus} at object path @var{path}. Example:
+
+@lisp
+(dbus-introspect-get-method-names
+ :session "org.freedesktop.xesam.searcher"
+ "/org/freedesktop/xesam/searcher/main"
+ "org.freedesktop.xesam.Search")
+
+@result{} ("GetState" "StartSearch" "GetHitCount" "GetHits" "NewSession"
+ "CloseSession" "GetHitData" "SetProperty" "NewSearch"
+ "GetProperty" "CloseSearch")
+@end lisp
+@end defun
+
+@defun dbus-introspect-get-method bus service path interface method
+This function returns @var{method} of @var{interface} as XML element.
+It must be located at @var{service} in D-Bus @var{bus} at object path
+@var{path}. @var{method} must be a string, element of the list
+returned by @code{dbus-introspect-get-method-names}. Example:
+
+@lisp
+(dbus-introspect-get-method
+ :session "org.freedesktop.xesam.searcher"
+ "/org/freedesktop/xesam/searcher/main"
+ "org.freedesktop.xesam.Search" "GetHitData")
+
+@result{} (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")))
+ )
+@end lisp
+@end defun
+
+@defun dbus-introspect-get-signal-names bus service path interface
+Return a list of strings of all signal names of @var{interface} of
+@var{service} in D-Bus @var{bus} at object path @var{path}. Example:
+
+@lisp
+(dbus-introspect-get-signal-names
+ :session "org.freedesktop.xesam.searcher"
+ "/org/freedesktop/xesam/searcher/main"
+ "org.freedesktop.xesam.Search")
+
+@result{} ("StateChanged" "SearchDone" "HitsModified"
+ "HitsRemoved" "HitsAdded")
+@end lisp
+@end defun
+
+@defun dbus-introspect-get-signal bus service path interface signal
+This function returns @var{signal} of @var{interface} as XML element.
+It must be located at @var{service} in D-Bus @var{bus} at object path
+@var{path}. @var{signal} must be a string, element of the list
+returned by @code{dbus-introspect-get-signal-names}. Example:
+
+@lisp
+(dbus-introspect-get-signal
+ :session "org.freedesktop.xesam.searcher"
+ "/org/freedesktop/xesam/searcher/main"
+ "org.freedesktop.xesam.Search" "HitsAdded")
+
+@result{} (signal ((name . "HitsAdded"))
+ (arg ((name . "search") (type . "s")))
+ (arg ((name . "count") (type . "u")))
+ )
+@end lisp
+@end defun
+
+
+@node Properties and Annotations
+@section What else to know about interfaces.
+
+Interfaces can have properties. These can be exposed via the
+@samp{org.freedesktop.DBus.Properties} interface@footnote{See
+@uref{http://dbus.freedesktop.org/doc/dbus-specification.html#standard-interfaces-properties}}.
+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.
+
+@defun dbus-introspect-get-property-names bus service path interface
+Return a list of strings with all property names of @var{interface} of
+@var{service} in D-Bus @var{bus} at object path @var{path}. Example:
+
+@lisp
+(dbus-introspect-get-property-names
+ :session "org.kde.kded" "/modules/networkstatus"
+ "org.kde.Solid.Networking.Client")
+
+@result{} ("Status")
+@end lisp
+
+If an interface declares properties, the corresponding element supports
+also the @samp{org.freedesktop.DBus.Properties} interface.
+@end defun
+
+@defun dbus-introspect-get-property bus service path interface property
+This function returns @var{property} of @var{interface} as XML element.
+It must be located at @var{service} in D-Bus @var{bus} at object path
+@var{path}. @var{property} must be a string, element of the list
+returned by @code{dbus-introspect-get-property-names}.
+
+A @var{property} value can be retrieved by the function
+@code{dbus-introspect-get-attribute}. Example:
+
+@lisp
+(dbus-introspect-get-property
+ :session "org.kde.kded" "/modules/networkstatus"
+ "org.kde.Solid.Networking.Client" "Status")
+
+@result{} (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")
+
+@result{} "read"
+@end lisp
+@end defun
+
+@defun dbus-get-property bus service path interface property
+This function returns the value of @var{property} of @var{interface}.
+It will be checked at @var{bus}, @var{service}, @var{path}. The
+result can be any valid D-Bus value, or nil if there is no
+@var{property}. Example:
+
+@lisp
+(dbus-get-property
+ :session "org.kde.kded" "/modules/networkstatus"
+ "org.kde.Solid.Networking.Client" "Status")
+
+@result{} 4
+@end lisp
+@end defun
+
+@defun dbus-set-property bus service path interface property value
+Set value of @var{property} of @var{interface} to @var{value}. It
+will be checked at @var{bus}, @var{service}, @var{path}. When the
+value has been set successful, the result is @var{value}. Otherwise,
+@code{nil} is returned. Example:
+
+@lisp
+(dbus-set-property
+ :session "org.kde.kaccess" "/MainApplication"
+ "com.trolltech.Qt.QApplication" "doubleClickInterval" 500)
+
+@result{} 500
+@end lisp
+@end defun
+
+@defun dbus-get-all-properties bus service path interface
+This function returns all properties of @var{interface}. It will be
+checked at @var{bus}, @var{service}, @var{path}. The result is a list
+of cons. Every cons contains the name of the property, and its value.
+If there are no properties, @code{nil} is returned. Example:
+
+@lisp
+(dbus-get-all-properties
+ :session "org.kde.kaccess" "/MainApplication"
+ "com.trolltech.Qt.QApplication")
+
+@result{} (("cursorFlashTime" . 1000) ("doubleClickInterval" . 500)
+ ("keyboardInputInterval" . 400) ("wheelScrollLines" . 3)
+ ("globalStrut" 0 0) ("startDragTime" . 500)
+ ("startDragDistance" . 4) ("quitOnLastWindowClosed" . t)
+ ("styleSheet" . ""))
+@end lisp
+@end defun
+
+@defun dbus-introspect-get-annotation-names bus service path interface &optional name
+Return a list of all annotation names as list of strings. If
+@var{name} is @code{nil}, the annotations are children of
+@var{interface}, otherwise @var{name} must be a @code{method},
+@code{signal}, or @code{property} XML element, where the annotations
+belong to. Example:
+
+@lisp
+(dbus-introspect-get-annotation-names
+ :session "de.berlios.Pinot" "/de/berlios/Pinot"
+ "de.berlios.Pinot" "GetStatistics")
+
+@result{} ("de.berlios.Pinot.GetStatistics")
+@end lisp
+
+Default annotation names@footnote{See
+@uref{http://dbus.freedesktop.org/doc/dbus-specification.html#introspection-format}}
+are
+
+@table @samp
+@item org.freedesktop.DBus.Deprecated
+Whether or not the entity is deprecated; defaults to @code{nil}
+
+@item org.freedesktop.DBus.GLib.CSymbol
+The C symbol; may be used for @code{methods} and @code{interfaces}
+
+@item org.freedesktop.DBus.Method.NoReply
+If set, don't expect a reply to the @code{method} call; defaults to @code{nil}
+@end table
+@end defun
+
+@defun dbus-introspect-get-annotation bus service path interface name annotation
+Return annotation @var{ANNOTATION} as XML object. If @var{name} is
+@code{nil}, @var{ANNOTATION} is a child of @var{interface}, otherwise
+@var{name} must be the name of a @code{method}, @code{signal}, or
+@code{property} XML element, where the @var{ANNOTATION} belongs to.
+
+An attribute value can be retrieved by
+@code{dbus-introspect-get-attribute}. Example:
+
+@lisp
+(dbus-introspect-get-annotation
+ :session "de.berlios.Pinot" "/de/berlios/Pinot"
+ "de.berlios.Pinot" "GetStatistics"
+ "de.berlios.Pinot.GetStatistics")
+
+@result{} (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")
+
+@result{} "pinotDBus"
+@end lisp
+@end defun
+
+
+@node Arguments and Signatures
+@section The final details.
+
+Methods and signals have arguments. They are described in the
+@code{arg} XML elements.
+
+@defun dbus-introspect-get-argument-names bus service path interface name
+Return a list of all argument names as list of strings. @var{name}
+must be a @code{method} or @code{signal} XML element. Example:
+
+@lisp
+(dbus-introspect-get-argument-names
+ :session "org.freedesktop.xesam.searcher"
+ "/org/freedesktop/xesam/searcher/main"
+ "org.freedesktop.xesam.Search" "GetHitData")
+
+@result{} ("search" "hit_ids" "fields" "hit_data")
+@end lisp
+
+Argument names are optional; the function can return @code{nil}
+therefore, even if the method or signal has arguments.
+@end defun
+
+@defun dbus-introspect-get-argument bus service path interface name arg
+Return argument @var{ARG} as XML object. @var{name}
+must be a @code{method} or @code{signal} XML element. Example:
+
+@lisp
+(dbus-introspect-get-argument
+ :session "org.freedesktop.xesam.searcher"
+ "/org/freedesktop/xesam/searcher/main"
+ "org.freedesktop.xesam.Search" "GetHitData" "search")
+
+@result{} (arg ((name . "search") (type . "s") (direction . "in")))
+@end lisp
+@end defun
+
+@defun dbus-introspect-get-signature bus service path interface name &optional direction
+Return signature of a @code{method} or @code{signal}, represented by
+@var{name}, as string.
+
+If @var{name} is a @code{method}, @var{direction} can be either
+@samp{in} or @samp{out}. If @var{direction} is @code{nil}, @samp{in}
+is assumed.
+
+If @var{name} is a @code{signal}, and @var{direction} is
+non-@code{nil}, @var{direction} must be @samp{out}. Example:
+
+@lisp
+(dbus-introspect-get-signature
+ :session "org.freedesktop.xesam.searcher"
+ "/org/freedesktop/xesam/searcher/main"
+ "org.freedesktop.xesam.Search" "GetHitData" "in")
+
+@result{} "sauas"
+
+(dbus-introspect-get-signature
+ :session "org.freedesktop.xesam.searcher"
+ "/org/freedesktop/xesam/searcher/main"
+ "org.freedesktop.xesam.Search" "HitsAdded")
+
+@result{} "su"
+@end lisp
+@end defun
+
@node Type Conversion
@chapter Mapping Lisp types and D-Bus types.
@@ -364,6 +945,37 @@ elements of this array. Example:
@result{} 3
@end lisp
+@defun 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 @var{string} is an
+UTF8 string, this function performs the conversion. Example:
+
+@lisp
+(dbus-string-to-byte-array "/etc/hosts")
+
+@result{} (:array :byte 47 :byte 101 :byte 116 :byte 99 :byte 47
+ :byte 104 :byte 111 :byte 115 :byte 116 :byte 115)
+@end lisp
+@end defun
+
+@defun dbus-escape-as-identifier string
+Escape an arbitrary @var{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:
+
+@lisp
+(dbus-escape-as-identifier "0123abc_xyz\x01\xff")
+
+@result{} "_30123abc_5fxyz_01_ff"
+@end lisp
+@end defun
+
@section Output parameters.
@@ -410,6 +1022,30 @@ The signal @code{PropertyModified}, discussed as example in
(@var{NUMBER} ((@var{STRING} @var{BOOL} @var{BOOL}) (@var{STRING} @var{BOOL} @var{BOOL}) @dots{}))
@end lisp
+@defun 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 @var{byte-array}
+to the corresponding string. Example:
+
+@lisp
+(dbus-byte-array-to-string '(47 101 116 99 47 104 111 115 116 115))
+
+@result{} "/etc/hosts"
+@end lisp
+@end defun
+
+@defun dbus-unescape-from-identifier string
+Retrieve the original string from the encoded @var{string}.
+@var{string} must have been coded with
+@code{dbus-escape-as-identifier}. Example:
+
+@lisp
+(dbus-unescape-from-identifier "_30123abc_5fxyz_01_ff")
+
+@result{} "0123abc_xyzÿ"
+@end lisp
+@end defun
+
@node Synchronous Methods
@chapter Calling methods in a blocking way.
@@ -417,15 +1053,14 @@ The signal @code{PropertyModified}, discussed as example in
@cindex synchronous method calls
Methods can be called synchronously (@dfn{blocking}) or asynchronously
-(@dfn{non-blocking}). Currently, just synchronous methods are
-implemented.
+(@dfn{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.
-@defun dbus-call-method bus service path interface method &rest args
+@defun dbus-call-method bus service path interface method &optional :timeout timeout &rest args
This function calls @var{method} on the D-Bus @var{bus}. @var{bus} is
either the symbol @code{:system} or the symbol @code{:session}.
@@ -433,6 +1068,12 @@ either the symbol @code{:system} or the symbol @code{:session}.
D-Bus object path, @var{service} is registered at. @var{interface} is
an interface offered by @var{service}. It must provide @var{method}.
+If the parameter @code{:timeout} is given, the following integer
+@var{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 (@pxref{Errors and
+Events}).
+
All other arguments args are passed to @var{method} as arguments.
They are converted into D-Bus types as described in @ref{Type
Conversion}.
@@ -506,6 +1147,70 @@ emulate the @code{lshal} command on GNU/Linux systems:
@end lisp
@end defun
+@defun dbus-call-method-non-blocking bus service path interface method &optional :timeout timeout &rest args
+Call @var{method} on the D-Bus @var{bus}, but don't block the event queue.
+This is necessary for communicating to registered D-Bus methods,
+which are running in the same Emacs process.
+
+The arguments are the same as in @code{dbus-call-method}. Example:
+
+@lisp
+(dbus-call-method-non-blocking
+ :system "org.freedesktop.Hal"
+ "/org/freedesktop/Hal/devices/computer"
+ "org.freedesktop.Hal.Device" "GetPropertyString"
+ "system.kernel.machine")
+
+@result{} "i686"
+@end lisp
+@end defun
+
+
+@node Asynchronous Methods
+@chapter Calling methods non-blocking.
+@cindex method calls, asynchronous
+@cindex asynchronous method calls
+
+@defun dbus-call-method-asynchronously bus service path interface method handler &optional :timeout timeout &rest args
+This function calls @var{method} on the D-Bus @var{bus}
+asynchronously. @var{bus} is either the symbol @code{:system} or the
+symbol @code{:session}.
+
+@var{service} is the D-Bus service name to be used. @var{path} is the
+D-Bus object path, @var{service} is registered at. @var{interface} is
+an interface offered by @var{service}. It must provide @var{method}.
+
+@var{handler} is a Lisp function, which is called when the
+corresponding return message has arrived.
+
+If the parameter @code{:timeout} is given, the following integer
+@var{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 (@pxref{Errors and
+Events}).
+
+All other arguments args are passed to @var{method} as arguments.
+They are converted into D-Bus types as described in @ref{Type
+Conversion}.
+
+The function returns a key into the hash table
+@code{dbus-registered-functions-table}. The corresponding entry in
+the hash table is removed, when the return message has been arrived,
+and @var{handler} is called. Example:
+
+@lisp
+(dbus-call-method-asynchronously
+ :system "org.freedesktop.Hal"
+ "/org/freedesktop/Hal/devices/computer"
+ "org.freedesktop.Hal.Device" "GetPropertyString" 'message
+ "system.kernel.machine")
+
+@result{} (:system 2)
+
+@print{} i686
+@end lisp
+@end defun
+
@node Receiving Method Calls
@chapter Offering own methods.
@@ -514,15 +1219,25 @@ emulate the @code{lshal} command on GNU/Linux systems:
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 @code{org.freedesktop.TextEditor}.
+interface of a well known service, like @samp{org.freedesktop.TextEditor}.
It could be also an implementation of an own interface. In this case,
-the service name must be @code{org.gnu.Emacs}. The object path shall
-begin with @code{/org/gnu/Emacs/@strong{Application}/}, and the
+the service name must be @samp{org.gnu.Emacs}. The object path shall
+begin with @samp{/org/gnu/Emacs/@strong{Application}/}, and the
interface name shall be @code{org.gnu.Emacs.@strong{Application}}.
-@code{@strong{Application}} is the name of the application which
+@samp{@strong{Application}} is the name of the application which
provides the interface.
+@deffn Constant dbus-service-emacs
+The well known service name of Emacs.
+@end deffn
+
+@deffn Constant dbus-path-emacs
+The object path head "/org/gnu/Emacs" used by Emacs. All object
+paths, used by offered methods or signals, shall start with this
+string.
+@end deffn
+
@defun dbus-register-method bus service path interface method handler
With this function, an application registers @var{method} on the D-Bus
@var{bus}.
@@ -539,13 +1254,23 @@ registered.
@var{interface} is the interface offered by @var{service}. It must
provide @var{method}.
-@var{handler} is a Lisp function to be called when when a @var{method}
-call is is received. It must accept as arguments the input arguments
-of @var{method}. @var{handler} must return a list, which elements are
-used as arguments for the reply message of @var{method}. This list
-can be composed like the input parameters in @ref{Type Conversion}.
+@var{handler} is a Lisp function to be called when a @var{method} call
+is received. It must accept as arguments the input arguments of
+@var{method}. @var{handler} should return a list, whose elements are
+to be used as arguments for the reply message of @var{method}. This
+list can be composed like the input parameters in @ref{Type
+Conversion}.
+
+If @var{handler} wants to return just one Lisp object and it is not a
+cons cell, @var{handler} can return this object directly, instead of
+returning a list containing the object.
-@code{dbus-register-method} returns a Lisp symbol, which can be used
+The default D-Bus timeout when waiting for a message reply is 25
+seconds. This value could be even smaller, depending on the calling
+client. Therefore, @var{handler} shall not last longer than
+absolutely necessary.
+
+@code{dbus-register-method} returns a Lisp object, which can be used
as argument in @code{dbus-unregister-object} for removing the
registration for @var{method}. Example:
@@ -564,12 +1289,12 @@ registration for @var{method}. Example:
"org.freedesktop.TextEditor" "OpenFile"
'my-dbus-method-handler)
-@result{} ((:system "org.freedesktop.TextEditor" "OpenFile")
+@result{} ((:session "org.freedesktop.TextEditor" "OpenFile")
("org.freedesktop.TextEditor" "/org/freedesktop/TextEditor"
- my-method-handler))
+ my-dbus-method-handler))
@end lisp
-If you invoke the method @code{org.freedesktop.TextEditor.OpenFile}
+If you invoke the method @samp{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 @var{true} or
@var{false}, indicating the success if the method. As test tool one
@@ -582,7 +1307,35 @@ could use the command line tool @code{dbus-send} in a shell:
"org.freedesktop.TextEditor.OpenFile" string:"/etc/hosts"
@print{} method return sender=:1.22 -> dest=:1.23 reply_serial=2
- boolean true
+ boolean true
+@end example
+
+You can indicate an error by raising the Emacs signal
+@code{dbus-error}. The handler above could be changed like this:
+
+@lisp
+(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)
+
+@result{} my-dbus-method-handler
+@end lisp
+
+The test runs then
+
+@example
+# dbus-send --session --print-reply \
+ --dest="org.freedesktop.TextEditor" \
+ "/org/freedesktop/TextEditor" \
+ "org.freedesktop.TextEditor.OpenFile" \
+ string:"/etc/hosts" string:"/etc/passwd"
+
+@print{} Error org.freedesktop.DBus.Error.Failed:
+ Wrong argument list: ("/etc/hosts" "/etc/passwd")
@end example
@end defun
@@ -613,12 +1366,13 @@ Conversion}. Example:
@lisp
(dbus-send-signal
- :session "org.gnu.Emacs" "/org/gnu/Emacs"
- "org.gnu.Emacs.FileManager" "FileModified" "/home/albinus/.emacs")
+ :session dbus-service-emacs dbus-path-emacs
+ (concat dbus-service-emacs ".FileManager") "FileModified"
+ "/home/albinus/.emacs")
@end lisp
@end defun
-@defun dbus-register-signal bus service path interface signal handler
+@defun dbus-register-signal bus service path interface signal handler &rest args
With this function, an application registers for @var{signal} on the
D-Bus @var{bus}.
@@ -643,7 +1397,16 @@ provide @var{signal}.
@var{handler} is a Lisp function to be called when the @var{signal} is
received. It must accept as arguments the output parameters
-@var{signal} is sending. Example:
+@var{signal} is sending.
+
+All other arguments @var{args}, if specified, must be strings. They
+stand for the respective arguments of @var{signal} in their order, and
+are used for filtering as well. A @code{nil} argument might be used
+to preserve the order.
+
+@code{dbus-register-signal} returns a Lisp object, which can be used
+as argument in @code{dbus-unregister-object} for removing the
+registration for @var{signal}. Example:
@lisp
(defun my-dbus-signal-handler (device)
@@ -661,17 +1424,13 @@ received. It must accept as arguments the output parameters
my-signal-handler))
@end lisp
-As we know from the inspection data of interface
-@code{org.freedesktop.Hal.Manager}, the signal @code{DeviceAdded}
+As we know from the introspection data of interface
+@samp{org.freedesktop.Hal.Manager}, the signal @samp{DeviceAdded}
provides one single parameter, which is mapped into a Lisp string.
The callback function @code{my-dbus-signal-handler} must define one
single string argument therefore. Plugging an USB device to your
-machine, when registered for signal @code{DeviceAdded}, will show you
+machine, when registered for signal @samp{DeviceAdded}, will show you
which objects the GNU/Linux @code{hal} daemon adds.
-
-@code{dbus-register-signal} returns a Lisp symbol, which can be used
-as argument in @code{dbus-unregister-object} for removing the
-registration for @var{signal}.
@end defun
@defun dbus-unregister-object object
@@ -687,7 +1446,9 @@ has been unregistered, @code{nil} otherwise.
@cindex errors
@cindex events
-Input parameters of @code{dbus-call-method} and
+Input parameters of @code{dbus-call-method},
+@code{dbus-call-method-non-blocking},
+@code{dbus-call-method-asynchronously}, and
@code{dbus-register-signal} are checked for correct D-Bus types. If
there is a type mismatch, the Lisp error @code{wrong-type-argument}
@code{D-Bus ARG} is raised.
@@ -707,14 +1468,19 @@ Incoming D-Bus messages are handled as Emacs events (see @pxref{Misc
Events, , , elisp}). The generated event has this form:
@lisp
-(dbus-event @var{bus} @var{serial} @var{service} @var{path} @var{interface} @var{member} @var{handler} &rest @var{args})
+(dbus-event @var{bus} @var{type} @var{serial} @var{service} @var{path} @var{interface} @var{member} @var{handler}
+ &rest @var{args})
@end lisp
-@var{bus} identifies the D-Bus the signal is coming from. It is
+@var{bus} identifies the D-Bus the message is coming from. It is
either the symbol @code{:system} or the symbol @code{:session}.
-@var{serial} is the serial number of the received D-Bus message if it
-is a method call, or @code{nil}.
+@var{type} is the D-Bus message type which has caused the event. It
+can be @code{dbus-message-type-invalid},
+@code{dbus-message-type-method-call},
+@code{dbus-message-type-method-return},
+@code{dbus-message-type-error}, or @code{dbus-message-type-signal}.
+@var{serial} is the serial number of the received D-Bus message.
@var{service} and @var{path} are the unique name and the object path
of the D-Bus object emitting the message. @var{interface} and
@@ -740,10 +1506,14 @@ Returns the bus name @var{event} is coming from.
The result is either the symbol @code{:system} or the symbol @code{:session}.
@end defun
+@defun dbus-event-message-type event
+Returns the message type of the corresponding D-Bus message. The
+result is a number.
+@end defun
+
@defun dbus-event-serial-number event
Returns the serial number of the corresponding D-Bus message.
-The result is a number in case the D-Bus message is a method
-call, or @code{nil} for all other mesage types.
+The result is a number.
@end defun
@defun dbus-event-service-name event
@@ -755,17 +1525,42 @@ Returns the object path of the D-Bus object @var{event} is coming from.
@end defun
@defun dbus-event-interface-name event
-Returns the interface name of of the D-Bus object @var{event} is coming from.
+Returns the interface name of the D-Bus object @var{event} is coming from.
@end defun
@defun dbus-event-member-name event
-Returns the member name of of the D-Bus object @var{event} is coming
+Returns the member name of the D-Bus object @var{event} is coming
from. It is either a signal name or a method name.
@end defun
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 @code{dbus-debug} to @code{t}.
+setting the variable @code{dbus-debug} to @code{t}. They can also be
+handled by a hook function.
+
+@defvar 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
+@code{condition-case} by @code{dbus-error}.
+
+Such functions can be used the adapt the error signal to be raised.
+Example:
+
+@lisp
+(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)
+@end lisp
+@end defvar
+
+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.
@node GNU Free Documentation License