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1 | \input texinfo @c -*-texinfo-*- |
2 | @setfilename ../../info/dbus | |
3 | @c %**start of header | |
4 | @settitle Using of D-Bus | |
5 | @c @setchapternewpage odd | |
6 | @c %**end of header | |
7 | ||
8 | @copying | |
6ed161e1 | 9 | Copyright @copyright{} 2007, 2008, 2009 Free Software Foundation, Inc. |
22d8ac3a MA |
10 | |
11 | @quotation | |
12 | Permission is granted to copy, distribute and/or modify this document | |
6a2c4aec | 13 | under the terms of the GNU Free Documentation License, Version 1.3 or |
22d8ac3a | 14 | any later version published by the Free Software Foundation; with no |
debf4439 GM |
15 | Invariant Sections, with the Front-Cover texts being ``A GNU Manual'', |
16 | and with the Back-Cover Texts as in (a) below. A copy of the license | |
17 | is included in the section entitled ``GNU Free Documentation License''. | |
22d8ac3a | 18 | |
6f093307 GM |
19 | (a) The FSF's Back-Cover Text is: ``You have the freedom to copy and |
20 | modify this GNU manual. Buying copies from the FSF supports it in | |
21 | developing GNU and promoting software freedom.'' | |
22d8ac3a MA |
22 | @end quotation |
23 | @end copying | |
24 | ||
25 | @dircategory Emacs | |
26 | @direntry | |
27 | * D-Bus: (dbus). Using D-Bus in Emacs. | |
28 | @end direntry | |
29 | ||
5dc584b5 | 30 | @contents |
cd71b9ae | 31 | |
22d8ac3a MA |
32 | @node Top, Overview, (dir), (dir) |
33 | @top D-Bus integration in Emacs | |
34 | ||
35 | This manual documents an API for usage of D-Bus in | |
36 | Emacs.@footnote{D-Bus is not enabled by default. You must run | |
37 | @command{./configure --with-dbus} in Emacs' top level directory, | |
38 | before you compile Emacs.} D-Bus is a message bus system, a simple | |
39 | way for applications to talk to one another. An overview of D-Bus can | |
40 | be found at @uref{http://dbus.freedesktop.org/}. | |
41 | ||
5dc584b5 | 42 | @ifnottex |
22d8ac3a | 43 | @insertcopying |
5dc584b5 | 44 | @end ifnottex |
22d8ac3a MA |
45 | |
46 | @menu | |
47 | * Overview:: An overview of D-Bus. | |
cd71b9ae | 48 | * Inspection:: Inspection of D-Bus services. |
22d8ac3a MA |
49 | * Type Conversion:: Mapping Lisp types and D-Bus types. |
50 | * Synchronous Methods:: Calling methods in a blocking way. | |
21956b56 | 51 | * Asynchronous Methods:: Calling methods non-blocking. |
addb7f2e | 52 | * Receiving Method Calls:: Offering own methods. |
22d8ac3a MA |
53 | * Signals:: Sending and receiving signals. |
54 | * Errors and Events:: Errors and events. | |
55 | * GNU Free Documentation License:: The license for this documentation. | |
56 | @end menu | |
57 | ||
cd71b9ae | 58 | |
22d8ac3a MA |
59 | @node Overview |
60 | @chapter An overview of D-Bus | |
61 | @cindex overview | |
62 | ||
63 | D-Bus is an inter-process communication mechanism for applications | |
64 | residing on the same host. The communication is based on | |
65 | @dfn{messages}. Data in the messages is carried in a structured way, | |
66 | it is not just a byte stream. | |
67 | ||
68 | The communication is connection oriented to two kinds of message | |
69 | buses: a so called @dfn{system bus}, and a @dfn{session bus}. On a | |
70 | given machine, there is always one single system bus for miscellaneous | |
71 | system-wide communication, like changing of hardware configuration. | |
72 | On the other hand, the session bus is always related to a single | |
73 | user's session. | |
74 | ||
75 | Every client application, which is connected to a bus, registers under | |
76 | a @dfn{unique name} at the bus. This name is used for identifying the | |
77 | client application. Such a unique name starts always with a colon, | |
78 | and looks like @samp{:1.42}. | |
79 | ||
80 | Additionally, a client application can register itself to a so called | |
81 | @dfn{known name}, which is a series of identifiers separated by dots, | |
7ef92bc9 | 82 | as in @samp{org.gnu.Emacs}. If several applications register to the |
22d8ac3a MA |
83 | same known name, these registrations are queued, and only the first |
84 | application which has registered for the known name is reachable via | |
85 | this name. If this application disconnects from the bus, the next | |
86 | queued unique name becomes the owner of this known name. | |
87 | ||
88 | An application can install one or several objects under its name. | |
89 | Such objects are identified by an @dfn{object path}, which looks | |
90 | similar to paths in a filesystem. An example of such an object path | |
91 | could be @samp{/org/gnu/Emacs/}. | |
92 | ||
93 | Applications might send a request to an object, that means sending a | |
94 | message with some data as input parameters, and receiving a message | |
95 | from that object with the result of this message, the output | |
96 | parameters. Such a request is called @dfn{method} in D-Bus. | |
97 | ||
98 | The other form of communication are @dfn{signals}. The underlying | |
99 | message is emitted from an object and will be received by all other | |
100 | applications which have registered for such a signal. | |
101 | ||
102 | All methods and signals an object supports are called @dfn{interface} | |
103 | of the object. Interfaces are specified under a hierarchical name in | |
104 | D-Bus; an object can support several interfaces. Such an interface | |
105 | name could be @samp{org.gnu.Emacs.TextEditor} or | |
106 | @samp{org.gnu.Emacs.FileManager}. | |
107 | ||
108 | ||
109 | @node Inspection | |
cd71b9ae | 110 | @chapter Inspection of D-Bus services. |
22d8ac3a MA |
111 | @cindex inspection |
112 | ||
cd71b9ae MA |
113 | @menu |
114 | * Bus names:: Discovering D-Bus names. | |
115 | * Introspection:: Knowing the details of D-Bus services. | |
116 | * Nodes and Interfaces:: Detecting object paths and interfaces. | |
117 | * Methods and Signal:: Applying the functionality. | |
118 | * Properties and Annotations:: What else to know about interfaces. | |
119 | * Arguments and Signatures:: The final details. | |
120 | @end menu | |
121 | ||
122 | ||
123 | @node Bus names | |
124 | @section Bus names. | |
125 | ||
22d8ac3a MA |
126 | There are several basic functions which inspect the buses for |
127 | registered names. Internally they use the basic interface | |
128 | @samp{org.freedesktop.DBus}, which is supported by all objects of a bus. | |
129 | ||
130 | @defun dbus-list-activatable-names | |
22d8ac3a MA |
131 | This function returns the D-Bus service names, which can be activated. |
132 | An activatable service is described in a service registration file. | |
133 | Under GNU/Linux, such files are located at | |
134 | @file{/usr/share/dbus-1/services/}. | |
135 | ||
136 | The result is a list of strings, which is @code{nil} when there are no | |
137 | activatable service names at all. | |
138 | @end defun | |
139 | ||
140 | @defun dbus-list-names bus | |
22d8ac3a MA |
141 | All service names, which are registered at D-Bus @var{bus}, are |
142 | returned. The result is a list of strings, which is @code{nil} when | |
143 | there are no registered service names at all. Well known names are | |
144 | strings like @samp{org.freedesktop.DBus}. Names starting with | |
145 | @samp{:} are unique names for services. | |
146 | ||
147 | @var{bus} must be either the symbol @code{:system} or the symbol | |
148 | @code{:session}. | |
149 | @end defun | |
150 | ||
151 | @defun dbus-list-known-names bus | |
22d8ac3a MA |
152 | Retrieves all services which correspond to a known name in @var{bus}. |
153 | A service has a known name if it doesn't start with @samp{:}. The | |
154 | result is a list of strings, which is @code{nil} when there are no | |
155 | known names at all. | |
156 | ||
157 | @var{bus} must be either the symbol @code{:system} or the symbol | |
158 | @code{:session}. | |
159 | @end defun | |
160 | ||
161 | @defun dbus-list-queued-owners bus service | |
22d8ac3a MA |
162 | For a given service, registered at D-Bus @var{bus} under the name |
163 | @var{service}, all queued unique names are returned. The result is a | |
164 | list of strings, or @code{nil} when there are no queued names for | |
165 | @var{service} at all. | |
166 | ||
167 | @var{bus} must be either the symbol @code{:system} or the symbol | |
168 | @code{:session}. @var{service} must be a known service name as | |
169 | string. | |
170 | @end defun | |
171 | ||
172 | @defun dbus-get-name-owner bus service | |
22d8ac3a | 173 | For a given service, registered at D-Bus @var{bus} under the name |
06c0751a MA |
174 | @var{service}, the unique name of the name owner is returned. The |
175 | result is a string, or @code{nil} when there exist no name owner of | |
176 | @var{service}. | |
22d8ac3a MA |
177 | |
178 | @var{bus} must be either the symbol @code{:system} or the symbol | |
179 | @code{:session}. @var{service} must be a known service name as | |
180 | string. | |
181 | @end defun | |
182 | ||
06c0751a MA |
183 | @defun dbus-ping bus service |
184 | Check whether the service name @var{service} is registered at D-Bus | |
185 | @var{bus}. @var{service} might not have been started yet. The result | |
186 | is either @code{t} or @code{nil}. | |
187 | ||
188 | @var{bus} must be either the symbol @code{:system} or the symbol | |
189 | @code{:session}. @var{service} must be a string. Example: | |
190 | ||
191 | @lisp | |
192 | (message | |
193 | "%s screensaver on board." | |
194 | (cond | |
195 | ((dbus-ping :session "org.gnome.ScreenSaver") "Gnome") | |
196 | ((dbus-ping :session "org.freedesktop.ScreenSaver") "KDE") | |
197 | (t "No"))) | |
198 | @end lisp | |
199 | @end defun | |
200 | ||
22d8ac3a | 201 | @defun dbus-get-unique-name bus |
22d8ac3a MA |
202 | The unique name, under which Emacs is registered at D-Bus @var{bus}, |
203 | is returned as string. | |
204 | ||
205 | @var{bus} must be either the symbol @code{:system} or the symbol | |
206 | @code{:session}. | |
207 | @end defun | |
208 | ||
cd71b9ae MA |
209 | |
210 | @node Introspection | |
211 | @section Knowing the details of D-Bus services. | |
212 | ||
213 | D-Bus services publish their interfaces. This can be retrieved and | |
214 | analyzed during runtime, in order to understand the used | |
215 | implementation. | |
216 | ||
217 | The resulting introspection data are in XML format. The root | |
218 | introspection element is always a @code{node} element. It might have | |
219 | a @code{name} attribute, which denotes the (absolute) object path an | |
220 | interface is introspected. | |
221 | ||
222 | The root @code{node} element may have @code{node} and @code{interface} | |
223 | children. A child @code{node} element must have a @code{name} | |
224 | attribute, this case it is the relative object path to the root | |
225 | @code{node} element. | |
226 | ||
227 | An @code{interface} element has just one attribute, @code{name}, which | |
228 | is the full name of that interface. The default interface | |
229 | @samp{org.freedesktop.DBus.Introspectable} is always present. Example: | |
230 | ||
231 | @example | |
232 | <node name="/org/bluez"> | |
233 | <interface name="org.freedesktop.DBus.Introspectable"> | |
234 | @dots{} | |
235 | </interface> | |
236 | <interface name="org.bluez.Manager"> | |
237 | @dots{} | |
238 | </interface> | |
239 | <interface name="org.bluez.Database"> | |
240 | @dots{} | |
241 | </interface> | |
242 | <interface name="org.bluez.Security"> | |
243 | @dots{} | |
244 | </interface> | |
245 | <node name="service_audio"/> | |
246 | <node name="service_input"/> | |
247 | <node name="service_network"/> | |
248 | <node name="service_serial"/> | |
249 | </node> | |
250 | @end example | |
251 | ||
252 | Children of an @code{interface} element can be @code{method}, | |
253 | @code{signal} and @code{property} elements. A @code{method} element | |
254 | stands for a D-Bus method of the surrounding interface. The element | |
255 | itself has a @code{name} attribute, showing the method name. Children | |
256 | elements @code{arg} stand for the arguments of a method. Example: | |
257 | ||
258 | @example | |
259 | <method name="ResolveHostName"> | |
260 | <arg name="interface" type="i" direction="in"/> | |
261 | <arg name="protocol" type="i" direction="in"/> | |
262 | <arg name="name" type="s" direction="in"/> | |
263 | <arg name="aprotocol" type="i" direction="in"/> | |
264 | <arg name="flags" type="u" direction="in"/> | |
265 | <arg name="interface" type="i" direction="out"/> | |
266 | <arg name="protocol" type="i" direction="out"/> | |
267 | <arg name="name" type="s" direction="out"/> | |
268 | <arg name="aprotocol" type="i" direction="out"/> | |
269 | <arg name="address" type="s" direction="out"/> | |
270 | <arg name="flags" type="u" direction="out"/> | |
271 | </method> | |
272 | @end example | |
273 | ||
274 | @code{arg} elements can have the attributes @code{name}, @code{type} | |
275 | and @code{direction}. The @code{name} attribute is optional. The | |
276 | @code{type} attribute stands for the @dfn{signature} of the argument | |
277 | in D-Bus. For a discussion of D-Bus types and their Lisp | |
278 | representation see @ref{Type Conversion}.@footnote{D-Bus signatures | |
279 | are explained in the D-Bus specification | |
280 | @uref{http://dbus.freedesktop.org/doc/dbus-specification.html#message-protocol-signatures}.} | |
281 | The @code{direction} attribute of an @code{arg} element can be only | |
282 | @samp{in} or @samp{out}; in case it is omitted, it defaults to | |
283 | @samp{in}. | |
284 | ||
285 | A @code{signal} element of an @code{interface} has a similar | |
286 | structure. The @code{direction} attribute of an @code{arg} child | |
287 | element can be only @samp{out} here; which is also the default value. | |
288 | Example: | |
289 | ||
290 | @example | |
291 | <signal name="StateChanged"> | |
292 | <arg name="state" type="i"/> | |
293 | <arg name="error" type="s"/> | |
294 | </signal> | |
295 | @end example | |
296 | ||
297 | A @code{property} element has no @code{arg} child | |
298 | element. It just has the attributes @code{name}, @code{type} and | |
299 | @code{access}, which are all mandatory. The @code{access} attribute | |
300 | allows the values @samp{readwrite}, @samp{read}, and @samp{write}. | |
301 | Example: | |
302 | ||
303 | @example | |
304 | <property name="Status" type="u" direction="read"/> | |
305 | @end example | |
306 | ||
307 | @code{annotation} elements can be children of @code{interface}, | |
308 | @code{method}, @code{signal}, and @code{property} elements. Unlike | |
309 | properties, which can change their values during lifetime of a D-Bus | |
310 | object, annotations are static. Often they are used for code | |
311 | generators of D-Bus langugae bindings. Example: | |
312 | ||
313 | @example | |
314 | <annotation name="de.berlios.Pinot.GetStatistics" value="pinotDBus"/> | |
315 | @end example | |
316 | ||
317 | Annotations have just @code{name} and @code{value} attributes, both | |
318 | must be strings. | |
319 | ||
22d8ac3a | 320 | @defun dbus-introspect bus service path |
cd71b9ae MA |
321 | This function returns all interfaces and sub-nodes of @var{service}, |
322 | registered at object path @var{path} at bus @var{bus}. | |
22d8ac3a MA |
323 | |
324 | @var{bus} must be either the symbol @code{:system} or the symbol | |
325 | @code{:session}. @var{service} must be a known service name, and | |
326 | @var{path} must be a valid object path. The last two parameters are | |
327 | strings. The result, the introspection data, is a string in XML | |
cd71b9ae | 328 | format. Example: |
22d8ac3a | 329 | |
06c0751a | 330 | @lisp |
22d8ac3a MA |
331 | (dbus-introspect |
332 | :system "org.freedesktop.Hal" | |
333 | "/org/freedesktop/Hal/devices/computer") | |
334 | ||
d9e21158 | 335 | @result{} "<!DOCTYPE node PUBLIC |
cd71b9ae MA |
336 | "-//freedesktop//DTD D-BUS Object Introspection 1.0//EN" |
337 | "http://www.freedesktop.org/standards/dbus/1.0/introspect.dtd"> | |
d9e21158 | 338 | <node> |
cd71b9ae MA |
339 | <interface name="org.freedesktop.Hal.Device"> |
340 | <method name="GetAllProperties"> | |
341 | <arg name="properties" direction="out" type="a@{sv@}"/> | |
d9e21158 | 342 | </method> |
c9ecb5a7 | 343 | @dots{} |
cd71b9ae MA |
344 | <signal name="PropertyModified"> |
345 | <arg name="num_updates" type="i"/> | |
346 | <arg name="updates" type="a(sbb)"/> | |
d9e21158 MA |
347 | </signal> |
348 | </interface> | |
c9ecb5a7 | 349 | @dots{} |
d9e21158 | 350 | </node>" |
06c0751a | 351 | @end lisp |
22d8ac3a | 352 | |
cd71b9ae MA |
353 | This example informs us, that the service @samp{org.freedesktop.Hal} |
354 | at object path @samp{/org/freedesktop/Hal/devices/computer} offers the | |
355 | interface @samp{org.freedesktop.Hal.Device} (and 2 other interfaces | |
22d8ac3a | 356 | not documented here). This interface contains the method |
cd71b9ae | 357 | @samp{GetAllProperties}, which needs no input parameters, but returns |
22d8ac3a MA |
358 | as output parameter an array of dictionary entries (key-value pairs). |
359 | Every dictionary entry has a string as key, and a variant as value. | |
360 | ||
361 | The interface offers also a signal, which returns 2 parameters: an | |
362 | integer, and an array consisting of elements which are a struct of a | |
cd71b9ae MA |
363 | string and 2 boolean values.@footnote{ The interfaces of the service |
364 | @samp{org.freedesktop.Hal} are described at | |
22d8ac3a MA |
365 | @uref{http://people.freedesktop.org/~david/hal-spec/hal-spec.html#interfaces}.} |
366 | @end defun | |
367 | ||
cd71b9ae MA |
368 | @defun dbus-introspect-xml bus service path |
369 | This function has the same intention as function | |
370 | @code{dbus-introspect}. The returned value is a parsed XML tree, | |
371 | which can be used for further analysis. Example: | |
372 | ||
373 | @lisp | |
374 | (dbus-introspect-xml | |
375 | :session "org.freedesktop.xesam.searcher" | |
376 | "/org/freedesktop/xesam/searcher/main") | |
377 | ||
378 | @result{} (node ((name . "/org/freedesktop/xesam/searcher/main")) | |
379 | (interface ((name . "org.freedesktop.xesam.Search")) | |
380 | (method ((name . "GetHitData")) | |
381 | (arg ((name . "search") (type . "s") (direction . "in"))) | |
382 | (arg ((name . "hit_ids") (type . "au") (direction . "in"))) | |
383 | (arg ((name . "fields") (type . "as") (direction . "in"))) | |
384 | (arg ((name . "hit_data") (type . "aav") (direction . "out"))) | |
385 | ) | |
386 | @dots{} | |
387 | (signal ((name . "HitsAdded")) | |
388 | (arg ((name . "search") (type . "s"))) | |
389 | (arg ((name . "count") (type . "u"))) | |
390 | ) | |
391 | ) | |
392 | @dots{} | |
393 | ) | |
394 | @end lisp | |
395 | @end defun | |
396 | ||
397 | @defun dbus-introspect-get-attribute object attribute | |
398 | It returns the @var{attribute} value of a D-Bus introspection | |
399 | @var{object}. @var{object} can be every subtree of a parsed XML tree | |
400 | as retrieved with @code{dbus-introspect-xml}. @var{attribute} must be | |
401 | a string according to the attribute names in the D-Bus specification. | |
402 | Example: | |
403 | ||
404 | @lisp | |
405 | (dbus-introspect-get-attribute | |
406 | (dbus-introspect-xml :system "org.freedesktop.SystemToolsBackends" | |
407 | "/org/freedesktop/SystemToolsBackends/UsersConfig") | |
408 | "name") | |
409 | ||
410 | @result{} "/org/freedesktop/SystemToolsBackends/UsersConfig" | |
411 | @end lisp | |
412 | ||
413 | If @var{object} has no @var{attribute}, the function returns nil. | |
414 | @end defun | |
415 | ||
416 | ||
417 | @node Nodes and Interfaces | |
418 | @section Detecting object paths and interfaces. | |
419 | ||
420 | The first elements, to be introspected for a D-Bus object, are further | |
421 | object paths and interfaces. | |
422 | ||
423 | @defun dbus-introspect-get-node-names bus service path | |
424 | All node names of @var{service} in D-Bus @var{bus} at object path | |
425 | @var{path} are returned as list of strings. Example: | |
426 | ||
427 | @lisp | |
428 | (dbus-introspect-get-node-names | |
429 | :session "org.gnome.seahorse" "/org/gnome/seahorse") | |
430 | ||
431 | @result{} ("crypto" "keys") | |
432 | @end lisp | |
433 | ||
434 | The node names stand for further object paths of the D-Bus | |
435 | @var{service}, relative to @var{path}. In the example, | |
436 | @samp{/org/gnome/seahorse/crypto} and @samp{/org/gnome/seahorse/keys} | |
437 | are also object paths of the D-Bus service @samp{org.gnome.seahorse}. | |
438 | @end defun | |
439 | ||
440 | @defun dbus-introspect-get-all-nodes bus service path | |
441 | This function returns all node names of @var{service} in D-Bus | |
442 | @var{bus} at object path @var{path}. It returns a list of strings | |
443 | with all object paths of @var{service}, starting at @var{path}. | |
444 | Example: | |
445 | ||
446 | @lisp | |
447 | (dbus-introspect-get-all-nodes :session "org.gnome.seahorse" "/") | |
448 | ||
449 | @result{} ("/" "/org" "/org/gnome" "/org/gnome/seahorse" | |
450 | "/org/gnome/seahorse/crypto" | |
451 | "/org/gnome/seahorse/keys" | |
452 | "/org/gnome/seahorse/keys/openpgp" | |
453 | "/org/gnome/seahorse/keys/openpgp/local" | |
454 | "/org/gnome/seahorse/keys/openssh" | |
455 | "/org/gnome/seahorse/keys/openssh/local") | |
456 | @end lisp | |
457 | @end defun | |
458 | ||
459 | @defun dbus-introspect-get-interface-names bus service path | |
460 | There will be returned a list strings of all interface names of | |
461 | @var{service} in D-Bus @var{bus} at object path @var{path}. This list | |
462 | will contain the default interface @samp{org.freedesktop.DBus.Introspectable}. | |
463 | ||
464 | Another default interface is @samp{org.freedesktop.DBus.Properties}. | |
465 | If present, @code{interface} elements can also have @code{property} | |
466 | children. Example: | |
467 | ||
468 | @lisp | |
469 | (dbus-introspect-get-interface-names | |
470 | :system "org.freedesktop.Hal" | |
471 | "/org/freedesktop/Hal/devices/computer") | |
472 | ||
473 | @result{} ("org.freedesktop.DBus.Introspectable" | |
474 | "org.freedesktop.Hal.Device" | |
475 | "org.freedesktop.Hal.Device.SystemPowerManagement" | |
476 | "org.freedesktop.Hal.Device.CPUFreq") | |
477 | @end lisp | |
478 | @end defun | |
479 | ||
480 | @defun dbus-introspect-get-interface bus service path interface | |
481 | Return @var{interface} of @var{service} in D-Bus @var{bus} at object | |
482 | path @var{path}. The return value is an XML element. @var{interface} | |
483 | must be a string, element of the list returned by | |
484 | @code{dbus-introspect-get-interface-names}. Example: | |
485 | ||
486 | @lisp | |
487 | (dbus-introspect-get-interface | |
488 | :session "org.freedesktop.xesam.searcher" | |
489 | "/org/freedesktop/xesam/searcher/main" | |
490 | "org.freedesktop.xesam.Search") | |
491 | ||
492 | @result{} (interface ((name . "org.freedesktop.xesam.Search")) | |
493 | (method ((name . "GetHitData")) | |
494 | (arg ((name . "search") (type . "s") (direction . "in"))) | |
495 | (arg ((name . "hit_ids") (type . "au") (direction . "in"))) | |
496 | (arg ((name . "fields") (type . "as") (direction . "in"))) | |
497 | (arg ((name . "hit_data") (type . "aav") (direction . "out"))) | |
498 | ) | |
499 | @dots{} | |
500 | (signal ((name . "HitsAdded")) | |
501 | (arg ((name . "search") (type . "s"))) | |
502 | (arg ((name . "count") (type . "u"))) | |
503 | ) | |
504 | ) | |
505 | @end lisp | |
506 | @end defun | |
507 | ||
508 | @noindent | |
509 | With these functions, it is possible to retrieve all introspection | |
510 | data from a running system: | |
511 | ||
512 | @lisp | |
513 | (with-current-buffer (switch-to-buffer "*introspect*") | |
514 | (erase-buffer) | |
515 | (dolist (service (dbus-list-known-names :session)) | |
516 | (dolist (path (dbus-introspect-get-all-nodes :session service "/")) | |
517 | ;; We want to introspect only elements, which have more than | |
518 | ;; the default interface "org.freedesktop.DBus.Introspectable". | |
519 | (when (delete | |
520 | "org.freedesktop.DBus.Introspectable" | |
521 | (dbus-introspect-get-interface-names :session service path)) | |
522 | (insert (message "\nservice: \"%s\" path: \"%s\"\n" service path) | |
523 | (dbus-introspect :session service path)) | |
524 | (redisplay t))))) | |
525 | @end lisp | |
526 | ||
527 | ||
528 | @node Methods and Signal | |
529 | @section Applying the functionality. | |
530 | ||
531 | Methods and signals are the communicatione means to D-Bus. The | |
532 | following functions return their specifications. | |
533 | ||
534 | @defun dbus-introspect-get-method-names bus service path interface | |
535 | Return a list of strings of all method names of @var{interface} of | |
536 | @var{service} in D-Bus @var{bus} at object path @var{path}. Example: | |
537 | ||
538 | @lisp | |
539 | (dbus-introspect-get-method-names | |
540 | :session "org.freedesktop.xesam.searcher" | |
541 | "/org/freedesktop/xesam/searcher/main" | |
542 | "org.freedesktop.xesam.Search") | |
543 | ||
544 | @result{} ("GetState" "StartSearch" "GetHitCount" "GetHits" "NewSession" | |
545 | "CloseSession" "GetHitData" "SetProperty" "NewSearch" | |
546 | "GetProperty" "CloseSearch") | |
547 | @end lisp | |
548 | @end defun | |
549 | ||
550 | @defun dbus-introspect-get-method bus service path interface method | |
551 | This function returns @var{method} of @var{interface} as XML element. | |
552 | It must be located at @var{service} in D-Bus @var{bus} at object path | |
553 | @var{path}. @var{method} must be a string, element of the list | |
554 | returned by @code{dbus-introspect-get-method-names}. Example: | |
555 | ||
556 | @lisp | |
557 | (dbus-introspect-get-method | |
558 | :session "org.freedesktop.xesam.searcher" | |
559 | "/org/freedesktop/xesam/searcher/main" | |
560 | "org.freedesktop.xesam.Search" "GetHitData") | |
561 | ||
562 | @result{} (method ((name . "GetHitData")) | |
563 | (arg ((name . "search") (type . "s") (direction . "in"))) | |
564 | (arg ((name . "hit_ids") (type . "au") (direction . "in"))) | |
565 | (arg ((name . "fields") (type . "as") (direction . "in"))) | |
566 | (arg ((name . "hit_data") (type . "aav") (direction . "out"))) | |
567 | ) | |
568 | @end lisp | |
569 | @end defun | |
570 | ||
571 | @defun dbus-introspect-get-signal-names bus service path interface | |
572 | Return a list of strings of all signal names of @var{interface} of | |
573 | @var{service} in D-Bus @var{bus} at object path @var{path}. Example: | |
574 | ||
575 | @lisp | |
576 | (dbus-introspect-get-signal-names | |
577 | :session "org.freedesktop.xesam.searcher" | |
578 | "/org/freedesktop/xesam/searcher/main" | |
579 | "org.freedesktop.xesam.Search") | |
580 | ||
581 | @result{} ("StateChanged" "SearchDone" "HitsModified" | |
582 | "HitsRemoved" "HitsAdded") | |
583 | @end lisp | |
584 | @end defun | |
585 | ||
586 | @defun dbus-introspect-get-signal bus service path interface signal | |
587 | This function returns @var{signal} of @var{interface} as XML element. | |
588 | It must be located at @var{service} in D-Bus @var{bus} at object path | |
589 | @var{path}. @var{signal} must be a string, element of the list | |
590 | returned by @code{dbus-introspect-get-signal-names}. Example: | |
591 | ||
592 | @lisp | |
593 | (dbus-introspect-get-signal | |
594 | :session "org.freedesktop.xesam.searcher" | |
595 | "/org/freedesktop/xesam/searcher/main" | |
596 | "org.freedesktop.xesam.Search" "HitsAdded") | |
597 | ||
598 | @result{} (signal ((name . "HitsAdded")) | |
599 | (arg ((name . "search") (type . "s"))) | |
600 | (arg ((name . "count") (type . "u"))) | |
601 | ) | |
602 | @end lisp | |
603 | @end defun | |
604 | ||
605 | ||
606 | @node Properties and Annotations | |
607 | @section What else to know about interfaces. | |
608 | ||
609 | Interfaces can have properties. These can be exposed via the | |
610 | @samp{org.freedesktop.DBus.Properties} interface@footnote{See | |
611 | @uref{http://dbus.freedesktop.org/doc/dbus-specification.html#standard-interfaces-properties}}. | |
612 | That is, properties can be retrieved and changed during lifetime of an | |
613 | element. | |
614 | ||
615 | Annotations, on the other hand, are static values for an element. | |
616 | Often, they are used to instruct generators, how to generate code from | |
617 | the interface for a given language binding. | |
618 | ||
619 | @defun dbus-introspect-get-property-names bus service path interface | |
620 | Return a list of strings with all property names of @var{interface} of | |
621 | @var{service} in D-Bus @var{bus} at object path @var{path}. Example: | |
622 | ||
623 | @lisp | |
624 | (dbus-introspect-get-property-names | |
625 | :session "org.kde.kded" "/modules/networkstatus" | |
626 | "org.kde.Solid.Networking.Client") | |
627 | ||
628 | @result{} ("Status") | |
629 | @end lisp | |
630 | ||
631 | If an interface declares properties, the corresponding element supports | |
632 | also the @samp{org.freedesktop.DBus.Properties} interface. | |
633 | @end defun | |
634 | ||
635 | @defun dbus-introspect-get-property bus service path interface property | |
636 | This function returns @var{property} of @var{interface} as XML element. | |
637 | It must be located at @var{service} in D-Bus @var{bus} at object path | |
638 | @var{path}. @var{property} must be a string, element of the list | |
639 | returned by @code{dbus-introspect-get-property-names}. | |
640 | ||
641 | A @var{property} value can be retrieved by the function | |
642 | @code{dbus-introspect-get-attribute}. Example: | |
643 | ||
644 | @lisp | |
645 | (dbus-introspect-get-property | |
646 | :session "org.kde.kded" "/modules/networkstatus" | |
647 | "org.kde.Solid.Networking.Client" "Status") | |
648 | ||
649 | @result{} (property ((access . "read") (type . "u") (name . "Status"))) | |
650 | ||
651 | (dbus-introspect-get-attribute | |
652 | (dbus-introspect-get-property | |
653 | :session "org.kde.kded" "/modules/networkstatus" | |
654 | "org.kde.Solid.Networking.Client" "Status") | |
655 | "access") | |
656 | ||
657 | @result{} "read" | |
658 | @end lisp | |
659 | @end defun | |
660 | ||
661 | @defun dbus-get-property bus service path interface property | |
662 | This function returns the value of @var{property} of @var{interface}. | |
663 | It will be checked at @var{bus}, @var{service}, @var{path}. The | |
664 | result can be any valid D-Bus value, or nil if there is no | |
665 | @var{property}. Example: | |
666 | ||
667 | @lisp | |
668 | (dbus-get-property | |
669 | :session "org.kde.kded" "/modules/networkstatus" | |
670 | "org.kde.Solid.Networking.Client" "Status") | |
671 | ||
672 | @result{} 4 | |
673 | @end lisp | |
674 | @end defun | |
675 | ||
676 | @defun dbus-set-property bus service path interface property value | |
677 | Set value of @var{property} of @var{interface} to @var{value}. It | |
678 | will be checked at @var{bus}, @var{service}, @var{path}. When the | |
679 | value has been set successful, the result is @var{value}. Otherwise, | |
680 | @code{nil} is returned. Example: | |
681 | ||
682 | @lisp | |
683 | (dbus-set-property | |
684 | :session "org.kde.kaccess" "/MainApplication" | |
685 | "com.trolltech.Qt.QApplication" "doubleClickInterval" 500) | |
686 | ||
687 | @result{} 500 | |
688 | @end lisp | |
689 | @end defun | |
690 | ||
691 | @defun dbus-get-all-properties bus service path interface | |
692 | This function returns all properties of @var{interface}. It will be | |
693 | checked at @var{bus}, @var{service}, @var{path}. The result is a list | |
694 | of cons. Every cons contains the name of the property, and its value. | |
695 | If there are no properties, @code{nil} is returned. Example: | |
696 | ||
697 | @lisp | |
698 | (dbus-get-all-properties | |
699 | :session "org.kde.kaccess" "/MainApplication" | |
700 | "com.trolltech.Qt.QApplication") | |
701 | ||
702 | @result{} (("cursorFlashTime" . 1000) ("doubleClickInterval" . 500) | |
703 | ("keyboardInputInterval" . 400) ("wheelScrollLines" . 3) | |
704 | ("globalStrut" 0 0) ("startDragTime" . 500) | |
705 | ("startDragDistance" . 4) ("quitOnLastWindowClosed" . t) | |
706 | ("styleSheet" . "")) | |
707 | @end lisp | |
708 | @end defun | |
709 | ||
710 | @defun dbus-introspect-get-annotation-names bus service path interface &optional name | |
711 | Return a list of all annotation names as list of strings. If | |
712 | @var{name} is @code{nil}, the annotations are children of | |
713 | @var{interface}, otherwise @var{name} must be a @code{method}, | |
714 | @code{signal}, or @code{property} XML element, where the annotations | |
715 | belong to. Example: | |
716 | ||
717 | @lisp | |
718 | (dbus-introspect-get-annotation-names | |
719 | :session "de.berlios.Pinot" "/de/berlios/Pinot" | |
720 | "de.berlios.Pinot" "GetStatistics") | |
721 | ||
722 | @result{} ("de.berlios.Pinot.GetStatistics") | |
723 | @end lisp | |
724 | ||
725 | Default annotation names@footnote{See | |
726 | @uref{http://dbus.freedesktop.org/doc/dbus-specification.html#introspection-format}} | |
727 | are | |
728 | ||
729 | @table @samp | |
730 | @item org.freedesktop.DBus.Deprecated | |
731 | Whether or not the entity is deprecated; defaults to @code{nil} | |
732 | ||
733 | @item org.freedesktop.DBus.GLib.CSymbol | |
734 | The C symbol; may be used for @code{methods} and @code{interfaces} | |
735 | ||
736 | @item org.freedesktop.DBus.Method.NoReply | |
737 | If set, don't expect a reply to the @code{method} call; defaults to @code{nil} | |
738 | @end table | |
739 | @end defun | |
740 | ||
741 | @defun dbus-introspect-get-annotation bus service path interface name annotation | |
742 | Return annotation @var{ANNOTATION} as XML object. If @var{name} is | |
743 | @code{nil}, @var{ANNOTATION} is a child of @var{interface}, otherwise | |
744 | @var{name} must be the name of a @code{method}, @code{signal}, or | |
745 | @code{property} XML element, where the @var{ANNOTATION} belongs to. | |
746 | ||
747 | An attribute value can be retrieved by | |
748 | @code{dbus-introspect-get-attribute}. Example: | |
749 | ||
750 | @lisp | |
751 | (dbus-introspect-get-annotation | |
752 | :session "de.berlios.Pinot" "/de/berlios/Pinot" | |
753 | "de.berlios.Pinot" "GetStatistics" | |
754 | "de.berlios.Pinot.GetStatistics") | |
755 | ||
756 | @result{} (annotation ((name . "de.berlios.Pinot.GetStatistics") | |
757 | (value . "pinotDBus"))) | |
758 | ||
759 | (dbus-introspect-get-attribute | |
760 | (dbus-introspect-get-annotation | |
761 | :session "de.berlios.Pinot" "/de/berlios/Pinot" | |
762 | "de.berlios.Pinot" "GetStatistics" | |
763 | "de.berlios.Pinot.GetStatistics") | |
764 | "value") | |
765 | ||
766 | @result{} "pinotDBus" | |
767 | @end lisp | |
768 | @end defun | |
769 | ||
770 | ||
771 | @node Arguments and Signatures | |
772 | @section The final details. | |
773 | ||
774 | Methods and signals have arguments. They are described in the | |
775 | @code{arg} XML elements. | |
776 | ||
777 | @defun dbus-introspect-get-argument-names bus service path interface name | |
778 | Return a list of all argument names as list of strings. @var{name} | |
779 | must be a @code{method} or @code{signal} XML element. Example: | |
780 | ||
781 | @lisp | |
782 | (dbus-introspect-get-argument-names | |
783 | :session "org.freedesktop.xesam.searcher" | |
784 | "/org/freedesktop/xesam/searcher/main" | |
785 | "org.freedesktop.xesam.Search" "GetHitData") | |
786 | ||
787 | @result{} ("search" "hit_ids" "fields" "hit_data") | |
788 | @end lisp | |
789 | ||
790 | Argument names are optional; the function can return @code{nil} | |
791 | therefore, even if the method or signal has arguments. | |
792 | @end defun | |
793 | ||
794 | @defun dbus-introspect-get-argument bus service path interface name arg | |
795 | Return argument @var{ARG} as XML object. @var{name} | |
796 | must be a @code{method} or @code{signal} XML element. Example: | |
797 | ||
798 | @lisp | |
799 | (dbus-introspect-get-argument | |
800 | :session "org.freedesktop.xesam.searcher" | |
801 | "/org/freedesktop/xesam/searcher/main" | |
802 | "org.freedesktop.xesam.Search" "GetHitData" "search") | |
803 | ||
804 | @result{} (arg ((name . "search") (type . "s") (direction . "in"))) | |
805 | @end lisp | |
806 | @end defun | |
807 | ||
808 | @defun dbus-introspect-get-signature bus service path interface name &optional direction | |
809 | Return signature of a @code{method} or @code{signal}, represented by | |
810 | @var{name}, as string. | |
811 | ||
812 | If @var{name} is a @code{method}, @var{direction} can be either | |
813 | @samp{in} or @samp{out}. If @var{direction} is @code{nil}, @samp{in} | |
814 | is assumed. | |
815 | ||
816 | If @var{name} is a @code{signal}, and @var{direction} is | |
817 | non-@code{nil}, @var{direction} must be @samp{out}. Example: | |
818 | ||
819 | @lisp | |
820 | (dbus-introspect-get-signature | |
821 | :session "org.freedesktop.xesam.searcher" | |
822 | "/org/freedesktop/xesam/searcher/main" | |
823 | "org.freedesktop.xesam.Search" "GetHitData" "in") | |
824 | ||
825 | @result{} "sauas" | |
826 | ||
827 | (dbus-introspect-get-signature | |
828 | :session "org.freedesktop.xesam.searcher" | |
829 | "/org/freedesktop/xesam/searcher/main" | |
830 | "org.freedesktop.xesam.Search" "HitsAdded") | |
831 | ||
21956b56 | 832 | @result{} "su" |
cd71b9ae MA |
833 | @end lisp |
834 | @end defun | |
835 | ||
22d8ac3a MA |
836 | |
837 | @node Type Conversion | |
838 | @chapter Mapping Lisp types and D-Bus types. | |
839 | @cindex type conversion | |
840 | ||
841 | D-Bus method calls and signals accept usually several arguments as | |
842 | parameters, either as input parameter, or as output parameter. Every | |
843 | argument belongs to a D-Bus type. | |
844 | ||
6a31c819 | 845 | Such arguments must be mapped between the value encoded as a D-Bus |
22d8ac3a MA |
846 | type, and the corresponding type of Lisp objects. The mapping is |
847 | applied Lisp object @expansion{} D-Bus type for input parameters, and | |
848 | D-Bus type @expansion{} Lisp object for output parameters. | |
849 | ||
850 | ||
851 | @section Input parameters. | |
852 | ||
853 | Input parameters for D-Bus methods and signals occur as arguments of a | |
6a31c819 | 854 | Lisp function call. The following mapping to D-Bus types is |
22d8ac3a MA |
855 | applied, when the corresponding D-Bus message is created: |
856 | ||
857 | @example | |
858 | @multitable {@code{t} and @code{nil}} {@expansion{}} {DBUS_TYPE_BOOLEAN} | |
859 | @item Lisp type @tab @tab D-Bus type | |
860 | @item | |
861 | @item @code{t} and @code{nil} @tab @expansion{} @tab DBUS_TYPE_BOOLEAN | |
862 | @item number @tab @expansion{} @tab DBUS_TYPE_UINT32 | |
863 | @item integer @tab @expansion{} @tab DBUS_TYPE_INT32 | |
864 | @item float @tab @expansion{} @tab DBUS_TYPE_DOUBLE | |
865 | @item string @tab @expansion{} @tab DBUS_TYPE_STRING | |
6a31c819 | 866 | @item list @tab @expansion{} @tab DBUS_TYPE_ARRAY |
22d8ac3a MA |
867 | @end multitable |
868 | @end example | |
869 | ||
6a31c819 MA |
870 | Other Lisp objects, like symbols or hash tables, are not accepted as |
871 | input parameter. | |
872 | ||
873 | If it is necessary to use another D-Bus type, a corresponding type | |
874 | symbol can be preceeded to the corresponding Lisp object. Basic D-Bus | |
d4e67bc5 MA |
875 | types are represented by the type symbols @code{:byte}, |
876 | @code{:boolean}, @code{:int16}, @code{:uint16}, @code{:int32}, | |
877 | @code{:uint32}, @code{:int64}, @code{:uint64}, @code{:double}, | |
878 | @code{:string}, @code{:object-path} and @code{:signature}. | |
6a31c819 | 879 | |
22d8ac3a | 880 | @noindent |
6a31c819 MA |
881 | Example: |
882 | ||
883 | @lisp | |
c9ecb5a7 | 884 | (dbus-call-method @dots{} @var{NUMBER} @var{STRING}) |
6a31c819 MA |
885 | @end lisp |
886 | ||
887 | is equivalent to | |
888 | ||
889 | @lisp | |
c9ecb5a7 | 890 | (dbus-call-method @dots{} :uint32 @var{NUMBER} :string @var{STRING}) |
6a31c819 MA |
891 | @end lisp |
892 | ||
893 | but different to | |
894 | ||
895 | @lisp | |
c9ecb5a7 | 896 | (dbus-call-method @dots{} :int32 @var{NUMBER} :signature @var{STRING}) |
6a31c819 MA |
897 | @end lisp |
898 | ||
4db2806c MA |
899 | The value for a byte D-Bus type can be any integer in the range 0 |
900 | through 255. If a character is used as argument, modifiers | |
901 | represented outside this range are stripped of. For example, | |
902 | @code{:byte ?x} is equal to @code{:byte ?\M-x}, but it is not equal to | |
903 | @code{:byte ?\C-x} or @code{:byte ?\M-\C-x}. | |
c9ecb5a7 | 904 | |
4db2806c MA |
905 | A D-Bus compound type is always represented as a list. The @sc{car} |
906 | of this list can be the type symbol @code{:array}, @code{:variant}, | |
d4e67bc5 MA |
907 | @code{:struct} or @code{:dict-entry}, which would result in a |
908 | corresponding D-Bus container. @code{:array} is optional, because | |
4db2806c | 909 | this is the default compound D-Bus type for a list. |
6a31c819 MA |
910 | |
911 | The objects being elements of the list are checked according to the | |
912 | D-Bus compound type rules. | |
913 | ||
914 | @itemize | |
4db2806c MA |
915 | @item An array must contain only elements of the same D-Bus type. It |
916 | can be empty. | |
917 | ||
6a31c819 | 918 | @item A variant must contain only one single element. |
4db2806c | 919 | |
6a31c819 | 920 | @item A dictionary entry must be element of an array, and it must |
4db2806c MA |
921 | contain only a key-value pair of two elements, with a basic D-Bus type |
922 | key. | |
923 | ||
6a31c819 MA |
924 | @item There is no restriction for structs. |
925 | @end itemize | |
926 | ||
4db2806c MA |
927 | If an empty array needs an element D-Bus type other than string, it |
928 | can contain exactly one element of D-Bus type @code{:signature}. The | |
929 | value of this element (a string) is used as the signature of the | |
930 | elements of this array. Example: | |
6a31c819 MA |
931 | |
932 | @lisp | |
4db2806c MA |
933 | (dbus-call-method |
934 | :session "org.freedesktop.Notifications" | |
935 | "/org/freedesktop/Notifications" | |
936 | "org.freedesktop.Notifications" "Notify" | |
937 | "GNU Emacs" ;; Application name. | |
938 | 0 ;; No replacement of other notifications. | |
939 | "" ;; No icon. | |
940 | "Notification summary" ;; Summary. | |
941 | (format ;; Body. | |
942 | "This is a test notification, raised from %s" (emacs-version)) | |
943 | '(:array) ;; No actions (empty array of strings). | |
944 | '(:array :signature "@{sv@}") ;; No hints | |
945 | ;; (empty array of dictionary entries). | |
946 | ':int32 -1) ;; Default timeout. | |
947 | ||
948 | @result{} 3 | |
6a31c819 | 949 | @end lisp |
22d8ac3a | 950 | |
ace706d1 MA |
951 | @defun dbus-string-to-byte-array string |
952 | Sometimes, D-Bus methods require as input parameter an array of bytes, | |
953 | instead of a string. If it is guaranteed, that @var{string} is an | |
954 | UTF8 string, this function performs the conversion. Example: | |
955 | ||
956 | @lisp | |
957 | (dbus-string-to-byte-array "/etc/hosts") | |
958 | ||
959 | @result{} (:array :byte 47 :byte 101 :byte 116 :byte 99 :byte 47 | |
960 | :byte 104 :byte 111 :byte 115 :byte 116 :byte 115) | |
961 | @end lisp | |
962 | @end defun | |
963 | ||
964 | @defun dbus-escape-as-identifier string | |
965 | Escape an arbitrary @var{string} so it follows the rules for a C | |
966 | identifier. The escaped string can be used as object path component, | |
967 | interface element component, bus name component or member name in | |
968 | D-Bus. | |
969 | ||
970 | The escaping consists of replacing all non-alphanumerics, and the | |
971 | first character if it's a digit, with an underscore and two | |
972 | lower-case hex digits. As a special case, "" is escaped to | |
973 | "_". Example: | |
974 | ||
975 | @lisp | |
976 | (dbus-escape-as-identifier "0123abc_xyz\x01\xff") | |
977 | ||
978 | @result{} "_30123abc_5fxyz_01_ff" | |
979 | @end lisp | |
980 | @end defun | |
981 | ||
22d8ac3a MA |
982 | |
983 | @section Output parameters. | |
984 | ||
985 | Output parameters of D-Bus methods and signals are mapped to Lisp | |
6a31c819 | 986 | objects. |
22d8ac3a MA |
987 | |
988 | @example | |
989 | @multitable {DBUS_TYPE_OBJECT_PATH} {@expansion{}} {@code{t} or @code{nil}} | |
990 | @item D-Bus type @tab @tab Lisp type | |
991 | @item | |
992 | @item DBUS_TYPE_BOOLEAN @tab @expansion{} @tab @code{t} or @code{nil} | |
d4e67bc5 | 993 | @item DBUS_TYPE_BYTE @tab @expansion{} @tab number |
6a31c819 | 994 | @item DBUS_TYPE_UINT16 @tab @expansion{} @tab number |
d4e67bc5 MA |
995 | @item DBUS_TYPE_INT16 @tab @expansion{} @tab number |
996 | @item DBUS_TYPE_UINT32 @tab @expansion{} @tab number or float | |
997 | @item DBUS_TYPE_INT32 @tab @expansion{} @tab number or float | |
998 | @item DBUS_TYPE_UINT64 @tab @expansion{} @tab number or float | |
999 | @item DBUS_TYPE_INT64 @tab @expansion{} @tab number or float | |
22d8ac3a MA |
1000 | @item DBUS_TYPE_DOUBLE @tab @expansion{} @tab float |
1001 | @item DBUS_TYPE_STRING @tab @expansion{} @tab string | |
1002 | @item DBUS_TYPE_OBJECT_PATH @tab @expansion{} @tab string | |
6a31c819 | 1003 | @item DBUS_TYPE_SIGNATURE @tab @expansion{} @tab string |
22d8ac3a MA |
1004 | @item DBUS_TYPE_ARRAY @tab @expansion{} @tab list |
1005 | @item DBUS_TYPE_VARIANT @tab @expansion{} @tab list | |
1006 | @item DBUS_TYPE_STRUCT @tab @expansion{} @tab list | |
1007 | @item DBUS_TYPE_DICT_ENTRY @tab @expansion{} @tab list | |
1008 | @end multitable | |
1009 | @end example | |
1010 | ||
d4e67bc5 MA |
1011 | A float object in case of @code{DBUS_TYPE_UINT32}, |
1012 | @code{DBUS_TYPE_INT32}, @code{DBUS_TYPE_UINT64} and | |
1013 | @code{DBUS_TYPE_INT6432} is returned, when the C value exceeds the | |
1014 | Emacs number size range. | |
1015 | ||
22d8ac3a MA |
1016 | The resulting list of the last 4 D-Bus compound types contains as |
1017 | elements the elements of the D-Bus container, mapped according to the | |
1018 | same rules. | |
1019 | ||
1020 | The signal @code{PropertyModified}, discussed as example in | |
1021 | @ref{Inspection}, would offer as Lisp data the following object | |
1022 | (@var{BOOL} stands here for either @code{nil} or @code{t}): | |
1023 | ||
1024 | @lisp | |
c9ecb5a7 | 1025 | (@var{NUMBER} ((@var{STRING} @var{BOOL} @var{BOOL}) (@var{STRING} @var{BOOL} @var{BOOL}) @dots{})) |
22d8ac3a MA |
1026 | @end lisp |
1027 | ||
ace706d1 MA |
1028 | @defun dbus-byte-array-to-string byte-array |
1029 | If a D-Bus method or signal returns an array of bytes, which are known | |
1030 | to represent an UTF8 string, this function converts @var{byte-array} | |
1031 | to the corresponding string. Example: | |
1032 | ||
1033 | @lisp | |
1034 | (dbus-byte-array-to-string '(47 101 116 99 47 104 111 115 116 115)) | |
1035 | ||
1036 | @result{} "/etc/hosts" | |
1037 | @end lisp | |
1038 | @end defun | |
1039 | ||
1040 | @defun dbus-unescape-from-identifier string | |
1041 | Retrieve the original string from the encoded @var{string}. | |
1042 | @var{string} must have been coded with | |
1043 | @code{dbus-escape-as-identifier}. Example: | |
1044 | ||
1045 | @lisp | |
1046 | (dbus-unescape-from-identifier "_30123abc_5fxyz_01_ff") | |
1047 | ||
1048 | @result{} "0123abc_xyz\ 1ÿ" | |
1049 | @end lisp | |
1050 | @end defun | |
1051 | ||
22d8ac3a MA |
1052 | |
1053 | @node Synchronous Methods | |
1054 | @chapter Calling methods in a blocking way. | |
1055 | @cindex method calls, synchronous | |
1056 | @cindex synchronous method calls | |
1057 | ||
1058 | Methods can be called synchronously (@dfn{blocking}) or asynchronously | |
21956b56 | 1059 | (@dfn{non-blocking}). |
22d8ac3a MA |
1060 | |
1061 | At D-Bus level, a method call consist of two messages: one message | |
1062 | which carries the input parameters to the object owning the method to | |
1063 | be called, and a reply message returning the resulting output | |
1064 | parameters from the object. | |
1065 | ||
134ce16c | 1066 | @defun dbus-call-method bus service path interface method &optional :timeout timeout &rest args |
22d8ac3a MA |
1067 | This function calls @var{method} on the D-Bus @var{bus}. @var{bus} is |
1068 | either the symbol @code{:system} or the symbol @code{:session}. | |
1069 | ||
1070 | @var{service} is the D-Bus service name to be used. @var{path} is the | |
1071 | D-Bus object path, @var{service} is registered at. @var{interface} is | |
1072 | an interface offered by @var{service}. It must provide @var{method}. | |
1073 | ||
134ce16c | 1074 | If the parameter @code{:timeout} is given, the following integer |
21956b56 | 1075 | @var{timeout} specifies the maximum number of milliseconds the method |
134ce16c MA |
1076 | call must return. The default value is 25.000. If the method call |
1077 | doesn't return in time, a D-Bus error is raised (@pxref{Errors and | |
1078 | Events}). | |
1079 | ||
22d8ac3a MA |
1080 | All other arguments args are passed to @var{method} as arguments. |
1081 | They are converted into D-Bus types as described in @ref{Type | |
1082 | Conversion}. | |
1083 | ||
1084 | The function returns the resulting values of @var{method} as a list of | |
1085 | Lisp objects, according to the type conversion rules described in | |
1086 | @ref{Type Conversion}. Example: | |
1087 | ||
06c0751a | 1088 | @lisp |
22d8ac3a | 1089 | (dbus-call-method |
0ce574ef MA |
1090 | :session "org.gnome.seahorse" "/org/gnome/seahorse/keys/openpgp" |
1091 | "org.gnome.seahorse.Keys" "GetKeyField" | |
22d8ac3a MA |
1092 | "openpgp:657984B8C7A966DD" "simple-name") |
1093 | ||
1094 | @result{} (t ("Philip R. Zimmermann")) | |
06c0751a | 1095 | @end lisp |
22d8ac3a MA |
1096 | |
1097 | If the result of the method call is just one value, the converted Lisp | |
1098 | object is returned instead of a list containing this single Lisp | |
1099 | object. Example: | |
1100 | ||
06c0751a | 1101 | @lisp |
22d8ac3a | 1102 | (dbus-call-method |
0ce574ef MA |
1103 | :system "org.freedesktop.Hal" |
1104 | "/org/freedesktop/Hal/devices/computer" | |
1105 | "org.freedesktop.Hal.Device" "GetPropertyString" | |
22d8ac3a MA |
1106 | "system.kernel.machine") |
1107 | ||
1108 | @result{} "i686" | |
06c0751a | 1109 | @end lisp |
22d8ac3a MA |
1110 | |
1111 | With the @code{dbus-introspect} function it is possible to explore the | |
1112 | interfaces of @samp{org.freedesktop.Hal} service. It offers the | |
1113 | interfaces @samp{org.freedesktop.Hal.Manager} for the object at the | |
1114 | path @samp{/org/freedesktop/Hal/Manager} as well as the interface | |
1115 | @samp{org.freedesktop.Hal.Device} for all objects prefixed with the | |
1116 | path @samp{/org/freedesktop/Hal/devices}. With the methods | |
1117 | @samp{GetAllDevices} and @samp{GetAllProperties}, it is simple to | |
1118 | emulate the @code{lshal} command on GNU/Linux systems: | |
1119 | ||
06c0751a | 1120 | @lisp |
22d8ac3a MA |
1121 | (dolist (device |
1122 | (dbus-call-method | |
0ce574ef | 1123 | :system "org.freedesktop.Hal" |
22d8ac3a | 1124 | "/org/freedesktop/Hal/Manager" |
0ce574ef | 1125 | "org.freedesktop.Hal.Manager" "GetAllDevices")) |
22d8ac3a MA |
1126 | (message "\nudi = %s" device) |
1127 | (dolist (properties | |
1128 | (dbus-call-method | |
0ce574ef MA |
1129 | :system "org.freedesktop.Hal" device |
1130 | "org.freedesktop.Hal.Device" "GetAllProperties")) | |
22d8ac3a MA |
1131 | (message " %s = %S" |
1132 | (car properties) (or (caar (cdr properties)) "")))) | |
1133 | ||
7b13a0f2 | 1134 | @print{} "udi = /org/freedesktop/Hal/devices/computer |
d9e21158 MA |
1135 | info.addons = (\"hald-addon-acpi\") |
1136 | info.bus = \"unknown\" | |
1137 | info.product = \"Computer\" | |
1138 | info.subsystem = \"unknown\" | |
1139 | info.udi = \"/org/freedesktop/Hal/devices/computer\" | |
1140 | linux.sysfs_path_device = \"(none)\" | |
1141 | power_management.acpi.linux.version = \"20051216\" | |
1142 | power_management.can_suspend_to_disk = t | |
1143 | power_management.can_suspend_to_ram = \"\" | |
1144 | power_management.type = \"acpi\" | |
1145 | smbios.bios.release_date = \"11/07/2001\" | |
1146 | system.chassis.manufacturer = \"COMPAL\" | |
1147 | system.chassis.type = \"Notebook\" | |
1148 | system.firmware.release_date = \"03/19/2005\" | |
c9ecb5a7 | 1149 | @dots{}" |
06c0751a | 1150 | @end lisp |
22d8ac3a MA |
1151 | @end defun |
1152 | ||
21956b56 MA |
1153 | @defun dbus-call-method-non-blocking bus service path interface method &optional :timeout timeout &rest args |
1154 | Call @var{method} on the D-Bus @var{bus}, but don't block the event queue. | |
1155 | This is necessary for communicating to registered D-Bus methods, | |
1156 | which are running in the same Emacs process. | |
1157 | ||
1158 | The arguments are the same as in @code{dbus-call-method}. Example: | |
1159 | ||
1160 | @lisp | |
1161 | (dbus-call-method-non-blocking | |
1162 | :system "org.freedesktop.Hal" | |
1163 | "/org/freedesktop/Hal/devices/computer" | |
1164 | "org.freedesktop.Hal.Device" "GetPropertyString" | |
1165 | "system.kernel.machine") | |
1166 | ||
1167 | @result{} "i686" | |
1168 | @end lisp | |
1169 | @end defun | |
1170 | ||
1171 | ||
1172 | @node Asynchronous Methods | |
1173 | @chapter Calling methods non-blocking. | |
1174 | @cindex method calls, asynchronous | |
1175 | @cindex asynchronous method calls | |
1176 | ||
1177 | @defun dbus-call-method-asynchronously bus service path interface method handler &optional :timeout timeout &rest args | |
1178 | This function calls @var{method} on the D-Bus @var{bus} | |
1179 | asynchronously. @var{bus} is either the symbol @code{:system} or the | |
1180 | symbol @code{:session}. | |
1181 | ||
1182 | @var{service} is the D-Bus service name to be used. @var{path} is the | |
1183 | D-Bus object path, @var{service} is registered at. @var{interface} is | |
1184 | an interface offered by @var{service}. It must provide @var{method}. | |
1185 | ||
1186 | @var{handler} is a Lisp function, which is called when the | |
1187 | corresponding return message has arrived. | |
1188 | ||
1189 | If the parameter @code{:timeout} is given, the following integer | |
1190 | @var{timeout} specifies the maximum number of milliseconds a reply | |
1191 | message must arrive. The default value is 25.000. If there is no | |
1192 | reply message in time, a D-Bus error is raised (@pxref{Errors and | |
1193 | Events}). | |
1194 | ||
1195 | All other arguments args are passed to @var{method} as arguments. | |
1196 | They are converted into D-Bus types as described in @ref{Type | |
1197 | Conversion}. | |
1198 | ||
1199 | The function returns a key into the hash table | |
1200 | @code{dbus-registered-functions-table}. The corresponding entry in | |
1201 | the hash table is removed, when the return message has been arrived, | |
1202 | and @var{handler} is called. Example: | |
1203 | ||
1204 | @lisp | |
1205 | (dbus-call-method-asynchronously | |
1206 | :system "org.freedesktop.Hal" | |
1207 | "/org/freedesktop/Hal/devices/computer" | |
1208 | "org.freedesktop.Hal.Device" "GetPropertyString" 'message | |
1209 | "system.kernel.machine") | |
1210 | ||
1211 | @result{} (:system 2) | |
1212 | ||
1213 | @print{} i686 | |
1214 | @end lisp | |
1215 | @end defun | |
1216 | ||
22d8ac3a | 1217 | |
addb7f2e MA |
1218 | @node Receiving Method Calls |
1219 | @chapter Offering own methods. | |
1220 | @cindex method calls, returning | |
1221 | @cindex returning method calls | |
1222 | ||
1223 | Emacs can also offer own methods, which can be called by other | |
1224 | applications. These methods could be an implementation of an | |
cd71b9ae | 1225 | interface of a well known service, like @samp{org.freedesktop.TextEditor}. |
addb7f2e MA |
1226 | |
1227 | It could be also an implementation of an own interface. In this case, | |
cd71b9ae MA |
1228 | the service name must be @samp{org.gnu.Emacs}. The object path shall |
1229 | begin with @samp{/org/gnu/Emacs/@strong{Application}/}, and the | |
addb7f2e | 1230 | interface name shall be @code{org.gnu.Emacs.@strong{Application}}. |
cd71b9ae | 1231 | @samp{@strong{Application}} is the name of the application which |
addb7f2e MA |
1232 | provides the interface. |
1233 | ||
ace706d1 MA |
1234 | @deffn Constant dbus-service-emacs |
1235 | The well known service name of Emacs. | |
1236 | @end deffn | |
1237 | ||
1238 | @deffn Constant dbus-path-emacs | |
1239 | The object path head "/org/gnu/Emacs" used by Emacs. All object | |
1240 | paths, used by offered methods or signals, shall start with this | |
1241 | string. | |
1242 | @end deffn | |
1243 | ||
addb7f2e MA |
1244 | @defun dbus-register-method bus service path interface method handler |
1245 | With this function, an application registers @var{method} on the D-Bus | |
1246 | @var{bus}. | |
1247 | ||
1248 | @var{bus} is either the symbol @code{:system} or the symbol | |
1249 | @code{:session}. | |
1250 | ||
1251 | @var{service} is the D-Bus service name of the D-Bus object | |
1252 | @var{method} is registered for. It must be a known name. | |
1253 | ||
1254 | @var{path} is the D-Bus object path @var{service} is | |
1255 | registered. | |
1256 | ||
1257 | @var{interface} is the interface offered by @var{service}. It must | |
1258 | provide @var{method}. | |
1259 | ||
ac134f2f RS |
1260 | @var{handler} is a Lisp function to be called when a @var{method} call |
1261 | is received. It must accept as arguments the input arguments of | |
1262 | @var{method}. @var{handler} should return a list, whose elements are | |
1263 | to be used as arguments for the reply message of @var{method}. This | |
1264 | list can be composed like the input parameters in @ref{Type | |
1265 | Conversion}. | |
1266 | ||
1267 | If @var{handler} wants to return just one Lisp object and it is not a | |
1268 | cons cell, @var{handler} can return this object directly, instead of | |
1269 | returning a list containing the object. | |
addb7f2e | 1270 | |
4a7c4c40 | 1271 | The default D-Bus timeout when waiting for a message reply is 25 |
134ce16c MA |
1272 | seconds. This value could be even smaller, depending on the calling |
1273 | client. Therefore, @var{handler} shall not last longer than | |
4a7c4c40 MA |
1274 | absolutely necessary. |
1275 | ||
9b7993b4 | 1276 | @code{dbus-register-method} returns a Lisp object, which can be used |
addb7f2e MA |
1277 | as argument in @code{dbus-unregister-object} for removing the |
1278 | registration for @var{method}. Example: | |
1279 | ||
06c0751a | 1280 | @lisp |
addb7f2e MA |
1281 | (defun my-dbus-method-handler (filename) |
1282 | (let (result) | |
1283 | (if (find-file filename) | |
1284 | (setq result '(:boolean t)) | |
1285 | (setq result '(:boolean nil))) | |
1286 | result)) | |
1287 | ||
1288 | @result{} my-dbus-method-handler | |
1289 | ||
1290 | (dbus-register-method | |
1291 | :session "org.freedesktop.TextEditor" "/org/freedesktop/TextEditor" | |
1292 | "org.freedesktop.TextEditor" "OpenFile" | |
1293 | 'my-dbus-method-handler) | |
1294 | ||
eb932e8a | 1295 | @result{} ((:session "org.freedesktop.TextEditor" "OpenFile") |
addb7f2e | 1296 | ("org.freedesktop.TextEditor" "/org/freedesktop/TextEditor" |
eb932e8a | 1297 | my-dbus-method-handler)) |
06c0751a | 1298 | @end lisp |
addb7f2e | 1299 | |
cd71b9ae | 1300 | If you invoke the method @samp{org.freedesktop.TextEditor.OpenFile} |
addb7f2e MA |
1301 | from another D-Bus application with a filename as parameter, the file |
1302 | is opened in Emacs, and the method returns either @var{true} or | |
1303 | @var{false}, indicating the success if the method. As test tool one | |
1304 | could use the command line tool @code{dbus-send} in a shell: | |
1305 | ||
1306 | @example | |
1307 | # dbus-send --session --print-reply \ | |
1308 | --dest="org.freedesktop.TextEditor" \ | |
1309 | "/org/freedesktop/TextEditor" \ | |
1310 | "org.freedesktop.TextEditor.OpenFile" string:"/etc/hosts" | |
1311 | ||
1312 | @print{} method return sender=:1.22 -> dest=:1.23 reply_serial=2 | |
eb932e8a MA |
1313 | boolean true |
1314 | @end example | |
1315 | ||
1316 | You can indicate an error by raising the Emacs signal | |
1317 | @code{dbus-error}. The handler above could be changed like this: | |
1318 | ||
1319 | @lisp | |
1320 | (defun my-dbus-method-handler (&rest args) | |
1321 | (unless (and (= (length args) 1) (stringp (car args))) | |
1322 | (signal 'dbus-error (list (format "Wrong argument list: %S" args)))) | |
1323 | (condition-case err | |
1324 | (find-file (car args)) | |
1325 | (error (signal 'dbus-error (cdr err)))) | |
1326 | t) | |
1327 | ||
1328 | @result{} my-dbus-method-handler | |
1329 | @end lisp | |
1330 | ||
1331 | The test runs then | |
1332 | ||
1333 | @example | |
1334 | # dbus-send --session --print-reply \ | |
1335 | --dest="org.freedesktop.TextEditor" \ | |
1336 | "/org/freedesktop/TextEditor" \ | |
1337 | "org.freedesktop.TextEditor.OpenFile" \ | |
1338 | string:"/etc/hosts" string:"/etc/passwd" | |
1339 | ||
1340 | @print{} Error org.freedesktop.DBus.Error.Failed: | |
1341 | Wrong argument list: ("/etc/hosts" "/etc/passwd") | |
addb7f2e MA |
1342 | @end example |
1343 | @end defun | |
1344 | ||
1345 | ||
22d8ac3a MA |
1346 | @node Signals |
1347 | @chapter Sending and receiving signals. | |
1348 | @cindex signals | |
1349 | ||
1350 | Signals are broadcast messages. They carry input parameters, which | |
1351 | are received by all objects which have registered for such a signal. | |
1352 | ||
0ce574ef | 1353 | @defun dbus-send-signal bus service path interface signal &rest args |
22d8ac3a MA |
1354 | This function is similar to @code{dbus-call-method}. The difference |
1355 | is, that there are no returning output parameters. | |
1356 | ||
1357 | The function emits @var{signal} on the D-Bus @var{bus}. @var{bus} is | |
1358 | either the symbol @code{:system} or the symbol @code{:session}. It | |
1359 | doesn't matter whether another object has registered for @var{signal}. | |
1360 | ||
1361 | @var{service} is the D-Bus service name of the object the signal is | |
1362 | emitted from. @var{path} is the corresponding D-Bus object path, | |
1363 | @var{service} is registered at. @var{interface} is an interface | |
1364 | offered by @var{service}. It must provide @var{signal}. | |
1365 | ||
1366 | All other arguments args are passed to @var{signal} as arguments. | |
1367 | They are converted into D-Bus types as described in @ref{Type | |
1368 | Conversion}. Example: | |
1369 | ||
06c0751a | 1370 | @lisp |
22d8ac3a | 1371 | (dbus-send-signal |
ace706d1 MA |
1372 | :session dbus-service-emacs dbus-path-emacs |
1373 | (concat dbus-service-emacs ".FileManager") "FileModified" | |
1374 | "/home/albinus/.emacs") | |
06c0751a | 1375 | @end lisp |
22d8ac3a MA |
1376 | @end defun |
1377 | ||
9b7993b4 | 1378 | @defun dbus-register-signal bus service path interface signal handler &rest args |
22d8ac3a MA |
1379 | With this function, an application registers for @var{signal} on the |
1380 | D-Bus @var{bus}. | |
1381 | ||
1382 | @var{bus} is either the symbol @code{:system} or the symbol | |
1383 | @code{:session}. | |
1384 | ||
a4397af9 MA |
1385 | @var{service} is the D-Bus service name used by the sending D-Bus |
1386 | object. It can be either a known name or the unique name of the D-Bus | |
1387 | object sending the signal. In case of a unique name, signals won't be | |
1388 | received any longer once the object owning this unique name has | |
1389 | disappeared, and a new queued object has replaced it. | |
1390 | ||
1391 | When @var{service} is @code{nil}, related signals from all D-Bus | |
1392 | objects shall be accepted. | |
1393 | ||
1394 | @var{path} is the corresponding D-Bus object path, @var{service} is | |
1395 | registered at. It can also be @code{nil} if the path name of incoming | |
1396 | signals shall not be checked. | |
1397 | ||
1398 | @var{interface} is an interface offered by @var{service}. It must | |
1399 | provide @var{signal}. | |
22d8ac3a MA |
1400 | |
1401 | @var{handler} is a Lisp function to be called when the @var{signal} is | |
1402 | received. It must accept as arguments the output parameters | |
9b7993b4 MA |
1403 | @var{signal} is sending. |
1404 | ||
1405 | All other arguments @var{args}, if specified, must be strings. They | |
1406 | stand for the respective arguments of @var{signal} in their order, and | |
1407 | are used for filtering as well. A @code{nil} argument might be used | |
1408 | to preserve the order. | |
1409 | ||
1410 | @code{dbus-register-signal} returns a Lisp object, which can be used | |
1411 | as argument in @code{dbus-unregister-object} for removing the | |
1412 | registration for @var{signal}. Example: | |
22d8ac3a | 1413 | |
06c0751a | 1414 | @lisp |
22d8ac3a MA |
1415 | (defun my-dbus-signal-handler (device) |
1416 | (message "Device %s added" device)) | |
1417 | ||
0ce574ef MA |
1418 | @result{} my-dbus-signal-handler |
1419 | ||
22d8ac3a | 1420 | (dbus-register-signal |
0ce574ef MA |
1421 | :system "org.freedesktop.Hal" "/org/freedesktop/Hal/Manager" |
1422 | "org.freedesktop.Hal.Manager" "DeviceAdded" | |
22d8ac3a MA |
1423 | 'my-dbus-signal-handler) |
1424 | ||
cd71c3ef MA |
1425 | @result{} ((:system "org.freedesktop.Hal.Manager" "DeviceAdded") |
1426 | ("org.freedesktop.Hal" "/org/freedesktop/Hal/Manager" | |
1427 | my-signal-handler)) | |
06c0751a | 1428 | @end lisp |
22d8ac3a | 1429 | |
cd71b9ae MA |
1430 | As we know from the introspection data of interface |
1431 | @samp{org.freedesktop.Hal.Manager}, the signal @samp{DeviceAdded} | |
22d8ac3a MA |
1432 | provides one single parameter, which is mapped into a Lisp string. |
1433 | The callback function @code{my-dbus-signal-handler} must define one | |
1434 | single string argument therefore. Plugging an USB device to your | |
cd71b9ae | 1435 | machine, when registered for signal @samp{DeviceAdded}, will show you |
22d8ac3a | 1436 | which objects the GNU/Linux @code{hal} daemon adds. |
22d8ac3a MA |
1437 | @end defun |
1438 | ||
c9ecb5a7 | 1439 | @defun dbus-unregister-object object |
867d4bb3 | 1440 | Unregister @var{object} from the D-Bus. @var{object} must be the |
c9ecb5a7 MA |
1441 | result of a preceding @code{dbus-register-signal} or |
1442 | @code{dbus-register-method} call. It returns @code{t} if @var{object} | |
1443 | has been unregistered, @code{nil} otherwise. | |
22d8ac3a MA |
1444 | @end defun |
1445 | ||
1446 | ||
1447 | @node Errors and Events | |
1448 | @chapter Errors and events. | |
1449 | @cindex errors | |
1450 | @cindex events | |
1451 | ||
21956b56 MA |
1452 | Input parameters of @code{dbus-call-method}, |
1453 | @code{dbus-call-method-non-blocking}, | |
1454 | @code{dbus-call-method-asynchronously}, and | |
6a31c819 MA |
1455 | @code{dbus-register-signal} are checked for correct D-Bus types. If |
1456 | there is a type mismatch, the Lisp error @code{wrong-type-argument} | |
1457 | @code{D-Bus ARG} is raised. | |
1458 | ||
22d8ac3a | 1459 | All errors raised by D-Bus are signaled with the error symbol |
d2e4a6c9 MA |
1460 | @code{dbus-error}. If possible, error messages from D-Bus are |
1461 | appended to the @code{dbus-error}. | |
1462 | ||
1463 | @defspec dbus-ignore-errors forms@dots{} | |
1464 | This executes @var{forms} exactly like a @code{progn}, except that | |
1465 | @code{dbus-error} errors are ignored during the @var{forms}. These | |
1466 | errors can be made visible when variable @code{dbus-debug} is set to | |
1467 | @code{t}. | |
1468 | @end defspec | |
22d8ac3a | 1469 | |
a4397af9 | 1470 | Incoming D-Bus messages are handled as Emacs events (see @pxref{Misc |
22d8ac3a MA |
1471 | Events, , , elisp}). The generated event has this form: |
1472 | ||
06c0751a | 1473 | @lisp |
21956b56 MA |
1474 | (dbus-event @var{bus} @var{type} @var{serial} @var{service} @var{path} @var{interface} @var{member} @var{handler} |
1475 | &rest @var{args}) | |
06c0751a | 1476 | @end lisp |
22d8ac3a | 1477 | |
21956b56 | 1478 | @var{bus} identifies the D-Bus the message is coming from. It is |
a4397af9 | 1479 | either the symbol @code{:system} or the symbol @code{:session}. |
22d8ac3a | 1480 | |
21956b56 MA |
1481 | @var{type} is the D-Bus message type which has caused the event. It |
1482 | can be @code{dbus-message-type-invalid}, | |
1483 | @code{dbus-message-type-method-call}, | |
1484 | @code{dbus-message-type-method-return}, | |
1485 | @code{dbus-message-type-error}, or @code{dbus-message-type-signal}. | |
1486 | @var{serial} is the serial number of the received D-Bus message. | |
addb7f2e | 1487 | |
22d8ac3a | 1488 | @var{service} and @var{path} are the unique name and the object path |
addb7f2e MA |
1489 | of the D-Bus object emitting the message. @var{interface} and |
1490 | @var{member} denote the message which has been sent. | |
22d8ac3a | 1491 | |
0ce574ef | 1492 | @var{handler} is the callback function which has been registered for |
addb7f2e | 1493 | this message (see @pxref{Signals}). When a @code{dbus-event} event |
0ce574ef MA |
1494 | arrives, @var{handler} is called with @var{args} as arguments. |
1495 | ||
22d8ac3a MA |
1496 | In order to inspect the @code{dbus-event} data, you could extend the |
1497 | definition of the callback function in @ref{Signals}: | |
1498 | ||
06c0751a | 1499 | @lisp |
22d8ac3a MA |
1500 | (defun my-dbus-signal-handler (&rest args) |
1501 | (message "my-dbus-signal-handler: %S" last-input-event)) | |
06c0751a | 1502 | @end lisp |
22d8ac3a MA |
1503 | |
1504 | There exist convenience functions which could be called inside a | |
1505 | callback function in order to retrieve the information from the event. | |
1506 | ||
1507 | @defun dbus-event-bus-name event | |
22d8ac3a MA |
1508 | Returns the bus name @var{event} is coming from. |
1509 | The result is either the symbol @code{:system} or the symbol @code{:session}. | |
1510 | @end defun | |
1511 | ||
21956b56 MA |
1512 | @defun dbus-event-message-type event |
1513 | Returns the message type of the corresponding D-Bus message. The | |
1514 | result is a number. | |
1515 | @end defun | |
1516 | ||
addb7f2e MA |
1517 | @defun dbus-event-serial-number event |
1518 | Returns the serial number of the corresponding D-Bus message. | |
21956b56 | 1519 | The result is a number. |
addb7f2e MA |
1520 | @end defun |
1521 | ||
22d8ac3a | 1522 | @defun dbus-event-service-name event |
22d8ac3a MA |
1523 | Returns the unique name of the D-Bus object @var{event} is coming from. |
1524 | @end defun | |
1525 | ||
1526 | @defun dbus-event-path-name event | |
22d8ac3a MA |
1527 | Returns the object path of the D-Bus object @var{event} is coming from. |
1528 | @end defun | |
1529 | ||
1530 | @defun dbus-event-interface-name event | |
74fc5047 | 1531 | Returns the interface name of the D-Bus object @var{event} is coming from. |
22d8ac3a MA |
1532 | @end defun |
1533 | ||
1534 | @defun dbus-event-member-name event | |
74fc5047 | 1535 | Returns the member name of the D-Bus object @var{event} is coming |
22d8ac3a MA |
1536 | from. It is either a signal name or a method name. |
1537 | @end defun | |
1538 | ||
c9ecb5a7 MA |
1539 | D-Bus errors are not propagated during event handling, because it is |
1540 | usually not desired. D-Bus errors in events can be made visible by | |
e7433508 MA |
1541 | setting the variable @code{dbus-debug} to @code{t}. They can also be |
1542 | handled by a hook function. | |
1543 | ||
1544 | @defvar dbus-event-error-hooks | |
1545 | This hook variable keeps a list of functions, which are called when a | |
1546 | D-Bus error happens in the event handler. Every function must accept | |
74fc5047 MA |
1547 | two arguments, the event and the error variable catched in |
1548 | @code{condition-case} by @code{dbus-error}. | |
1549 | ||
1550 | Such functions can be used the adapt the error signal to be raised. | |
1551 | Example: | |
e7433508 MA |
1552 | |
1553 | @lisp | |
74fc5047 MA |
1554 | (defun my-dbus-event-error-handler (event error) |
1555 | (when (string-equal (concat dbus-service-emacs ".FileManager") | |
1556 | (dbus-event-interface-name event)) | |
1557 | (message "my-dbus-event-error-handler: %S %S" event error) | |
1558 | (signal 'file-error (cdr error)))) | |
e7433508 MA |
1559 | |
1560 | (add-hook 'dbus-event-error-hooks 'my-dbus-event-error-handler) | |
1561 | @end lisp | |
1562 | @end defvar | |
c9ecb5a7 | 1563 | |
74fc5047 MA |
1564 | Hook functions shall take into account, that there might be other |
1565 | D-Bus applications running. Therefore, they shall check carefully, | |
1566 | whether a given D-Bus error is related to them. | |
1567 | ||
22d8ac3a MA |
1568 | |
1569 | @node GNU Free Documentation License | |
1570 | @appendix GNU Free Documentation License | |
1571 | @include doclicense.texi | |
1572 | ||
22d8ac3a | 1573 | @bye |
79f10da0 MB |
1574 | |
1575 | @ignore | |
1576 | arch-tag: 2eeec19d-0caf-44e0-a193-329d7f9951d8 | |
1577 | @end ignore |