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22d8ac3a MA |
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 | ||
5bd55c3c MA |
8 | @syncodeindex vr cp |
9 | @syncodeindex fn cp | |
10 | ||
22d8ac3a | 11 | @copying |
73b0cd50 | 12 | Copyright @copyright{} 2007-2011 Free Software Foundation, Inc. |
22d8ac3a MA |
13 | |
14 | @quotation | |
15 | Permission is granted to copy, distribute and/or modify this document | |
6a2c4aec | 16 | under the terms of the GNU Free Documentation License, Version 1.3 or |
22d8ac3a | 17 | any later version published by the Free Software Foundation; with no |
debf4439 GM |
18 | Invariant Sections, with the Front-Cover texts being ``A GNU Manual'', |
19 | and with the Back-Cover Texts as in (a) below. A copy of the license | |
20 | is included in the section entitled ``GNU Free Documentation License''. | |
22d8ac3a | 21 | |
6f093307 GM |
22 | (a) The FSF's Back-Cover Text is: ``You have the freedom to copy and |
23 | modify this GNU manual. Buying copies from the FSF supports it in | |
24 | developing GNU and promoting software freedom.'' | |
22d8ac3a MA |
25 | @end quotation |
26 | @end copying | |
27 | ||
0c973505 | 28 | @dircategory Emacs lisp libraries |
22d8ac3a MA |
29 | @direntry |
30 | * D-Bus: (dbus). Using D-Bus in Emacs. | |
31 | @end direntry | |
32 | ||
5dc584b5 | 33 | @contents |
cd71b9ae | 34 | |
977640ed | 35 | |
22d8ac3a MA |
36 | @node Top, Overview, (dir), (dir) |
37 | @top D-Bus integration in Emacs | |
38 | ||
78176e69 MA |
39 | This manual documents an API for usage of D-Bus in Emacs. D-Bus is a |
40 | message bus system, a simple way for applications to talk to one | |
41 | another. An overview of D-Bus can be found at | |
42 | @uref{http://dbus.freedesktop.org/}. | |
22d8ac3a | 43 | |
5dc584b5 | 44 | @ifnottex |
22d8ac3a | 45 | @insertcopying |
5dc584b5 | 46 | @end ifnottex |
22d8ac3a MA |
47 | |
48 | @menu | |
49 | * Overview:: An overview of D-Bus. | |
cd71b9ae | 50 | * Inspection:: Inspection of D-Bus services. |
22d8ac3a MA |
51 | * Type Conversion:: Mapping Lisp types and D-Bus types. |
52 | * Synchronous Methods:: Calling methods in a blocking way. | |
21956b56 | 53 | * Asynchronous Methods:: Calling methods non-blocking. |
addb7f2e | 54 | * Receiving Method Calls:: Offering own methods. |
22d8ac3a | 55 | * Signals:: Sending and receiving signals. |
7457f7b6 | 56 | * Alternative Buses:: Alternative buses. |
22d8ac3a | 57 | * Errors and Events:: Errors and events. |
5bd55c3c MA |
58 | * Index:: Index including concepts, functions, variables. |
59 | ||
22d8ac3a MA |
60 | * GNU Free Documentation License:: The license for this documentation. |
61 | @end menu | |
62 | ||
cd71b9ae | 63 | |
22d8ac3a MA |
64 | @node Overview |
65 | @chapter An overview of D-Bus | |
66 | @cindex overview | |
67 | ||
68 | D-Bus is an inter-process communication mechanism for applications | |
69 | residing on the same host. The communication is based on | |
70 | @dfn{messages}. Data in the messages is carried in a structured way, | |
71 | it is not just a byte stream. | |
72 | ||
73 | The communication is connection oriented to two kinds of message | |
74 | buses: a so called @dfn{system bus}, and a @dfn{session bus}. On a | |
75 | given machine, there is always one single system bus for miscellaneous | |
76 | system-wide communication, like changing of hardware configuration. | |
77 | On the other hand, the session bus is always related to a single | |
78 | user's session. | |
79 | ||
80 | Every client application, which is connected to a bus, registers under | |
81 | a @dfn{unique name} at the bus. This name is used for identifying the | |
82 | client application. Such a unique name starts always with a colon, | |
83 | and looks like @samp{:1.42}. | |
84 | ||
85 | Additionally, a client application can register itself to a so called | |
86 | @dfn{known name}, which is a series of identifiers separated by dots, | |
7ef92bc9 | 87 | as in @samp{org.gnu.Emacs}. If several applications register to the |
22d8ac3a MA |
88 | same known name, these registrations are queued, and only the first |
89 | application which has registered for the known name is reachable via | |
90 | this name. If this application disconnects from the bus, the next | |
91 | queued unique name becomes the owner of this known name. | |
92 | ||
93 | An application can install one or several objects under its name. | |
94 | Such objects are identified by an @dfn{object path}, which looks | |
95 | similar to paths in a filesystem. An example of such an object path | |
96 | could be @samp{/org/gnu/Emacs/}. | |
97 | ||
98 | Applications might send a request to an object, that means sending a | |
99 | message with some data as input parameters, and receiving a message | |
100 | from that object with the result of this message, the output | |
101 | parameters. Such a request is called @dfn{method} in D-Bus. | |
102 | ||
103 | The other form of communication are @dfn{signals}. The underlying | |
104 | message is emitted from an object and will be received by all other | |
105 | applications which have registered for such a signal. | |
106 | ||
107 | All methods and signals an object supports are called @dfn{interface} | |
108 | of the object. Interfaces are specified under a hierarchical name in | |
109 | D-Bus; an object can support several interfaces. Such an interface | |
110 | name could be @samp{org.gnu.Emacs.TextEditor} or | |
111 | @samp{org.gnu.Emacs.FileManager}. | |
112 | ||
113 | ||
114 | @node Inspection | |
cd71b9ae | 115 | @chapter Inspection of D-Bus services. |
22d8ac3a MA |
116 | @cindex inspection |
117 | ||
cd71b9ae MA |
118 | @menu |
119 | * Bus names:: Discovering D-Bus names. | |
120 | * Introspection:: Knowing the details of D-Bus services. | |
121 | * Nodes and Interfaces:: Detecting object paths and interfaces. | |
122 | * Methods and Signal:: Applying the functionality. | |
123 | * Properties and Annotations:: What else to know about interfaces. | |
124 | * Arguments and Signatures:: The final details. | |
125 | @end menu | |
126 | ||
127 | ||
128 | @node Bus names | |
129 | @section Bus names. | |
130 | ||
22d8ac3a MA |
131 | There are several basic functions which inspect the buses for |
132 | registered names. Internally they use the basic interface | |
133 | @samp{org.freedesktop.DBus}, which is supported by all objects of a bus. | |
134 | ||
1ff98217 MA |
135 | @defun dbus-list-activatable-names &optional bus |
136 | This function returns the D-Bus service names, which can be activated | |
137 | for @var{bus}. It must be either the symbol @code{:system} (the | |
138 | default) or the symbol @code{:session}. An activatable service is | |
139 | described in a service registration file. Under GNU/Linux, such files | |
140 | are located at @file{/usr/share/dbus-1/system-services/} (for the | |
141 | @code{:system} bus) or @file{/usr/share/dbus-1/services/}. An | |
142 | activatable service is not necessarily registered at @var{bus} at already. | |
22d8ac3a MA |
143 | |
144 | The result is a list of strings, which is @code{nil} when there are no | |
1ff98217 MA |
145 | activatable service names at all. Example: |
146 | ||
147 | @lisp | |
148 | ;; Check, whether the document viewer can be accessed via D-Bus. | |
149 | (member "org.gnome.evince.Daemon" | |
150 | (dbus-list-activatable-names :session)) | |
151 | @end lisp | |
152 | ||
22d8ac3a MA |
153 | @end defun |
154 | ||
155 | @defun dbus-list-names bus | |
22d8ac3a MA |
156 | All service names, which are registered at D-Bus @var{bus}, are |
157 | returned. The result is a list of strings, which is @code{nil} when | |
158 | there are no registered service names at all. Well known names are | |
159 | strings like @samp{org.freedesktop.DBus}. Names starting with | |
160 | @samp{:} are unique names for services. | |
161 | ||
162 | @var{bus} must be either the symbol @code{:system} or the symbol | |
163 | @code{:session}. | |
164 | @end defun | |
165 | ||
166 | @defun dbus-list-known-names bus | |
1ff98217 | 167 | Retrieves all registered services which correspond to a known name in @var{bus}. |
22d8ac3a MA |
168 | A service has a known name if it doesn't start with @samp{:}. The |
169 | result is a list of strings, which is @code{nil} when there are no | |
170 | known names at all. | |
171 | ||
172 | @var{bus} must be either the symbol @code{:system} or the symbol | |
173 | @code{:session}. | |
174 | @end defun | |
175 | ||
176 | @defun dbus-list-queued-owners bus service | |
22d8ac3a MA |
177 | For a given service, registered at D-Bus @var{bus} under the name |
178 | @var{service}, all queued unique names are returned. The result is a | |
179 | list of strings, or @code{nil} when there are no queued names for | |
180 | @var{service} at all. | |
181 | ||
182 | @var{bus} must be either the symbol @code{:system} or the symbol | |
183 | @code{:session}. @var{service} must be a known service name as | |
184 | string. | |
185 | @end defun | |
186 | ||
187 | @defun dbus-get-name-owner bus service | |
22d8ac3a | 188 | For a given service, registered at D-Bus @var{bus} under the name |
06c0751a MA |
189 | @var{service}, the unique name of the name owner is returned. The |
190 | result is a string, or @code{nil} when there exist no name owner of | |
191 | @var{service}. | |
22d8ac3a MA |
192 | |
193 | @var{bus} must be either the symbol @code{:system} or the symbol | |
194 | @code{:session}. @var{service} must be a known service name as | |
195 | string. | |
196 | @end defun | |
197 | ||
ecd3d54f | 198 | @defun dbus-ping bus service &optional timeout |
06c0751a | 199 | Check whether the service name @var{service} is registered at D-Bus |
ecd3d54f MA |
200 | @var{bus}. @var{service} might not have been started yet, it is |
201 | autostarted if possible. The result is either @code{t} or @code{nil}. | |
06c0751a MA |
202 | |
203 | @var{bus} must be either the symbol @code{:system} or the symbol | |
ecd3d54f MA |
204 | @code{:session}. @var{service} must be a string. @var{timeout}, a |
205 | nonnegative integer, specifies the maximum number of milliseconds | |
206 | @code{dbus-ping} must return. The default value is 25,000. Example: | |
06c0751a MA |
207 | |
208 | @lisp | |
209 | (message | |
210 | "%s screensaver on board." | |
211 | (cond | |
ecd3d54f MA |
212 | ((dbus-ping :session "org.gnome.ScreenSaver" 100) "Gnome") |
213 | ((dbus-ping :session "org.freedesktop.ScreenSaver" 100) "KDE") | |
06c0751a MA |
214 | (t "No"))) |
215 | @end lisp | |
ecd3d54f MA |
216 | |
217 | If it shall be checked whether @var{service} is already running | |
218 | without autostarting it, one shall apply | |
219 | ||
220 | @lisp | |
221 | (member service (dbus-list-known-names bus)) | |
222 | @end lisp | |
06c0751a MA |
223 | @end defun |
224 | ||
22d8ac3a | 225 | @defun dbus-get-unique-name bus |
22d8ac3a MA |
226 | The unique name, under which Emacs is registered at D-Bus @var{bus}, |
227 | is returned as string. | |
228 | ||
229 | @var{bus} must be either the symbol @code{:system} or the symbol | |
230 | @code{:session}. | |
231 | @end defun | |
232 | ||
cd71b9ae MA |
233 | |
234 | @node Introspection | |
235 | @section Knowing the details of D-Bus services. | |
236 | ||
237 | D-Bus services publish their interfaces. This can be retrieved and | |
238 | analyzed during runtime, in order to understand the used | |
239 | implementation. | |
240 | ||
241 | The resulting introspection data are in XML format. The root | |
242 | introspection element is always a @code{node} element. It might have | |
243 | a @code{name} attribute, which denotes the (absolute) object path an | |
244 | interface is introspected. | |
245 | ||
246 | The root @code{node} element may have @code{node} and @code{interface} | |
247 | children. A child @code{node} element must have a @code{name} | |
248 | attribute, this case it is the relative object path to the root | |
249 | @code{node} element. | |
250 | ||
251 | An @code{interface} element has just one attribute, @code{name}, which | |
252 | is the full name of that interface. The default interface | |
253 | @samp{org.freedesktop.DBus.Introspectable} is always present. Example: | |
254 | ||
255 | @example | |
256 | <node name="/org/bluez"> | |
257 | <interface name="org.freedesktop.DBus.Introspectable"> | |
258 | @dots{} | |
259 | </interface> | |
260 | <interface name="org.bluez.Manager"> | |
261 | @dots{} | |
262 | </interface> | |
263 | <interface name="org.bluez.Database"> | |
264 | @dots{} | |
265 | </interface> | |
266 | <interface name="org.bluez.Security"> | |
267 | @dots{} | |
268 | </interface> | |
269 | <node name="service_audio"/> | |
270 | <node name="service_input"/> | |
271 | <node name="service_network"/> | |
272 | <node name="service_serial"/> | |
273 | </node> | |
274 | @end example | |
275 | ||
276 | Children of an @code{interface} element can be @code{method}, | |
277 | @code{signal} and @code{property} elements. A @code{method} element | |
278 | stands for a D-Bus method of the surrounding interface. The element | |
279 | itself has a @code{name} attribute, showing the method name. Children | |
280 | elements @code{arg} stand for the arguments of a method. Example: | |
281 | ||
282 | @example | |
283 | <method name="ResolveHostName"> | |
284 | <arg name="interface" type="i" direction="in"/> | |
285 | <arg name="protocol" type="i" direction="in"/> | |
286 | <arg name="name" type="s" direction="in"/> | |
287 | <arg name="aprotocol" type="i" direction="in"/> | |
288 | <arg name="flags" type="u" direction="in"/> | |
289 | <arg name="interface" type="i" direction="out"/> | |
290 | <arg name="protocol" type="i" direction="out"/> | |
291 | <arg name="name" type="s" direction="out"/> | |
292 | <arg name="aprotocol" type="i" direction="out"/> | |
293 | <arg name="address" type="s" direction="out"/> | |
294 | <arg name="flags" type="u" direction="out"/> | |
295 | </method> | |
296 | @end example | |
297 | ||
298 | @code{arg} elements can have the attributes @code{name}, @code{type} | |
299 | and @code{direction}. The @code{name} attribute is optional. The | |
300 | @code{type} attribute stands for the @dfn{signature} of the argument | |
301 | in D-Bus. For a discussion of D-Bus types and their Lisp | |
302 | representation see @ref{Type Conversion}.@footnote{D-Bus signatures | |
303 | are explained in the D-Bus specification | |
304 | @uref{http://dbus.freedesktop.org/doc/dbus-specification.html#message-protocol-signatures}.} | |
305 | The @code{direction} attribute of an @code{arg} element can be only | |
306 | @samp{in} or @samp{out}; in case it is omitted, it defaults to | |
307 | @samp{in}. | |
308 | ||
309 | A @code{signal} element of an @code{interface} has a similar | |
310 | structure. The @code{direction} attribute of an @code{arg} child | |
311 | element can be only @samp{out} here; which is also the default value. | |
312 | Example: | |
313 | ||
314 | @example | |
315 | <signal name="StateChanged"> | |
316 | <arg name="state" type="i"/> | |
317 | <arg name="error" type="s"/> | |
318 | </signal> | |
319 | @end example | |
320 | ||
321 | A @code{property} element has no @code{arg} child | |
322 | element. It just has the attributes @code{name}, @code{type} and | |
323 | @code{access}, which are all mandatory. The @code{access} attribute | |
324 | allows the values @samp{readwrite}, @samp{read}, and @samp{write}. | |
325 | Example: | |
326 | ||
327 | @example | |
328 | <property name="Status" type="u" direction="read"/> | |
329 | @end example | |
330 | ||
331 | @code{annotation} elements can be children of @code{interface}, | |
332 | @code{method}, @code{signal}, and @code{property} elements. Unlike | |
333 | properties, which can change their values during lifetime of a D-Bus | |
334 | object, annotations are static. Often they are used for code | |
335 | generators of D-Bus langugae bindings. Example: | |
336 | ||
337 | @example | |
338 | <annotation name="de.berlios.Pinot.GetStatistics" value="pinotDBus"/> | |
339 | @end example | |
340 | ||
341 | Annotations have just @code{name} and @code{value} attributes, both | |
342 | must be strings. | |
343 | ||
22d8ac3a | 344 | @defun dbus-introspect bus service path |
cd71b9ae MA |
345 | This function returns all interfaces and sub-nodes of @var{service}, |
346 | registered at object path @var{path} at bus @var{bus}. | |
22d8ac3a MA |
347 | |
348 | @var{bus} must be either the symbol @code{:system} or the symbol | |
349 | @code{:session}. @var{service} must be a known service name, and | |
350 | @var{path} must be a valid object path. The last two parameters are | |
351 | strings. The result, the introspection data, is a string in XML | |
cd71b9ae | 352 | format. Example: |
22d8ac3a | 353 | |
06c0751a | 354 | @lisp |
22d8ac3a MA |
355 | (dbus-introspect |
356 | :system "org.freedesktop.Hal" | |
357 | "/org/freedesktop/Hal/devices/computer") | |
358 | ||
d9e21158 | 359 | @result{} "<!DOCTYPE node PUBLIC |
cd71b9ae MA |
360 | "-//freedesktop//DTD D-BUS Object Introspection 1.0//EN" |
361 | "http://www.freedesktop.org/standards/dbus/1.0/introspect.dtd"> | |
d9e21158 | 362 | <node> |
cd71b9ae MA |
363 | <interface name="org.freedesktop.Hal.Device"> |
364 | <method name="GetAllProperties"> | |
365 | <arg name="properties" direction="out" type="a@{sv@}"/> | |
d9e21158 | 366 | </method> |
c9ecb5a7 | 367 | @dots{} |
cd71b9ae MA |
368 | <signal name="PropertyModified"> |
369 | <arg name="num_updates" type="i"/> | |
370 | <arg name="updates" type="a(sbb)"/> | |
d9e21158 MA |
371 | </signal> |
372 | </interface> | |
c9ecb5a7 | 373 | @dots{} |
d9e21158 | 374 | </node>" |
06c0751a | 375 | @end lisp |
22d8ac3a | 376 | |
cd71b9ae MA |
377 | This example informs us, that the service @samp{org.freedesktop.Hal} |
378 | at object path @samp{/org/freedesktop/Hal/devices/computer} offers the | |
379 | interface @samp{org.freedesktop.Hal.Device} (and 2 other interfaces | |
22d8ac3a | 380 | not documented here). This interface contains the method |
cd71b9ae | 381 | @samp{GetAllProperties}, which needs no input parameters, but returns |
22d8ac3a MA |
382 | as output parameter an array of dictionary entries (key-value pairs). |
383 | Every dictionary entry has a string as key, and a variant as value. | |
384 | ||
385 | The interface offers also a signal, which returns 2 parameters: an | |
386 | integer, and an array consisting of elements which are a struct of a | |
cd71b9ae MA |
387 | string and 2 boolean values.@footnote{ The interfaces of the service |
388 | @samp{org.freedesktop.Hal} are described at | |
22d8ac3a MA |
389 | @uref{http://people.freedesktop.org/~david/hal-spec/hal-spec.html#interfaces}.} |
390 | @end defun | |
391 | ||
cd71b9ae MA |
392 | @defun dbus-introspect-xml bus service path |
393 | This function has the same intention as function | |
394 | @code{dbus-introspect}. The returned value is a parsed XML tree, | |
395 | which can be used for further analysis. Example: | |
396 | ||
397 | @lisp | |
398 | (dbus-introspect-xml | |
399 | :session "org.freedesktop.xesam.searcher" | |
400 | "/org/freedesktop/xesam/searcher/main") | |
401 | ||
402 | @result{} (node ((name . "/org/freedesktop/xesam/searcher/main")) | |
403 | (interface ((name . "org.freedesktop.xesam.Search")) | |
404 | (method ((name . "GetHitData")) | |
405 | (arg ((name . "search") (type . "s") (direction . "in"))) | |
406 | (arg ((name . "hit_ids") (type . "au") (direction . "in"))) | |
407 | (arg ((name . "fields") (type . "as") (direction . "in"))) | |
408 | (arg ((name . "hit_data") (type . "aav") (direction . "out"))) | |
409 | ) | |
410 | @dots{} | |
411 | (signal ((name . "HitsAdded")) | |
412 | (arg ((name . "search") (type . "s"))) | |
413 | (arg ((name . "count") (type . "u"))) | |
414 | ) | |
415 | ) | |
416 | @dots{} | |
417 | ) | |
418 | @end lisp | |
419 | @end defun | |
420 | ||
421 | @defun dbus-introspect-get-attribute object attribute | |
422 | It returns the @var{attribute} value of a D-Bus introspection | |
423 | @var{object}. @var{object} can be every subtree of a parsed XML tree | |
424 | as retrieved with @code{dbus-introspect-xml}. @var{attribute} must be | |
425 | a string according to the attribute names in the D-Bus specification. | |
426 | Example: | |
427 | ||
428 | @lisp | |
429 | (dbus-introspect-get-attribute | |
430 | (dbus-introspect-xml :system "org.freedesktop.SystemToolsBackends" | |
431 | "/org/freedesktop/SystemToolsBackends/UsersConfig") | |
432 | "name") | |
433 | ||
434 | @result{} "/org/freedesktop/SystemToolsBackends/UsersConfig" | |
435 | @end lisp | |
436 | ||
5bd55c3c MA |
437 | If @var{object} has no @var{attribute}, the function returns |
438 | @code{nil}. | |
cd71b9ae MA |
439 | @end defun |
440 | ||
441 | ||
442 | @node Nodes and Interfaces | |
443 | @section Detecting object paths and interfaces. | |
444 | ||
445 | The first elements, to be introspected for a D-Bus object, are further | |
446 | object paths and interfaces. | |
447 | ||
448 | @defun dbus-introspect-get-node-names bus service path | |
449 | All node names of @var{service} in D-Bus @var{bus} at object path | |
450 | @var{path} are returned as list of strings. Example: | |
451 | ||
452 | @lisp | |
453 | (dbus-introspect-get-node-names | |
454 | :session "org.gnome.seahorse" "/org/gnome/seahorse") | |
455 | ||
456 | @result{} ("crypto" "keys") | |
457 | @end lisp | |
458 | ||
459 | The node names stand for further object paths of the D-Bus | |
460 | @var{service}, relative to @var{path}. In the example, | |
461 | @samp{/org/gnome/seahorse/crypto} and @samp{/org/gnome/seahorse/keys} | |
462 | are also object paths of the D-Bus service @samp{org.gnome.seahorse}. | |
463 | @end defun | |
464 | ||
465 | @defun dbus-introspect-get-all-nodes bus service path | |
466 | This function returns all node names of @var{service} in D-Bus | |
467 | @var{bus} at object path @var{path}. It returns a list of strings | |
468 | with all object paths of @var{service}, starting at @var{path}. | |
469 | Example: | |
470 | ||
471 | @lisp | |
472 | (dbus-introspect-get-all-nodes :session "org.gnome.seahorse" "/") | |
473 | ||
474 | @result{} ("/" "/org" "/org/gnome" "/org/gnome/seahorse" | |
475 | "/org/gnome/seahorse/crypto" | |
476 | "/org/gnome/seahorse/keys" | |
477 | "/org/gnome/seahorse/keys/openpgp" | |
478 | "/org/gnome/seahorse/keys/openpgp/local" | |
479 | "/org/gnome/seahorse/keys/openssh" | |
480 | "/org/gnome/seahorse/keys/openssh/local") | |
481 | @end lisp | |
482 | @end defun | |
483 | ||
484 | @defun dbus-introspect-get-interface-names bus service path | |
485 | There will be returned a list strings of all interface names of | |
486 | @var{service} in D-Bus @var{bus} at object path @var{path}. This list | |
487 | will contain the default interface @samp{org.freedesktop.DBus.Introspectable}. | |
488 | ||
489 | Another default interface is @samp{org.freedesktop.DBus.Properties}. | |
490 | If present, @code{interface} elements can also have @code{property} | |
491 | children. Example: | |
492 | ||
493 | @lisp | |
494 | (dbus-introspect-get-interface-names | |
495 | :system "org.freedesktop.Hal" | |
496 | "/org/freedesktop/Hal/devices/computer") | |
497 | ||
498 | @result{} ("org.freedesktop.DBus.Introspectable" | |
499 | "org.freedesktop.Hal.Device" | |
500 | "org.freedesktop.Hal.Device.SystemPowerManagement" | |
501 | "org.freedesktop.Hal.Device.CPUFreq") | |
502 | @end lisp | |
503 | @end defun | |
504 | ||
505 | @defun dbus-introspect-get-interface bus service path interface | |
506 | Return @var{interface} of @var{service} in D-Bus @var{bus} at object | |
507 | path @var{path}. The return value is an XML element. @var{interface} | |
508 | must be a string, element of the list returned by | |
509 | @code{dbus-introspect-get-interface-names}. Example: | |
510 | ||
511 | @lisp | |
512 | (dbus-introspect-get-interface | |
513 | :session "org.freedesktop.xesam.searcher" | |
514 | "/org/freedesktop/xesam/searcher/main" | |
515 | "org.freedesktop.xesam.Search") | |
516 | ||
517 | @result{} (interface ((name . "org.freedesktop.xesam.Search")) | |
518 | (method ((name . "GetHitData")) | |
519 | (arg ((name . "search") (type . "s") (direction . "in"))) | |
520 | (arg ((name . "hit_ids") (type . "au") (direction . "in"))) | |
521 | (arg ((name . "fields") (type . "as") (direction . "in"))) | |
522 | (arg ((name . "hit_data") (type . "aav") (direction . "out"))) | |
523 | ) | |
524 | @dots{} | |
525 | (signal ((name . "HitsAdded")) | |
526 | (arg ((name . "search") (type . "s"))) | |
527 | (arg ((name . "count") (type . "u"))) | |
528 | ) | |
529 | ) | |
530 | @end lisp | |
531 | @end defun | |
532 | ||
533 | @noindent | |
534 | With these functions, it is possible to retrieve all introspection | |
535 | data from a running system: | |
536 | ||
537 | @lisp | |
538 | (with-current-buffer (switch-to-buffer "*introspect*") | |
539 | (erase-buffer) | |
540 | (dolist (service (dbus-list-known-names :session)) | |
541 | (dolist (path (dbus-introspect-get-all-nodes :session service "/")) | |
542 | ;; We want to introspect only elements, which have more than | |
543 | ;; the default interface "org.freedesktop.DBus.Introspectable". | |
544 | (when (delete | |
545 | "org.freedesktop.DBus.Introspectable" | |
546 | (dbus-introspect-get-interface-names :session service path)) | |
547 | (insert (message "\nservice: \"%s\" path: \"%s\"\n" service path) | |
548 | (dbus-introspect :session service path)) | |
549 | (redisplay t))))) | |
550 | @end lisp | |
551 | ||
552 | ||
553 | @node Methods and Signal | |
554 | @section Applying the functionality. | |
555 | ||
556 | Methods and signals are the communicatione means to D-Bus. The | |
557 | following functions return their specifications. | |
558 | ||
559 | @defun dbus-introspect-get-method-names bus service path interface | |
560 | Return a list of strings of all method names of @var{interface} of | |
561 | @var{service} in D-Bus @var{bus} at object path @var{path}. Example: | |
562 | ||
563 | @lisp | |
564 | (dbus-introspect-get-method-names | |
565 | :session "org.freedesktop.xesam.searcher" | |
566 | "/org/freedesktop/xesam/searcher/main" | |
567 | "org.freedesktop.xesam.Search") | |
568 | ||
569 | @result{} ("GetState" "StartSearch" "GetHitCount" "GetHits" "NewSession" | |
570 | "CloseSession" "GetHitData" "SetProperty" "NewSearch" | |
571 | "GetProperty" "CloseSearch") | |
572 | @end lisp | |
573 | @end defun | |
574 | ||
575 | @defun dbus-introspect-get-method bus service path interface method | |
576 | This function returns @var{method} of @var{interface} as XML element. | |
577 | It must be located at @var{service} in D-Bus @var{bus} at object path | |
578 | @var{path}. @var{method} must be a string, element of the list | |
579 | returned by @code{dbus-introspect-get-method-names}. Example: | |
580 | ||
581 | @lisp | |
582 | (dbus-introspect-get-method | |
583 | :session "org.freedesktop.xesam.searcher" | |
584 | "/org/freedesktop/xesam/searcher/main" | |
585 | "org.freedesktop.xesam.Search" "GetHitData") | |
586 | ||
587 | @result{} (method ((name . "GetHitData")) | |
588 | (arg ((name . "search") (type . "s") (direction . "in"))) | |
589 | (arg ((name . "hit_ids") (type . "au") (direction . "in"))) | |
590 | (arg ((name . "fields") (type . "as") (direction . "in"))) | |
591 | (arg ((name . "hit_data") (type . "aav") (direction . "out"))) | |
592 | ) | |
593 | @end lisp | |
594 | @end defun | |
595 | ||
596 | @defun dbus-introspect-get-signal-names bus service path interface | |
597 | Return a list of strings of all signal names of @var{interface} of | |
598 | @var{service} in D-Bus @var{bus} at object path @var{path}. Example: | |
599 | ||
600 | @lisp | |
601 | (dbus-introspect-get-signal-names | |
602 | :session "org.freedesktop.xesam.searcher" | |
603 | "/org/freedesktop/xesam/searcher/main" | |
604 | "org.freedesktop.xesam.Search") | |
605 | ||
606 | @result{} ("StateChanged" "SearchDone" "HitsModified" | |
607 | "HitsRemoved" "HitsAdded") | |
608 | @end lisp | |
609 | @end defun | |
610 | ||
611 | @defun dbus-introspect-get-signal bus service path interface signal | |
612 | This function returns @var{signal} of @var{interface} as XML element. | |
613 | It must be located at @var{service} in D-Bus @var{bus} at object path | |
614 | @var{path}. @var{signal} must be a string, element of the list | |
615 | returned by @code{dbus-introspect-get-signal-names}. Example: | |
616 | ||
617 | @lisp | |
618 | (dbus-introspect-get-signal | |
619 | :session "org.freedesktop.xesam.searcher" | |
620 | "/org/freedesktop/xesam/searcher/main" | |
621 | "org.freedesktop.xesam.Search" "HitsAdded") | |
622 | ||
623 | @result{} (signal ((name . "HitsAdded")) | |
624 | (arg ((name . "search") (type . "s"))) | |
625 | (arg ((name . "count") (type . "u"))) | |
626 | ) | |
627 | @end lisp | |
628 | @end defun | |
629 | ||
630 | ||
631 | @node Properties and Annotations | |
632 | @section What else to know about interfaces. | |
633 | ||
634 | Interfaces can have properties. These can be exposed via the | |
635 | @samp{org.freedesktop.DBus.Properties} interface@footnote{See | |
636 | @uref{http://dbus.freedesktop.org/doc/dbus-specification.html#standard-interfaces-properties}}. | |
637 | That is, properties can be retrieved and changed during lifetime of an | |
638 | element. | |
639 | ||
640 | Annotations, on the other hand, are static values for an element. | |
641 | Often, they are used to instruct generators, how to generate code from | |
642 | the interface for a given language binding. | |
643 | ||
644 | @defun dbus-introspect-get-property-names bus service path interface | |
645 | Return a list of strings with all property names of @var{interface} of | |
646 | @var{service} in D-Bus @var{bus} at object path @var{path}. Example: | |
647 | ||
648 | @lisp | |
649 | (dbus-introspect-get-property-names | |
650 | :session "org.kde.kded" "/modules/networkstatus" | |
651 | "org.kde.Solid.Networking.Client") | |
652 | ||
653 | @result{} ("Status") | |
654 | @end lisp | |
655 | ||
656 | If an interface declares properties, the corresponding element supports | |
657 | also the @samp{org.freedesktop.DBus.Properties} interface. | |
658 | @end defun | |
659 | ||
660 | @defun dbus-introspect-get-property bus service path interface property | |
661 | This function returns @var{property} of @var{interface} as XML element. | |
662 | It must be located at @var{service} in D-Bus @var{bus} at object path | |
663 | @var{path}. @var{property} must be a string, element of the list | |
664 | returned by @code{dbus-introspect-get-property-names}. | |
665 | ||
666 | A @var{property} value can be retrieved by the function | |
667 | @code{dbus-introspect-get-attribute}. Example: | |
668 | ||
669 | @lisp | |
670 | (dbus-introspect-get-property | |
671 | :session "org.kde.kded" "/modules/networkstatus" | |
672 | "org.kde.Solid.Networking.Client" "Status") | |
673 | ||
674 | @result{} (property ((access . "read") (type . "u") (name . "Status"))) | |
675 | ||
676 | (dbus-introspect-get-attribute | |
677 | (dbus-introspect-get-property | |
678 | :session "org.kde.kded" "/modules/networkstatus" | |
679 | "org.kde.Solid.Networking.Client" "Status") | |
680 | "access") | |
681 | ||
682 | @result{} "read" | |
683 | @end lisp | |
684 | @end defun | |
685 | ||
686 | @defun dbus-get-property bus service path interface property | |
687 | This function returns the value of @var{property} of @var{interface}. | |
688 | It will be checked at @var{bus}, @var{service}, @var{path}. The | |
5bd55c3c | 689 | result can be any valid D-Bus value, or @code{nil} if there is no |
cd71b9ae MA |
690 | @var{property}. Example: |
691 | ||
692 | @lisp | |
693 | (dbus-get-property | |
694 | :session "org.kde.kded" "/modules/networkstatus" | |
695 | "org.kde.Solid.Networking.Client" "Status") | |
696 | ||
697 | @result{} 4 | |
698 | @end lisp | |
699 | @end defun | |
700 | ||
701 | @defun dbus-set-property bus service path interface property value | |
702 | Set value of @var{property} of @var{interface} to @var{value}. It | |
703 | will be checked at @var{bus}, @var{service}, @var{path}. When the | |
704 | value has been set successful, the result is @var{value}. Otherwise, | |
705 | @code{nil} is returned. Example: | |
706 | ||
707 | @lisp | |
708 | (dbus-set-property | |
709 | :session "org.kde.kaccess" "/MainApplication" | |
710 | "com.trolltech.Qt.QApplication" "doubleClickInterval" 500) | |
711 | ||
712 | @result{} 500 | |
713 | @end lisp | |
714 | @end defun | |
715 | ||
716 | @defun dbus-get-all-properties bus service path interface | |
717 | This function returns all properties of @var{interface}. It will be | |
718 | checked at @var{bus}, @var{service}, @var{path}. The result is a list | |
719 | of cons. Every cons contains the name of the property, and its value. | |
720 | If there are no properties, @code{nil} is returned. Example: | |
721 | ||
722 | @lisp | |
723 | (dbus-get-all-properties | |
724 | :session "org.kde.kaccess" "/MainApplication" | |
725 | "com.trolltech.Qt.QApplication") | |
726 | ||
727 | @result{} (("cursorFlashTime" . 1000) ("doubleClickInterval" . 500) | |
728 | ("keyboardInputInterval" . 400) ("wheelScrollLines" . 3) | |
729 | ("globalStrut" 0 0) ("startDragTime" . 500) | |
730 | ("startDragDistance" . 4) ("quitOnLastWindowClosed" . t) | |
731 | ("styleSheet" . "")) | |
732 | @end lisp | |
733 | @end defun | |
734 | ||
735 | @defun dbus-introspect-get-annotation-names bus service path interface &optional name | |
736 | Return a list of all annotation names as list of strings. If | |
737 | @var{name} is @code{nil}, the annotations are children of | |
738 | @var{interface}, otherwise @var{name} must be a @code{method}, | |
739 | @code{signal}, or @code{property} XML element, where the annotations | |
740 | belong to. Example: | |
741 | ||
742 | @lisp | |
743 | (dbus-introspect-get-annotation-names | |
744 | :session "de.berlios.Pinot" "/de/berlios/Pinot" | |
745 | "de.berlios.Pinot" "GetStatistics") | |
746 | ||
747 | @result{} ("de.berlios.Pinot.GetStatistics") | |
748 | @end lisp | |
749 | ||
750 | Default annotation names@footnote{See | |
751 | @uref{http://dbus.freedesktop.org/doc/dbus-specification.html#introspection-format}} | |
752 | are | |
753 | ||
754 | @table @samp | |
755 | @item org.freedesktop.DBus.Deprecated | |
756 | Whether or not the entity is deprecated; defaults to @code{nil} | |
757 | ||
758 | @item org.freedesktop.DBus.GLib.CSymbol | |
759 | The C symbol; may be used for @code{methods} and @code{interfaces} | |
760 | ||
761 | @item org.freedesktop.DBus.Method.NoReply | |
762 | If set, don't expect a reply to the @code{method} call; defaults to @code{nil} | |
763 | @end table | |
764 | @end defun | |
765 | ||
766 | @defun dbus-introspect-get-annotation bus service path interface name annotation | |
767 | Return annotation @var{ANNOTATION} as XML object. If @var{name} is | |
768 | @code{nil}, @var{ANNOTATION} is a child of @var{interface}, otherwise | |
769 | @var{name} must be the name of a @code{method}, @code{signal}, or | |
770 | @code{property} XML element, where the @var{ANNOTATION} belongs to. | |
771 | ||
772 | An attribute value can be retrieved by | |
773 | @code{dbus-introspect-get-attribute}. Example: | |
774 | ||
775 | @lisp | |
776 | (dbus-introspect-get-annotation | |
777 | :session "de.berlios.Pinot" "/de/berlios/Pinot" | |
778 | "de.berlios.Pinot" "GetStatistics" | |
779 | "de.berlios.Pinot.GetStatistics") | |
780 | ||
781 | @result{} (annotation ((name . "de.berlios.Pinot.GetStatistics") | |
782 | (value . "pinotDBus"))) | |
783 | ||
784 | (dbus-introspect-get-attribute | |
785 | (dbus-introspect-get-annotation | |
786 | :session "de.berlios.Pinot" "/de/berlios/Pinot" | |
787 | "de.berlios.Pinot" "GetStatistics" | |
788 | "de.berlios.Pinot.GetStatistics") | |
789 | "value") | |
790 | ||
791 | @result{} "pinotDBus" | |
792 | @end lisp | |
793 | @end defun | |
794 | ||
795 | ||
796 | @node Arguments and Signatures | |
797 | @section The final details. | |
798 | ||
799 | Methods and signals have arguments. They are described in the | |
800 | @code{arg} XML elements. | |
801 | ||
802 | @defun dbus-introspect-get-argument-names bus service path interface name | |
803 | Return a list of all argument names as list of strings. @var{name} | |
804 | must be a @code{method} or @code{signal} XML element. Example: | |
805 | ||
806 | @lisp | |
807 | (dbus-introspect-get-argument-names | |
808 | :session "org.freedesktop.xesam.searcher" | |
809 | "/org/freedesktop/xesam/searcher/main" | |
810 | "org.freedesktop.xesam.Search" "GetHitData") | |
811 | ||
812 | @result{} ("search" "hit_ids" "fields" "hit_data") | |
813 | @end lisp | |
814 | ||
815 | Argument names are optional; the function can return @code{nil} | |
816 | therefore, even if the method or signal has arguments. | |
817 | @end defun | |
818 | ||
819 | @defun dbus-introspect-get-argument bus service path interface name arg | |
820 | Return argument @var{ARG} as XML object. @var{name} | |
821 | must be a @code{method} or @code{signal} XML element. Example: | |
822 | ||
823 | @lisp | |
824 | (dbus-introspect-get-argument | |
825 | :session "org.freedesktop.xesam.searcher" | |
826 | "/org/freedesktop/xesam/searcher/main" | |
827 | "org.freedesktop.xesam.Search" "GetHitData" "search") | |
828 | ||
829 | @result{} (arg ((name . "search") (type . "s") (direction . "in"))) | |
830 | @end lisp | |
831 | @end defun | |
832 | ||
833 | @defun dbus-introspect-get-signature bus service path interface name &optional direction | |
834 | Return signature of a @code{method} or @code{signal}, represented by | |
835 | @var{name}, as string. | |
836 | ||
837 | If @var{name} is a @code{method}, @var{direction} can be either | |
838 | @samp{in} or @samp{out}. If @var{direction} is @code{nil}, @samp{in} | |
839 | is assumed. | |
840 | ||
841 | If @var{name} is a @code{signal}, and @var{direction} is | |
842 | non-@code{nil}, @var{direction} must be @samp{out}. Example: | |
843 | ||
844 | @lisp | |
845 | (dbus-introspect-get-signature | |
846 | :session "org.freedesktop.xesam.searcher" | |
847 | "/org/freedesktop/xesam/searcher/main" | |
848 | "org.freedesktop.xesam.Search" "GetHitData" "in") | |
849 | ||
850 | @result{} "sauas" | |
851 | ||
852 | (dbus-introspect-get-signature | |
853 | :session "org.freedesktop.xesam.searcher" | |
854 | "/org/freedesktop/xesam/searcher/main" | |
855 | "org.freedesktop.xesam.Search" "HitsAdded") | |
856 | ||
21956b56 | 857 | @result{} "su" |
cd71b9ae MA |
858 | @end lisp |
859 | @end defun | |
860 | ||
22d8ac3a MA |
861 | |
862 | @node Type Conversion | |
863 | @chapter Mapping Lisp types and D-Bus types. | |
864 | @cindex type conversion | |
865 | ||
866 | D-Bus method calls and signals accept usually several arguments as | |
867 | parameters, either as input parameter, or as output parameter. Every | |
868 | argument belongs to a D-Bus type. | |
869 | ||
6a31c819 | 870 | Such arguments must be mapped between the value encoded as a D-Bus |
22d8ac3a MA |
871 | type, and the corresponding type of Lisp objects. The mapping is |
872 | applied Lisp object @expansion{} D-Bus type for input parameters, and | |
873 | D-Bus type @expansion{} Lisp object for output parameters. | |
874 | ||
875 | ||
876 | @section Input parameters. | |
877 | ||
878 | Input parameters for D-Bus methods and signals occur as arguments of a | |
6a31c819 | 879 | Lisp function call. The following mapping to D-Bus types is |
22d8ac3a MA |
880 | applied, when the corresponding D-Bus message is created: |
881 | ||
882 | @example | |
5bd55c3c | 883 | @multitable {negative integer} {@expansion{}} {DBUS_TYPE_BOOLEAN} |
22d8ac3a MA |
884 | @item Lisp type @tab @tab D-Bus type |
885 | @item | |
886 | @item @code{t} and @code{nil} @tab @expansion{} @tab DBUS_TYPE_BOOLEAN | |
5bd55c3c MA |
887 | @item natural number @tab @expansion{} @tab DBUS_TYPE_UINT32 |
888 | @item negative integer @tab @expansion{} @tab DBUS_TYPE_INT32 | |
22d8ac3a MA |
889 | @item float @tab @expansion{} @tab DBUS_TYPE_DOUBLE |
890 | @item string @tab @expansion{} @tab DBUS_TYPE_STRING | |
6a31c819 | 891 | @item list @tab @expansion{} @tab DBUS_TYPE_ARRAY |
22d8ac3a MA |
892 | @end multitable |
893 | @end example | |
894 | ||
6a31c819 | 895 | Other Lisp objects, like symbols or hash tables, are not accepted as |
61cf3a76 | 896 | input parameters. |
6a31c819 MA |
897 | |
898 | If it is necessary to use another D-Bus type, a corresponding type | |
61cf3a76 | 899 | symbol can be prepended to the corresponding Lisp object. Basic D-Bus |
d4e67bc5 MA |
900 | types are represented by the type symbols @code{:byte}, |
901 | @code{:boolean}, @code{:int16}, @code{:uint16}, @code{:int32}, | |
902 | @code{:uint32}, @code{:int64}, @code{:uint64}, @code{:double}, | |
6f8fc60c MA |
903 | @code{:string}, @code{:object-path}, @code{:signature} and |
904 | @code{:unix-fd}. | |
6a31c819 | 905 | |
22d8ac3a | 906 | @noindent |
6a31c819 MA |
907 | Example: |
908 | ||
909 | @lisp | |
5bd55c3c | 910 | (dbus-call-method @dots{} @var{NAT-NUMBER} @var{STRING}) |
6a31c819 MA |
911 | @end lisp |
912 | ||
913 | is equivalent to | |
914 | ||
915 | @lisp | |
5bd55c3c | 916 | (dbus-call-method @dots{} :uint32 @var{NAT-NUMBER} :string @var{STRING}) |
6a31c819 MA |
917 | @end lisp |
918 | ||
919 | but different to | |
920 | ||
921 | @lisp | |
5bd55c3c | 922 | (dbus-call-method @dots{} :int32 @var{NAT-NUMBER} :signature @var{STRING}) |
6a31c819 MA |
923 | @end lisp |
924 | ||
4db2806c MA |
925 | The value for a byte D-Bus type can be any integer in the range 0 |
926 | through 255. If a character is used as argument, modifiers | |
927 | represented outside this range are stripped of. For example, | |
928 | @code{:byte ?x} is equal to @code{:byte ?\M-x}, but it is not equal to | |
929 | @code{:byte ?\C-x} or @code{:byte ?\M-\C-x}. | |
c9ecb5a7 | 930 | |
4db2806c MA |
931 | A D-Bus compound type is always represented as a list. The @sc{car} |
932 | of this list can be the type symbol @code{:array}, @code{:variant}, | |
d4e67bc5 MA |
933 | @code{:struct} or @code{:dict-entry}, which would result in a |
934 | corresponding D-Bus container. @code{:array} is optional, because | |
4db2806c | 935 | this is the default compound D-Bus type for a list. |
6a31c819 MA |
936 | |
937 | The objects being elements of the list are checked according to the | |
938 | D-Bus compound type rules. | |
939 | ||
940 | @itemize | |
4db2806c MA |
941 | @item An array must contain only elements of the same D-Bus type. It |
942 | can be empty. | |
943 | ||
6a31c819 | 944 | @item A variant must contain only one single element. |
4db2806c | 945 | |
6a31c819 | 946 | @item A dictionary entry must be element of an array, and it must |
4db2806c MA |
947 | contain only a key-value pair of two elements, with a basic D-Bus type |
948 | key. | |
949 | ||
6a31c819 MA |
950 | @item There is no restriction for structs. |
951 | @end itemize | |
952 | ||
4db2806c MA |
953 | If an empty array needs an element D-Bus type other than string, it |
954 | can contain exactly one element of D-Bus type @code{:signature}. The | |
955 | value of this element (a string) is used as the signature of the | |
956 | elements of this array. Example: | |
6a31c819 MA |
957 | |
958 | @lisp | |
4db2806c MA |
959 | (dbus-call-method |
960 | :session "org.freedesktop.Notifications" | |
961 | "/org/freedesktop/Notifications" | |
962 | "org.freedesktop.Notifications" "Notify" | |
963 | "GNU Emacs" ;; Application name. | |
964 | 0 ;; No replacement of other notifications. | |
965 | "" ;; No icon. | |
966 | "Notification summary" ;; Summary. | |
967 | (format ;; Body. | |
968 | "This is a test notification, raised from %s" (emacs-version)) | |
969 | '(:array) ;; No actions (empty array of strings). | |
970 | '(:array :signature "@{sv@}") ;; No hints | |
971 | ;; (empty array of dictionary entries). | |
0ecd3c90 | 972 | :int32 -1) ;; Default timeout. |
4db2806c MA |
973 | |
974 | @result{} 3 | |
6a31c819 | 975 | @end lisp |
22d8ac3a | 976 | |
ace706d1 MA |
977 | @defun dbus-string-to-byte-array string |
978 | Sometimes, D-Bus methods require as input parameter an array of bytes, | |
979 | instead of a string. If it is guaranteed, that @var{string} is an | |
980 | UTF8 string, this function performs the conversion. Example: | |
981 | ||
982 | @lisp | |
983 | (dbus-string-to-byte-array "/etc/hosts") | |
984 | ||
985 | @result{} (:array :byte 47 :byte 101 :byte 116 :byte 99 :byte 47 | |
986 | :byte 104 :byte 111 :byte 115 :byte 116 :byte 115) | |
987 | @end lisp | |
988 | @end defun | |
989 | ||
990 | @defun dbus-escape-as-identifier string | |
991 | Escape an arbitrary @var{string} so it follows the rules for a C | |
992 | identifier. The escaped string can be used as object path component, | |
993 | interface element component, bus name component or member name in | |
994 | D-Bus. | |
995 | ||
996 | The escaping consists of replacing all non-alphanumerics, and the | |
997 | first character if it's a digit, with an underscore and two | |
998 | lower-case hex digits. As a special case, "" is escaped to | |
999 | "_". Example: | |
1000 | ||
1001 | @lisp | |
1002 | (dbus-escape-as-identifier "0123abc_xyz\x01\xff") | |
1003 | ||
1004 | @result{} "_30123abc_5fxyz_01_ff" | |
1005 | @end lisp | |
1006 | @end defun | |
1007 | ||
22d8ac3a MA |
1008 | |
1009 | @section Output parameters. | |
1010 | ||
1011 | Output parameters of D-Bus methods and signals are mapped to Lisp | |
6a31c819 | 1012 | objects. |
22d8ac3a MA |
1013 | |
1014 | @example | |
5bd55c3c | 1015 | @multitable {DBUS_TYPE_OBJECT_PATH} {@expansion{}} {natural number or float} |
22d8ac3a MA |
1016 | @item D-Bus type @tab @tab Lisp type |
1017 | @item | |
1018 | @item DBUS_TYPE_BOOLEAN @tab @expansion{} @tab @code{t} or @code{nil} | |
5bd55c3c MA |
1019 | @item DBUS_TYPE_BYTE @tab @expansion{} @tab natural number |
1020 | @item DBUS_TYPE_UINT16 @tab @expansion{} @tab natural number | |
1021 | @item DBUS_TYPE_INT16 @tab @expansion{} @tab integer | |
1022 | @item DBUS_TYPE_UINT32 @tab @expansion{} @tab natural number or float | |
6f8fc60c | 1023 | @item DBUS_TYPE_UNIX_FD @tab @expansion{} @tab natural number or float |
5bd55c3c MA |
1024 | @item DBUS_TYPE_INT32 @tab @expansion{} @tab integer or float |
1025 | @item DBUS_TYPE_UINT64 @tab @expansion{} @tab natural number or float | |
1026 | @item DBUS_TYPE_INT64 @tab @expansion{} @tab integer or float | |
22d8ac3a MA |
1027 | @item DBUS_TYPE_DOUBLE @tab @expansion{} @tab float |
1028 | @item DBUS_TYPE_STRING @tab @expansion{} @tab string | |
1029 | @item DBUS_TYPE_OBJECT_PATH @tab @expansion{} @tab string | |
6a31c819 | 1030 | @item DBUS_TYPE_SIGNATURE @tab @expansion{} @tab string |
22d8ac3a MA |
1031 | @item DBUS_TYPE_ARRAY @tab @expansion{} @tab list |
1032 | @item DBUS_TYPE_VARIANT @tab @expansion{} @tab list | |
1033 | @item DBUS_TYPE_STRUCT @tab @expansion{} @tab list | |
1034 | @item DBUS_TYPE_DICT_ENTRY @tab @expansion{} @tab list | |
1035 | @end multitable | |
1036 | @end example | |
1037 | ||
d4e67bc5 | 1038 | A float object in case of @code{DBUS_TYPE_UINT32}, |
6f8fc60c MA |
1039 | @code{DBUS_TYPE_INT32}, @code{DBUS_TYPE_UINT64}, |
1040 | @code{DBUS_TYPE_INT64} and @code{DBUS_TYPE_UNIX_FD} is returned, when | |
1041 | the C value exceeds the Emacs number size range. | |
d4e67bc5 | 1042 | |
22d8ac3a MA |
1043 | The resulting list of the last 4 D-Bus compound types contains as |
1044 | elements the elements of the D-Bus container, mapped according to the | |
1045 | same rules. | |
1046 | ||
1047 | The signal @code{PropertyModified}, discussed as example in | |
1048 | @ref{Inspection}, would offer as Lisp data the following object | |
1049 | (@var{BOOL} stands here for either @code{nil} or @code{t}): | |
1050 | ||
1051 | @lisp | |
5bd55c3c | 1052 | (@var{INTEGER} ((@var{STRING} @var{BOOL} @var{BOOL}) (@var{STRING} @var{BOOL} @var{BOOL}) @dots{})) |
22d8ac3a MA |
1053 | @end lisp |
1054 | ||
ace706d1 MA |
1055 | @defun dbus-byte-array-to-string byte-array |
1056 | If a D-Bus method or signal returns an array of bytes, which are known | |
1057 | to represent an UTF8 string, this function converts @var{byte-array} | |
1058 | to the corresponding string. Example: | |
1059 | ||
1060 | @lisp | |
1061 | (dbus-byte-array-to-string '(47 101 116 99 47 104 111 115 116 115)) | |
1062 | ||
1063 | @result{} "/etc/hosts" | |
1064 | @end lisp | |
1065 | @end defun | |
1066 | ||
1067 | @defun dbus-unescape-from-identifier string | |
1068 | Retrieve the original string from the encoded @var{string}. | |
1069 | @var{string} must have been coded with | |
1070 | @code{dbus-escape-as-identifier}. Example: | |
1071 | ||
1072 | @lisp | |
1073 | (dbus-unescape-from-identifier "_30123abc_5fxyz_01_ff") | |
1074 | ||
fa0f81b0 AS |
1075 | @ifinfo |
1076 | @result{} "0123abc_xyz^Aÿ" | |
1077 | @end ifinfo | |
1078 | @ifnotinfo | |
1079 | @result{} "0123abc_xyz^A@"y" | |
1080 | @end ifnotinfo | |
ace706d1 MA |
1081 | @end lisp |
1082 | @end defun | |
1083 | ||
22d8ac3a MA |
1084 | |
1085 | @node Synchronous Methods | |
1086 | @chapter Calling methods in a blocking way. | |
1087 | @cindex method calls, synchronous | |
1088 | @cindex synchronous method calls | |
1089 | ||
1090 | Methods can be called synchronously (@dfn{blocking}) or asynchronously | |
21956b56 | 1091 | (@dfn{non-blocking}). |
22d8ac3a MA |
1092 | |
1093 | At D-Bus level, a method call consist of two messages: one message | |
1094 | which carries the input parameters to the object owning the method to | |
1095 | be called, and a reply message returning the resulting output | |
1096 | parameters from the object. | |
1097 | ||
134ce16c | 1098 | @defun dbus-call-method bus service path interface method &optional :timeout timeout &rest args |
22d8ac3a MA |
1099 | This function calls @var{method} on the D-Bus @var{bus}. @var{bus} is |
1100 | either the symbol @code{:system} or the symbol @code{:session}. | |
1101 | ||
1102 | @var{service} is the D-Bus service name to be used. @var{path} is the | |
1103 | D-Bus object path, @var{service} is registered at. @var{interface} is | |
1104 | an interface offered by @var{service}. It must provide @var{method}. | |
1105 | ||
134ce16c | 1106 | If the parameter @code{:timeout} is given, the following integer |
21956b56 | 1107 | @var{timeout} specifies the maximum number of milliseconds the method |
ecd3d54f | 1108 | call must return. The default value is 25,000. If the method call |
134ce16c MA |
1109 | doesn't return in time, a D-Bus error is raised (@pxref{Errors and |
1110 | Events}). | |
1111 | ||
22d8ac3a MA |
1112 | All other arguments args are passed to @var{method} as arguments. |
1113 | They are converted into D-Bus types as described in @ref{Type | |
1114 | Conversion}. | |
1115 | ||
1116 | The function returns the resulting values of @var{method} as a list of | |
1117 | Lisp objects, according to the type conversion rules described in | |
1118 | @ref{Type Conversion}. Example: | |
1119 | ||
06c0751a | 1120 | @lisp |
22d8ac3a | 1121 | (dbus-call-method |
0ce574ef MA |
1122 | :session "org.gnome.seahorse" "/org/gnome/seahorse/keys/openpgp" |
1123 | "org.gnome.seahorse.Keys" "GetKeyField" | |
22d8ac3a MA |
1124 | "openpgp:657984B8C7A966DD" "simple-name") |
1125 | ||
1126 | @result{} (t ("Philip R. Zimmermann")) | |
06c0751a | 1127 | @end lisp |
22d8ac3a MA |
1128 | |
1129 | If the result of the method call is just one value, the converted Lisp | |
1130 | object is returned instead of a list containing this single Lisp | |
1131 | object. Example: | |
1132 | ||
06c0751a | 1133 | @lisp |
22d8ac3a | 1134 | (dbus-call-method |
0ce574ef MA |
1135 | :system "org.freedesktop.Hal" |
1136 | "/org/freedesktop/Hal/devices/computer" | |
1137 | "org.freedesktop.Hal.Device" "GetPropertyString" | |
22d8ac3a MA |
1138 | "system.kernel.machine") |
1139 | ||
1140 | @result{} "i686" | |
06c0751a | 1141 | @end lisp |
22d8ac3a MA |
1142 | |
1143 | With the @code{dbus-introspect} function it is possible to explore the | |
1144 | interfaces of @samp{org.freedesktop.Hal} service. It offers the | |
1145 | interfaces @samp{org.freedesktop.Hal.Manager} for the object at the | |
1146 | path @samp{/org/freedesktop/Hal/Manager} as well as the interface | |
1147 | @samp{org.freedesktop.Hal.Device} for all objects prefixed with the | |
1148 | path @samp{/org/freedesktop/Hal/devices}. With the methods | |
1149 | @samp{GetAllDevices} and @samp{GetAllProperties}, it is simple to | |
1150 | emulate the @code{lshal} command on GNU/Linux systems: | |
1151 | ||
06c0751a | 1152 | @lisp |
22d8ac3a MA |
1153 | (dolist (device |
1154 | (dbus-call-method | |
0ce574ef | 1155 | :system "org.freedesktop.Hal" |
22d8ac3a | 1156 | "/org/freedesktop/Hal/Manager" |
0ce574ef | 1157 | "org.freedesktop.Hal.Manager" "GetAllDevices")) |
22d8ac3a MA |
1158 | (message "\nudi = %s" device) |
1159 | (dolist (properties | |
1160 | (dbus-call-method | |
0ce574ef MA |
1161 | :system "org.freedesktop.Hal" device |
1162 | "org.freedesktop.Hal.Device" "GetAllProperties")) | |
22d8ac3a MA |
1163 | (message " %s = %S" |
1164 | (car properties) (or (caar (cdr properties)) "")))) | |
1165 | ||
7b13a0f2 | 1166 | @print{} "udi = /org/freedesktop/Hal/devices/computer |
d9e21158 MA |
1167 | info.addons = (\"hald-addon-acpi\") |
1168 | info.bus = \"unknown\" | |
1169 | info.product = \"Computer\" | |
1170 | info.subsystem = \"unknown\" | |
1171 | info.udi = \"/org/freedesktop/Hal/devices/computer\" | |
1172 | linux.sysfs_path_device = \"(none)\" | |
1173 | power_management.acpi.linux.version = \"20051216\" | |
1174 | power_management.can_suspend_to_disk = t | |
1175 | power_management.can_suspend_to_ram = \"\" | |
1176 | power_management.type = \"acpi\" | |
1177 | smbios.bios.release_date = \"11/07/2001\" | |
1178 | system.chassis.manufacturer = \"COMPAL\" | |
1179 | system.chassis.type = \"Notebook\" | |
1180 | system.firmware.release_date = \"03/19/2005\" | |
c9ecb5a7 | 1181 | @dots{}" |
06c0751a | 1182 | @end lisp |
22d8ac3a MA |
1183 | @end defun |
1184 | ||
21956b56 MA |
1185 | @defun dbus-call-method-non-blocking bus service path interface method &optional :timeout timeout &rest args |
1186 | Call @var{method} on the D-Bus @var{bus}, but don't block the event queue. | |
1187 | This is necessary for communicating to registered D-Bus methods, | |
1188 | which are running in the same Emacs process. | |
1189 | ||
1190 | The arguments are the same as in @code{dbus-call-method}. Example: | |
1191 | ||
1192 | @lisp | |
1193 | (dbus-call-method-non-blocking | |
1194 | :system "org.freedesktop.Hal" | |
1195 | "/org/freedesktop/Hal/devices/computer" | |
1196 | "org.freedesktop.Hal.Device" "GetPropertyString" | |
1197 | "system.kernel.machine") | |
1198 | ||
1199 | @result{} "i686" | |
1200 | @end lisp | |
1201 | @end defun | |
1202 | ||
1203 | ||
1204 | @node Asynchronous Methods | |
1205 | @chapter Calling methods non-blocking. | |
1206 | @cindex method calls, asynchronous | |
1207 | @cindex asynchronous method calls | |
1208 | ||
1209 | @defun dbus-call-method-asynchronously bus service path interface method handler &optional :timeout timeout &rest args | |
1210 | This function calls @var{method} on the D-Bus @var{bus} | |
1211 | asynchronously. @var{bus} is either the symbol @code{:system} or the | |
1212 | symbol @code{:session}. | |
1213 | ||
1214 | @var{service} is the D-Bus service name to be used. @var{path} is the | |
1215 | D-Bus object path, @var{service} is registered at. @var{interface} is | |
1216 | an interface offered by @var{service}. It must provide @var{method}. | |
1217 | ||
1218 | @var{handler} is a Lisp function, which is called when the | |
4f22e84d MA |
1219 | corresponding return message has arrived. If @var{handler} is |
1220 | @code{nil}, no return message will be expected. | |
21956b56 MA |
1221 | |
1222 | If the parameter @code{:timeout} is given, the following integer | |
1223 | @var{timeout} specifies the maximum number of milliseconds a reply | |
ecd3d54f | 1224 | message must arrive. The default value is 25,000. If there is no |
21956b56 MA |
1225 | reply message in time, a D-Bus error is raised (@pxref{Errors and |
1226 | Events}). | |
1227 | ||
1228 | All other arguments args are passed to @var{method} as arguments. | |
1229 | They are converted into D-Bus types as described in @ref{Type | |
1230 | Conversion}. | |
1231 | ||
4f22e84d | 1232 | Unless @var{handler} is @code{nil}, the function returns a key into |
0ecd3c90 | 1233 | the hash table @code{dbus-registered-objects-table}. The |
4f22e84d MA |
1234 | corresponding entry in the hash table is removed, when the return |
1235 | message has been arrived, and @var{handler} is called. Example: | |
21956b56 MA |
1236 | |
1237 | @lisp | |
1238 | (dbus-call-method-asynchronously | |
1239 | :system "org.freedesktop.Hal" | |
1240 | "/org/freedesktop/Hal/devices/computer" | |
1241 | "org.freedesktop.Hal.Device" "GetPropertyString" 'message | |
1242 | "system.kernel.machine") | |
1243 | ||
1244 | @result{} (:system 2) | |
1245 | ||
1246 | @print{} i686 | |
1247 | @end lisp | |
1248 | @end defun | |
1249 | ||
22d8ac3a | 1250 | |
addb7f2e MA |
1251 | @node Receiving Method Calls |
1252 | @chapter Offering own methods. | |
1253 | @cindex method calls, returning | |
1254 | @cindex returning method calls | |
1255 | ||
8c904d82 MA |
1256 | In order to register methods on the D-Bus, Emacs has to request a well |
1257 | known name on the D-Bus under which it will be available for other | |
1258 | clients. Names on the D-Bus can be registered and unregistered using | |
1259 | the following functions: | |
1260 | ||
1261 | @defun dbus-register-service bus service &rest flags | |
1262 | Register the known name @var{service} on D-Bus @var{bus}. | |
1263 | ||
1264 | @var{bus} is either the symbol @code{:system} or the symbol | |
1265 | @code{:session}. | |
1266 | ||
1267 | @var{service} is the service name to be registered on the D-Bus. It | |
1268 | must be a known name. | |
1269 | ||
1270 | @var{flags} is a subset of the following keywords: | |
1271 | ||
1272 | @itemize | |
1273 | @item @code{:allow-replacement}: Allow another service to become the primary | |
1274 | owner if requested. | |
1275 | ||
1276 | @item @code{:replace-existing}: Request to replace the current primary owner. | |
1277 | ||
1278 | @item @code{:do-not-queue}: If we can not become the primary owner do not | |
1279 | place us in the queue. | |
1280 | @end itemize | |
1281 | ||
1282 | One of the following keywords is returned: | |
1283 | ||
1284 | @itemize | |
1285 | ||
1286 | @item @code{:primary-owner}: We have become the primary owner of the name | |
1287 | @var{service}. | |
1288 | ||
1289 | @item @code{:in-queue}: We could not become the primary owner and | |
1290 | have been placed in the queue. | |
1291 | ||
1292 | @item @code{:exists}: We already are in the queue. | |
1293 | ||
1294 | @item @code{:already-owner}: We already are the primary | |
1295 | owner. | |
1296 | @end itemize | |
1297 | @end defun | |
1298 | ||
1299 | @defun dbus-unregister-service bus service | |
1300 | Unregister all objects from D-Bus @var{bus}, registered by Emacs for | |
1301 | @var{service}. | |
1302 | ||
1303 | @var{bus} is either the symbol @code{:system} or the symbol | |
1304 | @code{:session}. | |
1305 | ||
1306 | @var{service} is the D-Bus service name of the D-Bus. It must be a | |
1307 | known name. Emacs releases its association to @var{service} from | |
1308 | D-Bus. | |
1309 | ||
1310 | One of the following keywords is returned: | |
1311 | ||
1312 | @itemize | |
1313 | @item @code{:released}: We successfully released the name @var{service}. | |
1314 | @item @code{:non-existent}: The name @var{service} does not exist on the bus. | |
1315 | @item @code{:not-owner}: We are not an owner of the name @var{service}. | |
1316 | @end itemize | |
1317 | @end defun | |
1318 | ||
1319 | When a name has been chosen, Emacs can offer own methods, which can be | |
1320 | called by other applications. These methods could be an | |
1321 | implementation of an interface of a well known service, like | |
1322 | @samp{org.freedesktop.TextEditor}. | |
addb7f2e MA |
1323 | |
1324 | It could be also an implementation of an own interface. In this case, | |
cd71b9ae MA |
1325 | the service name must be @samp{org.gnu.Emacs}. The object path shall |
1326 | begin with @samp{/org/gnu/Emacs/@strong{Application}/}, and the | |
addb7f2e | 1327 | interface name shall be @code{org.gnu.Emacs.@strong{Application}}. |
cd71b9ae | 1328 | @samp{@strong{Application}} is the name of the application which |
addb7f2e MA |
1329 | provides the interface. |
1330 | ||
ace706d1 MA |
1331 | @deffn Constant dbus-service-emacs |
1332 | The well known service name of Emacs. | |
1333 | @end deffn | |
1334 | ||
1335 | @deffn Constant dbus-path-emacs | |
1336 | The object path head "/org/gnu/Emacs" used by Emacs. All object | |
1337 | paths, used by offered methods or signals, shall start with this | |
1338 | string. | |
1339 | @end deffn | |
1340 | ||
0fadf00e | 1341 | @defun dbus-register-method bus service path interface method handler dont-register-service |
addb7f2e MA |
1342 | With this function, an application registers @var{method} on the D-Bus |
1343 | @var{bus}. | |
1344 | ||
1345 | @var{bus} is either the symbol @code{:system} or the symbol | |
1346 | @code{:session}. | |
1347 | ||
1348 | @var{service} is the D-Bus service name of the D-Bus object | |
0fadf00e MA |
1349 | @var{method} is registered for. It must be a known name (See |
1350 | discussion of @var{dont-register-service} below). | |
addb7f2e | 1351 | |
0fadf00e MA |
1352 | @var{path} is the D-Bus object path @var{service} is registered (See |
1353 | discussion of @var{dont-register-service} below). | |
addb7f2e MA |
1354 | |
1355 | @var{interface} is the interface offered by @var{service}. It must | |
1356 | provide @var{method}. | |
1357 | ||
ac134f2f RS |
1358 | @var{handler} is a Lisp function to be called when a @var{method} call |
1359 | is received. It must accept as arguments the input arguments of | |
1360 | @var{method}. @var{handler} should return a list, whose elements are | |
1361 | to be used as arguments for the reply message of @var{method}. This | |
1362 | list can be composed like the input parameters in @ref{Type | |
1363 | Conversion}. | |
1364 | ||
1365 | If @var{handler} wants to return just one Lisp object and it is not a | |
1366 | cons cell, @var{handler} can return this object directly, instead of | |
1367 | returning a list containing the object. | |
addb7f2e | 1368 | |
42fb7e61 MA |
1369 | In case @var{handler} shall return a reply message with an empty |
1370 | argument list, @var{handler} must return the symbol @code{:ignore}. | |
1371 | ||
0fadf00e MA |
1372 | When @var{dont-register-service} is non-@code{nil}, the known name |
1373 | @var{service} is not registered. This means that other D-Bus clients | |
1374 | have no way of noticing the newly registered method. When interfaces | |
1375 | are constructed incrementally by adding single methods or properties | |
8c904d82 | 1376 | at a time, @var{dont-register-service} can be used to prevent other |
0fadf00e MA |
1377 | clients from discovering the still incomplete interface. |
1378 | ||
4a7c4c40 | 1379 | The default D-Bus timeout when waiting for a message reply is 25 |
134ce16c MA |
1380 | seconds. This value could be even smaller, depending on the calling |
1381 | client. Therefore, @var{handler} shall not last longer than | |
4a7c4c40 MA |
1382 | absolutely necessary. |
1383 | ||
9b7993b4 | 1384 | @code{dbus-register-method} returns a Lisp object, which can be used |
addb7f2e MA |
1385 | as argument in @code{dbus-unregister-object} for removing the |
1386 | registration for @var{method}. Example: | |
1387 | ||
06c0751a | 1388 | @lisp |
addb7f2e MA |
1389 | (defun my-dbus-method-handler (filename) |
1390 | (let (result) | |
1391 | (if (find-file filename) | |
1392 | (setq result '(:boolean t)) | |
1393 | (setq result '(:boolean nil))) | |
1394 | result)) | |
1395 | ||
1396 | @result{} my-dbus-method-handler | |
1397 | ||
1398 | (dbus-register-method | |
1399 | :session "org.freedesktop.TextEditor" "/org/freedesktop/TextEditor" | |
1400 | "org.freedesktop.TextEditor" "OpenFile" | |
1401 | 'my-dbus-method-handler) | |
1402 | ||
eb932e8a | 1403 | @result{} ((:session "org.freedesktop.TextEditor" "OpenFile") |
addb7f2e | 1404 | ("org.freedesktop.TextEditor" "/org/freedesktop/TextEditor" |
eb932e8a | 1405 | my-dbus-method-handler)) |
06c0751a | 1406 | @end lisp |
addb7f2e | 1407 | |
cd71b9ae | 1408 | If you invoke the method @samp{org.freedesktop.TextEditor.OpenFile} |
addb7f2e MA |
1409 | from another D-Bus application with a filename as parameter, the file |
1410 | is opened in Emacs, and the method returns either @var{true} or | |
0ecd3c90 | 1411 | @var{false}, indicating the success of the method. As test tool one |
addb7f2e MA |
1412 | could use the command line tool @code{dbus-send} in a shell: |
1413 | ||
1414 | @example | |
1415 | # dbus-send --session --print-reply \ | |
1416 | --dest="org.freedesktop.TextEditor" \ | |
1417 | "/org/freedesktop/TextEditor" \ | |
1418 | "org.freedesktop.TextEditor.OpenFile" string:"/etc/hosts" | |
1419 | ||
1420 | @print{} method return sender=:1.22 -> dest=:1.23 reply_serial=2 | |
eb932e8a MA |
1421 | boolean true |
1422 | @end example | |
1423 | ||
1424 | You can indicate an error by raising the Emacs signal | |
1425 | @code{dbus-error}. The handler above could be changed like this: | |
1426 | ||
1427 | @lisp | |
1428 | (defun my-dbus-method-handler (&rest args) | |
1429 | (unless (and (= (length args) 1) (stringp (car args))) | |
1430 | (signal 'dbus-error (list (format "Wrong argument list: %S" args)))) | |
1431 | (condition-case err | |
1432 | (find-file (car args)) | |
1433 | (error (signal 'dbus-error (cdr err)))) | |
1434 | t) | |
1435 | ||
1436 | @result{} my-dbus-method-handler | |
1437 | @end lisp | |
1438 | ||
1439 | The test runs then | |
1440 | ||
1441 | @example | |
1442 | # dbus-send --session --print-reply \ | |
1443 | --dest="org.freedesktop.TextEditor" \ | |
1444 | "/org/freedesktop/TextEditor" \ | |
1445 | "org.freedesktop.TextEditor.OpenFile" \ | |
1446 | string:"/etc/hosts" string:"/etc/passwd" | |
1447 | ||
1448 | @print{} Error org.freedesktop.DBus.Error.Failed: | |
1449 | Wrong argument list: ("/etc/hosts" "/etc/passwd") | |
addb7f2e MA |
1450 | @end example |
1451 | @end defun | |
1452 | ||
0fadf00e | 1453 | @defun dbus-register-property bus service path interface property access value &optional emits-signal dont-register-service |
0ecd3c90 MA |
1454 | With this function, an application declares a @var{property} on the D-Bus |
1455 | @var{bus}. | |
1456 | ||
1457 | @var{bus} is either the symbol @code{:system} or the symbol | |
1458 | @code{:session}. | |
1459 | ||
1460 | @var{service} is the D-Bus service name of the D-Bus. It must be a | |
1461 | known name. | |
1462 | ||
0fadf00e MA |
1463 | @var{path} is the D-Bus object path @var{service} is registered (See |
1464 | discussion of @var{dont-register-service} below). | |
0ecd3c90 MA |
1465 | |
1466 | @var{interface} is the name of the interface used at @var{path}, | |
1467 | @var{property} is the name of the property of @var{interface}. | |
1468 | ||
1469 | @var{access} indicates, whether the property can be changed by other | |
1470 | services via D-Bus. It must be either the symbol @code{:read} or | |
1471 | @code{:readwrite}. @var{value} is the initial value of the property, | |
1472 | it can be of any valid type (see @code{dbus-call-method} for details). | |
1473 | ||
1474 | If @var{property} already exists on @var{path}, it will be | |
1475 | overwritten. For properties with access type @code{:read} this is the | |
1476 | only way to change their values. Properties with access type | |
1477 | @code{:readwrite} can be changed by @code{dbus-set-property}. | |
1478 | ||
1479 | The interface @samp{org.freedesktop.DBus.Properties} is added to | |
1480 | @var{path}, including a default handler for the @samp{Get}, | |
820ae8fe | 1481 | @samp{GetAll} and @samp{Set} methods of this interface. When |
5bd55c3c MA |
1482 | @var{emits-signal} is non-@code{nil}, the signal |
1483 | @samp{PropertiesChanged} is sent when the property is changed by | |
1484 | @code{dbus-set-property}. | |
820ae8fe | 1485 | |
0fadf00e MA |
1486 | When @var{dont-register-service} is non-@code{nil}, the known name |
1487 | @var{service} is not registered. This means that other D-Bus clients | |
1488 | have no way of noticing the newly registered method. When interfaces | |
1489 | are constructed incrementally by adding single methods or properties | |
8c904d82 | 1490 | at a time, @var{dont-register-service} can be used to prevent other |
0fadf00e MA |
1491 | clients from discovering the still incomplete interface. |
1492 | ||
820ae8fe | 1493 | @noindent Example: |
0ecd3c90 MA |
1494 | |
1495 | @lisp | |
1496 | (dbus-register-property | |
1497 | :session "org.freedesktop.TextEditor" "/org/freedesktop/TextEditor" | |
1498 | "org.freedesktop.TextEditor" "name" :read "GNU Emacs") | |
1499 | ||
1500 | @result{} ((:session "org.freedesktop.TextEditor" "name") | |
1501 | ("org.freedesktop.TextEditor" "/org/freedesktop/TextEditor")) | |
1502 | ||
1503 | (dbus-register-property | |
1504 | :session "org.freedesktop.TextEditor" "/org/freedesktop/TextEditor" | |
820ae8fe | 1505 | "org.freedesktop.TextEditor" "version" :readwrite emacs-version t) |
0ecd3c90 MA |
1506 | |
1507 | @result{} ((:session "org.freedesktop.TextEditor" "version") | |
1508 | ("org.freedesktop.TextEditor" "/org/freedesktop/TextEditor")) | |
1509 | @end lisp | |
1510 | ||
1511 | Other D-Bus applications can read the property via the default methods | |
1512 | @samp{org.freedesktop.DBus.Properties.Get} and | |
1513 | @samp{org.freedesktop.DBus.Properties.GetAll}. Testing is also | |
1514 | possible via the command line tool @code{dbus-send} in a shell: | |
1515 | ||
1516 | @example | |
1517 | # dbus-send --session --print-reply \ | |
1518 | --dest="org.freedesktop.TextEditor" \ | |
1519 | "/org/freedesktop/TextEditor" \ | |
1520 | "org.freedesktop.DBus.Properties.GetAll" \ | |
1521 | string:"org.freedesktop.TextEditor" | |
1522 | ||
1523 | @print{} method return sender=:1.22 -> dest=:1.23 reply_serial=3 | |
1524 | array [ | |
1525 | dict entry( | |
1526 | string "name" | |
1527 | variant string "GNU Emacs" | |
1528 | ) | |
1529 | dict entry( | |
1530 | string "version" | |
1531 | variant string "23.1.50.5" | |
1532 | ) | |
1533 | ] | |
1534 | @end example | |
1535 | ||
1536 | It is also possible, to apply the @code{dbus-get-property}, | |
1537 | @code{dbus-get-all-properties} and @code{dbus-set-property} functions | |
1538 | (@pxref{Properties and Annotations}). | |
1539 | ||
1540 | @lisp | |
1541 | (dbus-set-property | |
1542 | :session "org.freedesktop.TextEditor" "/org/freedesktop/TextEditor" | |
1543 | "org.freedesktop.TextEditor" "version" "23.1.50") | |
1544 | ||
1545 | @result{} "23.1.50" | |
1546 | ||
1547 | (dbus-get-property | |
1548 | :session "org.freedesktop.TextEditor" "/org/freedesktop/TextEditor" | |
1549 | "org.freedesktop.TextEditor" "version") | |
1550 | ||
1551 | @result{} "23.1.50" | |
1552 | @end lisp | |
1553 | @end defun | |
1554 | ||
1555 | @defun dbus-unregister-object object | |
1556 | Unregister @var{object} from the D-Bus. @var{object} must be the | |
1557 | result of a preceding @code{dbus-register-method}, | |
1558 | @code{dbus-register-property} or @code{dbus-register-signal} call | |
1559 | (@pxref{Signals}). It returns @code{t} if @var{object} has been | |
1560 | unregistered, @code{nil} otherwise. | |
1561 | ||
1562 | When @var{object} identifies the last method or property, which is | |
1563 | registered for the respective service, Emacs releases its association | |
1564 | to the service from D-Bus. | |
1565 | @end defun | |
977640ed | 1566 | |
addb7f2e | 1567 | |
22d8ac3a MA |
1568 | @node Signals |
1569 | @chapter Sending and receiving signals. | |
1570 | @cindex signals | |
1571 | ||
1572 | Signals are broadcast messages. They carry input parameters, which | |
1573 | are received by all objects which have registered for such a signal. | |
1574 | ||
0ce574ef | 1575 | @defun dbus-send-signal bus service path interface signal &rest args |
22d8ac3a MA |
1576 | This function is similar to @code{dbus-call-method}. The difference |
1577 | is, that there are no returning output parameters. | |
1578 | ||
1579 | The function emits @var{signal} on the D-Bus @var{bus}. @var{bus} is | |
1580 | either the symbol @code{:system} or the symbol @code{:session}. It | |
1581 | doesn't matter whether another object has registered for @var{signal}. | |
1582 | ||
1583 | @var{service} is the D-Bus service name of the object the signal is | |
1584 | emitted from. @var{path} is the corresponding D-Bus object path, | |
1585 | @var{service} is registered at. @var{interface} is an interface | |
1586 | offered by @var{service}. It must provide @var{signal}. | |
1587 | ||
1588 | All other arguments args are passed to @var{signal} as arguments. | |
1589 | They are converted into D-Bus types as described in @ref{Type | |
1590 | Conversion}. Example: | |
1591 | ||
06c0751a | 1592 | @lisp |
22d8ac3a | 1593 | (dbus-send-signal |
ace706d1 MA |
1594 | :session dbus-service-emacs dbus-path-emacs |
1595 | (concat dbus-service-emacs ".FileManager") "FileModified" | |
1596 | "/home/albinus/.emacs") | |
06c0751a | 1597 | @end lisp |
22d8ac3a MA |
1598 | @end defun |
1599 | ||
9b7993b4 | 1600 | @defun dbus-register-signal bus service path interface signal handler &rest args |
22d8ac3a MA |
1601 | With this function, an application registers for @var{signal} on the |
1602 | D-Bus @var{bus}. | |
1603 | ||
1604 | @var{bus} is either the symbol @code{:system} or the symbol | |
1605 | @code{:session}. | |
1606 | ||
a4397af9 MA |
1607 | @var{service} is the D-Bus service name used by the sending D-Bus |
1608 | object. It can be either a known name or the unique name of the D-Bus | |
1609 | object sending the signal. In case of a unique name, signals won't be | |
1610 | received any longer once the object owning this unique name has | |
1611 | disappeared, and a new queued object has replaced it. | |
1612 | ||
1613 | When @var{service} is @code{nil}, related signals from all D-Bus | |
1614 | objects shall be accepted. | |
1615 | ||
1616 | @var{path} is the corresponding D-Bus object path, @var{service} is | |
1617 | registered at. It can also be @code{nil} if the path name of incoming | |
1618 | signals shall not be checked. | |
1619 | ||
1620 | @var{interface} is an interface offered by @var{service}. It must | |
1621 | provide @var{signal}. | |
22d8ac3a MA |
1622 | |
1623 | @var{handler} is a Lisp function to be called when the @var{signal} is | |
1624 | received. It must accept as arguments the output parameters | |
9b7993b4 MA |
1625 | @var{signal} is sending. |
1626 | ||
1627 | All other arguments @var{args}, if specified, must be strings. They | |
1628 | stand for the respective arguments of @var{signal} in their order, and | |
1629 | are used for filtering as well. A @code{nil} argument might be used | |
1630 | to preserve the order. | |
1631 | ||
1632 | @code{dbus-register-signal} returns a Lisp object, which can be used | |
1633 | as argument in @code{dbus-unregister-object} for removing the | |
1634 | registration for @var{signal}. Example: | |
22d8ac3a | 1635 | |
06c0751a | 1636 | @lisp |
22d8ac3a MA |
1637 | (defun my-dbus-signal-handler (device) |
1638 | (message "Device %s added" device)) | |
1639 | ||
0ce574ef MA |
1640 | @result{} my-dbus-signal-handler |
1641 | ||
22d8ac3a | 1642 | (dbus-register-signal |
0ce574ef MA |
1643 | :system "org.freedesktop.Hal" "/org/freedesktop/Hal/Manager" |
1644 | "org.freedesktop.Hal.Manager" "DeviceAdded" | |
22d8ac3a MA |
1645 | 'my-dbus-signal-handler) |
1646 | ||
cd71c3ef MA |
1647 | @result{} ((:system "org.freedesktop.Hal.Manager" "DeviceAdded") |
1648 | ("org.freedesktop.Hal" "/org/freedesktop/Hal/Manager" | |
1649 | my-signal-handler)) | |
06c0751a | 1650 | @end lisp |
22d8ac3a | 1651 | |
cd71b9ae MA |
1652 | As we know from the introspection data of interface |
1653 | @samp{org.freedesktop.Hal.Manager}, the signal @samp{DeviceAdded} | |
22d8ac3a MA |
1654 | provides one single parameter, which is mapped into a Lisp string. |
1655 | The callback function @code{my-dbus-signal-handler} must define one | |
1656 | single string argument therefore. Plugging an USB device to your | |
cd71b9ae | 1657 | machine, when registered for signal @samp{DeviceAdded}, will show you |
22d8ac3a | 1658 | which objects the GNU/Linux @code{hal} daemon adds. |
22d8ac3a MA |
1659 | @end defun |
1660 | ||
22d8ac3a | 1661 | |
7457f7b6 MA |
1662 | @node Alternative Buses |
1663 | @chapter Alternative buses. | |
1664 | @cindex bus names | |
1665 | @cindex UNIX domain socket | |
1666 | ||
1667 | Until now, we have spoken about the system and the session buses, | |
1668 | which are the default buses to be connected to. However, it is | |
1669 | possible to connect to any bus, from which the address is known. This | |
1670 | is a UNIX domain socket. Everywhere, where a @var{bus} is mentioned | |
1671 | as argument of a function (the symbol @code{:system} or the symbol | |
1672 | @code{:session}), this address can be used instead. The connection to | |
1673 | this bus must be initialized first. | |
1674 | ||
1675 | @defun dbus-init-bus bus | |
1676 | Establish the connection to D-Bus @var{bus}. | |
1677 | ||
1678 | @var{bus} can be either the symbol @code{:system} or the symbol | |
1679 | @code{:session}, or it can be a string denoting the address of the | |
1680 | corresponding bus. For the system and session busses, this function | |
1681 | is called when loading @file{dbus.el}, there is no need to call it | |
1682 | again. | |
1683 | ||
1684 | Example: You open another session bus in a terminal window on your host: | |
1685 | ||
1686 | @example | |
1687 | # eval `dbus-launch --auto-syntax` | |
1688 | # echo $DBUS_SESSION_BUS_ADDRESS | |
1689 | ||
1690 | @print{} unix:abstract=/tmp/dbus-JoFtAVG92w,guid=2f320a1ebe50b7ef58e | |
1691 | @end example | |
1692 | ||
1693 | In Emacs, you can access to this bus via its address: | |
1694 | ||
1695 | @lisp | |
1696 | (setq my-bus | |
1697 | "unix:abstract=/tmp/dbus-JoFtAVG92w,guid=2f320a1ebe50b7ef58e") | |
1698 | ||
1699 | @result{} "unix:abstract=/tmp/dbus-JoFtAVG92w,guid=2f320a1ebe50b7ef58e" | |
1700 | ||
1701 | (dbus-init-bus my-bus) | |
1702 | ||
1703 | @result{} nil | |
1704 | ||
1705 | (dbus-get-unique-name my-bus) | |
1706 | ||
1707 | @result{} ":1.0" | |
1708 | @end lisp | |
1709 | @end defun | |
1710 | ||
1711 | ||
22d8ac3a MA |
1712 | @node Errors and Events |
1713 | @chapter Errors and events. | |
5bd55c3c | 1714 | @cindex debugging |
22d8ac3a MA |
1715 | @cindex errors |
1716 | @cindex events | |
1717 | ||
5bd55c3c MA |
1718 | The internal actions can be traced by running in a debug mode. |
1719 | ||
1720 | @defvar dbus-debug | |
1721 | If this variable is non-@code{nil}, D-Bus specific debug messages are raised. | |
1722 | @end defvar | |
1723 | ||
21956b56 MA |
1724 | Input parameters of @code{dbus-call-method}, |
1725 | @code{dbus-call-method-non-blocking}, | |
1726 | @code{dbus-call-method-asynchronously}, and | |
6a31c819 MA |
1727 | @code{dbus-register-signal} are checked for correct D-Bus types. If |
1728 | there is a type mismatch, the Lisp error @code{wrong-type-argument} | |
1729 | @code{D-Bus ARG} is raised. | |
1730 | ||
22d8ac3a | 1731 | All errors raised by D-Bus are signaled with the error symbol |
d2e4a6c9 MA |
1732 | @code{dbus-error}. If possible, error messages from D-Bus are |
1733 | appended to the @code{dbus-error}. | |
1734 | ||
1735 | @defspec dbus-ignore-errors forms@dots{} | |
1736 | This executes @var{forms} exactly like a @code{progn}, except that | |
1737 | @code{dbus-error} errors are ignored during the @var{forms}. These | |
5bd55c3c | 1738 | errors can be made visible when @code{dbus-debug} is set to @code{t}. |
d2e4a6c9 | 1739 | @end defspec |
22d8ac3a | 1740 | |
5794c2a5 MA |
1741 | Incoming D-Bus messages are handled as Emacs events, see @pxref{Misc |
1742 | Events, , , elisp}. They are retrieved only, when Emacs runs in | |
1743 | interactive mode. The generated event has this form: | |
22d8ac3a | 1744 | |
06c0751a | 1745 | @lisp |
21956b56 MA |
1746 | (dbus-event @var{bus} @var{type} @var{serial} @var{service} @var{path} @var{interface} @var{member} @var{handler} |
1747 | &rest @var{args}) | |
06c0751a | 1748 | @end lisp |
22d8ac3a | 1749 | |
21956b56 | 1750 | @var{bus} identifies the D-Bus the message is coming from. It is |
a4397af9 | 1751 | either the symbol @code{:system} or the symbol @code{:session}. |
22d8ac3a | 1752 | |
21956b56 MA |
1753 | @var{type} is the D-Bus message type which has caused the event. It |
1754 | can be @code{dbus-message-type-invalid}, | |
1755 | @code{dbus-message-type-method-call}, | |
1756 | @code{dbus-message-type-method-return}, | |
1757 | @code{dbus-message-type-error}, or @code{dbus-message-type-signal}. | |
1758 | @var{serial} is the serial number of the received D-Bus message. | |
addb7f2e | 1759 | |
22d8ac3a | 1760 | @var{service} and @var{path} are the unique name and the object path |
addb7f2e MA |
1761 | of the D-Bus object emitting the message. @var{interface} and |
1762 | @var{member} denote the message which has been sent. | |
22d8ac3a | 1763 | |
0ce574ef | 1764 | @var{handler} is the callback function which has been registered for |
addb7f2e | 1765 | this message (see @pxref{Signals}). When a @code{dbus-event} event |
0ce574ef MA |
1766 | arrives, @var{handler} is called with @var{args} as arguments. |
1767 | ||
22d8ac3a MA |
1768 | In order to inspect the @code{dbus-event} data, you could extend the |
1769 | definition of the callback function in @ref{Signals}: | |
1770 | ||
06c0751a | 1771 | @lisp |
22d8ac3a MA |
1772 | (defun my-dbus-signal-handler (&rest args) |
1773 | (message "my-dbus-signal-handler: %S" last-input-event)) | |
06c0751a | 1774 | @end lisp |
22d8ac3a MA |
1775 | |
1776 | There exist convenience functions which could be called inside a | |
1777 | callback function in order to retrieve the information from the event. | |
1778 | ||
1779 | @defun dbus-event-bus-name event | |
22d8ac3a MA |
1780 | Returns the bus name @var{event} is coming from. |
1781 | The result is either the symbol @code{:system} or the symbol @code{:session}. | |
1782 | @end defun | |
1783 | ||
21956b56 MA |
1784 | @defun dbus-event-message-type event |
1785 | Returns the message type of the corresponding D-Bus message. The | |
5bd55c3c | 1786 | result is a natural number. |
21956b56 MA |
1787 | @end defun |
1788 | ||
addb7f2e MA |
1789 | @defun dbus-event-serial-number event |
1790 | Returns the serial number of the corresponding D-Bus message. | |
5bd55c3c | 1791 | The result is a natural number. |
addb7f2e MA |
1792 | @end defun |
1793 | ||
22d8ac3a | 1794 | @defun dbus-event-service-name event |
22d8ac3a MA |
1795 | Returns the unique name of the D-Bus object @var{event} is coming from. |
1796 | @end defun | |
1797 | ||
1798 | @defun dbus-event-path-name event | |
22d8ac3a MA |
1799 | Returns the object path of the D-Bus object @var{event} is coming from. |
1800 | @end defun | |
1801 | ||
1802 | @defun dbus-event-interface-name event | |
74fc5047 | 1803 | Returns the interface name of the D-Bus object @var{event} is coming from. |
22d8ac3a MA |
1804 | @end defun |
1805 | ||
1806 | @defun dbus-event-member-name event | |
74fc5047 | 1807 | Returns the member name of the D-Bus object @var{event} is coming |
22d8ac3a MA |
1808 | from. It is either a signal name or a method name. |
1809 | @end defun | |
1810 | ||
c9ecb5a7 MA |
1811 | D-Bus errors are not propagated during event handling, because it is |
1812 | usually not desired. D-Bus errors in events can be made visible by | |
e7433508 MA |
1813 | setting the variable @code{dbus-debug} to @code{t}. They can also be |
1814 | handled by a hook function. | |
1815 | ||
1816 | @defvar dbus-event-error-hooks | |
1817 | This hook variable keeps a list of functions, which are called when a | |
1818 | D-Bus error happens in the event handler. Every function must accept | |
74fc5047 MA |
1819 | two arguments, the event and the error variable catched in |
1820 | @code{condition-case} by @code{dbus-error}. | |
1821 | ||
1822 | Such functions can be used the adapt the error signal to be raised. | |
1823 | Example: | |
e7433508 MA |
1824 | |
1825 | @lisp | |
74fc5047 MA |
1826 | (defun my-dbus-event-error-handler (event error) |
1827 | (when (string-equal (concat dbus-service-emacs ".FileManager") | |
1828 | (dbus-event-interface-name event)) | |
1829 | (message "my-dbus-event-error-handler: %S %S" event error) | |
1830 | (signal 'file-error (cdr error)))) | |
e7433508 MA |
1831 | |
1832 | (add-hook 'dbus-event-error-hooks 'my-dbus-event-error-handler) | |
1833 | @end lisp | |
1834 | @end defvar | |
c9ecb5a7 | 1835 | |
74fc5047 MA |
1836 | Hook functions shall take into account, that there might be other |
1837 | D-Bus applications running. Therefore, they shall check carefully, | |
1838 | whether a given D-Bus error is related to them. | |
1839 | ||
22d8ac3a | 1840 | |
5bd55c3c MA |
1841 | @node Index |
1842 | @unnumbered Index | |
1843 | ||
1844 | @printindex cp | |
1845 | ||
1846 | ||
22d8ac3a MA |
1847 | @node GNU Free Documentation License |
1848 | @appendix GNU Free Documentation License | |
1849 | @include doclicense.texi | |
1850 | ||
22d8ac3a | 1851 | @bye |