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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 | |
5df4f04c | 9 | Copyright @copyright{} 2007, 2008, 2009, 2010, 2011 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 | ||
0c973505 | 25 | @dircategory Emacs lisp libraries |
22d8ac3a MA |
26 | @direntry |
27 | * D-Bus: (dbus). Using D-Bus in Emacs. | |
28 | @end direntry | |
29 | ||
5dc584b5 | 30 | @contents |
cd71b9ae | 31 | |
977640ed | 32 | |
22d8ac3a MA |
33 | @node Top, Overview, (dir), (dir) |
34 | @top D-Bus integration in Emacs | |
35 | ||
78176e69 MA |
36 | This manual documents an API for usage of D-Bus in Emacs. D-Bus is a |
37 | message bus system, a simple way for applications to talk to one | |
38 | another. An overview of D-Bus can be found at | |
39 | @uref{http://dbus.freedesktop.org/}. | |
22d8ac3a | 40 | |
5dc584b5 | 41 | @ifnottex |
22d8ac3a | 42 | @insertcopying |
5dc584b5 | 43 | @end ifnottex |
22d8ac3a MA |
44 | |
45 | @menu | |
46 | * Overview:: An overview of D-Bus. | |
cd71b9ae | 47 | * Inspection:: Inspection of D-Bus services. |
22d8ac3a MA |
48 | * Type Conversion:: Mapping Lisp types and D-Bus types. |
49 | * Synchronous Methods:: Calling methods in a blocking way. | |
21956b56 | 50 | * Asynchronous Methods:: Calling methods non-blocking. |
addb7f2e | 51 | * Receiving Method Calls:: Offering own methods. |
22d8ac3a MA |
52 | * Signals:: Sending and receiving signals. |
53 | * Errors and Events:: Errors and events. | |
54 | * GNU Free Documentation License:: The license for this documentation. | |
55 | @end menu | |
56 | ||
cd71b9ae | 57 | |
22d8ac3a MA |
58 | @node Overview |
59 | @chapter An overview of D-Bus | |
60 | @cindex overview | |
61 | ||
62 | D-Bus is an inter-process communication mechanism for applications | |
63 | residing on the same host. The communication is based on | |
64 | @dfn{messages}. Data in the messages is carried in a structured way, | |
65 | it is not just a byte stream. | |
66 | ||
67 | The communication is connection oriented to two kinds of message | |
68 | buses: a so called @dfn{system bus}, and a @dfn{session bus}. On a | |
69 | given machine, there is always one single system bus for miscellaneous | |
70 | system-wide communication, like changing of hardware configuration. | |
71 | On the other hand, the session bus is always related to a single | |
72 | user's session. | |
73 | ||
74 | Every client application, which is connected to a bus, registers under | |
75 | a @dfn{unique name} at the bus. This name is used for identifying the | |
76 | client application. Such a unique name starts always with a colon, | |
77 | and looks like @samp{:1.42}. | |
78 | ||
79 | Additionally, a client application can register itself to a so called | |
80 | @dfn{known name}, which is a series of identifiers separated by dots, | |
7ef92bc9 | 81 | as in @samp{org.gnu.Emacs}. If several applications register to the |
22d8ac3a MA |
82 | same known name, these registrations are queued, and only the first |
83 | application which has registered for the known name is reachable via | |
84 | this name. If this application disconnects from the bus, the next | |
85 | queued unique name becomes the owner of this known name. | |
86 | ||
87 | An application can install one or several objects under its name. | |
88 | Such objects are identified by an @dfn{object path}, which looks | |
89 | similar to paths in a filesystem. An example of such an object path | |
90 | could be @samp{/org/gnu/Emacs/}. | |
91 | ||
92 | Applications might send a request to an object, that means sending a | |
93 | message with some data as input parameters, and receiving a message | |
94 | from that object with the result of this message, the output | |
95 | parameters. Such a request is called @dfn{method} in D-Bus. | |
96 | ||
97 | The other form of communication are @dfn{signals}. The underlying | |
98 | message is emitted from an object and will be received by all other | |
99 | applications which have registered for such a signal. | |
100 | ||
101 | All methods and signals an object supports are called @dfn{interface} | |
102 | of the object. Interfaces are specified under a hierarchical name in | |
103 | D-Bus; an object can support several interfaces. Such an interface | |
104 | name could be @samp{org.gnu.Emacs.TextEditor} or | |
105 | @samp{org.gnu.Emacs.FileManager}. | |
106 | ||
107 | ||
108 | @node Inspection | |
cd71b9ae | 109 | @chapter Inspection of D-Bus services. |
22d8ac3a MA |
110 | @cindex inspection |
111 | ||
cd71b9ae MA |
112 | @menu |
113 | * Bus names:: Discovering D-Bus names. | |
114 | * Introspection:: Knowing the details of D-Bus services. | |
115 | * Nodes and Interfaces:: Detecting object paths and interfaces. | |
116 | * Methods and Signal:: Applying the functionality. | |
117 | * Properties and Annotations:: What else to know about interfaces. | |
118 | * Arguments and Signatures:: The final details. | |
119 | @end menu | |
120 | ||
121 | ||
122 | @node Bus names | |
123 | @section Bus names. | |
124 | ||
22d8ac3a MA |
125 | There are several basic functions which inspect the buses for |
126 | registered names. Internally they use the basic interface | |
127 | @samp{org.freedesktop.DBus}, which is supported by all objects of a bus. | |
128 | ||
129 | @defun dbus-list-activatable-names | |
22d8ac3a MA |
130 | This function returns the D-Bus service names, which can be activated. |
131 | An activatable service is described in a service registration file. | |
132 | Under GNU/Linux, such files are located at | |
133 | @file{/usr/share/dbus-1/services/}. | |
134 | ||
135 | The result is a list of strings, which is @code{nil} when there are no | |
136 | activatable service names at all. | |
137 | @end defun | |
138 | ||
139 | @defun dbus-list-names bus | |
22d8ac3a MA |
140 | All service names, which are registered at D-Bus @var{bus}, are |
141 | returned. The result is a list of strings, which is @code{nil} when | |
142 | there are no registered service names at all. Well known names are | |
143 | strings like @samp{org.freedesktop.DBus}. Names starting with | |
144 | @samp{:} are unique names for services. | |
145 | ||
146 | @var{bus} must be either the symbol @code{:system} or the symbol | |
147 | @code{:session}. | |
148 | @end defun | |
149 | ||
150 | @defun dbus-list-known-names bus | |
22d8ac3a MA |
151 | Retrieves all services which correspond to a known name in @var{bus}. |
152 | A service has a known name if it doesn't start with @samp{:}. The | |
153 | result is a list of strings, which is @code{nil} when there are no | |
154 | known names at all. | |
155 | ||
156 | @var{bus} must be either the symbol @code{:system} or the symbol | |
157 | @code{:session}. | |
158 | @end defun | |
159 | ||
160 | @defun dbus-list-queued-owners bus service | |
22d8ac3a MA |
161 | For a given service, registered at D-Bus @var{bus} under the name |
162 | @var{service}, all queued unique names are returned. The result is a | |
163 | list of strings, or @code{nil} when there are no queued names for | |
164 | @var{service} at all. | |
165 | ||
166 | @var{bus} must be either the symbol @code{:system} or the symbol | |
167 | @code{:session}. @var{service} must be a known service name as | |
168 | string. | |
169 | @end defun | |
170 | ||
171 | @defun dbus-get-name-owner bus service | |
22d8ac3a | 172 | For a given service, registered at D-Bus @var{bus} under the name |
06c0751a MA |
173 | @var{service}, the unique name of the name owner is returned. The |
174 | result is a string, or @code{nil} when there exist no name owner of | |
175 | @var{service}. | |
22d8ac3a MA |
176 | |
177 | @var{bus} must be either the symbol @code{:system} or the symbol | |
178 | @code{:session}. @var{service} must be a known service name as | |
179 | string. | |
180 | @end defun | |
181 | ||
ecd3d54f | 182 | @defun dbus-ping bus service &optional timeout |
06c0751a | 183 | Check whether the service name @var{service} is registered at D-Bus |
ecd3d54f MA |
184 | @var{bus}. @var{service} might not have been started yet, it is |
185 | autostarted if possible. The result is either @code{t} or @code{nil}. | |
06c0751a MA |
186 | |
187 | @var{bus} must be either the symbol @code{:system} or the symbol | |
ecd3d54f MA |
188 | @code{:session}. @var{service} must be a string. @var{timeout}, a |
189 | nonnegative integer, specifies the maximum number of milliseconds | |
190 | @code{dbus-ping} must return. The default value is 25,000. Example: | |
06c0751a MA |
191 | |
192 | @lisp | |
193 | (message | |
194 | "%s screensaver on board." | |
195 | (cond | |
ecd3d54f MA |
196 | ((dbus-ping :session "org.gnome.ScreenSaver" 100) "Gnome") |
197 | ((dbus-ping :session "org.freedesktop.ScreenSaver" 100) "KDE") | |
06c0751a MA |
198 | (t "No"))) |
199 | @end lisp | |
ecd3d54f MA |
200 | |
201 | If it shall be checked whether @var{service} is already running | |
202 | without autostarting it, one shall apply | |
203 | ||
204 | @lisp | |
205 | (member service (dbus-list-known-names bus)) | |
206 | @end lisp | |
06c0751a MA |
207 | @end defun |
208 | ||
22d8ac3a | 209 | @defun dbus-get-unique-name bus |
22d8ac3a MA |
210 | The unique name, under which Emacs is registered at D-Bus @var{bus}, |
211 | is returned as string. | |
212 | ||
213 | @var{bus} must be either the symbol @code{:system} or the symbol | |
214 | @code{:session}. | |
215 | @end defun | |
216 | ||
cd71b9ae MA |
217 | |
218 | @node Introspection | |
219 | @section Knowing the details of D-Bus services. | |
220 | ||
221 | D-Bus services publish their interfaces. This can be retrieved and | |
222 | analyzed during runtime, in order to understand the used | |
223 | implementation. | |
224 | ||
225 | The resulting introspection data are in XML format. The root | |
226 | introspection element is always a @code{node} element. It might have | |
227 | a @code{name} attribute, which denotes the (absolute) object path an | |
228 | interface is introspected. | |
229 | ||
230 | The root @code{node} element may have @code{node} and @code{interface} | |
231 | children. A child @code{node} element must have a @code{name} | |
232 | attribute, this case it is the relative object path to the root | |
233 | @code{node} element. | |
234 | ||
235 | An @code{interface} element has just one attribute, @code{name}, which | |
236 | is the full name of that interface. The default interface | |
237 | @samp{org.freedesktop.DBus.Introspectable} is always present. Example: | |
238 | ||
239 | @example | |
240 | <node name="/org/bluez"> | |
241 | <interface name="org.freedesktop.DBus.Introspectable"> | |
242 | @dots{} | |
243 | </interface> | |
244 | <interface name="org.bluez.Manager"> | |
245 | @dots{} | |
246 | </interface> | |
247 | <interface name="org.bluez.Database"> | |
248 | @dots{} | |
249 | </interface> | |
250 | <interface name="org.bluez.Security"> | |
251 | @dots{} | |
252 | </interface> | |
253 | <node name="service_audio"/> | |
254 | <node name="service_input"/> | |
255 | <node name="service_network"/> | |
256 | <node name="service_serial"/> | |
257 | </node> | |
258 | @end example | |
259 | ||
260 | Children of an @code{interface} element can be @code{method}, | |
261 | @code{signal} and @code{property} elements. A @code{method} element | |
262 | stands for a D-Bus method of the surrounding interface. The element | |
263 | itself has a @code{name} attribute, showing the method name. Children | |
264 | elements @code{arg} stand for the arguments of a method. Example: | |
265 | ||
266 | @example | |
267 | <method name="ResolveHostName"> | |
268 | <arg name="interface" type="i" direction="in"/> | |
269 | <arg name="protocol" type="i" direction="in"/> | |
270 | <arg name="name" type="s" direction="in"/> | |
271 | <arg name="aprotocol" type="i" direction="in"/> | |
272 | <arg name="flags" type="u" direction="in"/> | |
273 | <arg name="interface" type="i" direction="out"/> | |
274 | <arg name="protocol" type="i" direction="out"/> | |
275 | <arg name="name" type="s" direction="out"/> | |
276 | <arg name="aprotocol" type="i" direction="out"/> | |
277 | <arg name="address" type="s" direction="out"/> | |
278 | <arg name="flags" type="u" direction="out"/> | |
279 | </method> | |
280 | @end example | |
281 | ||
282 | @code{arg} elements can have the attributes @code{name}, @code{type} | |
283 | and @code{direction}. The @code{name} attribute is optional. The | |
284 | @code{type} attribute stands for the @dfn{signature} of the argument | |
285 | in D-Bus. For a discussion of D-Bus types and their Lisp | |
286 | representation see @ref{Type Conversion}.@footnote{D-Bus signatures | |
287 | are explained in the D-Bus specification | |
288 | @uref{http://dbus.freedesktop.org/doc/dbus-specification.html#message-protocol-signatures}.} | |
289 | The @code{direction} attribute of an @code{arg} element can be only | |
290 | @samp{in} or @samp{out}; in case it is omitted, it defaults to | |
291 | @samp{in}. | |
292 | ||
293 | A @code{signal} element of an @code{interface} has a similar | |
294 | structure. The @code{direction} attribute of an @code{arg} child | |
295 | element can be only @samp{out} here; which is also the default value. | |
296 | Example: | |
297 | ||
298 | @example | |
299 | <signal name="StateChanged"> | |
300 | <arg name="state" type="i"/> | |
301 | <arg name="error" type="s"/> | |
302 | </signal> | |
303 | @end example | |
304 | ||
305 | A @code{property} element has no @code{arg} child | |
306 | element. It just has the attributes @code{name}, @code{type} and | |
307 | @code{access}, which are all mandatory. The @code{access} attribute | |
308 | allows the values @samp{readwrite}, @samp{read}, and @samp{write}. | |
309 | Example: | |
310 | ||
311 | @example | |
312 | <property name="Status" type="u" direction="read"/> | |
313 | @end example | |
314 | ||
315 | @code{annotation} elements can be children of @code{interface}, | |
316 | @code{method}, @code{signal}, and @code{property} elements. Unlike | |
317 | properties, which can change their values during lifetime of a D-Bus | |
318 | object, annotations are static. Often they are used for code | |
319 | generators of D-Bus langugae bindings. Example: | |
320 | ||
321 | @example | |
322 | <annotation name="de.berlios.Pinot.GetStatistics" value="pinotDBus"/> | |
323 | @end example | |
324 | ||
325 | Annotations have just @code{name} and @code{value} attributes, both | |
326 | must be strings. | |
327 | ||
22d8ac3a | 328 | @defun dbus-introspect bus service path |
cd71b9ae MA |
329 | This function returns all interfaces and sub-nodes of @var{service}, |
330 | registered at object path @var{path} at bus @var{bus}. | |
22d8ac3a MA |
331 | |
332 | @var{bus} must be either the symbol @code{:system} or the symbol | |
333 | @code{:session}. @var{service} must be a known service name, and | |
334 | @var{path} must be a valid object path. The last two parameters are | |
335 | strings. The result, the introspection data, is a string in XML | |
cd71b9ae | 336 | format. Example: |
22d8ac3a | 337 | |
06c0751a | 338 | @lisp |
22d8ac3a MA |
339 | (dbus-introspect |
340 | :system "org.freedesktop.Hal" | |
341 | "/org/freedesktop/Hal/devices/computer") | |
342 | ||
d9e21158 | 343 | @result{} "<!DOCTYPE node PUBLIC |
cd71b9ae MA |
344 | "-//freedesktop//DTD D-BUS Object Introspection 1.0//EN" |
345 | "http://www.freedesktop.org/standards/dbus/1.0/introspect.dtd"> | |
d9e21158 | 346 | <node> |
cd71b9ae MA |
347 | <interface name="org.freedesktop.Hal.Device"> |
348 | <method name="GetAllProperties"> | |
349 | <arg name="properties" direction="out" type="a@{sv@}"/> | |
d9e21158 | 350 | </method> |
c9ecb5a7 | 351 | @dots{} |
cd71b9ae MA |
352 | <signal name="PropertyModified"> |
353 | <arg name="num_updates" type="i"/> | |
354 | <arg name="updates" type="a(sbb)"/> | |
d9e21158 MA |
355 | </signal> |
356 | </interface> | |
c9ecb5a7 | 357 | @dots{} |
d9e21158 | 358 | </node>" |
06c0751a | 359 | @end lisp |
22d8ac3a | 360 | |
cd71b9ae MA |
361 | This example informs us, that the service @samp{org.freedesktop.Hal} |
362 | at object path @samp{/org/freedesktop/Hal/devices/computer} offers the | |
363 | interface @samp{org.freedesktop.Hal.Device} (and 2 other interfaces | |
22d8ac3a | 364 | not documented here). This interface contains the method |
cd71b9ae | 365 | @samp{GetAllProperties}, which needs no input parameters, but returns |
22d8ac3a MA |
366 | as output parameter an array of dictionary entries (key-value pairs). |
367 | Every dictionary entry has a string as key, and a variant as value. | |
368 | ||
369 | The interface offers also a signal, which returns 2 parameters: an | |
370 | integer, and an array consisting of elements which are a struct of a | |
cd71b9ae MA |
371 | string and 2 boolean values.@footnote{ The interfaces of the service |
372 | @samp{org.freedesktop.Hal} are described at | |
22d8ac3a MA |
373 | @uref{http://people.freedesktop.org/~david/hal-spec/hal-spec.html#interfaces}.} |
374 | @end defun | |
375 | ||
cd71b9ae MA |
376 | @defun dbus-introspect-xml bus service path |
377 | This function has the same intention as function | |
378 | @code{dbus-introspect}. The returned value is a parsed XML tree, | |
379 | which can be used for further analysis. Example: | |
380 | ||
381 | @lisp | |
382 | (dbus-introspect-xml | |
383 | :session "org.freedesktop.xesam.searcher" | |
384 | "/org/freedesktop/xesam/searcher/main") | |
385 | ||
386 | @result{} (node ((name . "/org/freedesktop/xesam/searcher/main")) | |
387 | (interface ((name . "org.freedesktop.xesam.Search")) | |
388 | (method ((name . "GetHitData")) | |
389 | (arg ((name . "search") (type . "s") (direction . "in"))) | |
390 | (arg ((name . "hit_ids") (type . "au") (direction . "in"))) | |
391 | (arg ((name . "fields") (type . "as") (direction . "in"))) | |
392 | (arg ((name . "hit_data") (type . "aav") (direction . "out"))) | |
393 | ) | |
394 | @dots{} | |
395 | (signal ((name . "HitsAdded")) | |
396 | (arg ((name . "search") (type . "s"))) | |
397 | (arg ((name . "count") (type . "u"))) | |
398 | ) | |
399 | ) | |
400 | @dots{} | |
401 | ) | |
402 | @end lisp | |
403 | @end defun | |
404 | ||
405 | @defun dbus-introspect-get-attribute object attribute | |
406 | It returns the @var{attribute} value of a D-Bus introspection | |
407 | @var{object}. @var{object} can be every subtree of a parsed XML tree | |
408 | as retrieved with @code{dbus-introspect-xml}. @var{attribute} must be | |
409 | a string according to the attribute names in the D-Bus specification. | |
410 | Example: | |
411 | ||
412 | @lisp | |
413 | (dbus-introspect-get-attribute | |
414 | (dbus-introspect-xml :system "org.freedesktop.SystemToolsBackends" | |
415 | "/org/freedesktop/SystemToolsBackends/UsersConfig") | |
416 | "name") | |
417 | ||
418 | @result{} "/org/freedesktop/SystemToolsBackends/UsersConfig" | |
419 | @end lisp | |
420 | ||
421 | If @var{object} has no @var{attribute}, the function returns nil. | |
422 | @end defun | |
423 | ||
424 | ||
425 | @node Nodes and Interfaces | |
426 | @section Detecting object paths and interfaces. | |
427 | ||
428 | The first elements, to be introspected for a D-Bus object, are further | |
429 | object paths and interfaces. | |
430 | ||
431 | @defun dbus-introspect-get-node-names bus service path | |
432 | All node names of @var{service} in D-Bus @var{bus} at object path | |
433 | @var{path} are returned as list of strings. Example: | |
434 | ||
435 | @lisp | |
436 | (dbus-introspect-get-node-names | |
437 | :session "org.gnome.seahorse" "/org/gnome/seahorse") | |
438 | ||
439 | @result{} ("crypto" "keys") | |
440 | @end lisp | |
441 | ||
442 | The node names stand for further object paths of the D-Bus | |
443 | @var{service}, relative to @var{path}. In the example, | |
444 | @samp{/org/gnome/seahorse/crypto} and @samp{/org/gnome/seahorse/keys} | |
445 | are also object paths of the D-Bus service @samp{org.gnome.seahorse}. | |
446 | @end defun | |
447 | ||
448 | @defun dbus-introspect-get-all-nodes bus service path | |
449 | This function returns all node names of @var{service} in D-Bus | |
450 | @var{bus} at object path @var{path}. It returns a list of strings | |
451 | with all object paths of @var{service}, starting at @var{path}. | |
452 | Example: | |
453 | ||
454 | @lisp | |
455 | (dbus-introspect-get-all-nodes :session "org.gnome.seahorse" "/") | |
456 | ||
457 | @result{} ("/" "/org" "/org/gnome" "/org/gnome/seahorse" | |
458 | "/org/gnome/seahorse/crypto" | |
459 | "/org/gnome/seahorse/keys" | |
460 | "/org/gnome/seahorse/keys/openpgp" | |
461 | "/org/gnome/seahorse/keys/openpgp/local" | |
462 | "/org/gnome/seahorse/keys/openssh" | |
463 | "/org/gnome/seahorse/keys/openssh/local") | |
464 | @end lisp | |
465 | @end defun | |
466 | ||
467 | @defun dbus-introspect-get-interface-names bus service path | |
468 | There will be returned a list strings of all interface names of | |
469 | @var{service} in D-Bus @var{bus} at object path @var{path}. This list | |
470 | will contain the default interface @samp{org.freedesktop.DBus.Introspectable}. | |
471 | ||
472 | Another default interface is @samp{org.freedesktop.DBus.Properties}. | |
473 | If present, @code{interface} elements can also have @code{property} | |
474 | children. Example: | |
475 | ||
476 | @lisp | |
477 | (dbus-introspect-get-interface-names | |
478 | :system "org.freedesktop.Hal" | |
479 | "/org/freedesktop/Hal/devices/computer") | |
480 | ||
481 | @result{} ("org.freedesktop.DBus.Introspectable" | |
482 | "org.freedesktop.Hal.Device" | |
483 | "org.freedesktop.Hal.Device.SystemPowerManagement" | |
484 | "org.freedesktop.Hal.Device.CPUFreq") | |
485 | @end lisp | |
486 | @end defun | |
487 | ||
488 | @defun dbus-introspect-get-interface bus service path interface | |
489 | Return @var{interface} of @var{service} in D-Bus @var{bus} at object | |
490 | path @var{path}. The return value is an XML element. @var{interface} | |
491 | must be a string, element of the list returned by | |
492 | @code{dbus-introspect-get-interface-names}. Example: | |
493 | ||
494 | @lisp | |
495 | (dbus-introspect-get-interface | |
496 | :session "org.freedesktop.xesam.searcher" | |
497 | "/org/freedesktop/xesam/searcher/main" | |
498 | "org.freedesktop.xesam.Search") | |
499 | ||
500 | @result{} (interface ((name . "org.freedesktop.xesam.Search")) | |
501 | (method ((name . "GetHitData")) | |
502 | (arg ((name . "search") (type . "s") (direction . "in"))) | |
503 | (arg ((name . "hit_ids") (type . "au") (direction . "in"))) | |
504 | (arg ((name . "fields") (type . "as") (direction . "in"))) | |
505 | (arg ((name . "hit_data") (type . "aav") (direction . "out"))) | |
506 | ) | |
507 | @dots{} | |
508 | (signal ((name . "HitsAdded")) | |
509 | (arg ((name . "search") (type . "s"))) | |
510 | (arg ((name . "count") (type . "u"))) | |
511 | ) | |
512 | ) | |
513 | @end lisp | |
514 | @end defun | |
515 | ||
516 | @noindent | |
517 | With these functions, it is possible to retrieve all introspection | |
518 | data from a running system: | |
519 | ||
520 | @lisp | |
521 | (with-current-buffer (switch-to-buffer "*introspect*") | |
522 | (erase-buffer) | |
523 | (dolist (service (dbus-list-known-names :session)) | |
524 | (dolist (path (dbus-introspect-get-all-nodes :session service "/")) | |
525 | ;; We want to introspect only elements, which have more than | |
526 | ;; the default interface "org.freedesktop.DBus.Introspectable". | |
527 | (when (delete | |
528 | "org.freedesktop.DBus.Introspectable" | |
529 | (dbus-introspect-get-interface-names :session service path)) | |
530 | (insert (message "\nservice: \"%s\" path: \"%s\"\n" service path) | |
531 | (dbus-introspect :session service path)) | |
532 | (redisplay t))))) | |
533 | @end lisp | |
534 | ||
535 | ||
536 | @node Methods and Signal | |
537 | @section Applying the functionality. | |
538 | ||
539 | Methods and signals are the communicatione means to D-Bus. The | |
540 | following functions return their specifications. | |
541 | ||
542 | @defun dbus-introspect-get-method-names bus service path interface | |
543 | Return a list of strings of all method names of @var{interface} of | |
544 | @var{service} in D-Bus @var{bus} at object path @var{path}. Example: | |
545 | ||
546 | @lisp | |
547 | (dbus-introspect-get-method-names | |
548 | :session "org.freedesktop.xesam.searcher" | |
549 | "/org/freedesktop/xesam/searcher/main" | |
550 | "org.freedesktop.xesam.Search") | |
551 | ||
552 | @result{} ("GetState" "StartSearch" "GetHitCount" "GetHits" "NewSession" | |
553 | "CloseSession" "GetHitData" "SetProperty" "NewSearch" | |
554 | "GetProperty" "CloseSearch") | |
555 | @end lisp | |
556 | @end defun | |
557 | ||
558 | @defun dbus-introspect-get-method bus service path interface method | |
559 | This function returns @var{method} of @var{interface} as XML element. | |
560 | It must be located at @var{service} in D-Bus @var{bus} at object path | |
561 | @var{path}. @var{method} must be a string, element of the list | |
562 | returned by @code{dbus-introspect-get-method-names}. Example: | |
563 | ||
564 | @lisp | |
565 | (dbus-introspect-get-method | |
566 | :session "org.freedesktop.xesam.searcher" | |
567 | "/org/freedesktop/xesam/searcher/main" | |
568 | "org.freedesktop.xesam.Search" "GetHitData") | |
569 | ||
570 | @result{} (method ((name . "GetHitData")) | |
571 | (arg ((name . "search") (type . "s") (direction . "in"))) | |
572 | (arg ((name . "hit_ids") (type . "au") (direction . "in"))) | |
573 | (arg ((name . "fields") (type . "as") (direction . "in"))) | |
574 | (arg ((name . "hit_data") (type . "aav") (direction . "out"))) | |
575 | ) | |
576 | @end lisp | |
577 | @end defun | |
578 | ||
579 | @defun dbus-introspect-get-signal-names bus service path interface | |
580 | Return a list of strings of all signal names of @var{interface} of | |
581 | @var{service} in D-Bus @var{bus} at object path @var{path}. Example: | |
582 | ||
583 | @lisp | |
584 | (dbus-introspect-get-signal-names | |
585 | :session "org.freedesktop.xesam.searcher" | |
586 | "/org/freedesktop/xesam/searcher/main" | |
587 | "org.freedesktop.xesam.Search") | |
588 | ||
589 | @result{} ("StateChanged" "SearchDone" "HitsModified" | |
590 | "HitsRemoved" "HitsAdded") | |
591 | @end lisp | |
592 | @end defun | |
593 | ||
594 | @defun dbus-introspect-get-signal bus service path interface signal | |
595 | This function returns @var{signal} of @var{interface} as XML element. | |
596 | It must be located at @var{service} in D-Bus @var{bus} at object path | |
597 | @var{path}. @var{signal} must be a string, element of the list | |
598 | returned by @code{dbus-introspect-get-signal-names}. Example: | |
599 | ||
600 | @lisp | |
601 | (dbus-introspect-get-signal | |
602 | :session "org.freedesktop.xesam.searcher" | |
603 | "/org/freedesktop/xesam/searcher/main" | |
604 | "org.freedesktop.xesam.Search" "HitsAdded") | |
605 | ||
606 | @result{} (signal ((name . "HitsAdded")) | |
607 | (arg ((name . "search") (type . "s"))) | |
608 | (arg ((name . "count") (type . "u"))) | |
609 | ) | |
610 | @end lisp | |
611 | @end defun | |
612 | ||
613 | ||
614 | @node Properties and Annotations | |
615 | @section What else to know about interfaces. | |
616 | ||
617 | Interfaces can have properties. These can be exposed via the | |
618 | @samp{org.freedesktop.DBus.Properties} interface@footnote{See | |
619 | @uref{http://dbus.freedesktop.org/doc/dbus-specification.html#standard-interfaces-properties}}. | |
620 | That is, properties can be retrieved and changed during lifetime of an | |
621 | element. | |
622 | ||
623 | Annotations, on the other hand, are static values for an element. | |
624 | Often, they are used to instruct generators, how to generate code from | |
625 | the interface for a given language binding. | |
626 | ||
627 | @defun dbus-introspect-get-property-names bus service path interface | |
628 | Return a list of strings with all property names of @var{interface} of | |
629 | @var{service} in D-Bus @var{bus} at object path @var{path}. Example: | |
630 | ||
631 | @lisp | |
632 | (dbus-introspect-get-property-names | |
633 | :session "org.kde.kded" "/modules/networkstatus" | |
634 | "org.kde.Solid.Networking.Client") | |
635 | ||
636 | @result{} ("Status") | |
637 | @end lisp | |
638 | ||
639 | If an interface declares properties, the corresponding element supports | |
640 | also the @samp{org.freedesktop.DBus.Properties} interface. | |
641 | @end defun | |
642 | ||
643 | @defun dbus-introspect-get-property bus service path interface property | |
644 | This function returns @var{property} of @var{interface} as XML element. | |
645 | It must be located at @var{service} in D-Bus @var{bus} at object path | |
646 | @var{path}. @var{property} must be a string, element of the list | |
647 | returned by @code{dbus-introspect-get-property-names}. | |
648 | ||
649 | A @var{property} value can be retrieved by the function | |
650 | @code{dbus-introspect-get-attribute}. Example: | |
651 | ||
652 | @lisp | |
653 | (dbus-introspect-get-property | |
654 | :session "org.kde.kded" "/modules/networkstatus" | |
655 | "org.kde.Solid.Networking.Client" "Status") | |
656 | ||
657 | @result{} (property ((access . "read") (type . "u") (name . "Status"))) | |
658 | ||
659 | (dbus-introspect-get-attribute | |
660 | (dbus-introspect-get-property | |
661 | :session "org.kde.kded" "/modules/networkstatus" | |
662 | "org.kde.Solid.Networking.Client" "Status") | |
663 | "access") | |
664 | ||
665 | @result{} "read" | |
666 | @end lisp | |
667 | @end defun | |
668 | ||
669 | @defun dbus-get-property bus service path interface property | |
670 | This function returns the value of @var{property} of @var{interface}. | |
671 | It will be checked at @var{bus}, @var{service}, @var{path}. The | |
672 | result can be any valid D-Bus value, or nil if there is no | |
673 | @var{property}. Example: | |
674 | ||
675 | @lisp | |
676 | (dbus-get-property | |
677 | :session "org.kde.kded" "/modules/networkstatus" | |
678 | "org.kde.Solid.Networking.Client" "Status") | |
679 | ||
680 | @result{} 4 | |
681 | @end lisp | |
682 | @end defun | |
683 | ||
684 | @defun dbus-set-property bus service path interface property value | |
685 | Set value of @var{property} of @var{interface} to @var{value}. It | |
686 | will be checked at @var{bus}, @var{service}, @var{path}. When the | |
687 | value has been set successful, the result is @var{value}. Otherwise, | |
688 | @code{nil} is returned. Example: | |
689 | ||
690 | @lisp | |
691 | (dbus-set-property | |
692 | :session "org.kde.kaccess" "/MainApplication" | |
693 | "com.trolltech.Qt.QApplication" "doubleClickInterval" 500) | |
694 | ||
695 | @result{} 500 | |
696 | @end lisp | |
697 | @end defun | |
698 | ||
699 | @defun dbus-get-all-properties bus service path interface | |
700 | This function returns all properties of @var{interface}. It will be | |
701 | checked at @var{bus}, @var{service}, @var{path}. The result is a list | |
702 | of cons. Every cons contains the name of the property, and its value. | |
703 | If there are no properties, @code{nil} is returned. Example: | |
704 | ||
705 | @lisp | |
706 | (dbus-get-all-properties | |
707 | :session "org.kde.kaccess" "/MainApplication" | |
708 | "com.trolltech.Qt.QApplication") | |
709 | ||
710 | @result{} (("cursorFlashTime" . 1000) ("doubleClickInterval" . 500) | |
711 | ("keyboardInputInterval" . 400) ("wheelScrollLines" . 3) | |
712 | ("globalStrut" 0 0) ("startDragTime" . 500) | |
713 | ("startDragDistance" . 4) ("quitOnLastWindowClosed" . t) | |
714 | ("styleSheet" . "")) | |
715 | @end lisp | |
716 | @end defun | |
717 | ||
718 | @defun dbus-introspect-get-annotation-names bus service path interface &optional name | |
719 | Return a list of all annotation names as list of strings. If | |
720 | @var{name} is @code{nil}, the annotations are children of | |
721 | @var{interface}, otherwise @var{name} must be a @code{method}, | |
722 | @code{signal}, or @code{property} XML element, where the annotations | |
723 | belong to. Example: | |
724 | ||
725 | @lisp | |
726 | (dbus-introspect-get-annotation-names | |
727 | :session "de.berlios.Pinot" "/de/berlios/Pinot" | |
728 | "de.berlios.Pinot" "GetStatistics") | |
729 | ||
730 | @result{} ("de.berlios.Pinot.GetStatistics") | |
731 | @end lisp | |
732 | ||
733 | Default annotation names@footnote{See | |
734 | @uref{http://dbus.freedesktop.org/doc/dbus-specification.html#introspection-format}} | |
735 | are | |
736 | ||
737 | @table @samp | |
738 | @item org.freedesktop.DBus.Deprecated | |
739 | Whether or not the entity is deprecated; defaults to @code{nil} | |
740 | ||
741 | @item org.freedesktop.DBus.GLib.CSymbol | |
742 | The C symbol; may be used for @code{methods} and @code{interfaces} | |
743 | ||
744 | @item org.freedesktop.DBus.Method.NoReply | |
745 | If set, don't expect a reply to the @code{method} call; defaults to @code{nil} | |
746 | @end table | |
747 | @end defun | |
748 | ||
749 | @defun dbus-introspect-get-annotation bus service path interface name annotation | |
750 | Return annotation @var{ANNOTATION} as XML object. If @var{name} is | |
751 | @code{nil}, @var{ANNOTATION} is a child of @var{interface}, otherwise | |
752 | @var{name} must be the name of a @code{method}, @code{signal}, or | |
753 | @code{property} XML element, where the @var{ANNOTATION} belongs to. | |
754 | ||
755 | An attribute value can be retrieved by | |
756 | @code{dbus-introspect-get-attribute}. Example: | |
757 | ||
758 | @lisp | |
759 | (dbus-introspect-get-annotation | |
760 | :session "de.berlios.Pinot" "/de/berlios/Pinot" | |
761 | "de.berlios.Pinot" "GetStatistics" | |
762 | "de.berlios.Pinot.GetStatistics") | |
763 | ||
764 | @result{} (annotation ((name . "de.berlios.Pinot.GetStatistics") | |
765 | (value . "pinotDBus"))) | |
766 | ||
767 | (dbus-introspect-get-attribute | |
768 | (dbus-introspect-get-annotation | |
769 | :session "de.berlios.Pinot" "/de/berlios/Pinot" | |
770 | "de.berlios.Pinot" "GetStatistics" | |
771 | "de.berlios.Pinot.GetStatistics") | |
772 | "value") | |
773 | ||
774 | @result{} "pinotDBus" | |
775 | @end lisp | |
776 | @end defun | |
777 | ||
778 | ||
779 | @node Arguments and Signatures | |
780 | @section The final details. | |
781 | ||
782 | Methods and signals have arguments. They are described in the | |
783 | @code{arg} XML elements. | |
784 | ||
785 | @defun dbus-introspect-get-argument-names bus service path interface name | |
786 | Return a list of all argument names as list of strings. @var{name} | |
787 | must be a @code{method} or @code{signal} XML element. Example: | |
788 | ||
789 | @lisp | |
790 | (dbus-introspect-get-argument-names | |
791 | :session "org.freedesktop.xesam.searcher" | |
792 | "/org/freedesktop/xesam/searcher/main" | |
793 | "org.freedesktop.xesam.Search" "GetHitData") | |
794 | ||
795 | @result{} ("search" "hit_ids" "fields" "hit_data") | |
796 | @end lisp | |
797 | ||
798 | Argument names are optional; the function can return @code{nil} | |
799 | therefore, even if the method or signal has arguments. | |
800 | @end defun | |
801 | ||
802 | @defun dbus-introspect-get-argument bus service path interface name arg | |
803 | Return argument @var{ARG} as XML object. @var{name} | |
804 | must be a @code{method} or @code{signal} XML element. Example: | |
805 | ||
806 | @lisp | |
807 | (dbus-introspect-get-argument | |
808 | :session "org.freedesktop.xesam.searcher" | |
809 | "/org/freedesktop/xesam/searcher/main" | |
810 | "org.freedesktop.xesam.Search" "GetHitData" "search") | |
811 | ||
812 | @result{} (arg ((name . "search") (type . "s") (direction . "in"))) | |
813 | @end lisp | |
814 | @end defun | |
815 | ||
816 | @defun dbus-introspect-get-signature bus service path interface name &optional direction | |
817 | Return signature of a @code{method} or @code{signal}, represented by | |
818 | @var{name}, as string. | |
819 | ||
820 | If @var{name} is a @code{method}, @var{direction} can be either | |
821 | @samp{in} or @samp{out}. If @var{direction} is @code{nil}, @samp{in} | |
822 | is assumed. | |
823 | ||
824 | If @var{name} is a @code{signal}, and @var{direction} is | |
825 | non-@code{nil}, @var{direction} must be @samp{out}. Example: | |
826 | ||
827 | @lisp | |
828 | (dbus-introspect-get-signature | |
829 | :session "org.freedesktop.xesam.searcher" | |
830 | "/org/freedesktop/xesam/searcher/main" | |
831 | "org.freedesktop.xesam.Search" "GetHitData" "in") | |
832 | ||
833 | @result{} "sauas" | |
834 | ||
835 | (dbus-introspect-get-signature | |
836 | :session "org.freedesktop.xesam.searcher" | |
837 | "/org/freedesktop/xesam/searcher/main" | |
838 | "org.freedesktop.xesam.Search" "HitsAdded") | |
839 | ||
21956b56 | 840 | @result{} "su" |
cd71b9ae MA |
841 | @end lisp |
842 | @end defun | |
843 | ||
22d8ac3a MA |
844 | |
845 | @node Type Conversion | |
846 | @chapter Mapping Lisp types and D-Bus types. | |
847 | @cindex type conversion | |
848 | ||
849 | D-Bus method calls and signals accept usually several arguments as | |
850 | parameters, either as input parameter, or as output parameter. Every | |
851 | argument belongs to a D-Bus type. | |
852 | ||
6a31c819 | 853 | Such arguments must be mapped between the value encoded as a D-Bus |
22d8ac3a MA |
854 | type, and the corresponding type of Lisp objects. The mapping is |
855 | applied Lisp object @expansion{} D-Bus type for input parameters, and | |
856 | D-Bus type @expansion{} Lisp object for output parameters. | |
857 | ||
858 | ||
859 | @section Input parameters. | |
860 | ||
861 | Input parameters for D-Bus methods and signals occur as arguments of a | |
6a31c819 | 862 | Lisp function call. The following mapping to D-Bus types is |
22d8ac3a MA |
863 | applied, when the corresponding D-Bus message is created: |
864 | ||
865 | @example | |
866 | @multitable {@code{t} and @code{nil}} {@expansion{}} {DBUS_TYPE_BOOLEAN} | |
867 | @item Lisp type @tab @tab D-Bus type | |
868 | @item | |
869 | @item @code{t} and @code{nil} @tab @expansion{} @tab DBUS_TYPE_BOOLEAN | |
870 | @item number @tab @expansion{} @tab DBUS_TYPE_UINT32 | |
871 | @item integer @tab @expansion{} @tab DBUS_TYPE_INT32 | |
872 | @item float @tab @expansion{} @tab DBUS_TYPE_DOUBLE | |
873 | @item string @tab @expansion{} @tab DBUS_TYPE_STRING | |
6a31c819 | 874 | @item list @tab @expansion{} @tab DBUS_TYPE_ARRAY |
22d8ac3a MA |
875 | @end multitable |
876 | @end example | |
877 | ||
6a31c819 | 878 | Other Lisp objects, like symbols or hash tables, are not accepted as |
61cf3a76 | 879 | input parameters. |
6a31c819 MA |
880 | |
881 | If it is necessary to use another D-Bus type, a corresponding type | |
61cf3a76 | 882 | symbol can be prepended to the corresponding Lisp object. Basic D-Bus |
d4e67bc5 MA |
883 | types are represented by the type symbols @code{:byte}, |
884 | @code{:boolean}, @code{:int16}, @code{:uint16}, @code{:int32}, | |
885 | @code{:uint32}, @code{:int64}, @code{:uint64}, @code{:double}, | |
886 | @code{:string}, @code{:object-path} and @code{:signature}. | |
6a31c819 | 887 | |
22d8ac3a | 888 | @noindent |
6a31c819 MA |
889 | Example: |
890 | ||
891 | @lisp | |
c9ecb5a7 | 892 | (dbus-call-method @dots{} @var{NUMBER} @var{STRING}) |
6a31c819 MA |
893 | @end lisp |
894 | ||
895 | is equivalent to | |
896 | ||
897 | @lisp | |
c9ecb5a7 | 898 | (dbus-call-method @dots{} :uint32 @var{NUMBER} :string @var{STRING}) |
6a31c819 MA |
899 | @end lisp |
900 | ||
901 | but different to | |
902 | ||
903 | @lisp | |
c9ecb5a7 | 904 | (dbus-call-method @dots{} :int32 @var{NUMBER} :signature @var{STRING}) |
6a31c819 MA |
905 | @end lisp |
906 | ||
4db2806c MA |
907 | The value for a byte D-Bus type can be any integer in the range 0 |
908 | through 255. If a character is used as argument, modifiers | |
909 | represented outside this range are stripped of. For example, | |
910 | @code{:byte ?x} is equal to @code{:byte ?\M-x}, but it is not equal to | |
911 | @code{:byte ?\C-x} or @code{:byte ?\M-\C-x}. | |
c9ecb5a7 | 912 | |
4db2806c MA |
913 | A D-Bus compound type is always represented as a list. The @sc{car} |
914 | of this list can be the type symbol @code{:array}, @code{:variant}, | |
d4e67bc5 MA |
915 | @code{:struct} or @code{:dict-entry}, which would result in a |
916 | corresponding D-Bus container. @code{:array} is optional, because | |
4db2806c | 917 | this is the default compound D-Bus type for a list. |
6a31c819 MA |
918 | |
919 | The objects being elements of the list are checked according to the | |
920 | D-Bus compound type rules. | |
921 | ||
922 | @itemize | |
4db2806c MA |
923 | @item An array must contain only elements of the same D-Bus type. It |
924 | can be empty. | |
925 | ||
6a31c819 | 926 | @item A variant must contain only one single element. |
4db2806c | 927 | |
6a31c819 | 928 | @item A dictionary entry must be element of an array, and it must |
4db2806c MA |
929 | contain only a key-value pair of two elements, with a basic D-Bus type |
930 | key. | |
931 | ||
6a31c819 MA |
932 | @item There is no restriction for structs. |
933 | @end itemize | |
934 | ||
4db2806c MA |
935 | If an empty array needs an element D-Bus type other than string, it |
936 | can contain exactly one element of D-Bus type @code{:signature}. The | |
937 | value of this element (a string) is used as the signature of the | |
938 | elements of this array. Example: | |
6a31c819 MA |
939 | |
940 | @lisp | |
4db2806c MA |
941 | (dbus-call-method |
942 | :session "org.freedesktop.Notifications" | |
943 | "/org/freedesktop/Notifications" | |
944 | "org.freedesktop.Notifications" "Notify" | |
945 | "GNU Emacs" ;; Application name. | |
946 | 0 ;; No replacement of other notifications. | |
947 | "" ;; No icon. | |
948 | "Notification summary" ;; Summary. | |
949 | (format ;; Body. | |
950 | "This is a test notification, raised from %s" (emacs-version)) | |
951 | '(:array) ;; No actions (empty array of strings). | |
952 | '(:array :signature "@{sv@}") ;; No hints | |
953 | ;; (empty array of dictionary entries). | |
0ecd3c90 | 954 | :int32 -1) ;; Default timeout. |
4db2806c MA |
955 | |
956 | @result{} 3 | |
6a31c819 | 957 | @end lisp |
22d8ac3a | 958 | |
ace706d1 MA |
959 | @defun dbus-string-to-byte-array string |
960 | Sometimes, D-Bus methods require as input parameter an array of bytes, | |
961 | instead of a string. If it is guaranteed, that @var{string} is an | |
962 | UTF8 string, this function performs the conversion. Example: | |
963 | ||
964 | @lisp | |
965 | (dbus-string-to-byte-array "/etc/hosts") | |
966 | ||
967 | @result{} (:array :byte 47 :byte 101 :byte 116 :byte 99 :byte 47 | |
968 | :byte 104 :byte 111 :byte 115 :byte 116 :byte 115) | |
969 | @end lisp | |
970 | @end defun | |
971 | ||
972 | @defun dbus-escape-as-identifier string | |
973 | Escape an arbitrary @var{string} so it follows the rules for a C | |
974 | identifier. The escaped string can be used as object path component, | |
975 | interface element component, bus name component or member name in | |
976 | D-Bus. | |
977 | ||
978 | The escaping consists of replacing all non-alphanumerics, and the | |
979 | first character if it's a digit, with an underscore and two | |
980 | lower-case hex digits. As a special case, "" is escaped to | |
981 | "_". Example: | |
982 | ||
983 | @lisp | |
984 | (dbus-escape-as-identifier "0123abc_xyz\x01\xff") | |
985 | ||
986 | @result{} "_30123abc_5fxyz_01_ff" | |
987 | @end lisp | |
988 | @end defun | |
989 | ||
22d8ac3a MA |
990 | |
991 | @section Output parameters. | |
992 | ||
993 | Output parameters of D-Bus methods and signals are mapped to Lisp | |
6a31c819 | 994 | objects. |
22d8ac3a MA |
995 | |
996 | @example | |
997 | @multitable {DBUS_TYPE_OBJECT_PATH} {@expansion{}} {@code{t} or @code{nil}} | |
998 | @item D-Bus type @tab @tab Lisp type | |
999 | @item | |
1000 | @item DBUS_TYPE_BOOLEAN @tab @expansion{} @tab @code{t} or @code{nil} | |
d4e67bc5 | 1001 | @item DBUS_TYPE_BYTE @tab @expansion{} @tab number |
6a31c819 | 1002 | @item DBUS_TYPE_UINT16 @tab @expansion{} @tab number |
d4e67bc5 MA |
1003 | @item DBUS_TYPE_INT16 @tab @expansion{} @tab number |
1004 | @item DBUS_TYPE_UINT32 @tab @expansion{} @tab number or float | |
1005 | @item DBUS_TYPE_INT32 @tab @expansion{} @tab number or float | |
1006 | @item DBUS_TYPE_UINT64 @tab @expansion{} @tab number or float | |
1007 | @item DBUS_TYPE_INT64 @tab @expansion{} @tab number or float | |
22d8ac3a MA |
1008 | @item DBUS_TYPE_DOUBLE @tab @expansion{} @tab float |
1009 | @item DBUS_TYPE_STRING @tab @expansion{} @tab string | |
1010 | @item DBUS_TYPE_OBJECT_PATH @tab @expansion{} @tab string | |
6a31c819 | 1011 | @item DBUS_TYPE_SIGNATURE @tab @expansion{} @tab string |
22d8ac3a MA |
1012 | @item DBUS_TYPE_ARRAY @tab @expansion{} @tab list |
1013 | @item DBUS_TYPE_VARIANT @tab @expansion{} @tab list | |
1014 | @item DBUS_TYPE_STRUCT @tab @expansion{} @tab list | |
1015 | @item DBUS_TYPE_DICT_ENTRY @tab @expansion{} @tab list | |
1016 | @end multitable | |
1017 | @end example | |
1018 | ||
d4e67bc5 MA |
1019 | A float object in case of @code{DBUS_TYPE_UINT32}, |
1020 | @code{DBUS_TYPE_INT32}, @code{DBUS_TYPE_UINT64} and | |
1021 | @code{DBUS_TYPE_INT6432} is returned, when the C value exceeds the | |
1022 | Emacs number size range. | |
1023 | ||
22d8ac3a MA |
1024 | The resulting list of the last 4 D-Bus compound types contains as |
1025 | elements the elements of the D-Bus container, mapped according to the | |
1026 | same rules. | |
1027 | ||
1028 | The signal @code{PropertyModified}, discussed as example in | |
1029 | @ref{Inspection}, would offer as Lisp data the following object | |
1030 | (@var{BOOL} stands here for either @code{nil} or @code{t}): | |
1031 | ||
1032 | @lisp | |
c9ecb5a7 | 1033 | (@var{NUMBER} ((@var{STRING} @var{BOOL} @var{BOOL}) (@var{STRING} @var{BOOL} @var{BOOL}) @dots{})) |
22d8ac3a MA |
1034 | @end lisp |
1035 | ||
ace706d1 MA |
1036 | @defun dbus-byte-array-to-string byte-array |
1037 | If a D-Bus method or signal returns an array of bytes, which are known | |
1038 | to represent an UTF8 string, this function converts @var{byte-array} | |
1039 | to the corresponding string. Example: | |
1040 | ||
1041 | @lisp | |
1042 | (dbus-byte-array-to-string '(47 101 116 99 47 104 111 115 116 115)) | |
1043 | ||
1044 | @result{} "/etc/hosts" | |
1045 | @end lisp | |
1046 | @end defun | |
1047 | ||
1048 | @defun dbus-unescape-from-identifier string | |
1049 | Retrieve the original string from the encoded @var{string}. | |
1050 | @var{string} must have been coded with | |
1051 | @code{dbus-escape-as-identifier}. Example: | |
1052 | ||
1053 | @lisp | |
1054 | (dbus-unescape-from-identifier "_30123abc_5fxyz_01_ff") | |
1055 | ||
fa0f81b0 AS |
1056 | @ifinfo |
1057 | @result{} "0123abc_xyz^Aÿ" | |
1058 | @end ifinfo | |
1059 | @ifnotinfo | |
1060 | @result{} "0123abc_xyz^A@"y" | |
1061 | @end ifnotinfo | |
ace706d1 MA |
1062 | @end lisp |
1063 | @end defun | |
1064 | ||
22d8ac3a MA |
1065 | |
1066 | @node Synchronous Methods | |
1067 | @chapter Calling methods in a blocking way. | |
1068 | @cindex method calls, synchronous | |
1069 | @cindex synchronous method calls | |
1070 | ||
1071 | Methods can be called synchronously (@dfn{blocking}) or asynchronously | |
21956b56 | 1072 | (@dfn{non-blocking}). |
22d8ac3a MA |
1073 | |
1074 | At D-Bus level, a method call consist of two messages: one message | |
1075 | which carries the input parameters to the object owning the method to | |
1076 | be called, and a reply message returning the resulting output | |
1077 | parameters from the object. | |
1078 | ||
134ce16c | 1079 | @defun dbus-call-method bus service path interface method &optional :timeout timeout &rest args |
22d8ac3a MA |
1080 | This function calls @var{method} on the D-Bus @var{bus}. @var{bus} is |
1081 | either the symbol @code{:system} or the symbol @code{:session}. | |
1082 | ||
1083 | @var{service} is the D-Bus service name to be used. @var{path} is the | |
1084 | D-Bus object path, @var{service} is registered at. @var{interface} is | |
1085 | an interface offered by @var{service}. It must provide @var{method}. | |
1086 | ||
134ce16c | 1087 | If the parameter @code{:timeout} is given, the following integer |
21956b56 | 1088 | @var{timeout} specifies the maximum number of milliseconds the method |
ecd3d54f | 1089 | call must return. The default value is 25,000. If the method call |
134ce16c MA |
1090 | doesn't return in time, a D-Bus error is raised (@pxref{Errors and |
1091 | Events}). | |
1092 | ||
22d8ac3a MA |
1093 | All other arguments args are passed to @var{method} as arguments. |
1094 | They are converted into D-Bus types as described in @ref{Type | |
1095 | Conversion}. | |
1096 | ||
1097 | The function returns the resulting values of @var{method} as a list of | |
1098 | Lisp objects, according to the type conversion rules described in | |
1099 | @ref{Type Conversion}. Example: | |
1100 | ||
06c0751a | 1101 | @lisp |
22d8ac3a | 1102 | (dbus-call-method |
0ce574ef MA |
1103 | :session "org.gnome.seahorse" "/org/gnome/seahorse/keys/openpgp" |
1104 | "org.gnome.seahorse.Keys" "GetKeyField" | |
22d8ac3a MA |
1105 | "openpgp:657984B8C7A966DD" "simple-name") |
1106 | ||
1107 | @result{} (t ("Philip R. Zimmermann")) | |
06c0751a | 1108 | @end lisp |
22d8ac3a MA |
1109 | |
1110 | If the result of the method call is just one value, the converted Lisp | |
1111 | object is returned instead of a list containing this single Lisp | |
1112 | object. Example: | |
1113 | ||
06c0751a | 1114 | @lisp |
22d8ac3a | 1115 | (dbus-call-method |
0ce574ef MA |
1116 | :system "org.freedesktop.Hal" |
1117 | "/org/freedesktop/Hal/devices/computer" | |
1118 | "org.freedesktop.Hal.Device" "GetPropertyString" | |
22d8ac3a MA |
1119 | "system.kernel.machine") |
1120 | ||
1121 | @result{} "i686" | |
06c0751a | 1122 | @end lisp |
22d8ac3a MA |
1123 | |
1124 | With the @code{dbus-introspect} function it is possible to explore the | |
1125 | interfaces of @samp{org.freedesktop.Hal} service. It offers the | |
1126 | interfaces @samp{org.freedesktop.Hal.Manager} for the object at the | |
1127 | path @samp{/org/freedesktop/Hal/Manager} as well as the interface | |
1128 | @samp{org.freedesktop.Hal.Device} for all objects prefixed with the | |
1129 | path @samp{/org/freedesktop/Hal/devices}. With the methods | |
1130 | @samp{GetAllDevices} and @samp{GetAllProperties}, it is simple to | |
1131 | emulate the @code{lshal} command on GNU/Linux systems: | |
1132 | ||
06c0751a | 1133 | @lisp |
22d8ac3a MA |
1134 | (dolist (device |
1135 | (dbus-call-method | |
0ce574ef | 1136 | :system "org.freedesktop.Hal" |
22d8ac3a | 1137 | "/org/freedesktop/Hal/Manager" |
0ce574ef | 1138 | "org.freedesktop.Hal.Manager" "GetAllDevices")) |
22d8ac3a MA |
1139 | (message "\nudi = %s" device) |
1140 | (dolist (properties | |
1141 | (dbus-call-method | |
0ce574ef MA |
1142 | :system "org.freedesktop.Hal" device |
1143 | "org.freedesktop.Hal.Device" "GetAllProperties")) | |
22d8ac3a MA |
1144 | (message " %s = %S" |
1145 | (car properties) (or (caar (cdr properties)) "")))) | |
1146 | ||
7b13a0f2 | 1147 | @print{} "udi = /org/freedesktop/Hal/devices/computer |
d9e21158 MA |
1148 | info.addons = (\"hald-addon-acpi\") |
1149 | info.bus = \"unknown\" | |
1150 | info.product = \"Computer\" | |
1151 | info.subsystem = \"unknown\" | |
1152 | info.udi = \"/org/freedesktop/Hal/devices/computer\" | |
1153 | linux.sysfs_path_device = \"(none)\" | |
1154 | power_management.acpi.linux.version = \"20051216\" | |
1155 | power_management.can_suspend_to_disk = t | |
1156 | power_management.can_suspend_to_ram = \"\" | |
1157 | power_management.type = \"acpi\" | |
1158 | smbios.bios.release_date = \"11/07/2001\" | |
1159 | system.chassis.manufacturer = \"COMPAL\" | |
1160 | system.chassis.type = \"Notebook\" | |
1161 | system.firmware.release_date = \"03/19/2005\" | |
c9ecb5a7 | 1162 | @dots{}" |
06c0751a | 1163 | @end lisp |
22d8ac3a MA |
1164 | @end defun |
1165 | ||
21956b56 MA |
1166 | @defun dbus-call-method-non-blocking bus service path interface method &optional :timeout timeout &rest args |
1167 | Call @var{method} on the D-Bus @var{bus}, but don't block the event queue. | |
1168 | This is necessary for communicating to registered D-Bus methods, | |
1169 | which are running in the same Emacs process. | |
1170 | ||
1171 | The arguments are the same as in @code{dbus-call-method}. Example: | |
1172 | ||
1173 | @lisp | |
1174 | (dbus-call-method-non-blocking | |
1175 | :system "org.freedesktop.Hal" | |
1176 | "/org/freedesktop/Hal/devices/computer" | |
1177 | "org.freedesktop.Hal.Device" "GetPropertyString" | |
1178 | "system.kernel.machine") | |
1179 | ||
1180 | @result{} "i686" | |
1181 | @end lisp | |
1182 | @end defun | |
1183 | ||
1184 | ||
1185 | @node Asynchronous Methods | |
1186 | @chapter Calling methods non-blocking. | |
1187 | @cindex method calls, asynchronous | |
1188 | @cindex asynchronous method calls | |
1189 | ||
1190 | @defun dbus-call-method-asynchronously bus service path interface method handler &optional :timeout timeout &rest args | |
1191 | This function calls @var{method} on the D-Bus @var{bus} | |
1192 | asynchronously. @var{bus} is either the symbol @code{:system} or the | |
1193 | symbol @code{:session}. | |
1194 | ||
1195 | @var{service} is the D-Bus service name to be used. @var{path} is the | |
1196 | D-Bus object path, @var{service} is registered at. @var{interface} is | |
1197 | an interface offered by @var{service}. It must provide @var{method}. | |
1198 | ||
1199 | @var{handler} is a Lisp function, which is called when the | |
4f22e84d MA |
1200 | corresponding return message has arrived. If @var{handler} is |
1201 | @code{nil}, no return message will be expected. | |
21956b56 MA |
1202 | |
1203 | If the parameter @code{:timeout} is given, the following integer | |
1204 | @var{timeout} specifies the maximum number of milliseconds a reply | |
ecd3d54f | 1205 | message must arrive. The default value is 25,000. If there is no |
21956b56 MA |
1206 | reply message in time, a D-Bus error is raised (@pxref{Errors and |
1207 | Events}). | |
1208 | ||
1209 | All other arguments args are passed to @var{method} as arguments. | |
1210 | They are converted into D-Bus types as described in @ref{Type | |
1211 | Conversion}. | |
1212 | ||
4f22e84d | 1213 | Unless @var{handler} is @code{nil}, the function returns a key into |
0ecd3c90 | 1214 | the hash table @code{dbus-registered-objects-table}. The |
4f22e84d MA |
1215 | corresponding entry in the hash table is removed, when the return |
1216 | message has been arrived, and @var{handler} is called. Example: | |
21956b56 MA |
1217 | |
1218 | @lisp | |
1219 | (dbus-call-method-asynchronously | |
1220 | :system "org.freedesktop.Hal" | |
1221 | "/org/freedesktop/Hal/devices/computer" | |
1222 | "org.freedesktop.Hal.Device" "GetPropertyString" 'message | |
1223 | "system.kernel.machine") | |
1224 | ||
1225 | @result{} (:system 2) | |
1226 | ||
1227 | @print{} i686 | |
1228 | @end lisp | |
1229 | @end defun | |
1230 | ||
22d8ac3a | 1231 | |
addb7f2e MA |
1232 | @node Receiving Method Calls |
1233 | @chapter Offering own methods. | |
1234 | @cindex method calls, returning | |
1235 | @cindex returning method calls | |
1236 | ||
1237 | Emacs can also offer own methods, which can be called by other | |
1238 | applications. These methods could be an implementation of an | |
cd71b9ae | 1239 | interface of a well known service, like @samp{org.freedesktop.TextEditor}. |
addb7f2e MA |
1240 | |
1241 | It could be also an implementation of an own interface. In this case, | |
cd71b9ae MA |
1242 | the service name must be @samp{org.gnu.Emacs}. The object path shall |
1243 | begin with @samp{/org/gnu/Emacs/@strong{Application}/}, and the | |
addb7f2e | 1244 | interface name shall be @code{org.gnu.Emacs.@strong{Application}}. |
cd71b9ae | 1245 | @samp{@strong{Application}} is the name of the application which |
addb7f2e MA |
1246 | provides the interface. |
1247 | ||
ace706d1 MA |
1248 | @deffn Constant dbus-service-emacs |
1249 | The well known service name of Emacs. | |
1250 | @end deffn | |
1251 | ||
1252 | @deffn Constant dbus-path-emacs | |
1253 | The object path head "/org/gnu/Emacs" used by Emacs. All object | |
1254 | paths, used by offered methods or signals, shall start with this | |
1255 | string. | |
1256 | @end deffn | |
1257 | ||
addb7f2e MA |
1258 | @defun dbus-register-method bus service path interface method handler |
1259 | With this function, an application registers @var{method} on the D-Bus | |
1260 | @var{bus}. | |
1261 | ||
1262 | @var{bus} is either the symbol @code{:system} or the symbol | |
1263 | @code{:session}. | |
1264 | ||
1265 | @var{service} is the D-Bus service name of the D-Bus object | |
1266 | @var{method} is registered for. It must be a known name. | |
1267 | ||
1268 | @var{path} is the D-Bus object path @var{service} is | |
1269 | registered. | |
1270 | ||
1271 | @var{interface} is the interface offered by @var{service}. It must | |
1272 | provide @var{method}. | |
1273 | ||
ac134f2f RS |
1274 | @var{handler} is a Lisp function to be called when a @var{method} call |
1275 | is received. It must accept as arguments the input arguments of | |
1276 | @var{method}. @var{handler} should return a list, whose elements are | |
1277 | to be used as arguments for the reply message of @var{method}. This | |
1278 | list can be composed like the input parameters in @ref{Type | |
1279 | Conversion}. | |
1280 | ||
1281 | If @var{handler} wants to return just one Lisp object and it is not a | |
1282 | cons cell, @var{handler} can return this object directly, instead of | |
1283 | returning a list containing the object. | |
addb7f2e | 1284 | |
42fb7e61 MA |
1285 | In case @var{handler} shall return a reply message with an empty |
1286 | argument list, @var{handler} must return the symbol @code{:ignore}. | |
1287 | ||
4a7c4c40 | 1288 | The default D-Bus timeout when waiting for a message reply is 25 |
134ce16c MA |
1289 | seconds. This value could be even smaller, depending on the calling |
1290 | client. Therefore, @var{handler} shall not last longer than | |
4a7c4c40 MA |
1291 | absolutely necessary. |
1292 | ||
9b7993b4 | 1293 | @code{dbus-register-method} returns a Lisp object, which can be used |
addb7f2e MA |
1294 | as argument in @code{dbus-unregister-object} for removing the |
1295 | registration for @var{method}. Example: | |
1296 | ||
06c0751a | 1297 | @lisp |
addb7f2e MA |
1298 | (defun my-dbus-method-handler (filename) |
1299 | (let (result) | |
1300 | (if (find-file filename) | |
1301 | (setq result '(:boolean t)) | |
1302 | (setq result '(:boolean nil))) | |
1303 | result)) | |
1304 | ||
1305 | @result{} my-dbus-method-handler | |
1306 | ||
1307 | (dbus-register-method | |
1308 | :session "org.freedesktop.TextEditor" "/org/freedesktop/TextEditor" | |
1309 | "org.freedesktop.TextEditor" "OpenFile" | |
1310 | 'my-dbus-method-handler) | |
1311 | ||
eb932e8a | 1312 | @result{} ((:session "org.freedesktop.TextEditor" "OpenFile") |
addb7f2e | 1313 | ("org.freedesktop.TextEditor" "/org/freedesktop/TextEditor" |
eb932e8a | 1314 | my-dbus-method-handler)) |
06c0751a | 1315 | @end lisp |
addb7f2e | 1316 | |
cd71b9ae | 1317 | If you invoke the method @samp{org.freedesktop.TextEditor.OpenFile} |
addb7f2e MA |
1318 | from another D-Bus application with a filename as parameter, the file |
1319 | is opened in Emacs, and the method returns either @var{true} or | |
0ecd3c90 | 1320 | @var{false}, indicating the success of the method. As test tool one |
addb7f2e MA |
1321 | could use the command line tool @code{dbus-send} in a shell: |
1322 | ||
1323 | @example | |
1324 | # dbus-send --session --print-reply \ | |
1325 | --dest="org.freedesktop.TextEditor" \ | |
1326 | "/org/freedesktop/TextEditor" \ | |
1327 | "org.freedesktop.TextEditor.OpenFile" string:"/etc/hosts" | |
1328 | ||
1329 | @print{} method return sender=:1.22 -> dest=:1.23 reply_serial=2 | |
eb932e8a MA |
1330 | boolean true |
1331 | @end example | |
1332 | ||
1333 | You can indicate an error by raising the Emacs signal | |
1334 | @code{dbus-error}. The handler above could be changed like this: | |
1335 | ||
1336 | @lisp | |
1337 | (defun my-dbus-method-handler (&rest args) | |
1338 | (unless (and (= (length args) 1) (stringp (car args))) | |
1339 | (signal 'dbus-error (list (format "Wrong argument list: %S" args)))) | |
1340 | (condition-case err | |
1341 | (find-file (car args)) | |
1342 | (error (signal 'dbus-error (cdr err)))) | |
1343 | t) | |
1344 | ||
1345 | @result{} my-dbus-method-handler | |
1346 | @end lisp | |
1347 | ||
1348 | The test runs then | |
1349 | ||
1350 | @example | |
1351 | # dbus-send --session --print-reply \ | |
1352 | --dest="org.freedesktop.TextEditor" \ | |
1353 | "/org/freedesktop/TextEditor" \ | |
1354 | "org.freedesktop.TextEditor.OpenFile" \ | |
1355 | string:"/etc/hosts" string:"/etc/passwd" | |
1356 | ||
1357 | @print{} Error org.freedesktop.DBus.Error.Failed: | |
1358 | Wrong argument list: ("/etc/hosts" "/etc/passwd") | |
addb7f2e MA |
1359 | @end example |
1360 | @end defun | |
1361 | ||
0ecd3c90 MA |
1362 | @defun dbus-register-property bus service path interface property access value |
1363 | With this function, an application declares a @var{property} on the D-Bus | |
1364 | @var{bus}. | |
1365 | ||
1366 | @var{bus} is either the symbol @code{:system} or the symbol | |
1367 | @code{:session}. | |
1368 | ||
1369 | @var{service} is the D-Bus service name of the D-Bus. It must be a | |
1370 | known name. | |
1371 | ||
1372 | @var{path} is the D-Bus object path @var{service} is | |
1373 | registered. | |
1374 | ||
1375 | @var{interface} is the name of the interface used at @var{path}, | |
1376 | @var{property} is the name of the property of @var{interface}. | |
1377 | ||
1378 | @var{access} indicates, whether the property can be changed by other | |
1379 | services via D-Bus. It must be either the symbol @code{:read} or | |
1380 | @code{:readwrite}. @var{value} is the initial value of the property, | |
1381 | it can be of any valid type (see @code{dbus-call-method} for details). | |
1382 | ||
1383 | If @var{property} already exists on @var{path}, it will be | |
1384 | overwritten. For properties with access type @code{:read} this is the | |
1385 | only way to change their values. Properties with access type | |
1386 | @code{:readwrite} can be changed by @code{dbus-set-property}. | |
1387 | ||
1388 | The interface @samp{org.freedesktop.DBus.Properties} is added to | |
1389 | @var{path}, including a default handler for the @samp{Get}, | |
1390 | @samp{GetAll} and @samp{Set} methods of this interface. Example: | |
1391 | ||
1392 | @lisp | |
1393 | (dbus-register-property | |
1394 | :session "org.freedesktop.TextEditor" "/org/freedesktop/TextEditor" | |
1395 | "org.freedesktop.TextEditor" "name" :read "GNU Emacs") | |
1396 | ||
1397 | @result{} ((:session "org.freedesktop.TextEditor" "name") | |
1398 | ("org.freedesktop.TextEditor" "/org/freedesktop/TextEditor")) | |
1399 | ||
1400 | (dbus-register-property | |
1401 | :session "org.freedesktop.TextEditor" "/org/freedesktop/TextEditor" | |
1402 | "org.freedesktop.TextEditor" "version" :readwrite emacs-version) | |
1403 | ||
1404 | @result{} ((:session "org.freedesktop.TextEditor" "version") | |
1405 | ("org.freedesktop.TextEditor" "/org/freedesktop/TextEditor")) | |
1406 | @end lisp | |
1407 | ||
1408 | Other D-Bus applications can read the property via the default methods | |
1409 | @samp{org.freedesktop.DBus.Properties.Get} and | |
1410 | @samp{org.freedesktop.DBus.Properties.GetAll}. Testing is also | |
1411 | possible via the command line tool @code{dbus-send} in a shell: | |
1412 | ||
1413 | @example | |
1414 | # dbus-send --session --print-reply \ | |
1415 | --dest="org.freedesktop.TextEditor" \ | |
1416 | "/org/freedesktop/TextEditor" \ | |
1417 | "org.freedesktop.DBus.Properties.GetAll" \ | |
1418 | string:"org.freedesktop.TextEditor" | |
1419 | ||
1420 | @print{} method return sender=:1.22 -> dest=:1.23 reply_serial=3 | |
1421 | array [ | |
1422 | dict entry( | |
1423 | string "name" | |
1424 | variant string "GNU Emacs" | |
1425 | ) | |
1426 | dict entry( | |
1427 | string "version" | |
1428 | variant string "23.1.50.5" | |
1429 | ) | |
1430 | ] | |
1431 | @end example | |
1432 | ||
1433 | It is also possible, to apply the @code{dbus-get-property}, | |
1434 | @code{dbus-get-all-properties} and @code{dbus-set-property} functions | |
1435 | (@pxref{Properties and Annotations}). | |
1436 | ||
1437 | @lisp | |
1438 | (dbus-set-property | |
1439 | :session "org.freedesktop.TextEditor" "/org/freedesktop/TextEditor" | |
1440 | "org.freedesktop.TextEditor" "version" "23.1.50") | |
1441 | ||
1442 | @result{} "23.1.50" | |
1443 | ||
1444 | (dbus-get-property | |
1445 | :session "org.freedesktop.TextEditor" "/org/freedesktop/TextEditor" | |
1446 | "org.freedesktop.TextEditor" "version") | |
1447 | ||
1448 | @result{} "23.1.50" | |
1449 | @end lisp | |
1450 | @end defun | |
1451 | ||
1452 | @defun dbus-unregister-object object | |
1453 | Unregister @var{object} from the D-Bus. @var{object} must be the | |
1454 | result of a preceding @code{dbus-register-method}, | |
1455 | @code{dbus-register-property} or @code{dbus-register-signal} call | |
1456 | (@pxref{Signals}). It returns @code{t} if @var{object} has been | |
1457 | unregistered, @code{nil} otherwise. | |
1458 | ||
1459 | When @var{object} identifies the last method or property, which is | |
1460 | registered for the respective service, Emacs releases its association | |
1461 | to the service from D-Bus. | |
1462 | @end defun | |
977640ed MA |
1463 | |
1464 | @defun dbus-unregister-service bus service | |
1465 | Unregister all objects from D-Bus @var{bus}, registered by Emacs for | |
1466 | @var{service}. | |
1467 | ||
1468 | @var{bus} is either the symbol @code{:system} or the symbol | |
1469 | @code{:session}. | |
1470 | ||
1471 | @var{service} is the D-Bus service name of the D-Bus. It must be a | |
1472 | known name. Emacs releases its association to @var{service} from | |
1473 | D-Bus. | |
1474 | @end defun | |
0ecd3c90 | 1475 | |
addb7f2e | 1476 | |
22d8ac3a MA |
1477 | @node Signals |
1478 | @chapter Sending and receiving signals. | |
1479 | @cindex signals | |
1480 | ||
1481 | Signals are broadcast messages. They carry input parameters, which | |
1482 | are received by all objects which have registered for such a signal. | |
1483 | ||
0ce574ef | 1484 | @defun dbus-send-signal bus service path interface signal &rest args |
22d8ac3a MA |
1485 | This function is similar to @code{dbus-call-method}. The difference |
1486 | is, that there are no returning output parameters. | |
1487 | ||
1488 | The function emits @var{signal} on the D-Bus @var{bus}. @var{bus} is | |
1489 | either the symbol @code{:system} or the symbol @code{:session}. It | |
1490 | doesn't matter whether another object has registered for @var{signal}. | |
1491 | ||
1492 | @var{service} is the D-Bus service name of the object the signal is | |
1493 | emitted from. @var{path} is the corresponding D-Bus object path, | |
1494 | @var{service} is registered at. @var{interface} is an interface | |
1495 | offered by @var{service}. It must provide @var{signal}. | |
1496 | ||
1497 | All other arguments args are passed to @var{signal} as arguments. | |
1498 | They are converted into D-Bus types as described in @ref{Type | |
1499 | Conversion}. Example: | |
1500 | ||
06c0751a | 1501 | @lisp |
22d8ac3a | 1502 | (dbus-send-signal |
ace706d1 MA |
1503 | :session dbus-service-emacs dbus-path-emacs |
1504 | (concat dbus-service-emacs ".FileManager") "FileModified" | |
1505 | "/home/albinus/.emacs") | |
06c0751a | 1506 | @end lisp |
22d8ac3a MA |
1507 | @end defun |
1508 | ||
9b7993b4 | 1509 | @defun dbus-register-signal bus service path interface signal handler &rest args |
22d8ac3a MA |
1510 | With this function, an application registers for @var{signal} on the |
1511 | D-Bus @var{bus}. | |
1512 | ||
1513 | @var{bus} is either the symbol @code{:system} or the symbol | |
1514 | @code{:session}. | |
1515 | ||
a4397af9 MA |
1516 | @var{service} is the D-Bus service name used by the sending D-Bus |
1517 | object. It can be either a known name or the unique name of the D-Bus | |
1518 | object sending the signal. In case of a unique name, signals won't be | |
1519 | received any longer once the object owning this unique name has | |
1520 | disappeared, and a new queued object has replaced it. | |
1521 | ||
1522 | When @var{service} is @code{nil}, related signals from all D-Bus | |
1523 | objects shall be accepted. | |
1524 | ||
1525 | @var{path} is the corresponding D-Bus object path, @var{service} is | |
1526 | registered at. It can also be @code{nil} if the path name of incoming | |
1527 | signals shall not be checked. | |
1528 | ||
1529 | @var{interface} is an interface offered by @var{service}. It must | |
1530 | provide @var{signal}. | |
22d8ac3a MA |
1531 | |
1532 | @var{handler} is a Lisp function to be called when the @var{signal} is | |
1533 | received. It must accept as arguments the output parameters | |
9b7993b4 MA |
1534 | @var{signal} is sending. |
1535 | ||
1536 | All other arguments @var{args}, if specified, must be strings. They | |
1537 | stand for the respective arguments of @var{signal} in their order, and | |
1538 | are used for filtering as well. A @code{nil} argument might be used | |
1539 | to preserve the order. | |
1540 | ||
1541 | @code{dbus-register-signal} returns a Lisp object, which can be used | |
1542 | as argument in @code{dbus-unregister-object} for removing the | |
1543 | registration for @var{signal}. Example: | |
22d8ac3a | 1544 | |
06c0751a | 1545 | @lisp |
22d8ac3a MA |
1546 | (defun my-dbus-signal-handler (device) |
1547 | (message "Device %s added" device)) | |
1548 | ||
0ce574ef MA |
1549 | @result{} my-dbus-signal-handler |
1550 | ||
22d8ac3a | 1551 | (dbus-register-signal |
0ce574ef MA |
1552 | :system "org.freedesktop.Hal" "/org/freedesktop/Hal/Manager" |
1553 | "org.freedesktop.Hal.Manager" "DeviceAdded" | |
22d8ac3a MA |
1554 | 'my-dbus-signal-handler) |
1555 | ||
cd71c3ef MA |
1556 | @result{} ((:system "org.freedesktop.Hal.Manager" "DeviceAdded") |
1557 | ("org.freedesktop.Hal" "/org/freedesktop/Hal/Manager" | |
1558 | my-signal-handler)) | |
06c0751a | 1559 | @end lisp |
22d8ac3a | 1560 | |
cd71b9ae MA |
1561 | As we know from the introspection data of interface |
1562 | @samp{org.freedesktop.Hal.Manager}, the signal @samp{DeviceAdded} | |
22d8ac3a MA |
1563 | provides one single parameter, which is mapped into a Lisp string. |
1564 | The callback function @code{my-dbus-signal-handler} must define one | |
1565 | single string argument therefore. Plugging an USB device to your | |
cd71b9ae | 1566 | machine, when registered for signal @samp{DeviceAdded}, will show you |
22d8ac3a | 1567 | which objects the GNU/Linux @code{hal} daemon adds. |
22d8ac3a MA |
1568 | @end defun |
1569 | ||
22d8ac3a MA |
1570 | |
1571 | @node Errors and Events | |
1572 | @chapter Errors and events. | |
1573 | @cindex errors | |
1574 | @cindex events | |
1575 | ||
21956b56 MA |
1576 | Input parameters of @code{dbus-call-method}, |
1577 | @code{dbus-call-method-non-blocking}, | |
1578 | @code{dbus-call-method-asynchronously}, and | |
6a31c819 MA |
1579 | @code{dbus-register-signal} are checked for correct D-Bus types. If |
1580 | there is a type mismatch, the Lisp error @code{wrong-type-argument} | |
1581 | @code{D-Bus ARG} is raised. | |
1582 | ||
22d8ac3a | 1583 | All errors raised by D-Bus are signaled with the error symbol |
d2e4a6c9 MA |
1584 | @code{dbus-error}. If possible, error messages from D-Bus are |
1585 | appended to the @code{dbus-error}. | |
1586 | ||
1587 | @defspec dbus-ignore-errors forms@dots{} | |
1588 | This executes @var{forms} exactly like a @code{progn}, except that | |
1589 | @code{dbus-error} errors are ignored during the @var{forms}. These | |
1590 | errors can be made visible when variable @code{dbus-debug} is set to | |
1591 | @code{t}. | |
1592 | @end defspec | |
22d8ac3a | 1593 | |
5794c2a5 MA |
1594 | Incoming D-Bus messages are handled as Emacs events, see @pxref{Misc |
1595 | Events, , , elisp}. They are retrieved only, when Emacs runs in | |
1596 | interactive mode. The generated event has this form: | |
22d8ac3a | 1597 | |
06c0751a | 1598 | @lisp |
21956b56 MA |
1599 | (dbus-event @var{bus} @var{type} @var{serial} @var{service} @var{path} @var{interface} @var{member} @var{handler} |
1600 | &rest @var{args}) | |
06c0751a | 1601 | @end lisp |
22d8ac3a | 1602 | |
21956b56 | 1603 | @var{bus} identifies the D-Bus the message is coming from. It is |
a4397af9 | 1604 | either the symbol @code{:system} or the symbol @code{:session}. |
22d8ac3a | 1605 | |
21956b56 MA |
1606 | @var{type} is the D-Bus message type which has caused the event. It |
1607 | can be @code{dbus-message-type-invalid}, | |
1608 | @code{dbus-message-type-method-call}, | |
1609 | @code{dbus-message-type-method-return}, | |
1610 | @code{dbus-message-type-error}, or @code{dbus-message-type-signal}. | |
1611 | @var{serial} is the serial number of the received D-Bus message. | |
addb7f2e | 1612 | |
22d8ac3a | 1613 | @var{service} and @var{path} are the unique name and the object path |
addb7f2e MA |
1614 | of the D-Bus object emitting the message. @var{interface} and |
1615 | @var{member} denote the message which has been sent. | |
22d8ac3a | 1616 | |
0ce574ef | 1617 | @var{handler} is the callback function which has been registered for |
addb7f2e | 1618 | this message (see @pxref{Signals}). When a @code{dbus-event} event |
0ce574ef MA |
1619 | arrives, @var{handler} is called with @var{args} as arguments. |
1620 | ||
22d8ac3a MA |
1621 | In order to inspect the @code{dbus-event} data, you could extend the |
1622 | definition of the callback function in @ref{Signals}: | |
1623 | ||
06c0751a | 1624 | @lisp |
22d8ac3a MA |
1625 | (defun my-dbus-signal-handler (&rest args) |
1626 | (message "my-dbus-signal-handler: %S" last-input-event)) | |
06c0751a | 1627 | @end lisp |
22d8ac3a MA |
1628 | |
1629 | There exist convenience functions which could be called inside a | |
1630 | callback function in order to retrieve the information from the event. | |
1631 | ||
1632 | @defun dbus-event-bus-name event | |
22d8ac3a MA |
1633 | Returns the bus name @var{event} is coming from. |
1634 | The result is either the symbol @code{:system} or the symbol @code{:session}. | |
1635 | @end defun | |
1636 | ||
21956b56 MA |
1637 | @defun dbus-event-message-type event |
1638 | Returns the message type of the corresponding D-Bus message. The | |
1639 | result is a number. | |
1640 | @end defun | |
1641 | ||
addb7f2e MA |
1642 | @defun dbus-event-serial-number event |
1643 | Returns the serial number of the corresponding D-Bus message. | |
21956b56 | 1644 | The result is a number. |
addb7f2e MA |
1645 | @end defun |
1646 | ||
22d8ac3a | 1647 | @defun dbus-event-service-name event |
22d8ac3a MA |
1648 | Returns the unique name of the D-Bus object @var{event} is coming from. |
1649 | @end defun | |
1650 | ||
1651 | @defun dbus-event-path-name event | |
22d8ac3a MA |
1652 | Returns the object path of the D-Bus object @var{event} is coming from. |
1653 | @end defun | |
1654 | ||
1655 | @defun dbus-event-interface-name event | |
74fc5047 | 1656 | Returns the interface name of the D-Bus object @var{event} is coming from. |
22d8ac3a MA |
1657 | @end defun |
1658 | ||
1659 | @defun dbus-event-member-name event | |
74fc5047 | 1660 | Returns the member name of the D-Bus object @var{event} is coming |
22d8ac3a MA |
1661 | from. It is either a signal name or a method name. |
1662 | @end defun | |
1663 | ||
c9ecb5a7 MA |
1664 | D-Bus errors are not propagated during event handling, because it is |
1665 | usually not desired. D-Bus errors in events can be made visible by | |
e7433508 MA |
1666 | setting the variable @code{dbus-debug} to @code{t}. They can also be |
1667 | handled by a hook function. | |
1668 | ||
1669 | @defvar dbus-event-error-hooks | |
1670 | This hook variable keeps a list of functions, which are called when a | |
1671 | D-Bus error happens in the event handler. Every function must accept | |
74fc5047 MA |
1672 | two arguments, the event and the error variable catched in |
1673 | @code{condition-case} by @code{dbus-error}. | |
1674 | ||
1675 | Such functions can be used the adapt the error signal to be raised. | |
1676 | Example: | |
e7433508 MA |
1677 | |
1678 | @lisp | |
74fc5047 MA |
1679 | (defun my-dbus-event-error-handler (event error) |
1680 | (when (string-equal (concat dbus-service-emacs ".FileManager") | |
1681 | (dbus-event-interface-name event)) | |
1682 | (message "my-dbus-event-error-handler: %S %S" event error) | |
1683 | (signal 'file-error (cdr error)))) | |
e7433508 MA |
1684 | |
1685 | (add-hook 'dbus-event-error-hooks 'my-dbus-event-error-handler) | |
1686 | @end lisp | |
1687 | @end defvar | |
c9ecb5a7 | 1688 | |
74fc5047 MA |
1689 | Hook functions shall take into account, that there might be other |
1690 | D-Bus applications running. Therefore, they shall check carefully, | |
1691 | whether a given D-Bus error is related to them. | |
1692 | ||
22d8ac3a MA |
1693 | |
1694 | @node GNU Free Documentation License | |
1695 | @appendix GNU Free Documentation License | |
1696 | @include doclicense.texi | |
1697 | ||
22d8ac3a | 1698 | @bye |
79f10da0 MB |
1699 | |
1700 | @ignore | |
1701 | arch-tag: 2eeec19d-0caf-44e0-a193-329d7f9951d8 | |
1702 | @end ignore |