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22 * @file include/gnunet_psyc_service.h
23 * @brief PSYC service; high-level access to the PSYC protocol
24 * note that clients of this API are NOT expected to
25 * understand the PSYC message format, only the semantics!
26 * Parsing (and serializing) the PSYC stream format is done
27 * within the implementation of the libgnunetpsyc library,
28 * and this API deliberately exposes as little as possible
29 * of the actual data stream format to the application!
30 * @author Christian Grothoff
31 * @author Gabor X Toth
34 * - this API does not know about psyc's "root" and "places";
35 * there is no 'root' in GNUnet-Psyc as we're decentralized;
36 * 'places' and 'persons' are combined within the same
37 * abstraction, that of a "channel". Channels are identified
38 * and accessed in this API using a public/private key.
39 * Higher-level applications should use NAMES within GNS
40 * to obtain public keys, and the distinction between
41 * 'places' and 'persons' can then be made with the help
42 * of the naming system (and/or conventions).
43 * Channels are (as in PSYC) organized into a hierarchy; each
44 * channel master (the one with the private key) is then
45 * the operator of the multicast group (its Origin in
46 * the terminology of the multicast API).
47 * - The API supports passing large amounts of data using
48 * 'streaming' for the argument passed to a method. State
49 * and variables must fit into memory and cannot be streamed
50 * (thus, no passing of 4 GB of data in a variable;
51 * once we implement this, we might want to create a
52 * @c \#define for the maximum size of a variable).
53 * - PSYC defines standard variables, methods, etc. This
54 * library deliberately abstracts over all of these; a
55 * higher-level API should combine the naming system (GNS)
56 * and standard methods (message, join, part, warn,
57 * fail, error) and variables (action, color, time,
58 * tag, etc.). However, this API does take over the
59 * routing variables, specifically 'context' (channel),
60 * and 'source'. We only kind-of support 'target', as
61 * the target is either everyone in the group or the
62 * origin, and never just a single member of the group;
63 * for such individual messages, an application needs to
64 * construct an 'inbox' channel where the master (only)
65 * receives messages (but never forwards; private responses
66 * would be transmitted by joining the senders 'inbox'
67 * channel -- or a inbox#bob subchannel). The
68 * goal for all of this is to keep the abstractions in this
69 * API minimal: interaction with multicast, try \& slice,
70 * state/variable/channel management. Higher-level
71 * operations belong elsewhere (so maybe this API should
72 * be called 'PSYC-low', whereas a higher-level API
73 * implementing defaults for standard methods and
74 * variables might be called 'PSYC-std' or 'PSYC-high'.
77 #ifndef GNUNET_PSYC_SERVICE_H
78 #define GNUNET_PSYC_SERVICE_H
83 #if 0 /* keep Emacsens' auto-indent happy */
88 #include "gnunet_util_lib.h"
89 #include "gnunet_env_lib.h"
90 #include "gnunet_multicast_service.h"
94 * Version number of GNUnet-PSYC API.
96 #define GNUNET_PSYC_VERSION 0x00000000
100 * Policy flags for a channel.
102 enum GNUNET_PSYC_ChannelFlags
105 * Admission must be confirmed by the master.
107 GNUNET_PSYC_CHANNEL_ADMISSION_CONTROL = 1 << 0,
110 * Past messages are only available to slaves who were admitted at the time
111 * they were sent to the channel.
113 GNUNET_PSYC_CHANNEL_RESTRICTED_HISTORY = 1 << 1,
117 * PSYC channel policies.
119 enum GNUNET_PSYC_Policy
122 * Anyone can join the channel, without announcing his presence;
123 * all messages are always public and can be distributed freely.
124 * Joins may be announced, but this is not required.
126 GNUNET_PSYC_CHANNEL_ANONYMOUS = 0,
129 * The master must approve membership to the channel, messages must only be
130 * distributed to current channel slaves. This includes the channel
131 * state as well as transient messages.
133 GNUNET_PSYC_CHANNEL_PRIVATE
134 = GNUNET_PSYC_CHANNEL_ADMISSION_CONTROL
135 | GNUNET_PSYC_CHANNEL_RESTRICTED_HISTORY,
139 * Anyone can freely join the channel (no approval required);
140 * however, messages must only be distributed to current channel
141 * slaves, so the master must still acknowledge that the slave
142 * joined before transient messages are delivered. As approval is
143 * guaranteed, the presistent channel state can be synchronized freely
144 * immediately, prior to master confirmation.
146 GNUNET_PSYC_CHANNEL_OPEN
147 = GNUNET_PSYC_CHANNEL_RESTRICTED_HISTORY,
150 * The master must approve joins to the channel, but past messages can be
151 * freely distributed to slaves.
153 GNUNET_PSYC_CHANNEL_CLOSED
154 = GNUNET_PSYC_CHANNEL_ADMISSION_CONTROL,
161 enum GNUNET_PSYC_MessageFlags
164 * First fragment of a message.
166 GNUNET_PSYC_MESSAGE_FIRST_FRAGMENT = 1 << 0,
169 * Last fragment of a message.
171 GNUNET_PSYC_MESSAGE_LAST_FRAGMENT = 1 << 1,
174 * OR'ed flags if message is not fragmented.
176 GNUNET_PSYC_MESSAGE_NOT_FRAGMENTED
177 = GNUNET_PSYC_MESSAGE_FIRST_FRAGMENT
178 | GNUNET_PSYC_MESSAGE_LAST_FRAGMENT,
181 * Historic message, retrieved from PSYCstore.
183 GNUNET_PSYC_MESSAGE_HISTORIC = 1 << 30
190 struct GNUNET_PSYC_MessageMethod
193 * Type: GNUNET_MESSAGE_TYPE_PSYC_MESSAGE_METHOD
195 struct GNUNET_MessageHeader header;
197 uint32_t reserved GNUNET_PACKED;
200 * Number of modifiers in the message.
202 uint32_t mod_count GNUNET_PACKED;
205 * OR'ed GNUNET_PSYC_MasterTransmitFlags
207 uint32_t flags GNUNET_PACKED;
210 * Sending slave's public key. NULL if the message is from the master, or when
211 * transmitting a message.
213 struct GNUNET_CRYPTO_EccPublicSignKey slave_key;
215 /* Followed by NUL-terminated method name. */
219 struct GNUNET_PSYC_MessageModifier
222 * Type: GNUNET_MESSAGE_TYPE_PSYC_MESSAGE_MODIFIER
224 struct GNUNET_MessageHeader header;
229 uint32_t value_size GNUNET_PACKED;
232 * Size of name, including NUL terminator.
234 uint16_t name_size GNUNET_PACKED;
237 * enum GNUNET_ENV_Operator
241 /* Followed by NUL-terminated name, then the value. */
245 enum GNUNET_PSYC_DataStatus
250 GNUNET_PSYC_DATA_CONT = 0,
253 * Reached the end of message.
255 GNUNET_PSYC_DATA_END = 1,
258 * Cancelled before the end.
260 GNUNET_PSYC_DATA_CANCEL = 2
264 struct GNUNET_PSYC_MessageData
267 * Type: GNUNET_MESSAGE_TYPE_PSYC_MESSAGE_MODIFIER
269 struct GNUNET_MessageHeader header;
272 * enum GNUNET_PSYC_DataStatus
278 * Handle that identifies a join request.
280 * Used to match calls to #GNUNET_PSYC_JoinCallback to the
281 * corresponding calls to GNUNET_PSYC_join_decision().
283 struct GNUNET_PSYC_JoinHandle;
287 * Method called from PSYC upon receiving a message indicating a call to a
290 * @param cls Closure.
291 * @param slave_key Who transmitted the message.
292 * - NULL for multicast messages from the master.
293 * - The sending slave's public key for unicast requests from one of the
294 * slaves to the master.
295 * @param message_id Unique message counter for this message.
296 * Unique only in combination with the given sender for this channel.
297 * @param method_name Method name from PSYC.
298 * @param modifier_count Number of elements in the @a modifiers array.
299 * @param modifiers State modifiers and transient variables for the message.
300 * @param data_offset Byte offset of @a data in the overall data of the method.
301 * @param data Data stream given to the method (might not be zero-terminated
302 * if data is binary).
303 * @param data_size Number of bytes in @a data.
304 * @param frag Fragmentation status for the data.
307 (*GNUNET_PSYC_Method) (void *cls,
308 const struct GNUNET_CRYPTO_EccPublicSignKey *slave_key,
310 const char *method_name,
311 size_t modifier_count,
312 const struct GNUNET_ENV_Modifier *modifiers,
313 uint64_t data_offset,
316 enum GNUNET_PSYC_MessageFlags flags);
320 * Method called from PSYC upon receiving a join request.
322 * @param cls Closure.
323 * @param slave requesting to join.
324 * @param method_name Method name in the join request.
325 * @param variable_count Number of elements in the @a variables array.
326 * @param variables Transient variables for the join request.
327 * @param data Data stream given to the method (might not be zero-terminated
328 * if data is binary).
329 * @param data_size Number of bytes in @a data.
330 * @param jh Join handle to use with GNUNET_PSYC_join_decision()
333 (*GNUNET_PSYC_JoinCallback) (void *cls,
334 const struct GNUNET_CRYPTO_EccPublicSignKey
336 const char *method_name,
337 size_t variable_count,
338 const struct GNUNET_ENV_Modifier *variables,
341 struct GNUNET_PSYC_JoinHandle *jh);
345 * Function to call with the decision made for a join request.
347 * Must be called once and only once in response to an invocation of the
348 * #GNUNET_PSYC_JoinCallback.
350 * @param jh Join request handle.
351 * @param is_admitted #GNUNET_YES if joining is approved,
352 * #GNUNET_NO if it is disapproved.
353 * @param relay_count Number of relays given.
354 * @param relays Array of suggested peers that might be useful relays to use
355 * when joining the multicast group (essentially a list of peers that
356 * are already part of the multicast group and might thus be willing
357 * to help with routing). If empty, only this local peer (which must
358 * be the multicast origin) is a good candidate for building the
359 * multicast tree. Note that it is unnecessary to specify our own
360 * peer identity in this array.
361 * @param method_name Method name for the message transmitted with the response.
362 * @param env Environment containing transient variables for the message,
364 * @param data Data of the message.
365 * @param data_size Size of @a data.
368 GNUNET_PSYC_join_decision (struct GNUNET_PSYC_JoinHandle *jh,
370 unsigned int relay_count,
371 const struct GNUNET_PeerIdentity *relays,
372 const char *method_name,
373 const struct GNUNET_ENV_Environment *env,
379 * Handle for the master of a PSYC channel.
381 struct GNUNET_PSYC_Master;
385 * Function called after the channel master started.
387 * @param cls Closure.
388 * @param last_message_id Last message ID sent to the channel.
391 (*GNUNET_PSYC_MasterStartCallback) (void *cls, uint64_t max_message_id);
395 * Start a PSYC master channel.
397 * Will start a multicast group identified by the given ECC key. Messages
398 * received from group members will be given to the respective handler methods.
399 * If a new member wants to join a group, the "join" method handler will be
400 * invoked; the join handler must then generate a "join" message to approve the
401 * joining of the new member. The channel can also change group membership
402 * without explicit requests. Note that PSYC doesn't itself "understand" join
403 * or part messages, the respective methods must call other PSYC functions to
404 * inform PSYC about the meaning of the respective events.
406 * @param cfg Configuration to use (to connect to PSYC service).
407 * @param channel_key ECC key that will be used to sign messages for this
408 * PSYC session. The public key is used to identify the PSYC channel.
409 * Note that end-users will usually not use the private key directly, but
410 * rather look it up in GNS for places managed by other users, or select
411 * a file with the private key(s) when setting up their own channels
412 * FIXME: we'll likely want to use NOT the p521 curve here, but a cheaper
414 * @param policy Channel policy specifying join and history restrictions.
415 * Used to automate join decisions.
416 * @param method Function to invoke on messages received from slaves.
417 * @param join_cb Function to invoke when a peer wants to join.
418 * @param start_cb Function to invoke after the channel master started.
419 * @param cls Closure for @a method and @a join_cb.
420 * @return Handle for the channel master, NULL on error.
422 struct GNUNET_PSYC_Master *
423 GNUNET_PSYC_master_start (const struct GNUNET_CONFIGURATION_Handle *cfg,
424 const struct GNUNET_CRYPTO_EccPrivateKey *channel_key,
425 enum GNUNET_PSYC_Policy policy,
426 GNUNET_PSYC_Method method,
427 GNUNET_PSYC_JoinCallback join_cb,
428 GNUNET_PSYC_MasterStartCallback start_cb,
433 * Function called to provide data for a transmission via PSYC.
435 * Note that returning #GNUNET_OK or #GNUNET_SYSERR (but not #GNUNET_NO)
436 * invalidates the respective transmission handle.
438 * @param cls Closure.
439 * @param[in,out] data_size Initially set to the number of bytes available in
440 * @a data, should be set to the number of bytes written to data.
441 * @param[out] data Where to write the body of the message to give to the
442 * method. The function must copy at most @a data_size bytes to @a data.
443 * @return #GNUNET_SYSERR on error (fatal, aborts transmission)
444 * #GNUNET_NO on success, if more data is to be transmitted later.
445 * Should be used if @a data_size was not big enough to take all the
446 * data. If 0 is returned in @a data_size the transmission is paused,
447 * and can be resumed with GNUNET_PSYC_master_transmit_resume().
448 * #GNUNET_YES if this completes the transmission (all data supplied)
451 (*GNUNET_PSYC_MasterTransmitNotify) (void *cls,
457 * Flags for transmitting messages to a channel by the master.
459 enum GNUNET_PSYC_MasterTransmitFlags
461 GNUNET_PSYC_MASTER_TRANSMIT_NONE = 0,
463 * Whether this message should reset the channel state,
464 * i.e. remove all previously stored state variables.
466 GNUNET_PSYC_MASTER_TRANSMIT_RESET_STATE = 1 << 0,
469 * Whether we need to increment the group generation counter after
470 * transmitting this message.
472 GNUNET_PSYC_MASTER_TRANSMIT_INC_GROUP_GEN = 1 << 1,
475 * Add PSYC header variable with the hash of the current channel state.
477 GNUNET_PSYC_MASTER_TRANSMIT_ADD_STATE_HASH = 1 << 2
482 * Handle for a pending PSYC transmission operation.
484 struct GNUNET_PSYC_MasterTransmitHandle;
488 * Send a message to call a method to all members in the PSYC channel.
490 * @param master Handle to the PSYC channel.
491 * @param method_name Which method should be invoked.
492 * @param env Environment containing state operations and transient variables
493 * for the message, or NULL.
494 * @param notify Function to call to obtain the arguments.
495 * @param notify_cls Closure for @a notify.
496 * @param flags Flags for the message being transmitted.
497 * @return Transmission handle, NULL on error (i.e. more than one request queued).
499 struct GNUNET_PSYC_MasterTransmitHandle *
500 GNUNET_PSYC_master_transmit (struct GNUNET_PSYC_Master *master,
501 const char *method_name,
502 const struct GNUNET_ENV_Environment *env,
503 GNUNET_PSYC_MasterTransmitNotify notify,
505 enum GNUNET_PSYC_MasterTransmitFlags flags);
509 * Resume transmission to the channel.
511 * @param th Handle of the request that is being resumed.
514 GNUNET_PSYC_master_transmit_resume (struct GNUNET_PSYC_MasterTransmitHandle *th);
518 * Abort transmission request to channel.
520 * @param th Handle of the request that is being aborted.
523 GNUNET_PSYC_master_transmit_cancel (struct GNUNET_PSYC_MasterTransmitHandle *th);
527 * Stop a PSYC master channel.
529 * @param master PSYC channel master to stop.
532 GNUNET_PSYC_master_stop (struct GNUNET_PSYC_Master *master);
536 * Handle for a PSYC channel slave.
538 struct GNUNET_PSYC_Slave;
542 * Function called after the slave joined.
544 * @param cls Closure.
545 * @param max_message_id Last message ID sent to the channel.
548 (*GNUNET_PSYC_SlaveJoinCallback) (void *cls, uint64_t max_message_id);
552 * Join a PSYC channel.
554 * The entity joining is always the local peer. The user must immediately use
555 * the GNUNET_PSYC_slave_transmit() functions to transmit a @e join_msg to the
556 * channel; if the join request succeeds, the channel state (and @e recent
557 * method calls) will be replayed to the joining member. There is no explicit
558 * notification on failure (as the channel may simply take days to approve,
559 * and disapproval is simply being ignored).
561 * @param cfg Configuration to use.
562 * @param channel_key ECC public key that identifies the channel we wish to join.
563 * @param slave_key ECC private-public key pair that identifies the slave, and
564 * used by multicast to sign the join request and subsequent unicast
565 * requests sent to the master.
566 * @param origin Peer identity of the origin.
567 * @param relay_count Number of peers in the @a relays array.
568 * @param relays Peer identities of members of the multicast group, which serve
569 * as relays and used to join the group at.
570 * @param method Function to invoke on messages received from the channel,
571 * typically at least contains functions for @e join and @e part.
572 * @param join_cb Function to invoke when a peer wants to join.
573 * @param cls Closure for @a method_cb and @a join_cb.
574 * @param method_name Method name for the join request.
575 * @param env Environment containing transient variables for the request, or NULL.
576 * @param data Payload for the join message.
577 * @param data_size Number of bytes in @a data.
578 * @return Handle for the slave, NULL on error.
580 struct GNUNET_PSYC_Slave *
581 GNUNET_PSYC_slave_join (const struct GNUNET_CONFIGURATION_Handle *cfg,
582 const struct GNUNET_CRYPTO_EccPublicSignKey *channel_key,
583 const struct GNUNET_CRYPTO_EccPrivateKey *slave_key,
584 const struct GNUNET_PeerIdentity *origin,
586 const struct GNUNET_PeerIdentity *relays,
587 GNUNET_PSYC_Method method,
588 GNUNET_PSYC_JoinCallback join_cb,
589 GNUNET_PSYC_SlaveJoinCallback slave_joined_cb,
591 const char *method_name,
592 const struct GNUNET_ENV_Environment *env,
598 * Part a PSYC channel.
600 * Will terminate the connection to the PSYC service. Polite clients should
601 * first explicitly send a @e part request (via GNUNET_PSYC_slave_transmit()).
603 * @param slave Slave handle.
606 GNUNET_PSYC_slave_part (struct GNUNET_PSYC_Slave *slave);
610 * Function called to provide data for a transmission to the channel master
611 * (a.k.a. the @e host of the channel).
613 * Note that returning #GNUNET_OK or #GNUNET_SYSERR (but not #GNUNET_NO)
614 * invalidates the respective transmission handle.
616 * @param cls Closure.
617 * @param[in,out] data_size Initially set to the number of bytes available in
618 * @a data, should be set to the number of bytes written to data
620 * @param[out] data Where to write the body of the message to give to the method;
621 * function must copy at most @a *data_size bytes to @a data.
622 * @return #GNUNET_SYSERR on error (fatal, aborts transmission).
623 * #GNUNET_NO on success, if more data is to be transmitted later.
624 * #GNUNET_YES if this completes the transmission (all data supplied).
627 (*GNUNET_PSYC_SlaveTransmitNotify) (void *cls,
633 * Flags for transmitting messages to the channel master by a slave.
635 enum GNUNET_PSYC_SlaveTransmitFlags
637 GNUNET_PSYC_SLAVE_TRANSMIT_NONE = 0
642 * Handle for a pending PSYC transmission operation.
644 struct GNUNET_PSYC_SlaveTransmitHandle;
648 * Request a message to be sent to the channel master.
650 * @param slave Slave handle.
651 * @param method_name Which (PSYC) method should be invoked (on host).
652 * @param env Environment containing transient variables for the message, or NULL.
653 * @param notify Function to call when we are allowed to transmit (to get data).
654 * @param notify_cls Closure for @a notify.
655 * @param flags Flags for the message being transmitted.
656 * @return Transmission handle, NULL on error (i.e. more than one request queued).
658 struct GNUNET_PSYC_SlaveTransmitHandle *
659 GNUNET_PSYC_slave_transmit (struct GNUNET_PSYC_Slave *slave,
660 const char *method_name,
661 const struct GNUNET_ENV_Environment *env,
662 GNUNET_PSYC_SlaveTransmitNotify notify,
664 enum GNUNET_PSYC_SlaveTransmitFlags flags);
668 * Resume transmission to the master.
670 * @param th Handle of the request that is being resumed.
673 GNUNET_PSYC_slave_transmit_resume (struct GNUNET_PSYC_MasterTransmitHandle *th);
677 * Abort transmission request to master.
679 * @param th Handle of the request that is being aborted.
682 GNUNET_PSYC_slave_transmit_cancel (struct GNUNET_PSYC_SlaveTransmitHandle *th);
686 * Handle to access PSYC channel operations for both the master and slaves.
688 struct GNUNET_PSYC_Channel;
692 * Convert a channel @a master to a @e channel handle to access the @e channel
695 * @param master Channel master handle.
696 * @return Channel handle, valid for as long as @a master is valid.
698 struct GNUNET_PSYC_Channel *
699 GNUNET_PSYC_master_get_channel (struct GNUNET_PSYC_Master *master);
703 * Convert @a slave to a @e channel handle to access the @e channel APIs.
705 * @param slave Slave handle.
706 * @return Channel handle, valid for as long as @a slave is valid.
708 struct GNUNET_PSYC_Channel *
709 GNUNET_PSYC_slave_get_channel (struct GNUNET_PSYC_Slave *slave);
713 * Add a slave to the channel's membership list.
715 * Note that this will NOT generate any PSYC traffic, it will merely update the
716 * local database to modify how we react to <em>membership test</em> queries.
717 * The channel master still needs to explicitly transmit a @e join message to
718 * notify other channel members and they then also must still call this function
719 * in their respective methods handling the @e join message. This way, how @e
720 * join and @e part operations are exactly implemented is still up to the
721 * application; for example, there might be a @e part_all method to kick out
724 * Note that channel slaves are explicitly trusted to execute such methods
725 * correctly; not doing so correctly will result in either denying other slaves
726 * access or offering access to channel data to non-members.
728 * @param channel Channel handle.
729 * @param slave_key Identity of channel slave to add.
730 * @param announced_at ID of the message that announced the membership change.
731 * @param effective_since Addition of slave is in effect since this message ID.
734 GNUNET_PSYC_channel_slave_add (struct GNUNET_PSYC_Channel *channel,
735 const struct GNUNET_CRYPTO_EccPublicSignKey
737 uint64_t announced_at,
738 uint64_t effective_since);
742 * Remove a slave from the channel's membership list.
744 * Note that this will NOT generate any PSYC traffic, it will merely update the
745 * local database to modify how we react to <em>membership test</em> queries.
746 * The channel master still needs to explicitly transmit a @e part message to
747 * notify other channel members and they then also must still call this function
748 * in their respective methods handling the @e part message. This way, how
749 * @e join and @e part operations are exactly implemented is still up to the
750 * application; for example, there might be a @e part_all message to kick out
753 * Note that channel members are explicitly trusted to perform these
754 * operations correctly; not doing so correctly will result in either
755 * denying members access or offering access to channel data to
758 * @param channel Channel handle.
759 * @param slave_key Identity of channel slave to remove.
760 * @param announced_at ID of the message that announced the membership change.
763 GNUNET_PSYC_channel_slave_remove (struct GNUNET_PSYC_Channel *channel,
764 const struct GNUNET_CRYPTO_EccPublicSignKey
766 uint64_t announced_at);
770 * Function called to inform a member about stored state values for a channel.
772 * @param cls Closure.
773 * @param name Name of the state variable. A NULL value indicates that there
774 * are no more state variables to be returned.
775 * @param value Value of the state variable.
776 * @param value_size Number of bytes in @a value.
779 (*GNUNET_PSYC_StateCallback) (void *cls,
786 * Function called when a requested operation has finished.
788 * @param cls Closure.
791 (*GNUNET_PSYC_FinishCallback) (void *cls);
795 * Handle to a story telling operation.
797 struct GNUNET_PSYC_Story;
801 * Request to be told the message history of the channel.
803 * Historic messages (but NOT the state at the time) will be replayed (given to
804 * the normal method handlers) if available and if access is permitted.
806 * To get the latest message, use 0 for both the start and end message ID.
808 * @param channel Which channel should be replayed?
809 * @param start_message_id Earliest interesting point in history.
810 * @param end_message_id Last (exclusive) interesting point in history.
811 * @param method Function to invoke on messages received from the story.
812 * @param finish_cb Function to call when the requested story has been fully
813 * told (counting message IDs might not suffice, as some messages
814 * might be secret and thus the listener would not know the story is
815 * finished without being told explicitly); once this function
816 * has been called, the client must not call
817 * GNUNET_PSYC_channel_story_tell_cancel() anymore.
818 * @param cls Closure for the callbacks.
819 * @return Handle to cancel story telling operation.
821 struct GNUNET_PSYC_Story *
822 GNUNET_PSYC_channel_story_tell (struct GNUNET_PSYC_Channel *channel,
823 uint64_t start_message_id,
824 uint64_t end_message_id,
825 GNUNET_PSYC_Method method,
826 GNUNET_PSYC_FinishCallback *finish_cb,
831 * Abort story telling.
833 * This function must not be called from within method handlers (as given to
834 * GNUNET_PSYC_slave_join()) of the slave.
836 * @param story Story telling operation to stop.
839 GNUNET_PSYC_channel_story_tell_cancel (struct GNUNET_PSYC_Story *story);
843 * Handle for a state query operation.
845 struct GNUNET_PSYC_StateQuery;
849 * Retrieve the best matching channel state variable.
851 * If the requested variable name is not present in the state, the nearest
852 * less-specific name is matched; for example, requesting "_a_b" will match "_a"
853 * if "_a_b" does not exist.
855 * @param channel Channel handle.
856 * @param full_name Full name of the requested variable, the actual variable
857 * returned might have a shorter name..
858 * @param cb Function called once when a matching state variable is found.
859 * Not called if there's no matching state variable.
860 * @param cb_cls Closure for the callbacks.
861 * @return Handle that can be used to cancel the query operation.
863 struct GNUNET_PSYC_StateQuery *
864 GNUNET_PSYC_channel_state_get (struct GNUNET_PSYC_Channel *channel,
865 const char *full_name,
866 GNUNET_PSYC_StateCallback cb,
871 * Return all channel state variables whose name matches a given prefix.
873 * A name matches if it starts with the given @a name_prefix, thus requesting
874 * the empty prefix ("") will match all values; requesting "_a_b" will also
875 * return values stored under "_a_b_c".
877 * The @a state_cb is invoked on all matching state variables asynchronously, as
878 * the state is stored in and retrieved from the PSYCstore,
880 * @param channel Channel handle.
881 * @param name_prefix Prefix of the state variable name to match.
882 * @param cb Function to call with the matching state variables.
883 * @param cb_cls Closure for the callbacks.
884 * @return Handle that can be used to cancel the query operation.
886 struct GNUNET_PSYC_StateQuery *
887 GNUNET_PSYC_channel_state_get_prefix (struct GNUNET_PSYC_Channel *channel,
888 const char *name_prefix,
889 GNUNET_PSYC_StateCallback cb,
894 * Cancel a state query operation.
896 * @param query Handle for the operation to cancel.
899 GNUNET_PSYC_channel_state_get_cancel (struct GNUNET_PSYC_StateQuery *query);
902 #if 0 /* keep Emacsens' auto-indent happy */
909 /* ifndef GNUNET_PSYC_SERVICE_H */
911 /* end of gnunet_psyc_service.h */