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3 (C) 2012, 2013 Christian Grothoff (and other contributing authors)
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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 * Historic message, retrieved from PSYCstore.
166 GNUNET_PSYC_MESSAGE_HISTORIC = 1
169 GNUNET_NETWORK_STRUCT_BEGIN
172 * Header of a PSYC message.
174 struct GNUNET_PSYC_MessageHeader
177 * Generic message header with size and type information.
179 struct GNUNET_MessageHeader header;
182 * Flags for this message fragment.
184 * @see enum GNUNET_PSYC_MessageFlags
186 uint32_t flags GNUNET_PACKED;
189 * Number of the message this message part belongs to.
191 uint64_t message_id GNUNET_PACKED;
194 * Sending slave's public key.
195 * Not set if the message is from the master.
197 struct GNUNET_CRYPTO_EddsaPublicKey slave_key;
199 /* Followed by concatenated PSYC message parts:
200 * messages with GNUNET_MESSAGE_TYPE_PSYC_MESSAGE_* types
206 * The method of a message.
208 struct GNUNET_PSYC_MessageMethod
211 * Type: GNUNET_MESSAGE_TYPE_PSYC_MESSAGE_METHOD
213 struct GNUNET_MessageHeader header;
216 * OR'ed GNUNET_PSYC_MasterTransmitFlags
218 uint32_t flags GNUNET_PACKED;
220 /* Followed by NUL-terminated method name. */
225 * A modifier of a message.
227 struct GNUNET_PSYC_MessageModifier
230 * Type: GNUNET_MESSAGE_TYPE_PSYC_MESSAGE_MODIFIER
232 struct GNUNET_MessageHeader header;
237 uint32_t value_size GNUNET_PACKED;
240 * Size of name, including NUL terminator.
242 uint16_t name_size GNUNET_PACKED;
245 * enum GNUNET_ENV_Operator
249 /* Followed by NUL-terminated name, then the value. */
252 GNUNET_NETWORK_STRUCT_END
254 #define GNUNET_PSYC_MODIFIER_MAX_PAYLOAD \
255 GNUNET_MULTICAST_FRAGMENT_MAX_PAYLOAD \
256 - sizeof (struct GNUNET_PSYC_MessageModifier)
258 #define GNUNET_PSYC_MOD_CONT_MAX_PAYLOAD \
259 GNUNET_MULTICAST_FRAGMENT_MAX_PAYLOAD \
260 - sizeof (struct GNUNET_MessageHeader)
262 #define GNUNET_PSYC_DATA_MAX_PAYLOAD \
263 GNUNET_MULTICAST_FRAGMENT_MAX_PAYLOAD \
264 - sizeof (struct GNUNET_MessageHeader)
267 * Handle that identifies a join request.
269 * Used to match calls to #GNUNET_PSYC_JoinCallback to the
270 * corresponding calls to GNUNET_PSYC_join_decision().
272 struct GNUNET_PSYC_JoinHandle;
276 * Method called from PSYC upon receiving part of a message.
278 * @param cls Closure.
279 * @param msg Message part, one of the following types:
280 * - GNUNET_MESSAGE_TYPE_PSYC_MESSAGE_HEADER
281 * - GNUNET_MESSAGE_TYPE_PSYC_MESSAGE_METHOD
282 * - GNUNET_MESSAGE_TYPE_PSYC_MESSAGE_MODIFIER
283 * - GNUNET_MESSAGE_TYPE_PSYC_MESSAGE_MOD_CONT
284 * - GNUNET_MESSAGE_TYPE_PSYC_MESSAGE_DATA
287 (*GNUNET_PSYC_MessageCallback) (void *cls,
290 const struct GNUNET_MessageHeader *msg);
294 * Method called from PSYC upon receiving a join request.
296 * @param cls Closure.
297 * @param slave requesting to join.
298 * @param method_name Method name in the join request.
299 * @param variable_count Number of elements in the @a variables array.
300 * @param variables Transient variables for the join request.
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 jh Join handle to use with GNUNET_PSYC_join_decision()
307 (*GNUNET_PSYC_JoinCallback) (void *cls,
308 const struct GNUNET_CRYPTO_EddsaPublicKey
310 const char *method_name,
311 size_t variable_count,
312 const struct GNUNET_ENV_Modifier *variables,
315 struct GNUNET_PSYC_JoinHandle *jh);
319 * Function to call with the decision made for a join request.
321 * Must be called once and only once in response to an invocation of the
322 * #GNUNET_PSYC_JoinCallback.
324 * @param jh Join request handle.
325 * @param is_admitted #GNUNET_YES if joining is approved,
326 * #GNUNET_NO if it is disapproved.
327 * @param relay_count Number of relays given.
328 * @param relays Array of suggested peers that might be useful relays to use
329 * when joining the multicast group (essentially a list of peers that
330 * are already part of the multicast group and might thus be willing
331 * to help with routing). If empty, only this local peer (which must
332 * be the multicast origin) is a good candidate for building the
333 * multicast tree. Note that it is unnecessary to specify our own
334 * peer identity in this array.
335 * @param method_name Method name for the message transmitted with the response.
336 * @param env Environment containing transient variables for the message,
338 * @param data Data of the message.
339 * @param data_size Size of @a data.
342 GNUNET_PSYC_join_decision (struct GNUNET_PSYC_JoinHandle *jh,
344 uint32_t relay_count,
345 const struct GNUNET_PeerIdentity *relays,
346 const char *method_name,
347 const struct GNUNET_ENV_Environment *env,
353 * Handle for the master of a PSYC channel.
355 struct GNUNET_PSYC_Master;
359 * Function called after the channel master started.
361 * @param cls Closure.
362 * @param last_message_id Last message ID sent to the channel.
365 (*GNUNET_PSYC_MasterStartCallback) (void *cls, uint64_t max_message_id);
369 * Start a PSYC master channel.
371 * Will start a multicast group identified by the given ECC key. Messages
372 * received from group members will be given to the respective handler methods.
373 * If a new member wants to join a group, the "join" method handler will be
374 * invoked; the join handler must then generate a "join" message to approve the
375 * joining of the new member. The channel can also change group membership
376 * without explicit requests. Note that PSYC doesn't itself "understand" join
377 * or part messages, the respective methods must call other PSYC functions to
378 * inform PSYC about the meaning of the respective events.
380 * @param cfg Configuration to use (to connect to PSYC service).
381 * @param channel_key ECC key that will be used to sign messages for this
382 * PSYC session. The public key is used to identify the PSYC channel.
383 * Note that end-users will usually not use the private key directly, but
384 * rather look it up in GNS for places managed by other users, or select
385 * a file with the private key(s) when setting up their own channels
386 * FIXME: we'll likely want to use NOT the p521 curve here, but a cheaper
388 * @param policy Channel policy specifying join and history restrictions.
389 * Used to automate join decisions.
390 * @param message_cb Function to invoke on message parts received from slaves.
391 * @param join_cb Function to invoke when a peer wants to join.
392 * @param master_started_cb Function to invoke after the channel master started.
393 * @param cls Closure for @a method and @a join_cb.
394 * @return Handle for the channel master, NULL on error.
396 struct GNUNET_PSYC_Master *
397 GNUNET_PSYC_master_start (const struct GNUNET_CONFIGURATION_Handle *cfg,
398 const struct GNUNET_CRYPTO_EddsaPrivateKey *channel_key,
399 enum GNUNET_PSYC_Policy policy,
400 GNUNET_PSYC_MessageCallback message_cb,
401 GNUNET_PSYC_JoinCallback join_cb,
402 GNUNET_PSYC_MasterStartCallback master_started_cb,
407 * Function called to provide data for a transmission via PSYC.
409 * Note that returning #GNUNET_OK or #GNUNET_SYSERR (but not #GNUNET_NO)
410 * invalidates the respective transmission handle.
412 * @param cls Closure.
413 * @param[in,out] data_size Initially set to the number of bytes available in
414 * @a data, should be set to the number of bytes written to data.
415 * @param[out] data Where to write the body of the message to give to the
416 * method. The function must copy at most @a data_size bytes to @a data.
417 * @return #GNUNET_SYSERR on error (fatal, aborts transmission)
418 * #GNUNET_NO on success, if more data is to be transmitted later.
419 * Should be used if @a data_size was not big enough to take all the
420 * data. If 0 is returned in @a data_size the transmission is paused,
421 * and can be resumed with GNUNET_PSYC_master_transmit_resume().
422 * #GNUNET_YES if this completes the transmission (all data supplied)
425 (*GNUNET_PSYC_MasterTransmitNotify) (void *cls,
430 (*GNUNET_PSYC_MasterTransmitNotifyModifier) (void *cls,
436 * Flags for transmitting messages to a channel by the master.
438 enum GNUNET_PSYC_MasterTransmitFlags
440 GNUNET_PSYC_MASTER_TRANSMIT_NONE = 0,
442 * Whether this message should reset the channel state,
443 * i.e. remove all previously stored state variables.
445 GNUNET_PSYC_MASTER_TRANSMIT_RESET_STATE = 1 << 0,
448 * Whether we need to increment the group generation counter after
449 * transmitting this message.
451 GNUNET_PSYC_MASTER_TRANSMIT_INC_GROUP_GEN = 1 << 1,
454 * Add PSYC header variable with the hash of the current channel state.
456 GNUNET_PSYC_MASTER_TRANSMIT_ADD_STATE_HASH = 1 << 2
461 * Handle for a pending PSYC transmission operation.
463 struct GNUNET_PSYC_MasterTransmitHandle;
467 * Send a message to call a method to all members in the PSYC channel.
469 * @param master Handle to the PSYC channel.
470 * @param method_name Which method should be invoked.
471 * @param notify_mod Function to call to obtain modifiers.
472 * @param notify_data Function to call to obtain fragments of the data.
473 * @param notify_cls Closure for @a notify_mod and @a notify_data.
474 * @param flags Flags for the message being transmitted.
475 * @return Transmission handle, NULL on error (i.e. more than one request queued).
477 struct GNUNET_PSYC_MasterTransmitHandle *
478 GNUNET_PSYC_master_transmit (struct GNUNET_PSYC_Master *master,
479 const char *method_name,
480 GNUNET_PSYC_MasterTransmitNotifyModifier notify_mod,
481 GNUNET_PSYC_MasterTransmitNotify notify_data,
483 enum GNUNET_PSYC_MasterTransmitFlags flags);
487 * Resume transmission to the channel.
489 * @param th Handle of the request that is being resumed.
492 GNUNET_PSYC_master_transmit_resume (struct GNUNET_PSYC_MasterTransmitHandle *th);
496 * Abort transmission request to channel.
498 * @param th Handle of the request that is being aborted.
501 GNUNET_PSYC_master_transmit_cancel (struct GNUNET_PSYC_MasterTransmitHandle *th);
505 * Stop a PSYC master channel.
507 * @param master PSYC channel master to stop.
510 GNUNET_PSYC_master_stop (struct GNUNET_PSYC_Master *master);
514 * Handle for a PSYC channel slave.
516 struct GNUNET_PSYC_Slave;
520 * Function called after the slave joined.
522 * @param cls Closure.
523 * @param max_message_id Last message ID sent to the channel.
526 (*GNUNET_PSYC_SlaveJoinCallback) (void *cls, uint64_t max_message_id);
530 * Join a PSYC channel.
532 * The entity joining is always the local peer. The user must immediately use
533 * the GNUNET_PSYC_slave_transmit() functions to transmit a @e join_msg to the
534 * channel; if the join request succeeds, the channel state (and @e recent
535 * method calls) will be replayed to the joining member. There is no explicit
536 * notification on failure (as the channel may simply take days to approve,
537 * and disapproval is simply being ignored).
539 * @param cfg Configuration to use.
540 * @param channel_key ECC public key that identifies the channel we wish to join.
541 * @param slave_key ECC private-public key pair that identifies the slave, and
542 * used by multicast to sign the join request and subsequent unicast
543 * requests sent to the master.
544 * @param origin Peer identity of the origin.
545 * @param relay_count Number of peers in the @a relays array.
546 * @param relays Peer identities of members of the multicast group, which serve
547 * as relays and used to join the group at.
548 * @param message_cb Function to invoke on message parts received from the
549 * channel, typically at least contains method handlers for @e join and
551 * @param join_cb function invoked once we have joined with the current
552 * message ID of the channel
553 * @param slave_joined_cb Function to invoke when a peer wants to join.
554 * @param cls Closure for @a message_cb and @a slave_joined_cb.
555 * @param method_name Method name for the join request.
556 * @param env Environment containing transient variables for the request, or NULL.
557 * @param data Payload for the join message.
558 * @param data_size Number of bytes in @a data.
559 * @return Handle for the slave, NULL on error.
561 struct GNUNET_PSYC_Slave *
562 GNUNET_PSYC_slave_join (const struct GNUNET_CONFIGURATION_Handle *cfg,
563 const struct GNUNET_CRYPTO_EddsaPublicKey *channel_key,
564 const struct GNUNET_CRYPTO_EddsaPrivateKey *slave_key,
565 const struct GNUNET_PeerIdentity *origin,
566 uint32_t relay_count,
567 const struct GNUNET_PeerIdentity *relays,
568 GNUNET_PSYC_MessageCallback message_cb,
569 GNUNET_PSYC_JoinCallback join_cb,
570 GNUNET_PSYC_SlaveJoinCallback slave_joined_cb,
572 const char *method_name,
573 const struct GNUNET_ENV_Environment *env,
579 * Part a PSYC channel.
581 * Will terminate the connection to the PSYC service. Polite clients should
582 * first explicitly send a part request (via GNUNET_PSYC_slave_transmit()).
584 * @param slave Slave handle.
587 GNUNET_PSYC_slave_part (struct GNUNET_PSYC_Slave *slave);
591 * Function called to provide data for a transmission to the channel master
592 * (a.k.a. the @e host of the channel).
594 * Note that returning #GNUNET_OK or #GNUNET_SYSERR (but not #GNUNET_NO)
595 * invalidates the respective transmission handle.
597 * @param cls Closure.
598 * @param[in,out] data_size Initially set to the number of bytes available in
599 * @a data, should be set to the number of bytes written to data
601 * @param[out] data Where to write the body of the message to give to the method;
602 * function must copy at most @a *data_size bytes to @a data.
603 * @return #GNUNET_SYSERR on error (fatal, aborts transmission).
604 * #GNUNET_NO on success, if more data is to be transmitted later.
605 * #GNUNET_YES if this completes the transmission (all data supplied).
608 (*GNUNET_PSYC_SlaveTransmitNotify) (void *cls,
614 * Flags for transmitting messages to the channel master by a slave.
616 enum GNUNET_PSYC_SlaveTransmitFlags
618 GNUNET_PSYC_SLAVE_TRANSMIT_NONE = 0
623 * Handle for a pending PSYC transmission operation.
625 struct GNUNET_PSYC_SlaveTransmitHandle;
629 * Request a message to be sent to the channel master.
631 * @param slave Slave handle.
632 * @param method_name Which (PSYC) method should be invoked (on host).
633 * @param env Environment containing transient variables for the message, or NULL.
634 * @param notify Function to call when we are allowed to transmit (to get data).
635 * @param notify_cls Closure for @a notify.
636 * @param flags Flags for the message being transmitted.
637 * @return Transmission handle, NULL on error (i.e. more than one request queued).
639 struct GNUNET_PSYC_SlaveTransmitHandle *
640 GNUNET_PSYC_slave_transmit (struct GNUNET_PSYC_Slave *slave,
641 const char *method_name,
642 const struct GNUNET_ENV_Environment *env,
643 GNUNET_PSYC_SlaveTransmitNotify notify,
645 enum GNUNET_PSYC_SlaveTransmitFlags flags);
649 * Resume transmission to the master.
651 * @param th Handle of the request that is being resumed.
654 GNUNET_PSYC_slave_transmit_resume (struct GNUNET_PSYC_MasterTransmitHandle *th);
658 * Abort transmission request to master.
660 * @param th Handle of the request that is being aborted.
663 GNUNET_PSYC_slave_transmit_cancel (struct GNUNET_PSYC_SlaveTransmitHandle *th);
667 * Handle to access PSYC channel operations for both the master and slaves.
669 struct GNUNET_PSYC_Channel;
673 * Convert a channel @a master to a @e channel handle to access the @e channel
676 * @param master Channel master handle.
677 * @return Channel handle, valid for as long as @a master is valid.
679 struct GNUNET_PSYC_Channel *
680 GNUNET_PSYC_master_get_channel (struct GNUNET_PSYC_Master *master);
684 * Convert @a slave to a @e channel handle to access the @e channel APIs.
686 * @param slave Slave handle.
687 * @return Channel handle, valid for as long as @a slave is valid.
689 struct GNUNET_PSYC_Channel *
690 GNUNET_PSYC_slave_get_channel (struct GNUNET_PSYC_Slave *slave);
694 * Add a slave to the channel's membership list.
696 * Note that this will NOT generate any PSYC traffic, it will merely update the
697 * local database to modify how we react to <em>membership test</em> queries.
698 * The channel master still needs to explicitly transmit a @e join message to
699 * notify other channel members and they then also must still call this function
700 * in their respective methods handling the @e join message. This way, how @e
701 * join and @e part operations are exactly implemented is still up to the
702 * application; for example, there might be a @e part_all method to kick out
705 * Note that channel slaves are explicitly trusted to execute such methods
706 * correctly; not doing so correctly will result in either denying other slaves
707 * access or offering access to channel data to non-members.
709 * @param channel Channel handle.
710 * @param slave_key Identity of channel slave to add.
711 * @param announced_at ID of the message that announced the membership change.
712 * @param effective_since Addition of slave is in effect since this message ID.
715 GNUNET_PSYC_channel_slave_add (struct GNUNET_PSYC_Channel *channel,
716 const struct GNUNET_CRYPTO_EddsaPublicKey *slave_key,
717 uint64_t announced_at,
718 uint64_t effective_since);
722 * Remove a slave from the channel's membership list.
724 * Note that this will NOT generate any PSYC traffic, it will merely update the
725 * local database to modify how we react to <em>membership test</em> queries.
726 * The channel master still needs to explicitly transmit a @e part message to
727 * notify other channel members and they then also must still call this function
728 * in their respective methods handling the @e part message. This way, how
729 * @e join and @e part operations are exactly implemented is still up to the
730 * application; for example, there might be a @e part_all message to kick out
733 * Note that channel members are explicitly trusted to perform these
734 * operations correctly; not doing so correctly will result in either
735 * denying members access or offering access to channel data to
738 * @param channel Channel handle.
739 * @param slave_key Identity of channel slave to remove.
740 * @param announced_at ID of the message that announced the membership change.
743 GNUNET_PSYC_channel_slave_remove (struct GNUNET_PSYC_Channel *channel,
744 const struct GNUNET_CRYPTO_EddsaPublicKey
746 uint64_t announced_at);
750 * Function called to inform a member about stored state values for a channel.
752 * @param cls Closure.
753 * @param name Name of the state variable. A NULL value indicates that there
754 * are no more state variables to be returned.
755 * @param value Value of the state variable.
756 * @param value_size Number of bytes in @a value.
759 (*GNUNET_PSYC_StateCallback) (void *cls,
766 * Function called when a requested operation has finished.
768 * @param cls Closure.
771 (*GNUNET_PSYC_FinishCallback) (void *cls);
775 * Handle to a story telling operation.
777 struct GNUNET_PSYC_Story;
781 * Request to be told the message history of the channel.
783 * Historic messages (but NOT the state at the time) will be replayed (given to
784 * the normal method handlers) if available and if access is permitted.
786 * To get the latest message, use 0 for both the start and end message ID.
788 * @param channel Which channel should be replayed?
789 * @param start_message_id Earliest interesting point in history.
790 * @param end_message_id Last (exclusive) interesting point in history.
791 * @param message_cb Function to invoke on message parts received from the story.
792 * @param finish_cb Function to call when the requested story has been fully
793 * told (counting message IDs might not suffice, as some messages
794 * might be secret and thus the listener would not know the story is
795 * finished without being told explicitly); once this function
796 * has been called, the client must not call
797 * GNUNET_PSYC_channel_story_tell_cancel() anymore.
798 * @param cls Closure for the callbacks.
799 * @return Handle to cancel story telling operation.
801 struct GNUNET_PSYC_Story *
802 GNUNET_PSYC_channel_story_tell (struct GNUNET_PSYC_Channel *channel,
803 uint64_t start_message_id,
804 uint64_t end_message_id,
805 GNUNET_PSYC_MessageCallback message_cb,
806 GNUNET_PSYC_FinishCallback finish_cb,
811 * Abort story telling.
813 * This function must not be called from within method handlers (as given to
814 * GNUNET_PSYC_slave_join()) of the slave.
816 * @param story Story telling operation to stop.
819 GNUNET_PSYC_channel_story_tell_cancel (struct GNUNET_PSYC_Story *story);
823 * Handle for a state query operation.
825 struct GNUNET_PSYC_StateQuery;
829 * Retrieve the best matching channel state variable.
831 * If the requested variable name is not present in the state, the nearest
832 * less-specific name is matched; for example, requesting "_a_b" will match "_a"
833 * if "_a_b" does not exist.
835 * @param channel Channel handle.
836 * @param full_name Full name of the requested variable, the actual variable
837 * returned might have a shorter name..
838 * @param cb Function called once when a matching state variable is found.
839 * Not called if there's no matching state variable.
840 * @param cb_cls Closure for the callbacks.
841 * @return Handle that can be used to cancel the query operation.
843 struct GNUNET_PSYC_StateQuery *
844 GNUNET_PSYC_channel_state_get (struct GNUNET_PSYC_Channel *channel,
845 const char *full_name,
846 GNUNET_PSYC_StateCallback cb,
851 * Return all channel state variables whose name matches a given prefix.
853 * A name matches if it starts with the given @a name_prefix, thus requesting
854 * the empty prefix ("") will match all values; requesting "_a_b" will also
855 * return values stored under "_a_b_c".
857 * The @a state_cb is invoked on all matching state variables asynchronously, as
858 * the state is stored in and retrieved from the PSYCstore,
860 * @param channel Channel handle.
861 * @param name_prefix Prefix of the state variable name to match.
862 * @param cb Function to call with the matching state variables.
863 * @param cb_cls Closure for the callbacks.
864 * @return Handle that can be used to cancel the query operation.
866 struct GNUNET_PSYC_StateQuery *
867 GNUNET_PSYC_channel_state_get_prefix (struct GNUNET_PSYC_Channel *channel,
868 const char *name_prefix,
869 GNUNET_PSYC_StateCallback cb,
874 * Cancel a state query operation.
876 * @param query Handle for the operation to cancel.
879 GNUNET_PSYC_channel_state_get_cancel (struct GNUNET_PSYC_StateQuery *query);
882 #if 0 /* keep Emacsens' auto-indent happy */
889 /* ifndef GNUNET_PSYC_SERVICE_H */
891 /* end of gnunet_psyc_service.h */