[GNUnet-SVN] r26791 - gnunet/src/include

[gnunet]

Author: grothoff
Date: 2013-04-07 22:51:10 +0200 (Sun, 07 Apr 2013)
New Revision: 26791

Added:
   gnunet/src/include/gnunet_psyc_service.h
Modified:
   gnunet/src/include/gnunet_multicast_service.h
Log:
-first thoughs on a PSYC API, not finished

Modified: gnunet/src/include/gnunet_multicast_service.h
===================================================================
--- gnunet/src/include/gnunet_multicast_service.h       2013-04-07 17:05:57 UTC 
(rev 26790)
+++ gnunet/src/include/gnunet_multicast_service.h       2013-04-07 20:51:10 UTC 
(rev 26791)
@@ -311,7 +311,7 @@
 struct GNUNET_MULTICAST_Origin *
 GNUNET_MULTICAST_origin_start (const struct GNUNET_CONFIGURATION_Handle *cfg, 
                               void *cls,
-                              struct GNUNET_CRYPTO_EccPrivateKey *priv_key,
+                              const struct GNUNET_CRYPTO_EccPrivateKey 
*priv_key,
                               enum GNUNET_MULTICAST_JoinPolicy join_policy,
                               GNUNET_MULITCAST_ReplayCallback replay_cb,
                               GNUNET_MULITCAST_MembershipTestCallback test_cb,
@@ -324,6 +324,7 @@
  *
  * @param origin handle to the multicast group
  * @param msg_body body of the message to transmit
+ * FIXME: change to notify_transmit_ready-style to wait for ACKs?
  */
 void
 GNUNET_MULTICAST_origin_send_to_all (struct GNUNET_MULTICAST_Origin *origin,
@@ -370,7 +371,7 @@
 struct GNUNET_MULTICAST_Member *
 GNUNET_MULTICAST_member_join (const struct GNUNET_CONFIGURATION_Handle *cfg, 
                              void *cls,
-                             struct GNUNET_CRYPTO_EccPublicKey *pub_key,
+                             const struct GNUNET_CRYPTO_EccPublicKey *pub_key,
                              uint64_t max_known_message_id,
                              uint64_t max_known_state_message_id,
                              GNUNET_MULTICAST_ReplayCallback replay_cb,

Added: gnunet/src/include/gnunet_psyc_service.h
===================================================================
--- gnunet/src/include/gnunet_psyc_service.h                            (rev 0)
+++ gnunet/src/include/gnunet_psyc_service.h    2013-04-07 20:51:10 UTC (rev 
26791)
@@ -0,0 +1,677 @@
+/*
+     This file is part of GNUnet.
+     (C) 2012, 2013 Christian Grothoff (and other contributing authors)
+
+     GNUnet is free software; you can redistribute it and/or modify
+     it under the terms of the GNU General Public License as published
+     by the Free Software Foundation; either version 3, or (at your
+     option) any later version.
+
+     GNUnet is distributed in the hope that it will be useful, but
+     WITHOUT ANY WARRANTY; without even the implied warranty of
+     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+     General Public License for more details.
+
+     You should have received a copy of the GNU General Public License
+     along with GNUnet; see the file COPYING.  If not, write to the
+     Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+     Boston, MA 02111-1307, USA.
+*/
+
+/**
+ * @file include/gnunet_psyc_service.h
+ * @brief psyc service; high-level access to the PSYC protocol
+ *        note that clients of this API are NOT expected to
+ *        understand the PSYC message format, only the semantics!
+ * @author Christian Grothoff
+ *
+ * TODO:
+ * - how to deal with very large channel state (i.e. channel
+ *   containing a movie); this might relate to the question
+ *   of how (when/etc.) we replay method calls; is only the
+ *   channel state persistent? What about a 'bounded' 
+ *   channel history, how would we enable that?
+ * - how to deal with seeking in large channel state (i.e. 
+ *   skip to minute 45 in movie)
+ * - need to change send operations to 'notify_transmit_ready'-style;
+ *   deal better with 'streaming' arguments while we're at it
+ */
+
+#ifndef GNUNET_PSYC_SERVICE_H
+#define GNUNET_PSYC_SERVICE_H
+
+#ifdef __cplusplus
+extern "C"
+{
+#if 0                           /* keep Emacsens' auto-indent happy */
+}
+#endif
+#endif
+
+#include "gnunet_util_lib.h"
+#include "gnunet_multicast_service.h"
+
+
+/**
+ * Version number of GNUnet-PSYC API.
+ */
+#define GNUNET_PSYC_VERSION 0x00000000
+
+
+/**
+ * Bits describing special properties of arguments.
+ */
+enum GNUNET_PSYC_ArgumentFlags
+{
+  /**
+   * Argument is fixed size.
+   */
+  GNUNET_PSYC_AF_FIXED_SIZE = 0,
+
+  /**
+   * Argument is variable-length
+   */
+  GNUNET_PSYC_AF_VARIABLE_SIZE = 1,
+
+  /**
+   * Argument may be supplied incrementally to the callback 
+   */
+  GNUNET_PSYC_AF_STREAMABLE = 2,
+
+  /**
+   * Argument is variable-length, incrementally supplied
+   * data stream.
+   */
+  GNUNET_PSYC_AF_STREAM = 3,
+
+  /**
+   * Argument is zero-terminated character array.
+   */
+  GNUNET_PSYC_AF_ZERO_TERMINATED_CHARARRAY = 4,
+
+  /**
+   * Argument is variable-length UTF-8 encoded, zero-terminated string.
+   */
+  GNUNET_PSYC_AF_UTF8 = 5,
+
+  /**
+   * Payload is an unsigned integer and might thus be encoded as an
+   * integer when generating PSYC stream (useful if we want to
+   * generate human-readable PSYC streams, instead of just always
+   * using length-prefixed binary encodings).  Note that it
+   * is not sufficient to just test for this bit, as it is
+   * also set for 'REAL' numbers!
+   */
+  GNUNET_PSYC_AF_UNSIGNED_INTEGER = 8,
+
+  /**
+   * Payload is an unsigned integer and might thus be encoded as an
+   * integer when generating PSYC stream (useful if we want to
+   * generate human-readable PSYC streams, instead of just always
+   * using length-prefixed binary encodings).  Note that it
+   * is not sufficient to just test for this bit, as it is
+   * also set for 'REAL' numbers!
+   */
+  GNUNET_PSYC_AF_SIGNED_INTEGER = 16,
+
+  /**
+   * Payload is a 'real' number (float or double).  We save a bit here
+   * as a number cannot be both SIGNED and UNSIGNED, so setting both
+   * bits is fine to use for REALs.
+   */
+  GNUNET_PSYC_AF_REAL_NUMBER = 24
+
+};
+
+
+/**
+ * Argument descriptors are used to describe types that can be
+ * embedded in a PSYC stream.  For example, a "uint32_t" is 
+ * described as 4-byte, fixed-length data, whereas a movie 
+ * would be a variable-size, streaming argument.
+ */
+struct GNUNET_PSYC_ArgumentDescriptor
+{
+
+  /**
+   * Required length of the argument in bytes, zero for
+   * variable-size arguments.
+   */
+  size_t arg_len;
+
+  /**
+   * Flags describing additional properties of the argument,
+   * such as variable-size, streaming or 0-termination.  This
+   * argument is a bitfield.
+   */
+  enum GNUNET_PSYC_ArgumentFlags flags;
+
+};
+
+
+/**
+ * Convenience macro to define an argument descriptor for
+ * some fixed-size C data type.
+ *
+ * @param pt C data type (i.e. 'uint32_t')
+ */
+#define GNUNET_PSYC_AD_C_TYPE(pt) { sizeof (pt), GNUNET_PSYC_AF_FIXED_SIZE }
+
+/**
+ * Convenience macro to define an argument descriptor for
+ * some fixed-size unsigned integer type.
+ *
+ * @param it C integer data type (i.e. 'uint32_t')
+ */
+#define GNUNET_PSYC_AD_C_UINT_TYPE(it) { sizeof (it), 
GNUNET_PSYC_AF_FIXED_SIZE | GNUNET_PSYC_AF_UNSIGNED_INTEGER }
+
+/**
+ * Argument descriptor for a 'uint8_t' argument.
+ */
+#define GNUNET_PSYC_AD_UINT8 GNUNET_PSYC_AD_C_UINT_TYPE(uint8_t)
+
+/**
+ * Argument descriptor for a 'uint16_t' argument.
+ */
+#define GNUNET_PSYC_AD_UINT16 GNUNET_PSYC_AD_C_UINT_TYPE(uint16_t)
+
+/**
+ * Argument descriptor for a 'uint32_t' argument.
+ */
+#define GNUNET_PSYC_AD_UINT32 GNUNET_PSYC_AD_C_UINT_TYPE(uint32_t)
+
+/**
+ * Argument descriptor for a 'uint64_t' argument.
+ */
+#define GNUNET_PSYC_AD_UINT64 GNUNET_PSYC_AD_C_UINT_TYPE(uint64_t)
+
+/**
+ * Convenience macro to define an argument descriptor for
+ * a 0-terminated, variable-length UTF-8 string.
+ */
+#define GNUNET_PSYC_AD_UTF8 { 0, GNUNET_PSYC_AF_UTF8 }
+
+
+/* TODO: add more convenience macros for argument types later as needed */
+
+
+/**
+ * Abstract argument passed to a GNUNET_PSYC_Method.  
+ */
+struct GNUNET_PSYC_Argument
+{
+
+  /**
+   * Data of the argument.
+   */
+  const void *data;
+
+  /**
+   * Number of bytes in 'data', guaranteed to be the argument
+   * descriptor 'arg_len' MINUS 'data_off' unless
+   * GNUNET_PSYC_AF_VARIABLE_SIZE was set.
+   */
+  size_t data_size;
+
+  /**
+   * Offset of 'data' in the overall argument,
+   * always zero unless GNUNET_PSYC_AF_STREAMABLE was
+   * set for the argument.
+   */
+  uint64_t data_off;
+
+  /**
+   * Total number of bytes to be expected in 'data',
+   * UINT64_MAX for 'unknown' (i.e. for "infinite" 
+   * streams).
+   */
+  uint64_t value_size;
+};
+
+
+/**
+ * Method called from PSYC upon receiving a message indicating a call
+ * to a 'method'.  The arguments given will match those of the
+ * respective argument descriptor.  If some arguments were marked
+ * as 'streaming', the function can return a value other than -1
+ * to request "more" of the data for that argument.  Note that all
+ * non-streaming arguments will be replayed in full for each additional
+ * invocation of the method.  Using more than one streaming argument 
+ * is possible, in which case PSYC will ONLY advance the stream of the
+ * argument for which the index was returned; the values of other
+ * streaming arguments will be replayed at the current offset.
+ *
+ * Returning a value other than -1 or that of a streaming argument is
+ * not allowed.  Returning -1 does not indicate an error; it simply
+ * indicates that the client wants to proceed with the next method
+ * (and not see the rest of the data from any of the streaming
+ * arguments).
+ *
+ * TODO: note that this API currently doesn't allow for seeking
+ *       in streaming data (very advanced feature)
+ *
+ * @param cls closure
+ * @param full_method_name original method name from PSYC (may be more
+ *        specific than the registered method name due to try&slice matching)
+ * @param sender who transmitted the message (origin, except for messages
+ *        from one of the members to the origin)
+ * @param message_id unique message counter for this message
+ * @param group_generation group generation counter for this message
+ * @param argc number of arguments in argv
+ * @param argv array of argc arguments to the method
+ * @return -1 if we're finished with this method, index
+ *            of a streaming argument for which more data is
+ *            requested otherwise
+ */
+typedef int (*GNUNET_PSYC_Method)(void *cls,
+                                 const char *full_method_name,
+                                 const struct GNUNET_PeerIdentity *sender,
+                                 unsigned int argc,
+                                 const struct GNUNET_PSYC_Argument *argv);
+
+
+/**
+ * Descriptor for a PSYC method and its arguments.  Here is how this
+ * is expected to be used.  Imagine we have a method with the
+ * following signature:
+ * <pre>
+ * static void 
+ * logger (void *cls, uint32_t log_level, const char *log_message);
+ * </pre>
+ * where 'cls' is supposed to be a 'FILE *'.
+ * Then for PSYC to call this method with 'stderr' for 'cls',
+ * we would provide the following method descriptor:
+ * <pre>
+ * .method_name = "log";
+ * .method = &wrap_logger;
+ * .method_cls = stderr;
+ * .argc = 2;
+ * .argv = { GNUNET_PSYC_AD_UINT32, GNUNET_PSYC_AD_UTF8 };
+ * </pre>
+ * and define <tt>wrap_logger</tt> as follows:
+ * <pre>
+ * static void
+ * wrap_logger (void *cls, const char full_method_name, 
+ *              const struct GNUNET_PeerIdentity *sender,
+ *             unsigned int argc, const struct GNUNET_PSYC_Argument *argv)
+ * {
+ *    uint32_t *log_level = argv[0].data;
+ *    const char *log_message = argv[1].data;
+ *    logger (cls, *log_level, log_message);
+ * }
+ * </pre> 
+ * Note that the PSYC library will take care of making sure
+ * that 'argv[0].data_size == 4' and that the log message
+ * is 0-terminated, as those requirements were specified
+ * in the method descriptor for those arguments.  Finally,
+ * it is conceivable to generate the wrappers and method
+ * descriptors automatically, as they are trivial.
+ * <p>
+ * Note that due to try & slice, the given full method name
+ * might be more specific; for example, the given method
+ * might be called for a request to "log_warning" instead
+ * of just a request to "log".
+ */
+struct GNUNET_PSYC_MethodDescriptor
+{
+
+  /**
+   * Name of the method to be used in try-and-slice matching.
+   */
+  const char *method_name;
+
+  /**
+   * Function to call.  Note that if a more specific handler exists
+   * as well, the more generic handler will not be invoked.
+   */
+  GNUNET_PSYC_Method method;
+
+  /**
+   * Closure for the method (this argument and the 'sender' argument
+   * are both not included in 'argc').
+   */
+  void *method_cls;
+
+  /**
+   * Number of arguments to pass to the method (length of the 'ads'
+   * array).
+   */
+  unsigned int argc;
+
+  /**
+   * Array of 'argc' argument descriptors describing the arguments to
+   * be passed to the method.  Non-matching method calls will be
+   * ignored (but logged).  Note that the 'ads' of all methods with
+   * the same method name prefix should be identical.
+   */
+  const struct GNUNET_PSYC_ArgumentDescriptor *ads;
+
+};
+
+
+/**
+ * Handle for the origin of a psyc group.
+ */
+struct GNUNET_PSYC_Origin;
+
+
+/**
+ * Start a psyc group.  Will create a multicast group identified by
+ * the given public key.  Messages recevied from group members will be
+ * given to the respective handler methods.  If a new member wants to
+ * join a group, the "join" method handler will be invoked; the join
+ * handler must then generate a "join" message to approve the joining
+ * of the new member.  The origin can also change group membership
+ * without explicit requests.  Note that PSYC doesn't itself "understand"
+ * join or leave messages, the respective methods must call other
+ * PSYC functions to inform PSYC about the meaning of the respective
+ * events.
+ *
+ * @param cfg configuration to use (to connect to PSYC service)
+ * @param method_count number of methods in 'methods' array
+ * @param methods functions to invoke on messages received from members,
+ *                typcially at least contains functions for 'join' and 'leave'.
+ * @param priv_key ECC key that will be used to sign messages for this
+ *                 psyc session; public key is used to identify the
+ *                 psyc group; FIXME: we'll likely want to use
+ *                 NOT the p521 curve here, but a cheaper one in the future
+ * @param join_policy what is the membership policy of the group?
+ * @return handle for the origin, NULL on error 
+ */
+struct GNUNET_PSYC_Origin *
+GNUNET_PSYC_origin_start (const struct GNUNET_CONFIGURATION_Handle *cfg, 
+                         unsigned int method_count,
+                         const struct GNUNET_PSYC_MethodDescriptor *methods,
+                         const struct GNUNET_CRYPTO_EccPrivateKey *priv_key,
+                         enum GNUNET_MULTICAST_JoinPolicy join_policy);
+
+
+/**
+ * Update channel state.  The state of a channel must fit into the
+ * memory of each member (and the origin); large values that require
+ * streaming must only be passed as streaming arguments to methods.
+ * State updates might not be transmitted to group members until
+ * the next call to 'GNUNET_PSYC_origin_broadcast_call_method'.
+ *
+ * @param origin handle to the psyc group / channel
+ * @param full_state_name name of the field in the channel state to change
+ * @param data_size number of bytes in data
+ * @param data new state value
+ */
+void
+GNUNET_PSYC_origin_update_state (struct GNUNET_PSYC_Origin *origin,
+                                const char *full_state_name,
+                                size_t data_size,
+                                const void *data);
+
+
+/**
+ * Data needed to construct a PSYC message to call a method.
+ */
+struct GNUNET_PSYC_CallData
+{
+
+  /**
+   * Name of the function to call.  This name may be more specific
+   * than the registered method name due to try&slice matching.
+   */
+  const char *full_method_name;
+
+  /**
+   * Number of arguments to pass (other than closure and sender),
+   * length of the 'argv' array.
+   */
+  unsigned int argc;
+
+  /**
+   * Arguments to pass to the function.
+   */
+  const struct GNUNET_PSYC_Argument *argv;
+
+};
+
+
+/**
+ * Send a message to call a method to all members in the psyc group.
+ *
+ * @param origin handle to the psyc group
+ * @param increment_group_generation GNUNET_YES if we need to increment
+ *        the group generation counter after transmitting this message
+ * @param call_data data needed to determine how to call which method 
+ * @param message_id set to the unique message ID that was generated for
+ *        this message
+ * @param group_generation set to the group generation used for this
+ *        message
+ * FIXME: change to notify_transmit_ready-style to wait for ACKs?
+ *        that'd also help with streaming arguments!
+ *        => need to change multicast API first as well!
+ */
+void
+GNUNET_PSYC_origin_broadcast_call_method (struct GNUNET_PSYC_Origin *origin,
+                                         int increment_group_generation,
+                                         const struct GNUNET_PSYC_CallData 
*call_data,
+                                         uint64_t *message_id,
+                                         uint64_t *group_generation);
+
+
+/**
+ * End a psyc group.
+ *
+ * @param origin psyc group to terminate
+ */
+void
+GNUNET_PSYC_origin_end (struct GNUNET_PSYC_Origin *origin);
+
+
+/**
+ * Handle to access PSYC group operations for all members.
+ */
+struct GNUNET_PSYC_Group;
+
+
+/**
+ * Convert 'origin' to a 'group' handle to access the 'group' APIs.
+ * 
+ * @param origin origin handle
+ * @return group handle, valid for as long as 'origin' is valid
+ */ 
+struct GNUNET_PSYC_Group *
+GNUNET_PSYC_origin_get_group (struct GNUNET_PSYC_Origin *origin);
+
+
+/**
+ * Add a member to the group.    Note that this will NOT generate any
+ * PSYC traffic, it will merely update the local data base to modify
+ * how we react to 'membership test' queries.  The origin still needs to
+ * explicitly transmit a 'leave' message to notify other group members
+ * and they then also must still call this function in their respective
+ * methods handling the 'leave' message.  This way, how 'join' and 'leave'
+ * operations are exactly implemented is still up to the application;
+ * for example, there might be a 'leave_all' message to kick out everyone.
+ *
+ * Note that group members are explicitly trusted to perform these
+ * operations correctly; not doing so correctly will result in either
+ * denying members access or offering access to group data to
+ * non-members.
+ *
+ * @param group group handle
+ * @param member which peer to add
+ * @param message_id message ID for the message that changed the membership
+ * @param group_generation the generation ID where the change went into effect
+ */
+void
+GNUNET_PSYC_group_member_admit (struct GNUNET_PSYC_Group *group,
+                               const struct GNUNET_PeerIdentity *member,
+                               uint64_t message_id,
+                               uint64_t group_generation);
+
+
+/**
+ * Remove a member from the group.  Note that this will NOT generate any
+ * PSYC traffic, it will merely update the local data base to modify
+ * how we react to 'membership test' queries.  The origin still needs to
+ * explicitly transmit a 'leave' message to notify other group members
+ * and they then also must still call this function in their respective
+ * methods handling the 'leave' message.  This way, how 'join' and 'leave'
+ * operations are exactly implemented is still up to the application;
+ * for example, there might be a 'leave_all' message to kick out everyone.
+ *
+ * Note that group members are explicitly trusted to perform these
+ * operations correctly; not doing so correctly will result in either
+ * denying members access or offering access to group data to
+ * non-members.
+ *
+ * @param group group handle
+ * @param member which peer to remove
+ * @param message_id message ID for the message that changed the membership
+ * @param group_generation the generation ID where the change went into effect
+ */
+void
+GNUNET_PSYC_group_member_kick (struct GNUNET_PSYC_Group *group,
+                              const struct GNUNET_PeerIdentity *member,
+                              uint64_t message_id,
+                              uint64_t group_generation);
+
+
+/**
+ * Function called to inform a member about state values for a channel.
+ *
+ * @param cls closure
+ * @param full_state_name full name of the state
+ * @param data_size number of bytes in 'data'
+ * @param data raw data of the state
+ */
+typedef void (*GNUNET_PSYC_StateCallback)(void *cls,
+                                         const char *full_state_name,
+                                         size_t data_size,
+                                         const void *data);
+
+
+/**
+ * Descriptor for an event handler handling PSYC state updates.
+ */
+struct GNUNET_PSYC_StateHandler
+{
+
+  /**
+   * Name of the state this handler calls about, used in try-and-slice 
matching.
+   */
+  const char *state_name;
+
+  /**
+   * Function to call whenever the respective state changes.
+   */
+  GNUNET_PSYC_StateCallback event_handler;
+
+  /**
+   * Closure for the 'event_handler' function.
+   */
+  void *event_handler_cls;
+
+  /**
+   * Description of the kind of state that the handler expects to see.
+   * Non-matching state updates will be ignored (but logged).  Note
+   * that the state_types of all states with the same state name prefix
+   * should be identical.
+   */
+  struct GNUNET_PSYC_ArgumentDescriptor state_type;
+
+};
+
+
+/**
+ * Join a psyc group.  The entity joining is always the local peer.
+ * This will send a 'join_msg' to the origin; if it succeeds, the
+ * channel state will be replayed to the joining member and the 'join'
+ * method will be invoked to show that we joined successfully.  There
+ * is no explicit notification on failure (as the origin may simply
+ * take days to approve, and disapproval is simply being ignored).
+ *
+ * Note that we also specify the message to transmit to origin on
+ * 'leave' here, as a sudden crash might otherwise not permit sending
+ * a 'nice' leave message.   TODO: we might want an API to change
+ * the 'leave' message later during the session.
+ * 
+ * @param cfg configuration to use
+ * @param pub_key ECC key that identifies the group
+ * @param method_count number of methods in 'methods' array
+ * @param methods functions to invoke on messages received from the origin,
+ *                typcially at least contains functions for 'join' and 'leave'.
+ * @param state_count number of state handlers
+ * @param state_handlers array of state event handlers
+ * @param join_data method to invoke on origin to trigger joining;
+ *        use NULL to send nothing (useful for anonymous groups that permit 
anyone);
+          arguments to give to join method, must not include streaming args
+ * @param leave_data method to invoke on origin on leaving;
+ *        use NULL to send nothing (useful for anonymous groups that permit 
anyone);
+          arguments to give to leave method, must not include streaming args
+ * @return handle for the member, NULL on error 
+ */
+struct GNUNET_PSYC_Member *
+GNUNET_PSYC_member_join (const struct GNUNET_CONFIGURATION_Handle *cfg, 
+                        const struct GNUNET_CRYPTO_EccPublicKey *pub_key,
+                        unsigned int method_count,
+                        const struct GNUNET_PSYC_MethodDescriptor *methods,
+                        unsigned int state_count,
+                        struct GNUNET_PSYC_StateHandler *state_handlers,
+                        const struct GNUNET_PSYC_CallData *join_data,
+                        const struct GNUNET_PSYC_CallData *leave_data);
+
+
+/**
+ * Request a message to be send to the origin.
+ *
+ * @param member membership handle
+ * @param request_data which method should be invoked on origin (and how)
+ *
+ * FIXME: change to notify_transmit_ready-style to wait for ACKs
+ * and to enable streaming arguments!
+ */
+void
+GNUNET_PSYC_member_send_to_origin (struct GNUNET_PSYC_Member *member,
+                                  const struct GNUNET_PSYC_CallData 
*request_data);
+
+
+/**
+ * Call the given state callback on all matching states in the channel
+ * state.  The callback is invoked synchronously on all matching
+ * states (as the state is fully replicated in the library in this
+ * process; channel states should be small, large data is to be passed
+ * as streaming data to methods).
+ *
+ * @param member membership handle
+ * @param state_name name of the state to query (full name 
+ *        might be longer, this is only the prefix that must match)
+ * @param cb function to call on the matching state values
+ * @param cb_cls closure for 'cb'
+ */
+int
+GNUNET_PSYC_member_state_get (struct GNUNET_PSYC_Member *member,
+                             const char *state_name,
+                             GNUNET_PSYC_StateCallback cb,
+                             void *cb_cls);
+
+
+/**
+ * Leave a mutlicast group.  Will terminate the connection to the PSYC
+ * service, which will send the 'leave' method that was prepared
+ * earlier to the origin.  This function must not be called on a
+ * 'member' that was obtained from GNUNET_PSYC_origin_get_group.
+ *
+ * @param member membership handle
+ */
+void
+GNUNET_PSYC_member_leave (struct GNUNET_PSYC_Member *member);
+
+
+
+#if 0                           /* keep Emacsens' auto-indent happy */
+{
+#endif
+#ifdef __cplusplus
+}
+#endif
+
+/* ifndef GNUNET_PSYC_SERVICE_H */
+#endif
+/* end of gnunet_psyc_service.h */