X-Git-Url: https://git.librecmc.org/?a=blobdiff_plain;f=src%2Fpsycstore%2Fpsycstore_api.c;h=d79daa35774906a65f2fd6b3a4a1ca27b3586180;hb=b14f2e69adb39f4eaaaf3e26a847f29d256a1c68;hp=88ae1185b91021d47a59a1f3b75ff50459459a34;hpb=383a9603f7310b3156331a1ed9cc97cc6ed4d3a9;p=oweals%2Fgnunet.git

diff --git a/src/psycstore/psycstore_api.c b/src/psycstore/psycstore_api.c
index 88ae1185b..d79daa357 100644
--- a/src/psycstore/psycstore_api.c
+++ b/src/psycstore/psycstore_api.c
@@ -1,6 +1,6 @@
 /*
  * This file is part of GNUnet
- * (C) 2013 Christian Grothoff (and other contributing authors)
+ * Copyright (C) 2013 GNUnet e.V.
  *
  * GNUnet is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published
@@ -14,8 +14,8 @@
  *
  * 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.
+ * Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
+ * Boston, MA 02110-1301, USA.
  */
 
 /**
@@ -25,6 +25,8 @@
  * @author Christian Grothoff
  */
 
+#include <inttypes.h>
+
 #include "platform.h"
 #include "gnunet_util_lib.h"
 #include "gnunet_constants.h"
@@ -35,8 +37,6 @@
 
 #define LOG(kind,...) GNUNET_log_from (kind, "psycstore-api",__VA_ARGS__)
 
-typedef void (*DataCallback) ();
-
 /**
  * Handle for an operation with the PSYCstore service.
  */
@@ -49,40 +49,28 @@ struct GNUNET_PSYCSTORE_OperationHandle
   struct GNUNET_PSYCSTORE_Handle *h;
 
   /**
-   * We keep operations in a DLL.
-   */
-  struct GNUNET_PSYCSTORE_OperationHandle *next;
-
-  /**
-   * We keep operations in a DLL.
-   */
-  struct GNUNET_PSYCSTORE_OperationHandle *prev;
-
-  /**
-   * Continuation to invoke with the result of an operation.
-   */
-  GNUNET_PSYCSTORE_ResultCallback res_cb;
-
-  /**
-   * Continuation to invoke with the result of an operation returning data.
+   * Data callbacks.
    */
-  DataCallback data_cb;
+  union {
+    GNUNET_PSYCSTORE_FragmentCallback fragment_cb;
+    GNUNET_PSYCSTORE_CountersCallback counters_cb;
+    GNUNET_PSYCSTORE_StateCallback state_cb;
+  };
 
   /**
-   * Closure for the callbacks.
+   * Closure for callbacks.
    */
   void *cls;
 
   /**
-   * Operation ID.
+   * Message envelope.
    */
-  uint32_t op_id;
+  struct GNUNET_MQ_Envelope *env;
 
   /**
-   * Message to send to the PSYCstore service.
-   * Allocated at the end of this struct.
+   * Operation ID.
    */
-  const struct GNUNET_MessageHeader *msg;
+  uint64_t op_id;
 };
 
 
@@ -97,437 +85,272 @@ struct GNUNET_PSYCSTORE_Handle
   const struct GNUNET_CONFIGURATION_Handle *cfg;
 
   /**
-   * Socket (if available).
-   */
-  struct GNUNET_CLIENT_Connection *client;
-
-  /**
-   * Head of operations to transmit.
-   */
-  struct GNUNET_PSYCSTORE_OperationHandle *transmit_head;
-
-  /**
-   * Tail of operations to transmit.
-   */
-  struct GNUNET_PSYCSTORE_OperationHandle *transmit_tail;
-
-  /**
-   * Head of active operations waiting for response.
+   * Client connection.
    */
-  struct GNUNET_PSYCSTORE_OperationHandle *op_head;
+  struct GNUNET_MQ_Handle *mq;
 
   /**
-   * Tail of active operations waiting for response.
+   * Async operations.
    */
-  struct GNUNET_PSYCSTORE_OperationHandle *op_tail;
-
-  /**
-   * Currently pending transmission request, or NULL for none.
-   */
-  struct GNUNET_CLIENT_TransmitHandle *th;
+  struct GNUNET_OP_Handle *op;
 
   /**
    * Task doing exponential back-off trying to reconnect.
    */
-  GNUNET_SCHEDULER_TaskIdentifier reconnect_task;
+  struct GNUNET_SCHEDULER_Task *reconnect_task;
 
   /**
-   * Time for next connect retry.
+   * Delay for next connect retry.
    */
   struct GNUNET_TIME_Relative reconnect_delay;
 
-  /**
-   * Are we polling for incoming messages right now?
-   */
-  int in_receive;
 
+  GNUNET_PSYCSTORE_FragmentCallback *fragment_cb;
+
+  GNUNET_PSYCSTORE_CountersCallback *counters_cb;
+
+  GNUNET_PSYCSTORE_StateCallback *state_cb;
   /**
-   * The last operation id used for a PSYCstore operation.
+   * Closure for callbacks.
    */
-  uint32_t last_op_id_used;
-
+  void *cb_cls;
 };
 
 
-/**
- * Get a fresh operation ID to distinguish between PSYCstore requests.
- *
- * @param h Handle to the PSYCstore service.
- * @return next operation id to use
- */
-static uint32_t
-get_next_op_id (struct GNUNET_PSYCSTORE_Handle *h)
+static int
+check_result_code (void *cls, const struct OperationResult *opres)
 {
-  return h->last_op_id_used++;
-}
-
-
-/**
- * Find operation by ID.
- *
- * @return OperationHandle if found, or NULL otherwise.
- */
-static struct GNUNET_PSYCSTORE_OperationHandle *
-find_op_by_id (struct GNUNET_PSYCSTORE_Handle *h, uint32_t op_id)
-{
-  struct GNUNET_PSYCSTORE_OperationHandle *op = h->op_head;
-  while (NULL != op)
+  uint16_t size = ntohs (opres->header.size);
+  const char *str = (const char *) &opres[1];
+  if ( (sizeof (*opres) < size) &&
+       ('\0' != str[size - sizeof (*opres) - 1]) )
   {
-    if (op->op_id == op_id)
-      return op;
-    op = op->next;
+    GNUNET_break (0);
+    return GNUNET_SYSERR;
   }
-  return NULL;
-}
 
-
-/**
- * Try again to connect to the PSYCstore service.
- *
- * @param cls handle to the PSYCstore service.
- * @param tc scheduler context
- */
-static void
-reconnect (void *cls, const struct GNUNET_SCHEDULER_TaskContext *tc);
+  return GNUNET_OK;
+}
 
 
-/**
- * Reschedule a connect attempt to the service.
- *
- * @param h transport service to reconnect
- */
 static void
-reschedule_connect (struct GNUNET_PSYCSTORE_Handle *h)
+handle_result_code (void *cls, const struct OperationResult *opres)
 {
-  GNUNET_assert (h->reconnect_task == GNUNET_SCHEDULER_NO_TASK);
+  struct GNUNET_PSYCSTORE_Handle *h = cls;
+  struct GNUNET_PSYCSTORE_OperationHandle *op = NULL;
+  uint16_t size = ntohs (opres->header.size);
+
+  const char *
+    str = (sizeof (*opres) < size) ? (const char *) &opres[1] : "";
 
-  if (NULL != h->th)
+  if (GNUNET_YES == GNUNET_OP_result (h->op, GNUNET_ntohll (opres->op_id),
+                                      GNUNET_ntohll (opres->result_code) + INT64_MIN,
+                                      str, size - sizeof (*opres), (void **) &op))
   {
-    GNUNET_CLIENT_notify_transmit_ready_cancel (h->th);
-    h->th = NULL;
+    LOG (GNUNET_ERROR_TYPE_DEBUG,
+         "handle_result_code: Received result message with operation ID: %" PRIu64 "\n",
+         GNUNET_ntohll (opres->op_id));
+    GNUNET_free (op);
   }
-  if (NULL != h->client)
+  else
   {
-    GNUNET_CLIENT_disconnect (h->client);
-    h->client = NULL;
+    LOG (GNUNET_ERROR_TYPE_DEBUG,
+         "handle_result_code: No callback registered for operation with ID %" PRIu64 ".\n",
+         GNUNET_ntohll (opres->op_id));
   }
-  h->in_receive = GNUNET_NO;
-  LOG (GNUNET_ERROR_TYPE_DEBUG,
-       "Scheduling task to reconnect to PSYCstore service in %s.\n",
-       GNUNET_STRINGS_relative_time_to_string (h->reconnect_delay, GNUNET_YES));
-  h->reconnect_task =
-      GNUNET_SCHEDULER_add_delayed (h->reconnect_delay, &reconnect, h);
-  h->reconnect_delay = GNUNET_TIME_STD_BACKOFF (h->reconnect_delay);
+  h->reconnect_delay = GNUNET_TIME_UNIT_MILLISECONDS;
 }
 
 
-/**
- * Schedule transmission of the next message from our queue.
- *
- * @param h PSYCstore handle
- */
 static void
-transmit_next (struct GNUNET_PSYCSTORE_Handle *h);
-
-
-/**
- * Type of a function to call when we receive a message
- * from the service.
- *
- * @param cls closure
- * @param msg message received, NULL on timeout or fatal error
- */
-static void
-message_handler (void *cls, const struct GNUNET_MessageHeader *msg)
+handle_result_counters (void *cls, const struct CountersResult *cres)
 {
   struct GNUNET_PSYCSTORE_Handle *h = cls;
-  struct GNUNET_PSYCSTORE_OperationHandle *op;
-  const struct OperationResult *opres;
-  const struct CountersResult *cres;
-  const struct FragmentResult *fres;
-  const struct StateResult *sres;
-  const char *str;
-
-  if (NULL == msg)
-  {
-    reschedule_connect (h);
-    return;
-  }
-  LOG (GNUNET_ERROR_TYPE_DEBUG,
-       "Received message of type %d from PSYCstore service.\n",
-       ntohs (msg->type));
-  uint16_t size = ntohs (msg->size);
-  uint16_t type = ntohs (msg->type);
-  switch (type)
-  {
-  case GNUNET_MESSAGE_TYPE_PSYCSTORE_RESULT_CODE:
-    if (size < sizeof (struct OperationResult))
-    {
-      LOG (GNUNET_ERROR_TYPE_ERROR,
-           "Received message of type %d with length %lu bytes. "
-           "Expected >= %lu\n",
-           type, size, sizeof (struct OperationResult));
-      GNUNET_break (0);
-      reschedule_connect (h);
-      return;
-    }
-
-    opres = (const struct OperationResult *) msg;
-    str = (const char *) &opres[1];
-    if ( (size > sizeof (struct OperationResult)) &&
-	 ('\0' != str[size - sizeof (struct OperationResult) - 1]) )
-    {
-      GNUNET_break (0);
-      reschedule_connect (h);
-      return;
-    }
-    if (size == sizeof (struct OperationResult))
-      str = NULL;
-
-    op = find_op_by_id (h, ntohl (opres->op_id));
-    if (NULL == op)
-    {
-      LOG (GNUNET_ERROR_TYPE_DEBUG,
-           "No callback registered for operation with ID %ld.\n",
-           type, ntohl (opres->op_id));
-    }
-    else
-    {
-      LOG (GNUNET_ERROR_TYPE_DEBUG,
-           "Received result message (type %d) with operation ID: %ld\n",
-           type, op->op_id);
-
-      GNUNET_CONTAINER_DLL_remove (h->op_head, h->op_tail, op);
-      if (NULL != op->res_cb)
-      {
-        const struct StateModifyRequest *smreq;
-        const struct StateSyncRequest *ssreq;
-        switch (ntohs (op->msg->type))
-        {
-        case GNUNET_MESSAGE_TYPE_PSYCSTORE_STATE_MODIFY:
-          smreq = (const struct StateModifyRequest *) op->msg;
-          if (!(smreq->flags & STATE_OP_LAST
-                || GNUNET_OK != ntohl (opres->result_code)))
-            op->res_cb = NULL;
-          break;
-        case GNUNET_MESSAGE_TYPE_PSYCSTORE_STATE_SYNC:
-          ssreq = (const struct StateSyncRequest *) op->msg;
-          if (!(ssreq->flags & STATE_OP_LAST
-                || GNUNET_OK != ntohl (opres->result_code)))
-            op->res_cb = NULL;
-          break;
-        }
-      }
-      if (NULL != op->res_cb)
-        op->res_cb (op->cls, ntohl (opres->result_code), str);
-      GNUNET_free (op);
-    }
-    break;
-
-  case GNUNET_MESSAGE_TYPE_PSYCSTORE_RESULT_COUNTERS:
-    if (size != sizeof (struct CountersResult))
-    {
-      LOG (GNUNET_ERROR_TYPE_ERROR,
-           "Received message of type %d with length %lu bytes. "
-           "Expected %lu\n",
-           type, size, sizeof (struct CountersResult));
-      GNUNET_break (0);
-      reschedule_connect (h);
-      return;
-    }
-
-    cres = (const struct CountersResult *) msg;
+  struct GNUNET_PSYCSTORE_OperationHandle *op = NULL;
 
-    op = find_op_by_id (h, ntohl (cres->op_id));
-    if (NULL == op)
-    {
-      LOG (GNUNET_ERROR_TYPE_DEBUG,
-           "No callback registered for operation with ID %ld.\n",
-           type, ntohl (cres->op_id));
-    }
-    else
+  if (GNUNET_YES == GNUNET_OP_get (h->op, GNUNET_ntohll (cres->op_id),
+                                   NULL, NULL, (void **) &op))
+  {
+    GNUNET_assert (NULL != op);
+    if (NULL != op->counters_cb)
     {
-      GNUNET_CONTAINER_DLL_remove (h->op_head, h->op_tail, op);
-      if (NULL != op->data_cb)
-        ((GNUNET_PSYCSTORE_CountersCallback)
-         op->data_cb) (op->cls, ntohl (cres->result_code),
+      op->counters_cb (op->cls,
+                       ntohl (cres->result_code),
                        GNUNET_ntohll (cres->max_fragment_id),
                        GNUNET_ntohll (cres->max_message_id),
                        GNUNET_ntohll (cres->max_group_generation),
                        GNUNET_ntohll (cres->max_state_message_id));
-      GNUNET_free (op);
     }
-    break;
+    GNUNET_OP_remove (h->op, GNUNET_ntohll (cres->op_id));
+    GNUNET_free (op);
+  }
+  else
+  {
+    LOG (GNUNET_ERROR_TYPE_DEBUG,
+         "handle_result_counters: No callback registered for operation with ID %" PRIu64 ".\n",
+         GNUNET_ntohll (cres->op_id));
+  }
+  h->reconnect_delay = GNUNET_TIME_UNIT_MILLISECONDS;
+}
 
-  case GNUNET_MESSAGE_TYPE_PSYCSTORE_RESULT_FRAGMENT:
-    if (size < sizeof (struct FragmentResult))
-    {
-      LOG (GNUNET_ERROR_TYPE_ERROR,
-           "Received message of type %d with length %lu bytes. "
-           "Expected >= %lu\n",
-           type, size, sizeof (struct FragmentResult));
-      GNUNET_break (0);
-      reschedule_connect (h);
-      return;
-    }
 
-    fres = (const struct FragmentResult *) msg;
-    struct GNUNET_MULTICAST_MessageHeader *mmsg =
-      (struct GNUNET_MULTICAST_MessageHeader *) &fres[1];
-    if (size != sizeof (struct FragmentResult) + ntohs (mmsg->header.size))
-    {
-      LOG (GNUNET_ERROR_TYPE_ERROR,
-           "Received message of type %d with length %lu bytes. "
-           "Expected = %lu\n",
-           type, size,
-           sizeof (struct FragmentResult) + ntohs (mmsg->header.size));
-      GNUNET_break (0);
-      reschedule_connect (h);
-      return;
-    }
+static int
+check_result_fragment (void *cls, const struct FragmentResult *fres)
+{
+  uint16_t size = ntohs (fres->header.size);
+  struct GNUNET_MULTICAST_MessageHeader *mmsg =
+    (struct GNUNET_MULTICAST_MessageHeader *) &fres[1];
+  if (sizeof (*fres) + sizeof (*mmsg) < size
+      && sizeof (*fres) + ntohs (mmsg->header.size) != size)
+  {
+    LOG (GNUNET_ERROR_TYPE_ERROR,
+         "check_result_fragment: Received message with invalid length %lu bytes.\n",
+         size, sizeof (*fres));
+    GNUNET_break (0);
+    return GNUNET_SYSERR;
+  }
+  return GNUNET_OK;
+}
 
-    op = find_op_by_id (h, ntohl (fres->op_id));
-    if (NULL == op)
-    {
-      LOG (GNUNET_ERROR_TYPE_DEBUG,
-           "No callback registered for operation with ID %ld.\n",
-           type, ntohl (fres->op_id));
-    }
-    else
-    {
-      if (NULL != op->data_cb)
-        ((GNUNET_PSYCSTORE_FragmentCallback)
-         op->data_cb) (op->cls, mmsg, ntohl (fres->psycstore_flags));
-    }
-    break;
 
-  case GNUNET_MESSAGE_TYPE_PSYCSTORE_RESULT_STATE:
-    if (size < sizeof (struct StateResult))
-    {
-      LOG (GNUNET_ERROR_TYPE_ERROR,
-           "Received message of type %d with length %lu bytes. "
-           "Expected >= %lu\n",
-           type, size, sizeof (struct StateResult));
-      GNUNET_break (0);
-      reschedule_connect (h);
-      return;
-    }
+static void
+handle_result_fragment (void *cls, const struct FragmentResult *fres)
+{
+  struct GNUNET_PSYCSTORE_Handle *h = cls;
+  struct GNUNET_PSYCSTORE_OperationHandle *op = NULL;
 
-    sres = (const struct StateResult *) msg;
-    const char *name = (const char *) &sres[1];
-    uint16_t name_size = ntohs (sres->name_size);
+  if (GNUNET_YES == GNUNET_OP_get (h->op, GNUNET_ntohll (fres->op_id),
+                                   NULL, NULL, (void **) &op))
+  {
+    GNUNET_assert (NULL != op);
+    if (NULL != op->fragment_cb)
+      op->fragment_cb (op->cls,
+                       (struct GNUNET_MULTICAST_MessageHeader *) &fres[1],
+                       ntohl (fres->psycstore_flags));
+    //GNUNET_OP_remove (h->op, GNUNET_ntohll (fres->op_id));
+    //GNUNET_free (op);
+  }
+  else
+  {
+    LOG (GNUNET_ERROR_TYPE_DEBUG,
+         "handle_result_fragment: No callback registered for operation with ID %" PRIu64 ".\n",
+         GNUNET_ntohll (fres->op_id));
+  }
+  h->reconnect_delay = GNUNET_TIME_UNIT_MILLISECONDS;
+}
 
-    if (name_size <= 2 || '\0' != name[name_size - 1])
-    {
-      LOG (GNUNET_ERROR_TYPE_ERROR,
-           "Received state result message (type %d) with invalid name.\n",
-           type);
-      GNUNET_break (0);
-      reschedule_connect (h);
-      return;
-    }
 
-    op = find_op_by_id (h, ntohl (sres->op_id));
-    if (NULL == op)
-    {
-      LOG (GNUNET_ERROR_TYPE_DEBUG,
-           "No callback registered for operation with ID %ld.\n",
-           type, ntohl (sres->op_id));
-    }
-    else
-    {
-      if (NULL != op->data_cb)
-        ((GNUNET_PSYCSTORE_StateCallback)
-         op->data_cb) (op->cls, name, (char *) &sres[1] + name_size,
-                       ntohs (sres->header.size) - sizeof (*sres) - name_size);
-    }
-    break;
+static int
+check_result_state (void *cls, const struct StateResult *sres)
+{
+  const char *name = (const char *) &sres[1];
+  uint16_t size = ntohs (sres->header.size);
+  uint16_t name_size = ntohs (sres->name_size);
 
-  default:
+  if (name_size <= 2
+      || size - sizeof (*sres) < name_size
+      || '\0' != name[name_size - 1])
+  {
+    LOG (GNUNET_ERROR_TYPE_ERROR,
+         "check_result_state: Received state result message with invalid name.\n");
     GNUNET_break (0);
-    reschedule_connect (h);
-    return;
+    return GNUNET_SYSERR;
   }
-
-  GNUNET_CLIENT_receive (h->client, &message_handler, h,
-                         GNUNET_TIME_UNIT_FOREVER_REL);
+  return GNUNET_OK;
 }
 
 
-/**
- * Transmit next message to service.
- *
- * @param cls The 'struct GNUNET_PSYCSTORE_Handle'.
- * @param size Number of bytes available in buf.
- * @param buf Where to copy the message.
- * @return Number of bytes copied to buf.
- */
-static size_t
-send_next_message (void *cls, size_t size, void *buf)
+static void
+handle_result_state (void *cls, const struct StateResult *sres)
 {
   struct GNUNET_PSYCSTORE_Handle *h = cls;
-  struct GNUNET_PSYCSTORE_OperationHandle *op = h->transmit_head;
-  size_t ret;
-
-  h->th = NULL;
-  if (NULL == op)
-    return 0;
-  ret = ntohs (op->msg->size);
-  if (ret > size)
-  {
-    reschedule_connect (h);
-    return 0;
-  }
-  LOG (GNUNET_ERROR_TYPE_DEBUG,
-       "Sending message of type %d to PSYCstore service. ID: %u\n",
-       ntohs (op->msg->type), op->op_id);
-  memcpy (buf, op->msg, ret);
+  struct GNUNET_PSYCSTORE_OperationHandle *op = NULL;
 
-  GNUNET_CONTAINER_DLL_remove (h->transmit_head, h->transmit_tail, op);
+  const char *name = (const char *) &sres[1];
+  uint16_t name_size = ntohs (sres->name_size);
 
-  if (NULL == op->res_cb && NULL == op->data_cb)
+  if (GNUNET_YES == GNUNET_OP_get (h->op, GNUNET_ntohll (sres->op_id),
+                                   NULL, NULL, (void **) &op))
   {
-    GNUNET_free (op);
+    GNUNET_assert (NULL != op);
+    if (NULL != op->state_cb)
+       op->state_cb (op->cls, name, (char *) &sres[1] + name_size,
+                     ntohs (sres->header.size) - sizeof (*sres) - name_size);
+    //GNUNET_OP_remove (h->op, GNUNET_ntohll (sres->op_id));
+    //GNUNET_free (op);
   }
   else
   {
-    GNUNET_CONTAINER_DLL_insert_tail (h->op_head, h->op_tail, op);
+    LOG (GNUNET_ERROR_TYPE_DEBUG,
+         "handle_result_state: No callback registered for operation with ID %" PRIu64 ".\n",
+         GNUNET_ntohll (sres->op_id));
   }
+  h->reconnect_delay = GNUNET_TIME_UNIT_MILLISECONDS;
+}
 
-  if (NULL != h->transmit_head)
-    transmit_next (h);
 
-  if (GNUNET_NO == h->in_receive)
-  {
-    h->in_receive = GNUNET_YES;
-    GNUNET_CLIENT_receive (h->client, &message_handler, h,
-			   GNUNET_TIME_UNIT_FOREVER_REL);
-  }
-  return ret;
-}
+static void
+reconnect (void *cls);
 
 
 /**
- * Schedule transmission of the next message from our queue.
+ * Client disconnected from service.
  *
- * @param h PSYCstore handle.
+ * Reconnect after backoff period.=
  */
 static void
-transmit_next (struct GNUNET_PSYCSTORE_Handle *h)
+disconnected (void *cls, enum GNUNET_MQ_Error error)
 {
-  if (NULL != h->th || NULL == h->client)
-    return;
-
-  struct GNUNET_PSYCSTORE_OperationHandle *op = h->transmit_head;
-  if (NULL == op)
-    return;
-
-  h->th = GNUNET_CLIENT_notify_transmit_ready (h->client,
-					       ntohs (op->msg->size),
-					       GNUNET_TIME_UNIT_FOREVER_REL,
-					       GNUNET_NO,
-					       &send_next_message,
-					       h);
+  struct GNUNET_PSYCSTORE_Handle *h = cls;
+
+  LOG (GNUNET_ERROR_TYPE_DEBUG,
+       "Origin client disconnected (%d), re-connecting\n",
+       (int) error);
+  if (NULL != h->mq)
+  {
+    GNUNET_MQ_destroy (h->mq);
+    GNUNET_OP_destroy (h->op);
+    h->mq = NULL;
+    h->op = NULL;
+  }
+
+  h->reconnect_task = GNUNET_SCHEDULER_add_delayed (h->reconnect_delay,
+                                                    &reconnect, h);
+  h->reconnect_delay = GNUNET_TIME_STD_BACKOFF (h->reconnect_delay);
+}
+
+
+static void
+do_connect (struct GNUNET_PSYCSTORE_Handle *h)
+{
+  LOG (GNUNET_ERROR_TYPE_DEBUG,
+       "Connecting to PSYCstore service.\n");
+
+  struct GNUNET_MQ_MessageHandler handlers[] = {
+    GNUNET_MQ_hd_var_size (result_code,
+                           GNUNET_MESSAGE_TYPE_PSYCSTORE_RESULT_CODE,
+                           struct OperationResult,
+                           h),
+    GNUNET_MQ_hd_fixed_size (result_counters,
+                             GNUNET_MESSAGE_TYPE_PSYCSTORE_RESULT_COUNTERS,
+                             struct CountersResult,
+                             h),
+    GNUNET_MQ_hd_var_size (result_fragment,
+                           GNUNET_MESSAGE_TYPE_PSYCSTORE_RESULT_FRAGMENT,
+                           struct FragmentResult,
+                           h),
+    GNUNET_MQ_hd_var_size (result_state,
+                           GNUNET_MESSAGE_TYPE_PSYCSTORE_RESULT_STATE,
+                           struct StateResult,
+                           h),
+    GNUNET_MQ_handler_end ()
+  };
+
+  h->op = GNUNET_OP_create ();
+  GNUNET_assert (NULL == h->mq);
+  h->mq = GNUNET_CLIENT_connect (h->cfg, "psycstore",
+                                 handlers, disconnected, h);
+  GNUNET_assert (NULL != h->mq);
 }
 
 
@@ -535,20 +358,11 @@ transmit_next (struct GNUNET_PSYCSTORE_Handle *h)
  * Try again to connect to the PSYCstore service.
  *
  * @param cls Handle to the PSYCstore service.
- * @param tc Scheduler context.
  */
 static void
-reconnect (void *cls, const struct GNUNET_SCHEDULER_TaskContext *tc)
+reconnect (void *cls)
 {
-  struct GNUNET_PSYCSTORE_Handle *h = cls;
-
-  h->reconnect_task = GNUNET_SCHEDULER_NO_TASK;
-  LOG (GNUNET_ERROR_TYPE_DEBUG,
-       "Connecting to PSYCstore service.\n");
-  GNUNET_assert (NULL == h->client);
-  h->client = GNUNET_CLIENT_connect ("psycstore", h->cfg);
-  GNUNET_assert (NULL != h->client);
-  transmit_next (h);
+  do_connect (cls);
 }
 
 
@@ -564,8 +378,8 @@ GNUNET_PSYCSTORE_connect (const struct GNUNET_CONFIGURATION_Handle *cfg)
   struct GNUNET_PSYCSTORE_Handle *h
     = GNUNET_new (struct GNUNET_PSYCSTORE_Handle);
   h->cfg = cfg;
-  h->reconnect_delay = GNUNET_TIME_UNIT_ZERO;
-  h->reconnect_task = GNUNET_SCHEDULER_add_now (&reconnect, h);
+  h->reconnect_delay = GNUNET_TIME_UNIT_MILLISECONDS;
+  do_connect (h);
   return h;
 }
 
@@ -579,25 +393,84 @@ void
 GNUNET_PSYCSTORE_disconnect (struct GNUNET_PSYCSTORE_Handle *h)
 {
   GNUNET_assert (NULL != h);
-  if (h->reconnect_task != GNUNET_SCHEDULER_NO_TASK)
+  if (h->reconnect_task != NULL)
   {
     GNUNET_SCHEDULER_cancel (h->reconnect_task);
-    h->reconnect_task = GNUNET_SCHEDULER_NO_TASK;
-  }
-  if (NULL != h->th)
-  {
-    GNUNET_CLIENT_notify_transmit_ready_cancel (h->th);
-    h->th = NULL;
+    h->reconnect_task = NULL;
   }
-  if (NULL != h->client)
+  if (NULL != h->mq)
   {
-    GNUNET_CLIENT_disconnect (h->client);
-    h->client = NULL;
+    // FIXME: free data structures for pending operations
+    GNUNET_MQ_destroy (h->mq);
+    h->mq = NULL;
   }
   GNUNET_free (h);
 }
 
 
+/**
+ * Message sent notification.
+ *
+ * Remove invalidated envelope pointer.
+ */
+static void
+message_sent (void *cls)
+{
+  struct GNUNET_PSYCSTORE_OperationHandle *op = cls;
+  op->env = NULL;
+}
+
+
+/**
+ * Create a new operation.
+ */
+static struct GNUNET_PSYCSTORE_OperationHandle *
+op_create (struct GNUNET_PSYCSTORE_Handle *h,
+           struct GNUNET_OP_Handle *hop,
+           GNUNET_PSYCSTORE_ResultCallback result_cb,
+           void *cls)
+{
+  struct GNUNET_PSYCSTORE_OperationHandle *
+    op = GNUNET_malloc (sizeof (*op));
+  op->h = h;
+  op->op_id = GNUNET_OP_add (hop,
+                             (GNUNET_ResultCallback) result_cb,
+                             cls, op);
+  return op;
+}
+
+
+/**
+ * Send a message associated with an operation.
+ *
+ * @param h
+ *        PSYCstore handle.
+ * @param op
+ *        Operation handle.
+ * @param env
+ *        Message envelope to send.
+ * @param[out] op_id
+ *        Operation ID to write in network byte order. NULL if not needed.
+ *
+ * @return Operation handle.
+ *
+ */
+static struct GNUNET_PSYCSTORE_OperationHandle *
+op_send (struct GNUNET_PSYCSTORE_Handle *h,
+         struct GNUNET_PSYCSTORE_OperationHandle *op,
+         struct GNUNET_MQ_Envelope *env,
+         uint64_t *op_id)
+{
+  op->env = env;
+  if (NULL != op_id)
+    *op_id = GNUNET_htonll (op->op_id);
+
+  GNUNET_MQ_notify_sent (env, message_sent, op);
+  GNUNET_MQ_send (h->mq, env);
+  return op;
+}
+
+
 /**
  * Cancel a PSYCstore operation. Note that the operation MAY still
  * be executed; this merely cancels the continuation; if the request
@@ -605,32 +478,26 @@ GNUNET_PSYCSTORE_disconnect (struct GNUNET_PSYCSTORE_Handle *h)
  * the operation.
  *
  * @param op Operation to cancel.
+ *
+ * @return #GNUNET_YES if message was not sent yet and got discarded,
+ *         #GNUNET_NO  if it was already sent, and only the callbacks got cancelled.
  */
-void
+int
 GNUNET_PSYCSTORE_operation_cancel (struct GNUNET_PSYCSTORE_OperationHandle *op)
 {
   struct GNUNET_PSYCSTORE_Handle *h = op->h;
+  int ret = GNUNET_NO;
 
-  if (h->transmit_head != NULL && (h->transmit_head != op || NULL == h->client))
+  if (NULL != op->env)
   {
-    /* request not active, can simply remove */
-    GNUNET_CONTAINER_DLL_remove (h->transmit_head, h->transmit_tail, op);
-    GNUNET_free (op);
-    return;
+    GNUNET_MQ_send_cancel (op->env);
+    ret = GNUNET_YES;
   }
-  if (NULL != h->th)
-  {
-    /* request active but not yet with service, can still abort */
-    GNUNET_CLIENT_notify_transmit_ready_cancel (h->th);
-    h->th = NULL;
-    GNUNET_CONTAINER_DLL_remove (h->transmit_head, h->transmit_tail, op);
-    GNUNET_free (op);
-    transmit_next (h);
-    return;
-  }
-  /* request active with service, simply ensure continuations are not called */
-  op->res_cb = NULL;
-  op->data_cb = NULL;
+
+  GNUNET_OP_remove (h->op, op->op_id);
+  GNUNET_free (op);
+
+  return ret;
 }
 
 
@@ -638,64 +505,62 @@ GNUNET_PSYCSTORE_operation_cancel (struct GNUNET_PSYCSTORE_OperationHandle *op)
  * Store join/leave events for a PSYC channel in order to be able to answer
  * membership test queries later.
  *
- * @param h Handle for the PSYCstore.
- * @param channel_key The channel where the event happened.
- * @param slave_key Public key of joining/leaving slave.
- * @param did_join #GNUNET_YES on join, #GNUNET_NO on part.
- * @param announced_at ID of the message that announced the membership change.
- * @param effective_since Message ID this membership change is in effect since.
+ * @param h
+ *        Handle for the PSYCstore.
+ * @param channel_key
+ *        The channel where the event happened.
+ * @param slave_key
+ *        Public key of joining/leaving slave.
+ * @param did_join
+ *        #GNUNET_YES on join, #GNUNET_NO on part.
+ * @param announced_at
+ *        ID of the message that announced the membership change.
+ * @param effective_since
+ *        Message ID this membership change is in effect since.
  *        For joins it is <= announced_at, for parts it is always 0.
- * @param group_generation In case of a part, the last group generation the
- *        slave has access to.  It has relevance when a larger message have
- *        fragments with different group generations.
- * @param rcb Callback to call with the result of the storage operation.
- * @param rcb_cls Closure for the callback.
+ * @param group_generation
+ *        In case of a part, the last group generation the slave has access to.
+ *        It has relevance when a larger message have fragments with different
+ *        group generations.
+ * @param result_cb
+ *        Callback to call with the result of the storage operation.
+ * @param cls
+ *        Closure for the callback.
  *
  * @return Operation handle that can be used to cancel the operation.
  */
 struct GNUNET_PSYCSTORE_OperationHandle *
 GNUNET_PSYCSTORE_membership_store (struct GNUNET_PSYCSTORE_Handle *h,
                                    const struct GNUNET_CRYPTO_EddsaPublicKey *channel_key,
-                                   const struct GNUNET_CRYPTO_EddsaPublicKey *slave_key,
+                                   const struct GNUNET_CRYPTO_EcdsaPublicKey *slave_key,
                                    int did_join,
                                    uint64_t announced_at,
                                    uint64_t effective_since,
                                    uint64_t group_generation,
-                                   GNUNET_PSYCSTORE_ResultCallback rcb,
-                                   void *rcb_cls)
+                                   GNUNET_PSYCSTORE_ResultCallback result_cb,
+                                   void *cls)
 {
   GNUNET_assert (NULL != h);
   GNUNET_assert (NULL != channel_key);
   GNUNET_assert (NULL != slave_key);
+  GNUNET_assert (GNUNET_YES == did_join || GNUNET_NO == did_join);
   GNUNET_assert (did_join
                  ? effective_since <= announced_at
                  : effective_since == 0);
 
   struct MembershipStoreRequest *req;
-  struct GNUNET_PSYCSTORE_OperationHandle *op
-    = GNUNET_malloc (sizeof (*op) + sizeof (*req));
-  op->h = h;
-  op->res_cb = rcb;
-  op->cls = rcb_cls;
-
-  req = (struct MembershipStoreRequest *) &op[1];
-  op->msg = (struct GNUNET_MessageHeader *) req;
-  req->header.type = htons (GNUNET_MESSAGE_TYPE_PSYCSTORE_MEMBERSHIP_STORE);
-  req->header.size = htons (sizeof (*req));
+  struct GNUNET_MQ_Envelope *
+    env = GNUNET_MQ_msg (req, GNUNET_MESSAGE_TYPE_PSYCSTORE_MEMBERSHIP_STORE);
   req->channel_key = *channel_key;
   req->slave_key = *slave_key;
-  req->did_join = htonl (did_join);
+  req->did_join = did_join;
   req->announced_at = GNUNET_htonll (announced_at);
   req->effective_since = GNUNET_htonll (effective_since);
   req->group_generation = GNUNET_htonll (group_generation);
 
-  op->op_id = get_next_op_id (h);
-  req->op_id = htonl (op->op_id);
-
-  GNUNET_CONTAINER_DLL_insert_tail (h->transmit_head, h->transmit_tail, op);
-  transmit_next (h);
-
-  return op;
+  return
+    op_send (h, op_create (h, h->op, result_cb, cls),
+             env, &req->op_id);
 }
 
 
@@ -707,50 +572,45 @@ GNUNET_PSYCSTORE_membership_store (struct GNUNET_PSYCSTORE_Handle *h,
  * is also used when handling join requests to determine whether the slave is
  * currently admitted to the channel.
  *
- * @param h Handle for the PSYCstore.
- * @param channel_key The channel we are interested in.
- * @param slave_key Public key of slave whose membership to check.
- * @param message_id Message ID for which to do the membership test.
- * @param group_generation Group generation of the fragment of the message to
- *        test.  It has relevance if the message consists of multiple fragments
- *        with different group generations.
- * @param rcb Callback to call with the test result.
- * @param rcb_cls Closure for the callback.
+ * @param h
+ *        Handle for the PSYCstore.
+ * @param channel_key
+ *        The channel we are interested in.
+ * @param slave_key
+ *        Public key of slave whose membership to check.
+ * @param message_id
+ *        Message ID for which to do the membership test.
+ * @param group_generation
+ *        Group generation of the fragment of the message to test.
+ *        It has relevance if the message consists of multiple fragments with
+ *        different group generations.
+ * @param result_cb
+ *        Callback to call with the test result.
+ * @param cls
+ *        Closure for the callback.
  *
  * @return Operation handle that can be used to cancel the operation.
  */
 struct GNUNET_PSYCSTORE_OperationHandle *
 GNUNET_PSYCSTORE_membership_test (struct GNUNET_PSYCSTORE_Handle *h,
                                   const struct GNUNET_CRYPTO_EddsaPublicKey *channel_key,
-                                  const struct GNUNET_CRYPTO_EddsaPublicKey *slave_key,
+                                  const struct GNUNET_CRYPTO_EcdsaPublicKey *slave_key,
                                   uint64_t message_id,
                                   uint64_t group_generation,
-                                  GNUNET_PSYCSTORE_ResultCallback rcb,
-                                  void *rcb_cls)
+                                  GNUNET_PSYCSTORE_ResultCallback result_cb,
+                                  void *cls)
 {
   struct MembershipTestRequest *req;
-  struct GNUNET_PSYCSTORE_OperationHandle *op
-    = GNUNET_malloc (sizeof (*op) + sizeof (*req));
-  op->h = h;
-  op->res_cb = rcb;
-  op->cls = rcb_cls;
-
-  req = (struct MembershipTestRequest *) &op[1];
-  op->msg = (struct GNUNET_MessageHeader *) req;
-  req->header.type = htons (GNUNET_MESSAGE_TYPE_PSYCSTORE_MEMBERSHIP_TEST);
-  req->header.size = htons (sizeof (*req));
+  struct GNUNET_MQ_Envelope *
+    env = GNUNET_MQ_msg (req, GNUNET_MESSAGE_TYPE_PSYCSTORE_MEMBERSHIP_TEST);
   req->channel_key = *channel_key;
   req->slave_key = *slave_key;
   req->message_id = GNUNET_htonll (message_id);
   req->group_generation = GNUNET_htonll (group_generation);
 
-  op->op_id = get_next_op_id (h);
-  req->op_id = htonl (op->op_id);
-
-  GNUNET_CONTAINER_DLL_insert_tail (h->transmit_head, h->transmit_tail, op);
-  transmit_next (h);
-
-  return op;
+  return
+    op_send (h, op_create (h, h->op, result_cb, cls),
+             env, &req->op_id);
 }
 
 
@@ -762,132 +622,280 @@ GNUNET_PSYCSTORE_membership_test (struct GNUNET_PSYCSTORE_Handle *h,
  * @param message Message to store.
  * @param psycstore_flags Flags indicating whether the PSYC message contains
  *        state modifiers.
- * @param rcb Callback to call with the result of the operation.
- * @param rcb_cls Closure for the callback.
+ * @param result_cb Callback to call with the result of the operation.
+ * @param cls Closure for the callback.
  *
  * @return Handle that can be used to cancel the operation.
  */
 struct GNUNET_PSYCSTORE_OperationHandle *
 GNUNET_PSYCSTORE_fragment_store (struct GNUNET_PSYCSTORE_Handle *h,
                                  const struct GNUNET_CRYPTO_EddsaPublicKey *channel_key,
-                                 const struct GNUNET_MULTICAST_MessageHeader *message,
-                                 uint32_t psycstore_flags,
-                                 GNUNET_PSYCSTORE_ResultCallback rcb,
-                                 void *rcb_cls)
+                                 const struct GNUNET_MULTICAST_MessageHeader *msg,
+                                 enum GNUNET_PSYCSTORE_MessageFlags psycstore_flags,
+                                 GNUNET_PSYCSTORE_ResultCallback result_cb,
+                                 void *cls)
 {
-  uint16_t size = ntohs (message->header.size);
+  uint16_t size = ntohs (msg->header.size);
   struct FragmentStoreRequest *req;
-  struct GNUNET_PSYCSTORE_OperationHandle *op
-    = GNUNET_malloc (sizeof (*op) + sizeof (*req) + size);
-  op->h = h;
-  op->res_cb = rcb;
-  op->cls = rcb_cls;
-
-  req = (struct FragmentStoreRequest *) &op[1];
-  op->msg = (struct GNUNET_MessageHeader *) req;
-  req->header.type = htons (GNUNET_MESSAGE_TYPE_PSYCSTORE_FRAGMENT_STORE);
-  req->header.size = htons (sizeof (*req) + size);
+  struct GNUNET_MQ_Envelope *
+    env = GNUNET_MQ_msg_extra (req, size,
+                               GNUNET_MESSAGE_TYPE_PSYCSTORE_FRAGMENT_STORE);
   req->channel_key = *channel_key;
   req->psycstore_flags = htonl (psycstore_flags);
-  memcpy (&req[1], message, size);
-
-  op->op_id = get_next_op_id (h);
-  req->op_id = htonl (op->op_id);
+  GNUNET_memcpy (&req[1], msg, size);
 
-  GNUNET_CONTAINER_DLL_insert_tail (h->transmit_head, h->transmit_tail, op);
-  transmit_next (h);
-
-  return op;
+  return
+    op_send (h, op_create (h, h->op, result_cb, cls),
+             env, &req->op_id);
 }
 
 
 /**
- * Retrieve a message fragment by fragment ID.
+ * Retrieve message fragments by fragment ID range.
  *
- * @param h Handle for the PSYCstore.
- * @param channel_key The channel we are interested in.
- * @param fragment_id Fragment ID to check.  Use 0 to get the latest message fragment.
- * @param fcb Callback to call with the retrieved fragments.
- * @param rcb Callback to call with the result of the operation.
- * @param cls Closure for the callbacks.
+ * @param h
+ *        Handle for the PSYCstore.
+ * @param channel_key
+ *        The channel we are interested in.
+ * @param slave_key
+ *        The slave requesting the fragment.  If not NULL, a membership test is
+ *        performed first and the fragment is only returned if the slave has
+ *        access to it.
+ * @param first_fragment_id
+ *        First fragment ID to retrieve.
+ *        Use 0 to get the latest message fragment.
+ * @param last_fragment_id
+ *        Last consecutive fragment ID to retrieve.
+ *        Use 0 to get the latest message fragment.
+ * @param fragment_limit
+ *        Maximum number of fragments to retrieve.
+ * @param fragment_cb
+ *        Callback to call with the retrieved fragments.
+ * @param result_cb
+ *        Callback to call with the result of the operation.
+ * @param cls
+ *        Closure for the callbacks.
  *
  * @return Handle that can be used to cancel the operation.
  */
 struct GNUNET_PSYCSTORE_OperationHandle *
 GNUNET_PSYCSTORE_fragment_get (struct GNUNET_PSYCSTORE_Handle *h,
                                const struct GNUNET_CRYPTO_EddsaPublicKey *channel_key,
-                               uint64_t fragment_id,
-                               GNUNET_PSYCSTORE_FragmentCallback fcb,
-                               GNUNET_PSYCSTORE_ResultCallback rcb,
+                               const struct GNUNET_CRYPTO_EcdsaPublicKey *slave_key,
+                               uint64_t first_fragment_id,
+                               uint64_t last_fragment_id,
+                               GNUNET_PSYCSTORE_FragmentCallback fragment_cb,
+                               GNUNET_PSYCSTORE_ResultCallback result_cb,
                                void *cls)
 {
   struct FragmentGetRequest *req;
-  struct GNUNET_PSYCSTORE_OperationHandle *op
-    = GNUNET_malloc (sizeof (*op) + sizeof (*req));
-  op->h = h;
-  op->data_cb = (DataCallback) fcb;
-  op->res_cb = rcb;
-  op->cls = cls;
-
-  req = (struct FragmentGetRequest *) &op[1];
-  op->msg = (struct GNUNET_MessageHeader *) req;
-  req->header.type = htons (GNUNET_MESSAGE_TYPE_PSYCSTORE_FRAGMENT_GET);
-  req->header.size = htons (sizeof (*req));
+  struct GNUNET_MQ_Envelope *
+    env = GNUNET_MQ_msg (req, GNUNET_MESSAGE_TYPE_PSYCSTORE_FRAGMENT_GET);
   req->channel_key = *channel_key;
-  req->fragment_id = GNUNET_htonll (fragment_id);
+  req->first_fragment_id = GNUNET_htonll (first_fragment_id);
+  req->last_fragment_id = GNUNET_htonll (last_fragment_id);
+  if (NULL != slave_key)
+  {
+    req->slave_key = *slave_key;
+    req->do_membership_test = GNUNET_YES;
+  }
 
-  op->op_id = get_next_op_id (h);
-  req->op_id = htonl (op->op_id);
+  struct GNUNET_PSYCSTORE_OperationHandle *
+    op = op_create (h, h->op, result_cb, cls);
+  op->fragment_cb = fragment_cb;
+  op->cls = cls;
+  return op_send (h, op, env, &req->op_id);
+}
 
-  GNUNET_CONTAINER_DLL_insert_tail (h->transmit_head, h->transmit_tail, op);
-  transmit_next (h);
 
-  return op;
+/**
+ * Retrieve latest message fragments.
+ *
+ * @param h
+ *        Handle for the PSYCstore.
+ * @param channel_key
+ *        The channel we are interested in.
+ * @param slave_key
+ *        The slave requesting the fragment.  If not NULL, a membership test is
+ *        performed first and the fragment is only returned if the slave has
+ *        access to it.
+ * @param first_fragment_id
+ *        First fragment ID to retrieve.
+ *        Use 0 to get the latest message fragment.
+ * @param last_fragment_id
+ *        Last consecutive fragment ID to retrieve.
+ *        Use 0 to get the latest message fragment.
+ * @param fragment_limit
+ *        Maximum number of fragments to retrieve.
+ * @param fragment_cb
+ *        Callback to call with the retrieved fragments.
+ * @param result_cb
+ *        Callback to call with the result of the operation.
+ * @param cls
+ *        Closure for the callbacks.
+ *
+ * @return Handle that can be used to cancel the operation.
+ */
+struct GNUNET_PSYCSTORE_OperationHandle *
+GNUNET_PSYCSTORE_fragment_get_latest (struct GNUNET_PSYCSTORE_Handle *h,
+                                      const struct GNUNET_CRYPTO_EddsaPublicKey *channel_key,
+                                      const struct GNUNET_CRYPTO_EcdsaPublicKey *slave_key,
+                                      uint64_t fragment_limit,
+                                      GNUNET_PSYCSTORE_FragmentCallback fragment_cb,
+                                      GNUNET_PSYCSTORE_ResultCallback result_cb,
+                                      void *cls)
+{
+  struct FragmentGetRequest *req;
+  struct GNUNET_MQ_Envelope *
+    env = GNUNET_MQ_msg (req, GNUNET_MESSAGE_TYPE_PSYCSTORE_FRAGMENT_GET);
+  req->channel_key = *channel_key;
+  req->fragment_limit = GNUNET_ntohll (fragment_limit);
+  if (NULL != slave_key)
+  {
+    req->slave_key = *slave_key;
+    req->do_membership_test = GNUNET_YES;
+  }
+
+  struct GNUNET_PSYCSTORE_OperationHandle *
+    op = op_create (h, h->op, result_cb, cls);
+  op->fragment_cb = fragment_cb;
+  op->cls = cls;
+  return op_send (h, op, env, &req->op_id);
 }
 
 
 /**
- * Retrieve all fragments of a message.
+ * Retrieve all fragments of messages in a message ID range.
  *
- * @param h Handle for the PSYCstore.
- * @param channel_key The channel we are interested in.
- * @param message_id Message ID to check.  Use 0 to get the latest message.
- * @param fcb Callback to call with the retrieved fragments.
- * @param rcb Callback to call with the result of the operation.
- * @param cls Closure for the callbacks.
+ * @param h
+ *        Handle for the PSYCstore.
+ * @param channel_key
+ *        The channel we are interested in.
+ * @param slave_key
+ *        The slave requesting the message.
+ *        If not NULL, a membership test is performed first
+ *        and the message is only returned if the slave has access to it.
+ * @param first_message_id
+ *        First message ID to retrieve.
+ * @param last_message_id
+ *        Last consecutive message ID to retrieve.
+ * @param fragment_limit
+ *        Maximum number of fragments to retrieve.
+ * @param method_prefix
+ *        Retrieve only messages with a matching method prefix.
+ * @todo Implement method_prefix query.
+ * @param fragment_cb
+ *        Callback to call with the retrieved fragments.
+ * @param result_cb
+ *        Callback to call with the result of the operation.
+ * @param cls
+ *        Closure for the callbacks.
  *
  * @return Handle that can be used to cancel the operation.
  */
 struct GNUNET_PSYCSTORE_OperationHandle *
 GNUNET_PSYCSTORE_message_get (struct GNUNET_PSYCSTORE_Handle *h,
                               const struct GNUNET_CRYPTO_EddsaPublicKey *channel_key,
-                              uint64_t message_id,
-                              GNUNET_PSYCSTORE_FragmentCallback fcb,
-                              GNUNET_PSYCSTORE_ResultCallback rcb,
+                              const struct GNUNET_CRYPTO_EcdsaPublicKey *slave_key,
+                              uint64_t first_message_id,
+                              uint64_t last_message_id,
+                              uint64_t fragment_limit,
+                              const char *method_prefix,
+                              GNUNET_PSYCSTORE_FragmentCallback fragment_cb,
+                              GNUNET_PSYCSTORE_ResultCallback result_cb,
                               void *cls)
 {
   struct MessageGetRequest *req;
-  struct GNUNET_PSYCSTORE_OperationHandle *op
-    = GNUNET_malloc (sizeof (*op) + sizeof (*req));
-  op->h = h;
-  op->data_cb = (DataCallback) fcb;
-  op->res_cb = rcb;
+  if (NULL == method_prefix)
+    method_prefix = "";
+  uint16_t method_size = strnlen (method_prefix,
+                                  GNUNET_MAX_MESSAGE_SIZE
+                                  - sizeof (*req)) + 1;
+
+  struct GNUNET_MQ_Envelope *
+    env = GNUNET_MQ_msg_extra (req, method_size,
+                               GNUNET_MESSAGE_TYPE_PSYCSTORE_MESSAGE_GET);
+  req->channel_key = *channel_key;
+  req->first_message_id = GNUNET_htonll (first_message_id);
+  req->last_message_id = GNUNET_htonll (last_message_id);
+  req->fragment_limit = GNUNET_htonll (fragment_limit);
+  if (NULL != slave_key)
+  {
+    req->slave_key = *slave_key;
+    req->do_membership_test = GNUNET_YES;
+  }
+  GNUNET_memcpy (&req[1], method_prefix, method_size);
+  ((char *) &req[1])[method_size - 1] = '\0';
+
+  struct GNUNET_PSYCSTORE_OperationHandle *
+    op = op_create (h, h->op, result_cb, cls);
+  op->fragment_cb = fragment_cb;
   op->cls = cls;
+  return op_send (h, op, env, &req->op_id);
+}
 
-  req = (struct MessageGetRequest *) &op[1];
-  op->msg = (struct GNUNET_MessageHeader *) req;
-  req->header.type = htons (GNUNET_MESSAGE_TYPE_PSYCSTORE_MESSAGE_GET);
-  req->header.size = htons (sizeof (*req));
-  req->channel_key = *channel_key;
-  req->message_id = GNUNET_htonll (message_id);
 
-  op->op_id = get_next_op_id (h);
-  req->op_id = htonl (op->op_id);
+/**
+ * Retrieve all fragments of the latest messages.
+ *
+ * @param h
+ *        Handle for the PSYCstore.
+ * @param channel_key
+ *        The channel we are interested in.
+ * @param slave_key
+ *        The slave requesting the message.
+ *        If not NULL, a membership test is performed first
+ *        and the message is only returned if the slave has access to it.
+ * @param message_limit
+ *        Maximum number of messages to retrieve.
+ * @param method_prefix
+ *        Retrieve only messages with a matching method prefix.
+ * @todo Implement method_prefix query.
+ * @param fragment_cb
+ *        Callback to call with the retrieved fragments.
+ * @param result_cb
+ *        Callback to call with the result of the operation.
+ * @param cls
+ *        Closure for the callbacks.
+ *
+ * @return Handle that can be used to cancel the operation.
+ */
+struct GNUNET_PSYCSTORE_OperationHandle *
+GNUNET_PSYCSTORE_message_get_latest (struct GNUNET_PSYCSTORE_Handle *h,
+                                     const struct GNUNET_CRYPTO_EddsaPublicKey *channel_key,
+                                     const struct GNUNET_CRYPTO_EcdsaPublicKey *slave_key,
+                                     uint64_t message_limit,
+                                     const char *method_prefix,
+                                     GNUNET_PSYCSTORE_FragmentCallback fragment_cb,
+                                     GNUNET_PSYCSTORE_ResultCallback result_cb,
+                                     void *cls)
+{
+  struct MessageGetRequest *req;
+
+  if (NULL == method_prefix)
+    method_prefix = "";
+  uint16_t method_size = strnlen (method_prefix,
+                                  GNUNET_MAX_MESSAGE_SIZE
+                                  - sizeof (*req)) + 1;
+  GNUNET_assert ('\0' == method_prefix[method_size - 1]);
 
-  GNUNET_CONTAINER_DLL_insert_tail (h->transmit_head, h->transmit_tail, op);
-  transmit_next (h);
+  struct GNUNET_MQ_Envelope *
+    env = GNUNET_MQ_msg_extra (req, method_size,
+                               GNUNET_MESSAGE_TYPE_PSYCSTORE_MESSAGE_GET);
+  req->channel_key = *channel_key;
+  req->message_limit = GNUNET_ntohll (message_limit);
+  if (NULL != slave_key)
+  {
+    req->slave_key = *slave_key;
+    req->do_membership_test = GNUNET_YES;
+  }
+  GNUNET_memcpy (&req[1], method_prefix, method_size);
 
-  return op;
+  struct GNUNET_PSYCSTORE_OperationHandle *
+    op = op_create (h, h->op, result_cb, cls);
+  op->fragment_cb = fragment_cb;
+  op->cls = cls;
+  return op_send (h, op, env, &req->op_id);
 }
 
 
@@ -895,48 +903,55 @@ GNUNET_PSYCSTORE_message_get (struct GNUNET_PSYCSTORE_Handle *h,
  * Retrieve a fragment of message specified by its message ID and fragment
  * offset.
  *
- * @param h Handle for the PSYCstore.
- * @param channel_key The channel we are interested in.
- * @param message_id Message ID to check.  Use 0 to get the latest message.
- * @param fragment_offset Offset of the fragment to retrieve.
- * @param fcb Callback to call with the retrieved fragments.
- * @param rcb Callback to call with the result of the operation.
- * @param cls Closure for the callbacks.
+ * @param h
+ *        Handle for the PSYCstore.
+ * @param channel_key
+ *        The channel we are interested in.
+ * @param slave_key
+ *        The slave requesting the message fragment.  If not NULL, a membership
+ *        test is performed first and the message fragment is only returned
+ *        if the slave has access to it.
+ * @param message_id
+ *        Message ID to retrieve.  Use 0 to get the latest message.
+ * @param fragment_offset
+ *        Offset of the fragment to retrieve.
+ * @param fragment_cb
+ *        Callback to call with the retrieved fragments.
+ * @param result_cb
+ *        Callback to call with the result of the operation.
+ * @param cls
+ *        Closure for the callbacks.
  *
  * @return Handle that can be used to cancel the operation.
  */
 struct GNUNET_PSYCSTORE_OperationHandle *
 GNUNET_PSYCSTORE_message_get_fragment (struct GNUNET_PSYCSTORE_Handle *h,
                                        const struct GNUNET_CRYPTO_EddsaPublicKey *channel_key,
+                                       const struct GNUNET_CRYPTO_EcdsaPublicKey *slave_key,
                                        uint64_t message_id,
                                        uint64_t fragment_offset,
-                                       GNUNET_PSYCSTORE_FragmentCallback fcb,
-                                       GNUNET_PSYCSTORE_ResultCallback rcb,
+                                       GNUNET_PSYCSTORE_FragmentCallback fragment_cb,
+                                       GNUNET_PSYCSTORE_ResultCallback result_cb,
                                        void *cls)
 {
   struct MessageGetFragmentRequest *req;
-  struct GNUNET_PSYCSTORE_OperationHandle *op
-    = GNUNET_malloc (sizeof (*op) + sizeof (*req));
-  op->h = h;
-  op->data_cb = (DataCallback) fcb;
-  op->res_cb = rcb;
-  op->cls = cls;
+  struct GNUNET_MQ_Envelope *
+    env = GNUNET_MQ_msg (req, GNUNET_MESSAGE_TYPE_PSYCSTORE_MESSAGE_GET_FRAGMENT);
 
-  req = (struct MessageGetFragmentRequest *) &op[1];
-  op->msg = (struct GNUNET_MessageHeader *) req;
-  req->header.type = htons (GNUNET_MESSAGE_TYPE_PSYCSTORE_MESSAGE_GET_FRAGMENT);
-  req->header.size = htons (sizeof (*req));
   req->channel_key = *channel_key;
   req->message_id = GNUNET_htonll (message_id);
   req->fragment_offset = GNUNET_htonll (fragment_offset);
+  if (NULL != slave_key)
+  {
+    req->slave_key = *slave_key;
+    req->do_membership_test = GNUNET_YES;
+  }
 
-  op->op_id = get_next_op_id (h);
-  req->op_id = htonl (op->op_id);
-
-  GNUNET_CONTAINER_DLL_insert_tail (h->transmit_head, h->transmit_tail, op);
-  transmit_next (h);
-
-  return op;
+  struct GNUNET_PSYCSTORE_OperationHandle *
+    op = op_create (h, h->op, result_cb, cls);
+  op->fragment_cb = fragment_cb;
+  op->cls = cls;
+  return op_send (h, op, env, &req->op_id);
 }
 
 
@@ -946,39 +961,33 @@ GNUNET_PSYCSTORE_message_get_fragment (struct GNUNET_PSYCSTORE_Handle *h,
  * The current value of counters are needed when a channel master is restarted,
  * so that it can continue incrementing the counters from their last value.
  *
- * @param h Handle for the PSYCstore.
- * @param channel_key Public key that identifies the channel.
- * @param ccb Callback to call with the result.
- * @param ccb_cls Closure for the @a ccb callback.
+ * @param h
+ *        Handle for the PSYCstore.
+ * @param channel_key
+ *        Public key that identifies the channel.
+ * @param ccb
+ *        Callback to call with the result.
+ * @param ccb_cls
+ *        Closure for the @a ccb callback.
  *
  * @return Handle that can be used to cancel the operation.
  */
 struct GNUNET_PSYCSTORE_OperationHandle *
 GNUNET_PSYCSTORE_counters_get (struct GNUNET_PSYCSTORE_Handle *h,
                                struct GNUNET_CRYPTO_EddsaPublicKey *channel_key,
-                               GNUNET_PSYCSTORE_CountersCallback ccb,
-                               void *ccb_cls)
+                               GNUNET_PSYCSTORE_CountersCallback counters_cb,
+                               void *cls)
 {
   struct OperationRequest *req;
-  struct GNUNET_PSYCSTORE_OperationHandle *op
-    = GNUNET_malloc (sizeof (*op) + sizeof (*req));
-  op->h = h;
-  op->data_cb = ccb;
-  op->cls = ccb_cls;
-
-  req = (struct OperationRequest *) &op[1];
-  op->msg = (struct GNUNET_MessageHeader *) req;
-  req->header.type = htons (GNUNET_MESSAGE_TYPE_PSYCSTORE_COUNTERS_GET);
-  req->header.size = htons (sizeof (*req));
+  struct GNUNET_MQ_Envelope *
+    env = GNUNET_MQ_msg (req, GNUNET_MESSAGE_TYPE_PSYCSTORE_COUNTERS_GET);
   req->channel_key = *channel_key;
 
-  op->op_id = get_next_op_id (h);
-  req->op_id = htonl (op->op_id);
-
-  GNUNET_CONTAINER_DLL_insert_tail (h->transmit_head, h->transmit_tail, op);
-  transmit_next (h);
-
-  return op;
+  struct GNUNET_PSYCSTORE_OperationHandle *
+    op = op_create (h, h->op, NULL, NULL);
+  op->counters_cb = counters_cb;
+  op->cls = cls;
+  return op_send (h, op, env, &req->op_id);
 }
 
 
@@ -988,14 +997,18 @@ GNUNET_PSYCSTORE_counters_get (struct GNUNET_PSYCSTORE_Handle *h,
  * An error is returned if there are missing messages containing state
  * operations before the current one.
  *
- * @param h Handle for the PSYCstore.
- * @param channel_key The channel we are interested in.
- * @param message_id ID of the message that contains the @a modifiers.
- * @param state_delta Value of the _state_delta PSYC header variable of the message.
- * @param modifier_count Number of elements in the @a modifiers array.
- * @param modifiers List of modifiers to apply.
- * @param rcb Callback to call with the result of the operation.
- * @param rcb_cls Closure for the @a rcb callback.
+ * @param h
+ *        Handle for the PSYCstore.
+ * @param channel_key
+ *        The channel we are interested in.
+ * @param message_id
+ *        ID of the message that contains the @a modifiers.
+ * @param state_delta
+ *        Value of the _state_delta PSYC header variable of the message.
+ * @param result_cb
+ *        Callback to call with the result of the operation.
+ * @param cls
+ *        Closure for @a result_cb.
  *
  * @return Handle that can be used to cancel the operation.
  */
@@ -1004,78 +1017,71 @@ GNUNET_PSYCSTORE_state_modify (struct GNUNET_PSYCSTORE_Handle *h,
                                const struct GNUNET_CRYPTO_EddsaPublicKey *channel_key,
                                uint64_t message_id,
                                uint64_t state_delta,
-                               size_t modifier_count,
-                               const struct GNUNET_ENV_Modifier *modifiers,
-                               GNUNET_PSYCSTORE_ResultCallback rcb,
-                               void *rcb_cls)
+                               GNUNET_PSYCSTORE_ResultCallback result_cb,
+                               void *cls)
 {
-  struct GNUNET_PSYCSTORE_OperationHandle *op = NULL;
-  size_t i;
-
-  for (i = 0; i < modifier_count; i++) {
-    struct StateModifyRequest *req;
-    uint16_t name_size = strlen (modifiers[i].name) + 1;
+  struct StateModifyRequest *req;
+  struct GNUNET_MQ_Envelope *
+    env = GNUNET_MQ_msg (req, GNUNET_MESSAGE_TYPE_PSYCSTORE_STATE_MODIFY);
+  req->channel_key = *channel_key;
+  req->message_id = GNUNET_htonll (message_id);
+  req->state_delta = GNUNET_htonll (state_delta);
 
-    op = GNUNET_malloc (sizeof (*op) + sizeof (*req) + name_size +
-                        modifiers[i].value_size);
-    op->h = h;
-    op->res_cb = rcb;
-    op->cls = rcb_cls;
+  return op_send (h, op_create (h, h->op, result_cb, cls),
+                  env, &req->op_id);
+}
 
-    req = (struct StateModifyRequest *) &op[1];
-    op->msg = (struct GNUNET_MessageHeader *) req;
-    req->header.type = htons (GNUNET_MESSAGE_TYPE_PSYCSTORE_STATE_MODIFY);
-    req->header.size = htons (sizeof (*req) + name_size
-                              + modifiers[i].value_size);
-    req->channel_key = *channel_key;
-    req->message_id = GNUNET_htonll (message_id);
-    req->state_delta = GNUNET_htonll (state_delta);
-    req->oper = modifiers[i].oper;
-    req->name_size = htons (name_size);
-    req->flags
-      = 0 == i
-      ? STATE_OP_FIRST
-      : modifier_count - 1 == i
-      ? STATE_OP_LAST
-      : 0;
 
-    memcpy (&req[1], modifiers[i].name, name_size);
-    memcpy ((char *) &req[1] + name_size, modifiers[i].value, modifiers[i].value_size);
+struct StateSyncClosure
+{
+  GNUNET_PSYCSTORE_ResultCallback result_cb;
+  void *cls;
+  uint8_t last;
+};
 
-    op->op_id = get_next_op_id (h);
-    req->op_id = htonl (op->op_id);
 
-    GNUNET_CONTAINER_DLL_insert_tail (h->transmit_head, h->transmit_tail, op);
-    transmit_next (h);
-  }
-  return op;
-  /* FIXME: only the last operation is returned,
-   *        operation_cancel() should be able to cancel all of them.
-   */
+static void
+state_sync_result (void *cls, int64_t result,
+                   const char *err_msg, uint16_t err_msg_size)
+{
+  struct StateSyncClosure *ssc = cls;
+  if (GNUNET_OK != result || ssc->last)
+    ssc->result_cb (ssc->cls, result, err_msg, err_msg_size);
+  GNUNET_free (ssc);
 }
 
 
 /**
  * Store synchronized state.
  *
- * @param h Handle for the PSYCstore.
- * @param channel_key The channel we are interested in.
- * @param message_id ID of the message that contains the state_hash PSYC header variable.
- * @param modifier_count Number of elements in the @a modifiers array.
- * @param modifiers Full state to store.
- * @param rcb Callback to call with the result of the operation.
- * @param rcb_cls Closure for the callback.
+ * @param h
+ *        Handle for the PSYCstore.
+ * @param channel_key
+ *        The channel we are interested in.
+ * @param max_state_message_id
+ *        ID of the last stateful message before @a state_hash_message_id.
+ * @param state_hash_message_id
+ *        ID of the message that contains the state_hash PSYC header variable.
+ * @param modifier_count
+ *        Number of elements in the @a modifiers array.
+ * @param modifiers
+ *        Full state to store.
+ * @param result_cb
+ *        Callback to call with the result of the operation.
+ * @param cls
+ *        Closure for the callback.
  *
  * @return Handle that can be used to cancel the operation.
  */
 struct GNUNET_PSYCSTORE_OperationHandle *
 GNUNET_PSYCSTORE_state_sync (struct GNUNET_PSYCSTORE_Handle *h,
                              const struct GNUNET_CRYPTO_EddsaPublicKey *channel_key,
-                             uint64_t message_id,
+                             uint64_t max_state_message_id,
+                             uint64_t state_hash_message_id,
                              size_t modifier_count,
-                             const struct GNUNET_ENV_Modifier *modifiers,
-                             GNUNET_PSYCSTORE_ResultCallback rcb,
-                             void *rcb_cls)
+                             const struct GNUNET_PSYC_Modifier *modifiers,
+                             GNUNET_PSYCSTORE_ResultCallback result_cb,
+                             void *cls)
 {
   struct GNUNET_PSYCSTORE_OperationHandle *op = NULL;
   size_t i;
@@ -1084,36 +1090,38 @@ GNUNET_PSYCSTORE_state_sync (struct GNUNET_PSYCSTORE_Handle *h,
     struct StateSyncRequest *req;
     uint16_t name_size = strlen (modifiers[i].name) + 1;
 
-    op = GNUNET_malloc (sizeof (*op) + sizeof (*req) + name_size +
-                        modifiers[i].value_size);
-    op->h = h;
-    op->res_cb = rcb;
-    op->cls = rcb_cls;
+    struct GNUNET_MQ_Envelope *
+      env = GNUNET_MQ_msg_extra (req,
+                                 sizeof (*req) + name_size + modifiers[i].value_size,
+                                 GNUNET_MESSAGE_TYPE_PSYCSTORE_STATE_SYNC);
 
-    req = (struct StateSyncRequest *) &op[1];
-    op->msg = (struct GNUNET_MessageHeader *) req;
     req->header.type = htons (GNUNET_MESSAGE_TYPE_PSYCSTORE_STATE_SYNC);
     req->header.size = htons (sizeof (*req) + name_size
                               + modifiers[i].value_size);
     req->channel_key = *channel_key;
-    req->message_id = GNUNET_htonll (message_id);
+    req->max_state_message_id = GNUNET_htonll (max_state_message_id);
+    req->state_hash_message_id = GNUNET_htonll (state_hash_message_id);
     req->name_size = htons (name_size);
     req->flags
-      = 0 == i
+      = (0 == i)
       ? STATE_OP_FIRST
-      : modifier_count - 1 == i
+      : (modifier_count - 1 == i)
       ? STATE_OP_LAST
       : 0;
 
-    memcpy (&req[1], modifiers[i].name, name_size);
-    memcpy ((char *) &req[1] + name_size, modifiers[i].value, modifiers[i].value_size);
+    GNUNET_memcpy (&req[1], modifiers[i].name, name_size);
+    GNUNET_memcpy ((char *) &req[1] + name_size, modifiers[i].value, modifiers[i].value_size);
 
-    op->op_id = get_next_op_id (h);
-    req->op_id = htonl (op->op_id);
+    struct StateSyncClosure *ssc = GNUNET_malloc (sizeof (*ssc));
+    ssc->last = (req->flags & STATE_OP_LAST);
+    ssc->result_cb = result_cb;
+    ssc->cls = cls;
 
-    GNUNET_CONTAINER_DLL_insert_tail (h->transmit_head, h->transmit_tail, op);
-    transmit_next (h);
+    op_send (h, op_create (h, h->op, state_sync_result, ssc),
+             env, &req->op_id);
   }
+  // FIXME: only one operation is returned,
+  //        add pointers to other operations and make all cancellable.
   return op;
 }
 
@@ -1123,10 +1131,14 @@ GNUNET_PSYCSTORE_state_sync (struct GNUNET_PSYCSTORE_Handle *h,
  *
  * Delete all state variables stored for the given channel.
  *
- * @param h Handle for the PSYCstore.
- * @param channel_key The channel we are interested in.
- * @param rcb Callback to call with the result of the operation.
- * @param rcb_cls Closure for the callback.
+ * @param h
+ *        Handle for the PSYCstore.
+ * @param channel_key
+ *        The channel we are interested in.
+ * @param result_cb
+ *        Callback to call with the result of the operation.
+ * @param cls
+ *        Closure for the callback.
  *
  * @return Handle that can be used to cancel the operation.
  */
@@ -1134,85 +1146,71 @@ struct GNUNET_PSYCSTORE_OperationHandle *
 GNUNET_PSYCSTORE_state_reset (struct GNUNET_PSYCSTORE_Handle *h,
                               const struct GNUNET_CRYPTO_EddsaPublicKey
                               *channel_key,
-                              GNUNET_PSYCSTORE_ResultCallback rcb,
-                              void *rcb_cls)
+                              GNUNET_PSYCSTORE_ResultCallback result_cb,
+                              void *cls)
 {
   struct OperationRequest *req;
-  struct GNUNET_PSYCSTORE_OperationHandle *op
-    = GNUNET_malloc (sizeof (*op) + sizeof (*req));
-  op->h = h;
-  op->res_cb = rcb;
-  op->cls = rcb_cls;
-
-  req = (struct OperationRequest *) &op[1];
-  op->msg = (struct GNUNET_MessageHeader *) req;
-  req->header.type = htons (GNUNET_MESSAGE_TYPE_PSYCSTORE_STATE_RESET);
-  req->header.size = htons (sizeof (*req));
+  struct GNUNET_MQ_Envelope *
+    env = GNUNET_MQ_msg (req, GNUNET_MESSAGE_TYPE_PSYCSTORE_STATE_RESET);
   req->channel_key = *channel_key;
 
-  op->op_id = get_next_op_id (h);
-  req->op_id = htonl (op->op_id);
-
-  GNUNET_CONTAINER_DLL_insert_tail (h->transmit_head, h->transmit_tail, op);
-  transmit_next (h);
-
-  return op;
+  return
+    op_send (h, op_create (h, h->op, result_cb, cls),
+             env, &req->op_id);
 }
 
 
-
 /**
  * Update signed values of state variables in the state store.
  *
- * @param h Handle for the PSYCstore.
- * @param channel_key The channel we are interested in.
- * @param message_id Message ID that contained the state @a hash.
- * @param hash Hash of the serialized full state.
- * @param rcb Callback to call with the result of the operation.
- * @param rcb_cls Closure for the callback.
- *
+ * @param h
+ *        Handle for the PSYCstore.
+ * @param channel_key
+ *        The channel we are interested in.
+ * @param message_id
+ *        Message ID that contained the state @a hash.
+ * @param hash
+ *        Hash of the serialized full state.
+ * @param result_cb
+ *        Callback to call with the result of the operation.
+ * @param cls
+ *        Closure for the callback.
  */
 struct GNUNET_PSYCSTORE_OperationHandle *
 GNUNET_PSYCSTORE_state_hash_update (struct GNUNET_PSYCSTORE_Handle *h,
                                     const struct GNUNET_CRYPTO_EddsaPublicKey *channel_key,
                                     uint64_t message_id,
                                     const struct GNUNET_HashCode *hash,
-                                    GNUNET_PSYCSTORE_ResultCallback rcb,
-                                    void *rcb_cls)
+                                    GNUNET_PSYCSTORE_ResultCallback result_cb,
+                                    void *cls)
 {
   struct StateHashUpdateRequest *req;
-  struct GNUNET_PSYCSTORE_OperationHandle *op
-    = GNUNET_malloc (sizeof (*op) + sizeof (*req));
-  op->h = h;
-  op->res_cb = rcb;
-  op->cls = rcb_cls;
-
-  req = (struct StateHashUpdateRequest *) &op[1];
-  op->msg = (struct GNUNET_MessageHeader *) req;
-  req->header.type = htons (GNUNET_MESSAGE_TYPE_PSYCSTORE_STATE_RESET);
-  req->header.size = htons (sizeof (*req));
+  struct GNUNET_MQ_Envelope *
+    env = GNUNET_MQ_msg (req, GNUNET_MESSAGE_TYPE_PSYCSTORE_STATE_HASH_UPDATE);
   req->channel_key = *channel_key;
   req->hash = *hash;
 
-  op->op_id = get_next_op_id (h);
-  req->op_id = htonl (op->op_id);
-
-  GNUNET_CONTAINER_DLL_insert_tail (h->transmit_head, h->transmit_tail, op);
-  transmit_next (h);
-
-  return op;
+  return
+    op_send (h, op_create (h, h->op, result_cb, cls),
+             env, &req->op_id);
 }
 
 
 /**
  * Retrieve the best matching state variable.
  *
- * @param h Handle for the PSYCstore.
- * @param channel_key The channel we are interested in.
- * @param name Name of variable to match, the returned variable might be less specific.
- * @param scb Callback to return the matching state variable.
- * @param rcb Callback to call with the result of the operation.
- * @param cls Closure for the callbacks.
+ * @param h
+ *        Handle for the PSYCstore.
+ * @param channel_key
+ *        The channel we are interested in.
+ * @param name
+ *        Name of variable to match, the returned variable might be less specific.
+ * @param state_cb
+ *        Callback to return the matching state variable.
+ * @param result_cb
+ *        Callback to call with the result of the operation.
+ * @param cls
+ *        Closure for the callbacks.
  *
  * @return Handle that can be used to cancel the operation.
  */
@@ -1220,46 +1218,41 @@ struct GNUNET_PSYCSTORE_OperationHandle *
 GNUNET_PSYCSTORE_state_get (struct GNUNET_PSYCSTORE_Handle *h,
                             const struct GNUNET_CRYPTO_EddsaPublicKey *channel_key,
                             const char *name,
-                            GNUNET_PSYCSTORE_StateCallback scb,
-                            GNUNET_PSYCSTORE_ResultCallback rcb,
+                            GNUNET_PSYCSTORE_StateCallback state_cb,
+                            GNUNET_PSYCSTORE_ResultCallback result_cb,
                             void *cls)
 {
   size_t name_size = strlen (name) + 1;
   struct OperationRequest *req;
-  struct GNUNET_PSYCSTORE_OperationHandle *op
-    = GNUNET_malloc (sizeof (*op) + sizeof (*req) + name_size);
-  op->h = h;
-  op->data_cb = (DataCallback) scb;
-  op->res_cb = rcb;
-  op->cls = cls;
-
-  req = (struct OperationRequest *) &op[1];
-  op->msg = (struct GNUNET_MessageHeader *) req;
-  req->header.type = htons (GNUNET_MESSAGE_TYPE_PSYCSTORE_STATE_GET);
-  req->header.size = htons (sizeof (*req) + name_size);
+  struct GNUNET_MQ_Envelope *
+    env = GNUNET_MQ_msg_extra (req, name_size,
+                               GNUNET_MESSAGE_TYPE_PSYCSTORE_STATE_GET);
   req->channel_key = *channel_key;
-  memcpy (&req[1], name, name_size);
-
-  op->op_id = get_next_op_id (h);
-  req->op_id = htonl (op->op_id);
+  GNUNET_memcpy (&req[1], name, name_size);
 
-  GNUNET_CONTAINER_DLL_insert_tail (h->transmit_head, h->transmit_tail, op);
-  transmit_next (h);
-
-  return op;
+  struct GNUNET_PSYCSTORE_OperationHandle *
+    op = op_create (h, h->op, result_cb, cls);
+  op->state_cb = state_cb;
+  op->cls = cls;
+  return op_send (h, op, env, &req->op_id);
 }
 
 
-
 /**
  * Retrieve all state variables for a channel with the given prefix.
  *
- * @param h Handle for the PSYCstore.
- * @param channel_key The channel we are interested in.
- * @param name_prefix Prefix of state variable names to match.
- * @param scb Callback to return matching state variables.
- * @param rcb Callback to call with the result of the operation.
- * @param cls Closure for the callbacks.
+ * @param h
+ *        Handle for the PSYCstore.
+ * @param channel_key
+ *        The channel we are interested in.
+ * @param name_prefix
+ *        Prefix of state variable names to match.
+ * @param state_cb
+ *        Callback to return matching state variables.
+ * @param result_cb
+ *        Callback to call with the result of the operation.
+ * @param cls
+ *        Closure for the callbacks.
  *
  * @return Handle that can be used to cancel the operation.
  */
@@ -1267,33 +1260,23 @@ struct GNUNET_PSYCSTORE_OperationHandle *
 GNUNET_PSYCSTORE_state_get_prefix (struct GNUNET_PSYCSTORE_Handle *h,
                                    const struct GNUNET_CRYPTO_EddsaPublicKey *channel_key,
                                    const char *name_prefix,
-                                   GNUNET_PSYCSTORE_StateCallback scb,
-                                   GNUNET_PSYCSTORE_ResultCallback rcb,
+                                   GNUNET_PSYCSTORE_StateCallback state_cb,
+                                   GNUNET_PSYCSTORE_ResultCallback result_cb,
                                    void *cls)
 {
   size_t name_size = strlen (name_prefix) + 1;
   struct OperationRequest *req;
-  struct GNUNET_PSYCSTORE_OperationHandle *op
-    = GNUNET_malloc (sizeof (*op) + sizeof (*req) + name_size);
-  op->h = h;
-  op->data_cb = (DataCallback) scb;
-  op->res_cb = rcb;
-  op->cls = cls;
-
-  req = (struct OperationRequest *) &op[1];
-  op->msg = (struct GNUNET_MessageHeader *) req;
-  req->header.type = htons (GNUNET_MESSAGE_TYPE_PSYCSTORE_STATE_GET_PREFIX);
-  req->header.size = htons (sizeof (*req) + name_size);
+  struct GNUNET_MQ_Envelope *
+    env = GNUNET_MQ_msg_extra (req, name_size,
+                               GNUNET_MESSAGE_TYPE_PSYCSTORE_STATE_GET_PREFIX);
   req->channel_key = *channel_key;
-  memcpy (&req[1], name_prefix, name_size);
-
-  op->op_id = get_next_op_id (h);
-  req->op_id = htonl (op->op_id);
-
-  GNUNET_CONTAINER_DLL_insert_tail (h->transmit_head, h->transmit_tail, op);
-  transmit_next (h);
+  GNUNET_memcpy (&req[1], name_prefix, name_size);
 
-  return op;
+  struct GNUNET_PSYCSTORE_OperationHandle *
+    op = op_create (h, h->op, result_cb, cls);
+  op->state_cb = state_cb;
+  op->cls = cls;
+  return op_send (h, op, env, &req->op_id);
 }
 
 /* end of psycstore_api.c */