+/**
+ * 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 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.
+ * @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,
+ 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);
+
+
+/**
+ * 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.
+ * @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);
+
+
+/**
+ * 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 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.