polite.h

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00001 /**
00002  * \addtogroup rime
00003  * @{
00004  */
00005 
00006 /**
00007  * \defgroup rimepolite Polite anonymous best effort local broadcast
00008  * @{
00009  *
00010  * The polite module sends one local area broadcast packet within one
00011  * time interval. If a packet with the same header is received from a
00012  * neighbor within the interval, the packet is not sent.
00013  *
00014  * The polite primitive is a generalization of the polite gossip
00015  * algorithm from Trickle (Levis et al, NSDI 2004).  The polite gossip
00016  * algorithm is designed to reduce the total amount of packet
00017  * transmissions by not repeating a message that other nodes have
00018  * already sent.  The purpose of the polite broadcast primitive is to
00019  * avoid that multiple copies of a specific set of packet attributes
00020  * is sent on a specified logical channel in the local neighborhood
00021  * during a time interval.
00022  *
00023  * The polite broadcast primitive is useful for implementing broadcast
00024  * protocols that use, e.g., negative acknowledgements.  If many nodes
00025  * need to send the negative acknowledgement to a sender, it is enough
00026  * if only a single message is delivered to the sender.
00027  *
00028  * The upper layer protocol or application that uses the polite
00029  * broadcast primitive provides an interval time, and message along
00030  * with a list of packet attributes for which multiple copies should
00031  * be avoided.  The polite broadcast primitive stores the outgoing
00032  * message in a queue buffer, stores the list of packet attributes,
00033  * and sets up a timer.  The timer is set to a random time during the
00034  * second half of the interval time.
00035  *
00036  * During the first half of the time interval, the sender listens for
00037  * other transmissions.  If it hears a packet that matches the
00038  * attributes provided by the upper layer protocol or application, the
00039  * sender drops the packet.  The send timer has been set to a random
00040  * time some time during the second half of the interval.  When the
00041  * timer fires, and the sender has not yet heard a transmission of the
00042  * same packet attributes, the sender broadcasts its packet to all its
00043  * neighbors.
00044  *
00045  * The polite broadcast module does not add any packet attributes to
00046  * outgoing packets apart from those added by the upper layer.
00047  *
00048  * \section channels Channels
00049  *
00050  * The polite module uses 1 channel.
00051  *
00052  */
00053 
00054 /*
00055  * Copyright (c) 2007, Swedish Institute of Computer Science.
00056  * All rights reserved.
00057  *
00058  * Redistribution and use in source and binary forms, with or without
00059  * modification, are permitted provided that the following conditions
00060  * are met:
00061  * 1. Redistributions of source code must retain the above copyright
00062  *    notice, this list of conditions and the following disclaimer.
00063  * 2. Redistributions in binary form must reproduce the above copyright
00064  *    notice, this list of conditions and the following disclaimer in the
00065  *    documentation and/or other materials provided with the distribution.
00066  * 3. Neither the name of the Institute nor the names of its contributors
00067  *    may be used to endorse or promote products derived from this software
00068  *    without specific prior written permission.
00069  *
00070  * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
00071  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
00072  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
00073  * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
00074  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
00075  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
00076  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
00077  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
00078  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
00079  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
00080  * SUCH DAMAGE.
00081  *
00082  * This file is part of the Contiki operating system.
00083  *
00084  * $Id: polite.h,v 1.10 2010/06/18 08:28:56 nifi Exp $
00085  */
00086 
00087 /**
00088  * \file
00089  *         Header file for Polite Anonymous best effort local Broadcast (polite)
00090  * \author
00091  *         Adam Dunkels <adam@sics.se>
00092  */
00093 
00094 #ifndef __POLITE_H__
00095 #define __POLITE_H__
00096 
00097 #include "net/rime/abc.h"
00098 #include "net/queuebuf.h"
00099 #include "sys/ctimer.h"
00100 
00101 struct polite_conn;
00102 
00103 #define POLITE_ATTRIBUTES ABC_ATTRIBUTES
00104 
00105 /**
00106  * \brief      A structure with callback functions for a polite connection.
00107  *
00108  *             This structure holds a list of callback functions used
00109  *             a a polite connection. The functions are called when
00110  *             events occur on the connection.
00111  *
00112  */
00113 struct polite_callbacks {
00114   /**
00115    * Called when a packet is received on the connection.
00116    */
00117   void (* recv)(struct polite_conn *c);
00118 
00119   /**
00120    * Called when a packet is sent on the connection.
00121    */
00122   void (* sent)(struct polite_conn *c);
00123 
00124   /**
00125    * Called when a packet is dropped because a packet was heard from a
00126    * neighbor.
00127    */
00128   void (* dropped)(struct polite_conn *c);
00129 };
00130 
00131 /**
00132  * An opaque structure with no user-visible elements that holds the
00133  * state of a polite connection,
00134  */
00135 struct polite_conn {
00136   struct abc_conn c;
00137   const struct polite_callbacks *cb;
00138   struct ctimer t;
00139   struct queuebuf *q;
00140   uint8_t hdrsize;
00141 };
00142 
00143 /**
00144  * \brief      Open a polite connection
00145  * \param c    A pointer to a struct polite_conn.
00146  * \param channel The channel number to be used for this connection
00147  * \param cb   A pointer to the callbacks used for this connection
00148  *
00149  *             This function opens a polite connection on the
00150  *             specified channel. The callbacks are called when a
00151  *             packet is received, or when another event occurs on the
00152  *             connection (see \ref "struct polite_callbacks").
00153  */
00154 void polite_open(struct polite_conn *c, uint16_t channel,
00155                  const struct polite_callbacks *cb);
00156 
00157 /**
00158  * \brief      Close a polite connection
00159  * \param c    A pointer to a struct polite_conn that has previously been opened with polite_open().
00160  *
00161  *             This function closes a polite connection that has
00162  *             previously been opened with polite_open().
00163  */
00164 void polite_close(struct polite_conn *c);
00165 
00166 
00167 /**
00168  * \brief      Send a packet on a polite connection.
00169  * \param c    A pointer to a struct polite_conn that has previously been opened with polite_open().
00170  * \param interval The timer interval in which the packet should be sent.
00171  * \param hdrsize The size of the header that should be unique within the time interval.
00172  *
00173  *             This function sends a packet from the packetbuf on the
00174  *             polite connection. The packet is sent some time during
00175  *             the time interval, but only if no other packet is
00176  *             received with the same header.
00177  *
00178  */
00179 int  polite_send(struct polite_conn *c, clock_time_t interval, uint8_t hdrsize);
00180 
00181 /**
00182  * \brief      Cancel a pending packet
00183  * \param c    A pointer to a struct polite_conn that has previously been opened with polite_open().
00184  *
00185  *             This function cancels a pending transmission that has
00186  *             previously been started with polite_send().
00187  */
00188 void polite_cancel(struct polite_conn *c);
00189 
00190 #endif /* __POLITE_H__ */
00191 
00192 /** @} */
00193 /** @} */

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