nes-proj/examples/coap/coap-example-server/resources/res-event.c

/*
 * Copyright (c) 2013, Institute for Pervasive Computing, ETH Zurich
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the Institute nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 * This file is part of the Contiki operating system.
 */

/**
 * \file
 *      Example resource
 * \author
 *      Matthias Kovatsch <kovatsch@inf.ethz.ch>
 */

#include <stdio.h>
#include <string.h>
#include "coap-engine.h"
#include "coap.h"

/* Log configuration */
#include "sys/log.h"
#define LOG_MODULE "App"
#define LOG_LEVEL LOG_LEVEL_APP

static void res_get_handler(coap_message_t *request, coap_message_t *response, uint8_t *buffer, uint16_t preferred_size, int32_t *offset);
static void res_event_handler(void);

/*
 * Example for an event resource.
 * Additionally takes a period parameter that defines the interval to call [name]_periodic_handler().
 * A default post_handler takes care of subscriptions and manages a list of subscribers to notify.
 */
EVENT_RESOURCE(res_event,
               "title=\"Event demo\";obs",
               res_get_handler,
               NULL,
               NULL,
               NULL,
               res_event_handler);

/*
 * Use local resource state that is accessed by res_get_handler() and altered by res_event_handler() or PUT or POST.
 */
static int32_t event_counter = 0;

static void
res_get_handler(coap_message_t *request, coap_message_t *response, uint8_t *buffer, uint16_t preferred_size, int32_t *offset)
{
  coap_set_header_content_format(response, TEXT_PLAIN);
  coap_set_payload(response, buffer, snprintf((char *)buffer, preferred_size, "EVENT %lu", (unsigned long) event_counter));

  /* A post_handler that handles subscriptions/observing will be called for periodic resources by the framework. */
}
/*
 * Additionally, res_event_handler must be implemented for each EVENT_RESOURCE.
 * It is called through <res_name>.trigger(), usually from the server process.
 */
static void
res_event_handler(void)
{
  /* Do the update triggered by the event here, e.g., sampling a sensor. */
  ++event_counter;

  /* Usually a condition is defined under with subscribers are notified, e.g., event was above a threshold. */
  if(1) {
    LOG_DBG("TICK %u for /%s\n", (unsigned)event_counter, res_event.url);

    /* Notify the registered observers which will trigger the res_get_handler to create the response. */
    coap_notify_observers(&res_event);
  }
}