nes-proj/examples/coap/resources/res-temperature.c

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/*
* 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 of an observable "on-change" temperature resource
* \author
* Matthias Kovatsch <kovatsch@inf.ethz.ch>
* \author
* Cristiano De Alti <cristiano_dealti@hotmail.com>
*/
#include "contiki.h"
#if PLATFORM_HAS_TEMPERATURE
#include <limits.h>
#include <stdlib.h>
#include <string.h>
#include "rest-engine.h"
#include "dev/temperature-sensor.h"
static void res_get_handler(void *request, void *response, uint8_t *buffer, uint16_t preferred_size, int32_t *offset);
static void res_periodic_handler(void);
#define MAX_AGE 60
#define INTERVAL_MIN 5
#define INTERVAL_MAX (MAX_AGE - 1)
#define CHANGE 1
static int32_t interval_counter = INTERVAL_MIN;
static int temperature_old = INT_MIN;
PERIODIC_RESOURCE(res_temperature,
"title=\"Temperature\";rt=\"Temperature\";obs",
res_get_handler,
NULL,
NULL,
NULL,
CLOCK_SECOND,
res_periodic_handler);
static void
res_get_handler(void *request, void *response, uint8_t *buffer, uint16_t preferred_size, int32_t *offset)
{
/*
* For minimal complexity, request query and options should be ignored for GET on observable resources.
* Otherwise the requests must be stored with the observer list and passed by REST.notify_subscribers().
* This would be a TODO in the corresponding files in contiki/apps/erbium/!
*/
int temperature = temperature_sensor.value(0);
unsigned int accept = -1;
REST.get_header_accept(request, &accept);
if(accept == -1 || accept == REST.type.TEXT_PLAIN) {
REST.set_header_content_type(response, REST.type.TEXT_PLAIN);
snprintf((char *)buffer, REST_MAX_CHUNK_SIZE, "%d", temperature);
REST.set_response_payload(response, (uint8_t *)buffer, strlen((char *)buffer));
} else if(accept == REST.type.APPLICATION_JSON) {
REST.set_header_content_type(response, REST.type.APPLICATION_JSON);
snprintf((char *)buffer, REST_MAX_CHUNK_SIZE, "{'temperature':%d}", temperature);
REST.set_response_payload(response, buffer, strlen((char *)buffer));
} else {
REST.set_response_status(response, REST.status.NOT_ACCEPTABLE);
const char *msg = "Supporting content-types text/plain and application/json";
REST.set_response_payload(response, msg, strlen(msg));
}
REST.set_header_max_age(response, MAX_AGE);
/* The REST.subscription_handler() will be called for observable resources by the REST framework. */
}
/*
* Additionally, a handler function named [resource name]_handler must be implemented for each PERIODIC_RESOURCE.
* It will be called by the REST manager process with the defined period.
*/
static void
res_periodic_handler()
{
int temperature = temperature_sensor.value(0);
++interval_counter;
if((abs(temperature - temperature_old) >= CHANGE && interval_counter >= INTERVAL_MIN) ||
interval_counter >= INTERVAL_MAX) {
interval_counter = 0;
temperature_old = temperature;
/* Notify the registered observers which will trigger the res_get_handler to create the response. */
REST.notify_subscribers(&res_temperature);
}
}
#endif /* PLATFORM_HAS_TEMPERATURE */