127 lines
4.7 KiB
C
127 lines
4.7 KiB
C
/*
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* Copyright (c) 2013, Institute for Pervasive Computing, ETH Zurich
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the name of the Institute nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* This file is part of the Contiki operating system.
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*/
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/**
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* \file
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* Example of an observable "on-change" temperature resource
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* \author
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* Matthias Kovatsch <kovatsch@inf.ethz.ch>
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* \author
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* Cristiano De Alti <cristiano_dealti@hotmail.com>
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*/
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#include "contiki.h"
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#if PLATFORM_HAS_TEMPERATURE
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#include <limits.h>
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#include <stdlib.h>
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#include <stdio.h>
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#include <string.h>
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#include "coap-engine.h"
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#include "dev/temperature-sensor.h"
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static void res_get_handler(coap_message_t *request, coap_message_t *response, uint8_t *buffer, uint16_t preferred_size, int32_t *offset);
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static void res_periodic_handler(void);
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#define MAX_AGE 60
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#define INTERVAL_MIN 5
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#define INTERVAL_MAX (MAX_AGE - 1)
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#define CHANGE 1
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static int32_t interval_counter = INTERVAL_MIN;
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static int temperature_old = INT_MIN;
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PERIODIC_RESOURCE(res_temperature,
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"title=\"Temperature\";rt=\"Temperature\";obs",
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res_get_handler,
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NULL,
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NULL,
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NULL,
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CLOCK_SECOND,
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res_periodic_handler);
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static void
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res_get_handler(coap_message_t *request, coap_message_t *response, uint8_t *buffer, uint16_t preferred_size, int32_t *offset)
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{
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/*
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* For minimal complexity, request query and options should be ignored for GET on observable resources.
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* Otherwise the requests must be stored with the observer list and passed by coap_notify_observers().
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* This would be a TODO in the corresponding files in contiki/apps/erbium/!
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*/
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int temperature = temperature_sensor.value(0);
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unsigned int accept = -1;
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coap_get_header_accept(request, &accept);
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if(accept == -1 || accept == TEXT_PLAIN) {
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coap_set_header_content_format(response, TEXT_PLAIN);
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snprintf((char *)buffer, COAP_MAX_CHUNK_SIZE, "%d", temperature);
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coap_set_payload(response, (uint8_t *)buffer, strlen((char *)buffer));
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} else if(accept == APPLICATION_JSON) {
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coap_set_header_content_format(response, APPLICATION_JSON);
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snprintf((char *)buffer, COAP_MAX_CHUNK_SIZE, "{'temperature':%d}", temperature);
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coap_set_payload(response, buffer, strlen((char *)buffer));
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} else {
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coap_set_status_code(response, NOT_ACCEPTABLE_4_06);
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const char *msg = "Supporting content-types text/plain and application/json";
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coap_set_payload(response, msg, strlen(msg));
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}
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coap_set_header_max_age(response, MAX_AGE);
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/* The coap_subscription_handler() will be called for observable resources by the coap_framework. */
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}
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/*
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* Additionally, a handler function named [resource name]_handler must be implemented for each PERIODIC_RESOURCE.
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* It will be called by the coap_manager process with the defined period.
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*/
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static void
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res_periodic_handler()
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{
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int temperature = temperature_sensor.value(0);
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++interval_counter;
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if((abs(temperature - temperature_old) >= CHANGE && interval_counter >= INTERVAL_MIN) ||
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interval_counter >= INTERVAL_MAX) {
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interval_counter = 0;
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temperature_old = temperature;
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/* Notify the registered observers which will trigger the res_get_handler to create the response. */
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coap_notify_observers(&res_temperature);
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}
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}
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#endif /* PLATFORM_HAS_TEMPERATURE */
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