aws_iot_shadow_interface.h

00001 /*
00002  * Copyright 2010-2015 Amazon.com, Inc. or its affiliates. All Rights Reserved.
00003  *
00004  * Licensed under the Apache License, Version 2.0 (the "License").
00005  * You may not use this file except in compliance with the License.
00006  * A copy of the License is located at
00007  *
00008  *  http://aws.amazon.com/apache2.0
00009  *
00010  * or in the "license" file accompanying this file. This file is distributed
00011  * on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
00012  * express or implied. See the License for the specific language governing
00013  * permissions and limitations under the License.
00014  */
00015 #ifndef AWS_IOT_SDK_SRC_IOT_SHADOW_H_
00016 #define AWS_IOT_SDK_SRC_IOT_SHADOW_H_
00017 
00018 
00019 /**
00020  * @file aws_iot_shadow_interface.h
00021  * @brief Interface for thing shadow
00022  *
00023  * These are the functions and structs to manage/interact the Thing Shadow(in the cloud).
00024  * This SDK will let you interact with your own thing shadow or any other shadow using its Thing Name.
00025  * There are totally 3 actions a device can perform on the shadow - Get, Update and Delete.
00026  *
00027  * Currently the device should use MQTT/S underneath. In the future this will also support other protocols. As it supports MQTT, the shadow needs to connect and disconnect.
00028  * It will also work on the pub/sub model. On performing any action, the acknowledgment will be received in either accepted or rejected. For Example:
00029  * If we want to perform a GET on the thing shadow the following messages will be sent and received:
00030  * 1. A MQTT Publish on the topic - $aws/things/{thingName}/shadow/get
00031  * 2. Subscribe to MQTT topics - $aws/things/{thingName}/shadow/get/accepted and $aws/things/{thingName}/shadow/get/rejected.
00032  * If the request was successful we will receive the things json document in the accepted topic.
00033  *
00034  *
00035  */
00036 #include "aws_iot_mqtt_interface.h"
00037 #include "aws_iot_shadow_json_data.h"
00038 
00039 /*!
00040  * @brief Shadow Connect parameters
00041  *
00042  * As the Shadow SDK uses MQTT underneath, it could be connected and disconnected on events to save some battery.
00043  * @note Always use the \c ShadowParametersDefault to initialize this struct
00044  *
00045  *
00046  *
00047  */
00048 typedef struct {
00049     char *pMyThingName; ///< Every device has a Thing Shadow and this is the placeholder for name
00050     char *pMqttClientId; ///< Currently the Shadow uses MQTT to connect and it is important to ensure we have unique client id
00051     char *pHost; ///< This will be unique to a customer and can be retrieved from the console
00052     int port; ///< By default the port is 8883
00053     char *pRootCA; ///< Location with the Filename of the Root CA
00054     char *pClientCRT; ///< Location of Device certs signed by AWS IoT service
00055     char *pClientKey; ///< Location of Device private key
00056 } ShadowParameters_t;
00057 
00058 /*!
00059  * @brief This is set to defaults from the configuration file
00060  * The certs are set to NULL because they need the path to the file. shadow_sample.c file demonstrates on how to get the relative path
00061  *
00062  * \relates ShadowParameters_t
00063  */
00064 extern const ShadowParameters_t ShadowParametersDefault;
00065 
00066 
00067 /**
00068  * @brief Initialize the Thing Shadow before use
00069  *
00070  * This function takes care of initializing the internal book-keeping data structures
00071  *
00072  * @param pClient   MQTT Client used as the protocol layer
00073  * @return An IoT Error Type defining successful/failed Initialization
00074  */
00075 IoT_Error_t aws_iot_shadow_init(MQTTClient_t *pClient);
00076 /**
00077  * @brief Connect to the AWS IoT Thing Shadow service over MQTT
00078  *
00079  * This function does the TLSv1.2 handshake and establishes the MQTT connection
00080  *
00081  * @param pClient   MQTT Client used as the protocol layer
00082  * @param pParams   Shadow Conenction parameters like TLS cert location
00083  * @return An IoT Error Type defining successful/failed Connection
00084  */
00085 IoT_Error_t aws_iot_shadow_connect(MQTTClient_t *pClient, ShadowParameters_t *pParams);
00086 /**
00087  * @brief Yield function to let the background tasks of MQTT and Shadow
00088  *
00089  * This function could be use in a separate thread waiting for the incoming messages, ensuring the connection is kept alive with the AWS Service.
00090  * It also ensures the expired requests of Shadow actions are cleared and Timeout callback is executed.
00091  * @note All callbacks ever used in the SDK will be executed in the context of this function.
00092  *
00093  * @param pClient   MQTT Client used as the protocol layer
00094  * @param timeout   in milliseconds, This is the maximum time the yield function will wait for a message and/or read the messages from the TLS buffer
00095  * @return An IoT Error Type defining successful/failed Yield
00096  */
00097 IoT_Error_t aws_iot_shadow_yield(MQTTClient_t *pClient, int timeout);
00098 /**
00099  * @brief Disconnect from the AWS IoT Thing Shadow service over MQTT
00100  *
00101  * This will close the underlying TCP connection, MQTT connection will also be closed
00102  *
00103  * @param pClient   MQTT Client used as the protocol layer
00104  * @return An IoT Error Type defining successful/failed disconnect status
00105  */
00106 IoT_Error_t aws_iot_shadow_disconnect(MQTTClient_t *pClient);
00107 
00108 /**
00109  * @brief Thing Shadow Acknowledgment enum
00110  *
00111  * This enum type is use in the callback for the action response
00112  *
00113  */
00114 typedef enum {
00115     SHADOW_ACK_TIMEOUT, SHADOW_ACK_REJECTED, SHADOW_ACK_ACCEPTED
00116 } Shadow_Ack_Status_t;
00117 
00118 /**
00119  * @brief Thing Shadow Action type enum
00120  *
00121  * This enum type is use in the callback for the action response
00122  *
00123  */
00124 typedef enum {
00125     SHADOW_GET, SHADOW_UPDATE, SHADOW_DELETE
00126 } ShadowActions_t;
00127 
00128 
00129 /**
00130  * @brief Function Pointer typedef used as the callback for every action
00131  *
00132  * This function will be called from the context of \c aws_iot_shadow_yield() context
00133  *
00134  * @param pThingName Thing Name of the response received
00135  * @param action The response of the action
00136  * @param status Informs if the action was Accepted/Rejected or Timed out
00137  * @param pReceivedJsonDocument Received JSON document
00138  * @param pContextData the void* data passed in during the action call(update, get or delete)
00139  *
00140  */
00141 typedef void (*fpActionCallback_t)(const char *pThingName, ShadowActions_t action, Shadow_Ack_Status_t status,
00142         const char *pReceivedJsonDocument, void *pContextData);
00143 
00144 /**
00145  * @brief This function is the one used to perform an Update action to a Thing Name's Shadow.
00146  *
00147  * update is one of the most frequently used functionality by a device. In most cases the device may be just reporting few params to update the thing shadow in the cloud
00148  * Update Action if no callback or if the JSON document does not have a client token then will just publish the update and not track it.
00149  *
00150  * @note The update has to subscribe to two topics update/accepted and update/rejected. This function waits 2 seconds to ensure the subscriptions are registered before publishing the update message.
00151  * The following steps are performed on using this function:
00152  * 1. Subscribe to Shadow topics - $aws/things/{thingName}/shadow/update/accepted and $aws/things/{thingName}/shadow/update/rejected
00153  * 2. wait for 2 seconds for the subscription to take effect
00154  * 3. Publish on the update topic - $aws/things/{thingName}/shadow/update
00155  * 4. In the \c aws_iot_shadow_yield() function the response will be handled. In case of timeout or if the response is received, the subscription to shadow response topics are un-subscribed from.
00156  *    On the contrary if the persistent subscription is set to true then the un-subscribe will not be done. The topics will always be listened to.
00157  *
00158  * @param pClient   MQTT Client used as the protocol layer
00159  * @param pThingName Thing Name of the shadow that needs to be Updated
00160  * @param pJsonString The update action expects a JSON document to send. The JSO String should be a null terminated string. This JSON document should adhere to the AWS IoT Thing Shadow specification. To help in the process of creating this document- SDK provides apis in \c aws_iot_shadow_json_data.h
00161  * @param callback This is the callback that will be used to inform the caller of the response from the AWS IoT Shadow service.Callback could be set to NULL if response is not important
00162  * @param pContextData This is an extra parameter that could be passed along with the callback. It should be set to NULL if not used
00163  * @param timeout_seconds It is the time the SDK will wait for the response on either accepted/rejected before declaring timeout on the action
00164  * @param isPersistentSubscribe As mentioned above, every  time if a device updates the same shadow then this should be set to true to avoid repeated subscription and unsubscription. If the Thing Name is one off update then this should be set to false
00165  * @return An IoT Error Type defining successful/failed update action
00166  */
00167 IoT_Error_t aws_iot_shadow_update(MQTTClient_t *pClient, const char *pThingName, char *pJsonString,
00168         fpActionCallback_t callback, void *pContextData, uint8_t timeout_seconds, bool isPersistentSubscribe);
00169 
00170 /**
00171  * @brief This function is the one used to perform an Get action to a Thing Name's Shadow.
00172  *
00173  * One use of this function is usually to get the config of a device at boot up.
00174  * It is similar to the Update function internally except it does not take a JSON document as the input. The entire JSON document will be sent over the accepted topic
00175  *
00176  * @param pClient   MQTT Client used as the protocol layer
00177  * @param pThingName Thing Name of the JSON document that is needed
00178  * @param callback This is the callback that will be used to inform the caller of the response from the AWS IoT Shadow service.Callback could be set to NULL if response is not important
00179  * @param pContextData This is an extra parameter that could be passed along with the callback. It should be set to NULL if not used
00180  * @param timeout_seconds It is the time the SDK will wait for the response on either accepted/rejected before declaring timeout on the action
00181  * @param isPersistentSubscribe As mentioned above, every  time if a device gets the same Sahdow (JSON document) then this should be set to true to avoid repeated subscription and un-subscription. If the Thing Name is one off get then this should be set to false
00182  * @return An IoT Error Type defining successful/failed get action
00183  */
00184 IoT_Error_t aws_iot_shadow_get(MQTTClient_t *pClient, const char *pThingName, fpActionCallback_t callback,
00185         void *pContextData, uint8_t timeout_seconds, bool isPersistentSubscribe);
00186 /**
00187  * @brief This function is the one used to perform an Delete action to a Thing Name's Shadow.
00188  *
00189  * This is not a very common use case for  device. It is generally the responsibility of the accompanying app to do the delete.
00190  * It is similar to the Update function internally except it does not take a JSON document as the input. The Thing Shadow referred by the ThingName will be deleted.
00191  *
00192  * @param pClient MQTT Client used as the protocol layer
00193  * @param pThingName Thing Name of the Shadow that should be deleted
00194  * @param callback This is the callback that will be used to inform the caller of the response from the AWS IoT Shadow service.Callback could be set to NULL if response is not important
00195  * @param pContextData This is an extra parameter that could be passed along with the callback. It should be set to NULL if not used
00196  * @param timeout_seconds It is the time the SDK will wait for the response on either accepted/rejected before declaring timeout on the action
00197  * @param isPersistentSubscribe As mentioned above, every  time if a device deletes the same Sahdow (JSON document) then this should be set to true to avoid repeated subscription and un-subscription. If the Thing Name is one off delete then this should be set to false
00198  * @return An IoT Error Type defining successful/failed delete action
00199  */
00200 IoT_Error_t aws_iot_shadow_delete(MQTTClient_t *pClient, const char *pThingName, fpActionCallback_t callback,
00201         void *pContextData, uint8_t timeout_seconds, bool isPersistentSubscriptions);
00202 
00203 /**
00204  * @brief This function is used to listen on the delta topic of #AWS_IOT_MY_THING_NAME mentioned in the aws_iot_config.h file.
00205  *
00206  * Any time a delta is published the Json document will be delivered to the pStruct->cb. If you don't want the parsing done by the SDK then use the jsonStruct_t key set to "state". A good example of this is displayed in the sample_apps/shadow_console_echo.c
00207  *
00208  * @param pClient MQTT Client used as the protocol layer
00209  * @param pStruct The struct used to parse JSON value
00210  * @return An IoT Error Type defining successful/failed delta registering
00211  */
00212 IoT_Error_t aws_iot_shadow_register_delta(MQTTClient_t *pClient, jsonStruct_t *pStruct);
00213 
00214 /**
00215  * @brief Reset the last received version number to zero.
00216  * This will be useful if the Thing Shadow is deleted and would like to to reset the local version
00217  * @return no return values
00218  *
00219  */
00220 void aws_iot_shadow_reset_last_received_version(void);
00221 /**
00222  * @brief Version of a document is received with every accepted/rejected and the SDK keeps track of the last received version of the JSON document of #AWS_IOT_MY_THING_NAME shadow
00223  *
00224  * One exception to this version tracking is that, the SDK will ignore the version from update/accepted topic. Rest of the responses will be scanned to update the version number.
00225  * Accepting version change for update/accepted may cause version conflicts for delta message if the update message is received before the delta.
00226  *
00227  * @return version number of the last received response
00228  *
00229  */
00230 uint32_t aws_iot_shadow_get_last_received_version(void);
00231 /**
00232  * @brief Enable the ignoring of delta messages with old version number
00233  *
00234  * As we use MQTT underneath, there could be more than 1 of the same message if we use QoS 0. To avoid getting called for the same message, this functionality should be enabled. All the old message will be ignored
00235  */
00236 void aws_iot_shadow_enable_discard_old_delta_msgs(void);
00237 /**
00238  * @brief Disable the ignoring of delta messages with old version number
00239  */
00240 void aws_iot_shadow_disable_discard_old_delta_msgs(void);
00241 
00242 #endif //AWS_IOT_SDK_SRC_IOT_SHADOW_H_
00243