Changes to prepare for Jobs Library Demo (#401)

* Add submodule pointer to the aws/jobs-for-aws-iot-embedded-sdk repository for the Jobs library
* Commonize the MQTT helper functions used by the Device Shadow demo by re-locating them to FreeRTOS-Plus/Demo/AWS/MQTT_Demo_Helpers and updating the Device Shadow demo to use the new files

5 files changed, 87 insertions, 1085 deletions

diff --git a/FreeRTOS-Plus/Demo/AWS/Device_Shadow_Windows_Simulator/Device_Shadow_Demo/DemoTasks/ShadowDemoMainExample.c b/FreeRTOS-Plus/Demo/AWS/Device_Shadow_Windows_Simulator/Device_Shadow_Demo/DemoTasks/ShadowDemoMainExample.c
index 5547a4db2..7fde51167 100644..100755
--- a/FreeRTOS-Plus/Demo/AWS/Device_Shadow_Windows_Simulator/Device_Shadow_Demo/DemoTasks/ShadowDemoMainExample.c
+++ b/FreeRTOS-Plus/Demo/AWS/Device_Shadow_Windows_Simulator/Device_Shadow_Demo/DemoTasks/ShadowDemoMainExample.c
@@ -62,10 +62,10 @@
 /* JSON library includes. */
 #include "core_json.h"
 
-/* Shadow demo helpers header. */
-#include "shadow_demo_helpers.h"
+/* Include MQTT demo helpers header. */
+#include "mqtt_demo_helpers.h"
 
-/* Demo Specific configs. */
+/* Demo Specific config file. */
 #include "demo_config.h"
 
 
@@ -148,24 +148,42 @@
  */
 #define SHADOW_REPORTED_JSON_LENGTH    ( sizeof( SHADOW_REPORTED_JSON ) - 3 )
 
-#ifndef THING_NAME
+/*------------- Demo configurations -------------------------*/
+
+#ifndef democonfigTHING_NAME
+    #define democonfigTHING_NAME    democonfigCLIENT_IDENTIFIER
+#endif
 
 /**
- * @brief Predefined thing name.
- *
- * This is the example predefine thing name and could be compiled in ROM code.
+ * @brief The length of #democonfigTHING_NAME.
  */
-    #define THING_NAME    democonfigCLIENT_IDENTIFIER
-#endif
+#define THING_NAME_LENGTH    ( ( uint16_t ) ( sizeof( democonfigTHING_NAME ) - 1 ) )
+
+/*-----------------------------------------------------------*/
 
 /**
- * @brief The length of #THING_NAME.
+ * @brief The MQTT context used for MQTT operation.
  */
-#define THING_NAME_LENGTH    ( ( uint16_t ) ( sizeof( THING_NAME ) - 1 ) )
+static MQTTContext_t xMqttContext;
 
+/**
+ * @brief The network context used for mbedTLS operation.
+ */
+static NetworkContext_t xNetworkContext;
 
+/**
+ * @brief Static buffer used to hold MQTT messages being sent and received.
+ */
+static uint8_t ucSharedBuffer[ democonfigNETWORK_BUFFER_SIZE ];
 
-/*-----------------------------------------------------------*/
+/**
+ * @brief Static buffer used to hold MQTT messages being sent and received.
+ */
+static MQTTFixedBuffer_t xBuffer =
+{
+    .pBuffer = ucSharedBuffer,
+    .size    = democonfigNETWORK_BUFFER_SIZE
+};
 
 /**
  * @brief The simulated device current power on state.
@@ -523,14 +541,15 @@ static void prvEventCallback( MQTTContext_t * pxMqttContext,
 /*-----------------------------------------------------------*/
 
 /*
- * @brief Create the task that demonstrates the Shadow API Demo via a
- * MQTT mutually authenticated network connection with MQTT broker.
+ * @brief Create the task that demonstrates the Device Shadow library API via a
+ * MQTT mutually authenticated network connection with the AWS IoT broker.
  */
 void vStartShadowDemo( void )
 {
     /* This example uses a single application task, which shows that how to
-     * use Device Shadow library to get shadow topics and validate shadow topics
-     * via MQTT APIs communicating with the MQTT broker. */
+     * use Device Shadow library to generate and validate AWS IoT Device Shadow
+     * MQTT topics, and use the coreMQTT library to communicate with the AWS IoT
+     * Device Shadow service. */
     xTaskCreate( prvShadowDemoTask,        /* Function that implements the task. */
                  "DemoTask",               /* Text name for the task - only used for debugging. */
                  democonfigDEMO_STACKSIZE, /* Size of stack (in words, not bytes) to allocate for the task. */
@@ -538,7 +557,6 @@ void vStartShadowDemo( void )
                  tskIDLE_PRIORITY,         /* Task priority, must be between 0 and configMAX_PRIORITIES - 1. */
                  NULL );                   /* Used to pass out a handle to the created task - not used in this case. */
 }
-
 /*-----------------------------------------------------------*/
 
 /**
@@ -564,14 +582,17 @@ void prvShadowDemoTask( void * pvParameters )
 {
     BaseType_t demoStatus = pdPASS;
 
-    /* Remove compiler warnings about unused parameters. */
-    ( void ) pvParameters;
-
     /* A buffer containing the update document. It has static duration to prevent
      * it from being placed on the call stack. */
     static char pcUpdateDocument[ SHADOW_REPORTED_JSON_LENGTH + 1 ] = { 0 };
 
-    demoStatus = xEstablishMqttSession( prvEventCallback );
+    /* Remove compiler warnings about unused parameters. */
+    ( void ) pvParameters;
+
+    demoStatus = xEstablishMqttSession( &xMqttContext,
+                                        &xNetworkContext,
+                                        &xBuffer,
+                                        prvEventCallback );
 
     if( pdFAIL == demoStatus )
     {
@@ -581,7 +602,8 @@ void prvShadowDemoTask( void * pvParameters )
     else
     {
         /* First of all, try to delete any Shadow document in the cloud. */
-        demoStatus = xPublishToTopic( SHADOW_TOPIC_STRING_DELETE( THING_NAME ),
+        demoStatus = xPublishToTopic( &xMqttContext,
+                                      SHADOW_TOPIC_STRING_DELETE( democonfigTHING_NAME ),
                                       SHADOW_TOPIC_LENGTH_DELETE( THING_NAME_LENGTH ),
                                       pcUpdateDocument,
                                       0U );
@@ -589,23 +611,26 @@ void prvShadowDemoTask( void * pvParameters )
         /* Then try to subscribe shadow topics. */
         if( demoStatus == pdPASS )
         {
-            demoStatus = xSubscribeToTopic( SHADOW_TOPIC_STRING_UPDATE_DELTA( THING_NAME ),
+            demoStatus = xSubscribeToTopic( &xMqttContext,
+                                            SHADOW_TOPIC_STRING_UPDATE_DELTA( democonfigTHING_NAME ),
                                             SHADOW_TOPIC_LENGTH_UPDATE_DELTA( THING_NAME_LENGTH ) );
         }
 
         if( demoStatus == pdPASS )
         {
-            demoStatus = xSubscribeToTopic( SHADOW_TOPIC_STRING_UPDATE_ACCEPTED( THING_NAME ),
+            demoStatus = xSubscribeToTopic( &xMqttContext,
+                                            SHADOW_TOPIC_STRING_UPDATE_ACCEPTED( democonfigTHING_NAME ),
                                             SHADOW_TOPIC_LENGTH_UPDATE_ACCEPTED( THING_NAME_LENGTH ) );
         }
 
         if( demoStatus == pdPASS )
         {
-            demoStatus = xSubscribeToTopic( SHADOW_TOPIC_STRING_UPDATE_REJECTED( THING_NAME ),
+            demoStatus = xSubscribeToTopic( &xMqttContext,
+                                            SHADOW_TOPIC_STRING_UPDATE_REJECTED( democonfigTHING_NAME ),
                                             SHADOW_TOPIC_LENGTH_UPDATE_REJECTED( THING_NAME_LENGTH ) );
         }
 
-        /* This demo uses a constant #THING_NAME known at compile time therefore we can use macros to
+        /* This demo uses a constant #democonfigTHING_NAME known at compile time therefore we can use macros to
          * assemble shadow topic strings.
          * If the thing name is known at run time, then we could use the API #Shadow_GetTopicString to
          * assemble shadow topic strings, here is the example for /update/delta:
@@ -651,7 +676,8 @@ void prvShadowDemoTask( void * pvParameters )
                       ( int ) 1,
                       ( long unsigned ) ( xTaskGetTickCount() % 1000000 ) );
 
-            demoStatus = xPublishToTopic( SHADOW_TOPIC_STRING_UPDATE( THING_NAME ),
+            demoStatus = xPublishToTopic( &xMqttContext,
+                                          SHADOW_TOPIC_STRING_UPDATE( democonfigTHING_NAME ),
                                           SHADOW_TOPIC_LENGTH_UPDATE( THING_NAME_LENGTH ),
                                           pcUpdateDocument,
                                           ( SHADOW_DESIRED_JSON_LENGTH + 1 ) );
@@ -683,7 +709,8 @@ void prvShadowDemoTask( void * pvParameters )
                           ( int ) ulCurrentPowerOnState,
                           ( long unsigned ) ulClientToken );
 
-                demoStatus = xPublishToTopic( SHADOW_TOPIC_STRING_UPDATE( THING_NAME ),
+                demoStatus = xPublishToTopic( &xMqttContext,
+                                              SHADOW_TOPIC_STRING_UPDATE( democonfigTHING_NAME ),
                                               SHADOW_TOPIC_LENGTH_UPDATE( THING_NAME_LENGTH ),
                                               pcUpdateDocument,
                                               ( SHADOW_DESIRED_JSON_LENGTH + 1 ) );
@@ -698,42 +725,45 @@ void prvShadowDemoTask( void * pvParameters )
         {
             LogInfo( ( "Start to unsubscribe shadow topics and disconnect from MQTT. \r\n" ) );
 
-            demoStatus = xUnsubscribeFromTopic( SHADOW_TOPIC_STRING_UPDATE_DELTA( THING_NAME ),
+            demoStatus = xUnsubscribeFromTopic( &xMqttContext,
+                                                SHADOW_TOPIC_STRING_UPDATE_DELTA( democonfigTHING_NAME ),
                                                 SHADOW_TOPIC_LENGTH_UPDATE_DELTA( THING_NAME_LENGTH ) );
 
             if( demoStatus != pdPASS )
             {
                 LogError( ( "Failed to unsubscribe the topic %s",
-                            SHADOW_TOPIC_STRING_UPDATE_DELTA( THING_NAME ) ) );
+                            SHADOW_TOPIC_STRING_UPDATE_DELTA( democonfigTHING_NAME ) ) );
             }
         }
 
         if( demoStatus == pdPASS )
         {
-            demoStatus = xUnsubscribeFromTopic( SHADOW_TOPIC_STRING_UPDATE_ACCEPTED( THING_NAME ),
+            demoStatus = xUnsubscribeFromTopic( &xMqttContext,
+                                                SHADOW_TOPIC_STRING_UPDATE_ACCEPTED( democonfigTHING_NAME ),
                                                 SHADOW_TOPIC_LENGTH_UPDATE_ACCEPTED( THING_NAME_LENGTH ) );
 
             if( demoStatus != pdPASS )
             {
                 LogError( ( "Failed to unsubscribe the topic %s",
-                            SHADOW_TOPIC_STRING_UPDATE_ACCEPTED( THING_NAME ) ) );
+                            SHADOW_TOPIC_STRING_UPDATE_ACCEPTED( democonfigTHING_NAME ) ) );
             }
         }
 
         if( demoStatus == pdPASS )
         {
-            demoStatus = xUnsubscribeFromTopic( SHADOW_TOPIC_STRING_UPDATE_REJECTED( THING_NAME ),
+            demoStatus = xUnsubscribeFromTopic( &xMqttContext,
+                                                SHADOW_TOPIC_STRING_UPDATE_REJECTED( democonfigTHING_NAME ),
                                                 SHADOW_TOPIC_LENGTH_UPDATE_REJECTED( THING_NAME_LENGTH ) );
 
             if( demoStatus != pdPASS )
             {
                 LogError( ( "Failed to unsubscribe the topic %s",
-                            SHADOW_TOPIC_STRING_UPDATE_REJECTED( THING_NAME ) ) );
+                            SHADOW_TOPIC_STRING_UPDATE_REJECTED( democonfigTHING_NAME ) ) );
             }
         }
 
         /* The MQTT session is always disconnected, even there were prior failures. */
-        demoStatus = xDisconnectMqttSession();
+        demoStatus = xDisconnectMqttSession( &xMqttContext, &xNetworkContext );
 
         /* This demo performs only Device Shadow operations. If matching the Shadow
          * MQTT topic fails or there are failure in parsing the received JSON document,
diff --git a/FreeRTOS-Plus/Demo/AWS/Device_Shadow_Windows_Simulator/Device_Shadow_Demo/DemoTasks/shadow_demo_helpers.c b/FreeRTOS-Plus/Demo/AWS/Device_Shadow_Windows_Simulator/Device_Shadow_Demo/DemoTasks/shadow_demo_helpers.c
deleted file mode 100644
index 4345ac90d..000000000
--- a/FreeRTOS-Plus/Demo/AWS/Device_Shadow_Windows_Simulator/Device_Shadow_Demo/DemoTasks/shadow_demo_helpers.c
+++ /dev/null
@@ -1,929 +0,0 @@
-/*
- * FreeRTOS V202011.00
- * Copyright (C) 2020 Amazon.com, Inc. or its affiliates.  All Rights Reserved.
- *
- * Permission is hereby granted, free of charge, to any person obtaining a copy of
- * this software and associated documentation files (the "Software"), to deal in
- * the Software without restriction, including without limitation the rights to
- * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
- * the Software, and to permit persons to whom the Software is furnished to do so,
- * subject to the following conditions:
- *
- * The above copyright notice and this permission notice shall be included in all
- * copies or substantial portions of the Software.
- *
- * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
- * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
- * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
- * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
- * IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
- * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
- */
-
-/**
- * @file shadow_demo_helpers.c
- *
- * @brief This file provides helper functions used by the Shadow demo application to
- * do MQTT operations over a mutually authenticated TLS connection.
- *
- * A mutually authenticated TLS connection is used to connect to the AWS IoT
- * MQTT message broker in this example. Define democonfigCLIENT_PRIVATE_KEY_PEM,
- * democonfigCLIENT_CERTIFICATE_PEM, and democonfigMQTT_BROKER_ENDPOINT in
- * demo_config.h to achieve mutual authentication.
- */
-
-/* Standard includes. */
-#include <stdlib.h>
-#include <string.h>
-
-/* Kernel includes. */
-#include "FreeRTOS.h"
-#include "task.h"
-
-/* Shadow includes */
-#include "shadow_demo_helpers.h"
-
-/* Demo Specific configs. */
-#include "demo_config.h"
-
-/* MQTT library includes. */
-#include "core_mqtt.h"
-
-/* Exponential backoff retry include. */
-#include "exponential_backoff.h"
-
-/* Transport interface implementation include header for TLS. */
-#include "using_mbedtls.h"
-
-/*------------- Demo configurations -------------------------*/
-
-/** Note: The device client certificate and private key credentials are
- * obtained by the TLS transport interface implementation from the
- * demo_config.h file.
- */
-
-#ifndef democonfigCLIENT_PRIVATE_KEY_PEM
-    #error "Please define client private key(democonfigCLIENT_PRIVATE_KEY_PEM) in demo_config.h."
-#endif
-
-#ifndef democonfigCLIENT_CERTIFICATE_PEM
-    #error "Please define client certificate(democonfigCLIENT_CERTIFICATE_PEM) in demo_config.h."
-#endif
-
-#ifndef democonfigMQTT_BROKER_ENDPOINT
-    #error "Please define democonfigMQTT_BROKER_ENDPOINT in demo_config.h."
-#endif
-
-#ifndef democonfigMQTT_BROKER_PORT
-
-/**
- * @brief The port to use for the demo.
- */
-    #define democonfigMQTT_BROKER_PORT    ( 8883 )
-#endif
-/*-----------------------------------------------------------*/
-
-/**
- * @brief Timeout for receiving CONNACK packet in milliseconds.
- */
-#define mqttexampleCONNACK_RECV_TIMEOUT_MS           ( 1000U )
-
-/**
- * @brief The number of topic filters to subscribe.
- */
-#define mqttexampleTOPIC_COUNT                       ( 1 )
-
-/**
- * @brief Time to wait between each cycle of the demo implemented by prvMQTTDemoTask().
- */
-#define mqttexampleDELAY_BETWEEN_DEMO_ITERATIONS     ( pdMS_TO_TICKS( 5000U ) )
-
-/**
- * @brief Timeout for MQTT_ProcessLoop in milliseconds.
- */
-#define mqttexamplePROCESS_LOOP_TIMEOUT_MS           ( 500U )
-
-/**
- * @brief Keep alive time reported to the broker while establishing an MQTT connection.
- *
- * It is the responsibility of the Client to ensure that the interval between
- * Control Packets being sent does not exceed this Keep Alive value. In the
- * absence of sending any other Control Packets, the Client MUST send a
- * PINGREQ Packet.
- */
-#define mqttexampleKEEP_ALIVE_TIMEOUT_SECONDS        ( 60U )
-
-/**
- * @brief Delay between MQTT publishes. Note that the process loop also has a
- * timeout, so the total time between publishes is the sum of the two delays.
- */
-#define mqttexampleDELAY_BETWEEN_PUBLISHES           ( pdMS_TO_TICKS( 500U ) )
-
-/**
- * @brief Transport timeout in milliseconds for transport send and receive.
- */
-#define mqttexampleTRANSPORT_SEND_RECV_TIMEOUT_MS    ( 200U )
-
-/**
- * @brief Maximum number of outgoing publishes maintained in the application
- * until an ack is received from the broker.
- */
-#define MAX_OUTGOING_PUBLISHES                       ( 1U )
-
-/**
- * @brief Milliseconds per second.
- */
-#define MILLISECONDS_PER_SECOND                      ( 1000U )
-
-/**
- * @brief Milliseconds per FreeRTOS tick.
- */
-#define MILLISECONDS_PER_TICK                        ( MILLISECONDS_PER_SECOND / configTICK_RATE_HZ )
-
-/**
- * @brief The MQTT metrics string expected by AWS IoT.
- */
-#define AWS_IOT_METRICS_STRING                                 \
-    "?SDK=" democonfigOS_NAME "&Version=" democonfigOS_VERSION \
-    "&Platform=" democonfigHARDWARE_PLATFORM_NAME "&MQTTLib=" democonfigMQTT_LIB
-
-/**
- * @brief The length of the MQTT metrics string expected by AWS IoT.
- */
-#define AWS_IOT_METRICS_STRING_LENGTH    ( ( uint16_t ) ( sizeof( AWS_IOT_METRICS_STRING ) - 1 ) )
-
-/**
- * @brief ALPN (Application-Layer Protocol Negotiation) protocol name for AWS IoT MQTT.
- *
- * This will be used if democonfigMQTT_BROKER_PORT is configured as 443 for the AWS IoT MQTT broker.
- * Please see more details about the ALPN protocol for AWS IoT MQTT endpoint
- * in the link below.
- * https://aws.amazon.com/blogs/iot/mqtt-with-tls-client-authentication-on-port-443-why-it-is-useful-and-how-it-works/
- */
-#define AWS_IOT_MQTT_ALPN                "\x0ex-amzn-mqtt-ca"
-
-/*-----------------------------------------------------------*/
-
-/**
- * @brief Structure to keep the MQTT publish packets until an ack is received
- * for QoS1 publishes.
- */
-typedef struct PublishPackets
-{
-    /**
-     * @brief Packet identifier of the publish packet.
-     */
-    uint16_t packetId;
-
-    /**
-     * @brief Publish info of the publish packet.
-     */
-    MQTTPublishInfo_t pubInfo;
-} PublishPackets_t;
-
-/**
- * @brief Global entry time into the application to use as a reference timestamp
- * in the #prvGetTimeMs function. #prvGetTimeMs will always return the difference
- * between the current time and the global entry time. This will reduce the chances
- * of overflow for the 32 bit unsigned integer used for holding the timestamp.
- */
-static uint32_t ulGlobalEntryTimeMs;
-
-/*-----------------------------------------------------------*/
-
-/**
- * @brief Packet Identifier generated when Subscribe request was sent to the broker;
- * it is used to match received Subscribe ACK to the transmitted subscribe.
- */
-static uint16_t globalSubscribePacketIdentifier = 0U;
-
-/**
- * @brief Packet Identifier generated when Unsubscribe request was sent to the broker;
- * it is used to match received Unsubscribe ACK to the transmitted unsubscribe
- * request.
- */
-static uint16_t globalUnsubscribePacketIdentifier = 0U;
-
-/**
- * @brief Array to keep the outgoing publish messages.
- * These stored outgoing publish messages are kept until a successful ack
- * is received.
- */
-static PublishPackets_t outgoingPublishPackets[ MAX_OUTGOING_PUBLISHES ] = { 0 };
-
-/**
- * @brief Static buffer used to hold MQTT messages being sent and received.
- */
-static uint8_t ucSharedBuffer[ democonfigNETWORK_BUFFER_SIZE ];
-
-/**
- * @brief The MQTT context used for MQTT operation.
- */
-static MQTTContext_t mqttContext = { 0 };
-
-/**
- * @brief The network context used for Openssl operation.
- */
-static NetworkContext_t networkContext = { 0 };
-
-/**
- * @brief The flag to indicate the mqtt session changed.
- */
-static bool mqttSessionEstablished = false;
-
-/**
- * @brief Static buffer used to hold MQTT messages being sent and received.
- */
-static MQTTFixedBuffer_t xBuffer =
-{
-    .pBuffer = ucSharedBuffer,
-    .size    = democonfigNETWORK_BUFFER_SIZE
-};
-
-/*-----------------------------------------------------------*/
-
-/**
- * @brief Connect to MQTT broker with reconnection retries.
- *
- * If connection fails, retry is attempted after a timeout.
- * Timeout value will exponentially increase until maximum
- * timeout value is reached or the number of attempts are exhausted.
- *
- * @param[out] pxNetworkContext The output parameter to return the created network context.
- *
- * @return The status of the final connection attempt.
- */
-static TlsTransportStatus_t prvConnectToServerWithBackoffRetries( NetworkContext_t * pxNetworkContext );
-
-/**
- * @brief Function to get the free index at which an outgoing publish
- * can be stored.
- *
- * @param[out] pucIndex The output parameter to return the index at which an
- * outgoing publish message can be stored.
- *
- * @return pdFAIL if no more publishes can be stored;
- * pdTRUE if an index to store the next outgoing publish is obtained.
- */
-static BaseType_t prvGetNextFreeIndexForOutgoingPublishes( uint8_t * pucIndex );
-
-/**
- * @brief Function to clean up an outgoing publish at given index from the
- * #outgoingPublishPackets array.
- *
- * @param[in] ucIndex The index at which a publish message has to be cleaned up.
- */
-static void vCleanupOutgoingPublishAt( uint8_t ucIndex );
-
-/**
- * @brief Function to clean up all the outgoing publishes maintained in the
- * array.
- */
-static void vCleanupOutgoingPublishes( void );
-
-/**
- * @brief Function to clean up the publish packet with the given packet id.
- *
- * @param[in] usPacketId Packet identifier of the packet to be cleaned up from
- * the array.
- */
-static void vCleanupOutgoingPublishWithPacketID( uint16_t usPacketId );
-
-/**
- * @brief Function to resend the publishes if a session is re-established with
- * the broker. This function handles the resending of the QoS1 publish packets,
- * which are maintained locally.
- *
- * @param[in] pxMqttContext MQTT context pointer.
- */
-static BaseType_t xHandlePublishResend( MQTTContext_t * pxMqttContext );
-
-/**
- * @brief The timer query function provided to the MQTT context.
- *
- * @return Time in milliseconds.
- */
-static uint32_t prvGetTimeMs( void );
-
-/*-----------------------------------------------------------*/
-
-static TlsTransportStatus_t prvConnectToServerWithBackoffRetries( NetworkContext_t * pxNetworkContext )
-{
-    TlsTransportStatus_t xNetworkStatus = TLS_TRANSPORT_SUCCESS;
-    RetryUtilsStatus_t xRetryUtilsStatus = RetryUtilsSuccess;
-    RetryUtilsParams_t xReconnectParams = { 0 };
-    NetworkCredentials_t xNetworkCredentials = { 0 };
-
-    /* ALPN protocols must be a NULL-terminated list of strings. Therefore,
-     * the first entry will contain the actual ALPN protocol string while the
-     * second entry must remain NULL. */
-    char * pcAlpnProtocols[] = { NULL, NULL };
-
-    /* Set the credentials for establishing a TLS connection. */
-    xNetworkCredentials.pRootCa = ( const unsigned char * ) democonfigROOT_CA_PEM;
-    xNetworkCredentials.rootCaSize = sizeof( democonfigROOT_CA_PEM );
-    #ifdef democonfigCLIENT_CERTIFICATE_PEM
-        xNetworkCredentials.pClientCert = ( const unsigned char * ) democonfigCLIENT_CERTIFICATE_PEM;
-        xNetworkCredentials.clientCertSize = sizeof( democonfigCLIENT_CERTIFICATE_PEM );
-        xNetworkCredentials.pPrivateKey = ( const unsigned char * ) democonfigCLIENT_PRIVATE_KEY_PEM;
-        xNetworkCredentials.privateKeySize = sizeof( democonfigCLIENT_PRIVATE_KEY_PEM );
-    #endif
-
-    xNetworkCredentials.disableSni = pdFALSE;
-/* The ALPN string changes depending on whether username/password authentication is used. */
-    #ifdef democonfigCLIENT_USERNAME
-        pcAlpnProtocols[ 0 ] = AWS_IOT_CUSTOM_AUTH_ALPN;
-    #else
-        pcAlpnProtocols[ 0 ] = AWS_IOT_MQTT_ALPN;
-    #endif
-    xNetworkCredentials.pAlpnProtos = pcAlpnProtocols;
-
-    /* Initialize reconnect attempts and interval. */
-    RetryUtils_ParamsReset( &xReconnectParams );
-    xReconnectParams.maxRetryAttempts = MAX_RETRY_ATTEMPTS;
-
-    /* Attempt to connect to MQTT broker. If connection fails, retry after
-     * a timeout. Timeout value will exponentially increase until maximum
-     * attempts are reached.
-     */
-    do
-    {
-        /* Establish a TCP connection with the MQTT broker. This example connects to
-         * the MQTT broker as specified in democonfigMQTT_BROKER_ENDPOINT and
-         * democonfigMQTT_BROKER_PORT at the top of this file. */
-        LogInfo( ( "Create a TCP connection to %s:%d.",
-                   democonfigMQTT_BROKER_ENDPOINT,
-                   democonfigMQTT_BROKER_PORT ) );
-        xNetworkStatus = TLS_FreeRTOS_Connect( pxNetworkContext,
-                                               democonfigMQTT_BROKER_ENDPOINT,
-                                               democonfigMQTT_BROKER_PORT,
-                                               &xNetworkCredentials,
-                                               mqttexampleTRANSPORT_SEND_RECV_TIMEOUT_MS,
-                                               mqttexampleTRANSPORT_SEND_RECV_TIMEOUT_MS );
-
-        if( xNetworkStatus != TLS_TRANSPORT_SUCCESS )
-        {
-            LogWarn( ( "Connection to the broker failed. Retrying connection with backoff and jitter." ) );
-            xRetryUtilsStatus = RetryUtils_BackoffAndSleep( &xReconnectParams );
-        }
-
-        if( xRetryUtilsStatus == RetryUtilsRetriesExhausted )
-        {
-            LogError( ( "Connection to the broker failed, all attempts exhausted." ) );
-            xNetworkStatus = TLS_TRANSPORT_CONNECT_FAILURE;
-        }
-    } while( ( xNetworkStatus != TLS_TRANSPORT_SUCCESS ) && ( xRetryUtilsStatus == RetryUtilsSuccess ) );
-
-    return xNetworkStatus;
-}
-
-/*-----------------------------------------------------------*/
-
-static BaseType_t prvGetNextFreeIndexForOutgoingPublishes( uint8_t * pucIndex )
-{
-    BaseType_t returnStatus = pdFAIL;
-    uint8_t ucIndex = 0;
-
-    configASSERT( outgoingPublishPackets != NULL );
-    configASSERT( pucIndex != NULL );
-
-    for( ucIndex = 0; ucIndex < MAX_OUTGOING_PUBLISHES; ucIndex++ )
-    {
-        /* A free ucIndex is marked by invalid packet id.
-         * Check if the the ucIndex has a free slot. */
-        if( outgoingPublishPackets[ ucIndex ].packetId == MQTT_PACKET_ID_INVALID )
-        {
-            returnStatus = pdPASS;
-            break;
-        }
-    }
-
-    /* Copy the available ucIndex into the output param. */
-    *pucIndex = ucIndex;
-
-    return returnStatus;
-}
-/*-----------------------------------------------------------*/
-
-static void vCleanupOutgoingPublishAt( uint8_t ucIndex )
-{
-    configASSERT( outgoingPublishPackets != NULL );
-    configASSERT( ucIndex < MAX_OUTGOING_PUBLISHES );
-
-    /* Clear the outgoing publish packet. */
-    ( void ) memset( &( outgoingPublishPackets[ ucIndex ] ),
-                     0x00,
-                     sizeof( outgoingPublishPackets[ ucIndex ] ) );
-}
-
-/*-----------------------------------------------------------*/
-
-static void vCleanupOutgoingPublishes( void )
-{
-    configASSERT( outgoingPublishPackets != NULL );
-
-    /* Clean up all the outgoing publish packets. */
-    ( void ) memset( outgoingPublishPackets, 0x00, sizeof( outgoingPublishPackets ) );
-}
-
-/*-----------------------------------------------------------*/
-
-static void vCleanupOutgoingPublishWithPacketID( uint16_t usPacketId )
-{
-    uint8_t ucIndex = 0;
-
-    configASSERT( outgoingPublishPackets != NULL );
-    configASSERT( usPacketId != MQTT_PACKET_ID_INVALID );
-
-    /* Clean up all the saved outgoing publishes. */
-    for( ; ucIndex < MAX_OUTGOING_PUBLISHES; ucIndex++ )
-    {
-        if( outgoingPublishPackets[ ucIndex ].packetId == usPacketId )
-        {
-            vCleanupOutgoingPublishAt( ucIndex );
-            LogInfo( ( "Cleaned up outgoing publish packet with packet id %u.\n\n",
-                       usPacketId ) );
-            break;
-        }
-    }
-}
-
-/*-----------------------------------------------------------*/
-
-void vHandleOtherIncomingPacket( MQTTPacketInfo_t * pxPacketInfo,
-                                 uint16_t usPacketIdentifier )
-{
-    /* Handle other packets. */
-    switch( pxPacketInfo->type )
-    {
-        case MQTT_PACKET_TYPE_SUBACK:
-            LogInfo( ( "MQTT_PACKET_TYPE_SUBACK.\n\n" ) );
-            /* Make sure ACK packet identifier matches with Request packet identifier. */
-            configASSERT( globalSubscribePacketIdentifier == usPacketIdentifier );
-            break;
-
-        case MQTT_PACKET_TYPE_UNSUBACK:
-            LogInfo( ( "MQTT_PACKET_TYPE_UNSUBACK.\n\n" ) );
-            /* Make sure ACK packet identifier matches with Request packet identifier. */
-            configASSERT( globalUnsubscribePacketIdentifier == usPacketIdentifier );
-            break;
-
-        case MQTT_PACKET_TYPE_PINGRESP:
-
-            /* Nothing to be done from application as library handles
-             * PINGRESP with the use of MQTT_ProcessLoop API function. */
-            LogWarn( ( "PINGRESP should not be handled by the application "
-                       "callback when using MQTT_ProcessLoop.\n" ) );
-            break;
-
-        case MQTT_PACKET_TYPE_PUBACK:
-            LogInfo( ( "PUBACK received for packet id %u.\n\n",
-                       usPacketIdentifier ) );
-            /* Cleanup publish packet when a PUBACK is received. */
-            vCleanupOutgoingPublishWithPacketID( usPacketIdentifier );
-            break;
-
-        /* Any other packet type is invalid. */
-        default:
-            LogError( ( "Unknown packet type received:(%02x).\n\n",
-                        pxPacketInfo->type ) );
-    }
-}
-
-/*-----------------------------------------------------------*/
-
-static BaseType_t xHandlePublishResend( MQTTContext_t * pxMqttContext )
-{
-    BaseType_t returnStatus = pdTRUE;
-    MQTTStatus_t xMQTTStatus = MQTTSuccess;
-    uint8_t ucIndex = 0U;
-
-    configASSERT( outgoingPublishPackets != NULL );
-
-    /* Resend all the QoS1 publishes still in the array. These are the
-     * publishes that haven't received a PUBACK. When a PUBACK is
-     * received, the publish is removed from the array. */
-    for( ucIndex = 0U; ucIndex < MAX_OUTGOING_PUBLISHES; ucIndex++ )
-    {
-        if( outgoingPublishPackets[ ucIndex ].packetId != MQTT_PACKET_ID_INVALID )
-        {
-            outgoingPublishPackets[ ucIndex ].pubInfo.dup = true;
-
-            LogInfo( ( "Sending duplicate PUBLISH with packet id %u.",
-                       outgoingPublishPackets[ ucIndex ].packetId ) );
-            xMQTTStatus = MQTT_Publish( pxMqttContext,
-                                        &outgoingPublishPackets[ ucIndex ].pubInfo,
-                                        outgoingPublishPackets[ ucIndex ].packetId );
-
-            if( xMQTTStatus != MQTTSuccess )
-            {
-                LogError( ( "Sending duplicate PUBLISH for packet id %u "
-                            " failed with status %u.",
-                            outgoingPublishPackets[ ucIndex ].packetId,
-                            xMQTTStatus ) );
-                returnStatus = pdFAIL;
-                break;
-            }
-            else
-            {
-                LogInfo( ( "Sent duplicate PUBLISH successfully for packet id %u.\n\n",
-                           outgoingPublishPackets[ ucIndex ].packetId ) );
-            }
-        }
-    }
-
-    return returnStatus;
-}
-
-/*-----------------------------------------------------------*/
-
-BaseType_t xEstablishMqttSession( MQTTEventCallback_t eventCallback )
-{
-    BaseType_t returnStatus = pdTRUE;
-    MQTTStatus_t xMQTTStatus;
-    MQTTConnectInfo_t xConnectInfo;
-    TransportInterface_t xTransport;
-    MQTTContext_t * pxMqttContext = &mqttContext;
-    NetworkContext_t * pxNetworkContext = &networkContext;
-    bool sessionPresent = false;
-
-    configASSERT( pxMqttContext != NULL );
-    configASSERT( pxNetworkContext != NULL );
-
-    /* Initialize the mqtt context and network context. */
-    ( void ) memset( pxMqttContext, 0U, sizeof( MQTTContext_t ) );
-    ( void ) memset( pxNetworkContext, 0U, sizeof( NetworkContext_t ) );
-
-    if( prvConnectToServerWithBackoffRetries( pxNetworkContext ) != TLS_TRANSPORT_SUCCESS )
-    {
-        /* Log error to indicate connection failure after all
-         * reconnect attempts are over. */
-        LogError( ( "Failed to connect to MQTT broker %.*s.",
-                    strlen( democonfigMQTT_BROKER_ENDPOINT ),
-                    democonfigMQTT_BROKER_ENDPOINT ) );
-        returnStatus = pdFAIL;
-    }
-    else
-    {
-        /* Fill in Transport Interface send and receive function pointers. */
-        xTransport.pNetworkContext = pxNetworkContext;
-        xTransport.send = TLS_FreeRTOS_send;
-        xTransport.recv = TLS_FreeRTOS_recv;
-
-        /* Initialize MQTT library. */
-        xMQTTStatus = MQTT_Init( pxMqttContext,
-                                 &xTransport,
-                                 prvGetTimeMs,
-                                 eventCallback,
-                                 &xBuffer );
-
-        if( xMQTTStatus != MQTTSuccess )
-        {
-            returnStatus = pdFAIL;
-            LogError( ( "MQTT init failed with status %u.", xMQTTStatus ) );
-        }
-        else
-        {
-            /* Establish MQTT session by sending a CONNECT packet. */
-
-            /* Many fields not used in this demo so start with everything at 0. */
-            ( void ) memset( ( void * ) &xConnectInfo, 0x00, sizeof( xConnectInfo ) );
-
-            /* Start with a clean session i.e. direct the MQTT broker to discard any
-             * previous session data. Also, establishing a connection with clean session
-             * will ensure that the broker does not store any data when this client
-             * gets disconnected. */
-            xConnectInfo.cleanSession = true;
-
-            /* The client identifier is used to uniquely identify this MQTT client to
-             * the MQTT broker. In a production device the identifier can be something
-             * unique, such as a device serial number. */
-            xConnectInfo.pClientIdentifier = democonfigCLIENT_IDENTIFIER;
-            xConnectInfo.clientIdentifierLength = ( uint16_t ) strlen( democonfigCLIENT_IDENTIFIER );
-
-            /* The maximum time interval in seconds which is allowed to elapse
-             * between two Control Packets.
-             * It is the responsibility of the Client to ensure that the interval between
-             * Control Packets being sent does not exceed this Keep Alive value. In the
-             * absence of sending any other Control Packets, the Client MUST send a
-             * PINGREQ Packet. */
-            xConnectInfo.keepAliveSeconds = mqttexampleKEEP_ALIVE_TIMEOUT_SECONDS;
-
-/* Append metrics when connecting to the AWS IoT Core broker. */
-            #ifdef democonfigCLIENT_USERNAME
-                xConnectInfo.pUserName = CLIENT_USERNAME_WITH_METRICS;
-                xConnectInfo.userNameLength = ( uint16_t ) strlen( CLIENT_USERNAME_WITH_METRICS );
-                xConnectInfo.pPassword = democonfigCLIENT_PASSWORD;
-                xConnectInfo.passwordLength = ( uint16_t ) strlen( democonfigCLIENT_PASSWORD );
-            #else
-                xConnectInfo.pUserName = AWS_IOT_METRICS_STRING;
-                xConnectInfo.userNameLength = AWS_IOT_METRICS_STRING_LENGTH;
-                /* Password for authentication is not used. */
-                xConnectInfo.pPassword = NULL;
-                xConnectInfo.passwordLength = 0U;
-            #endif /* ifdef democonfigCLIENT_USERNAME */
-
-            /* Send MQTT CONNECT packet to broker. */
-            xMQTTStatus = MQTT_Connect( pxMqttContext,
-                                        &xConnectInfo,
-                                        NULL,
-                                        mqttexampleCONNACK_RECV_TIMEOUT_MS,
-                                        &sessionPresent );
-
-            if( xMQTTStatus != MQTTSuccess )
-            {
-                returnStatus = pdFAIL;
-                LogError( ( "Connection with MQTT broker failed with status %u.", xMQTTStatus ) );
-            }
-            else
-            {
-                LogInfo( ( "MQTT connection successfully established with broker.\n\n" ) );
-            }
-        }
-
-        if( returnStatus == pdFAIL )
-        {
-            /* Keep a flag for indicating if MQTT session is established. This
-             * flag will mark that an MQTT DISCONNECT has to be sent at the end
-             * of the demo even if there are intermediate failures. */
-            mqttSessionEstablished = true;
-        }
-
-        if( returnStatus == pdFAIL )
-        {
-            /* Check if session is present and if there are any outgoing publishes
-             * that need to resend. This is only valid if the broker is
-             * re-establishing a session which was already present. */
-            if( sessionPresent == true )
-            {
-                LogInfo( ( "An MQTT session with broker is re-established. "
-                           "Resending unacked publishes." ) );
-
-                /* Handle all the resend of publish messages. */
-                returnStatus = xHandlePublishResend( &mqttContext );
-            }
-            else
-            {
-                LogInfo( ( "A clean MQTT connection is established."
-                           " Cleaning up all the stored outgoing publishes.\n\n" ) );
-
-                /* Clean up the outgoing publishes waiting for ack as this new
-                 * connection doesn't re-establish an existing session. */
-                vCleanupOutgoingPublishes();
-            }
-        }
-    }
-
-    return returnStatus;
-}
-
-/*-----------------------------------------------------------*/
-
-BaseType_t xDisconnectMqttSession( void )
-{
-    MQTTStatus_t xMQTTStatus = MQTTSuccess;
-    BaseType_t returnStatus = pdTRUE;
-    TlsTransportStatus_t xNetworkStatus;
-    MQTTContext_t * pxMqttContext = &mqttContext;
-    NetworkContext_t * pxNetworkContext = &networkContext;
-
-    configASSERT( pxMqttContext != NULL );
-    configASSERT( pxNetworkContext != NULL );
-
-    if( mqttSessionEstablished == true )
-    {
-        /* Send DISCONNECT. */
-        xMQTTStatus = MQTT_Disconnect( pxMqttContext );
-
-        if( xMQTTStatus != MQTTSuccess )
-        {
-            LogError( ( "Sending MQTT DISCONNECT failed with status=%u.",
-                        xMQTTStatus ) );
-            returnStatus = pdFAIL;
-        }
-    }
-
-    /* Close the network connection.  */
-    TLS_FreeRTOS_Disconnect( pxNetworkContext );
-
-    return returnStatus;
-}
-
-/*-----------------------------------------------------------*/
-
-BaseType_t xSubscribeToTopic( const char * pcTopicFilter,
-                              uint16_t usTopicFilterLength )
-{
-    BaseType_t returnStatus = pdTRUE;
-    MQTTStatus_t xMQTTStatus;
-    MQTTContext_t * pxMqttContext = &mqttContext;
-    MQTTSubscribeInfo_t pSubscriptionList[ mqttexampleTOPIC_COUNT ];
-
-    configASSERT( pxMqttContext != NULL );
-    configASSERT( pcTopicFilter != NULL );
-    configASSERT( usTopicFilterLength > 0 );
-
-    /* Start with everything at 0. */
-    ( void ) memset( ( void * ) pSubscriptionList, 0x00, sizeof( pSubscriptionList ) );
-
-    /* This example subscribes to only one topic and uses QOS1. */
-    pSubscriptionList[ 0 ].qos = MQTTQoS1;
-    pSubscriptionList[ 0 ].pTopicFilter = pcTopicFilter;
-    pSubscriptionList[ 0 ].topicFilterLength = usTopicFilterLength;
-
-    /* Generate packet identifier for the SUBSCRIBE packet. */
-    globalSubscribePacketIdentifier = MQTT_GetPacketId( pxMqttContext );
-
-    /* Send SUBSCRIBE packet. */
-    xMQTTStatus = MQTT_Subscribe( pxMqttContext,
-                                  pSubscriptionList,
-                                  sizeof( pSubscriptionList ) / sizeof( MQTTSubscribeInfo_t ),
-                                  globalSubscribePacketIdentifier );
-
-    if( xMQTTStatus != MQTTSuccess )
-    {
-        LogError( ( "Failed to send SUBSCRIBE packet to broker with error = %u.",
-                    xMQTTStatus ) );
-        returnStatus = pdFAIL;
-    }
-    else
-    {
-        LogInfo( ( "SUBSCRIBE topic %.*s to broker.\n\n",
-                   usTopicFilterLength,
-                   pcTopicFilter ) );
-
-        /* Process incoming packet from the broker. Acknowledgment for subscription
-         * ( SUBACK ) will be received here. However after sending the subscribe, the
-         * client may receive a publish before it receives a subscribe ack. Since this
-         * demo is subscribing to the topic to which no one is publishing, probability
-         * of receiving publish message before subscribe ack is zero; but application
-         * must be ready to receive any packet. This demo uses MQTT_ProcessLoop to
-         * receive packet from network. */
-        xMQTTStatus = MQTT_ProcessLoop( pxMqttContext, mqttexamplePROCESS_LOOP_TIMEOUT_MS );
-
-        if( xMQTTStatus != MQTTSuccess )
-        {
-            returnStatus = pdFAIL;
-            LogError( ( "MQTT_ProcessLoop returned with status = %u.",
-                        xMQTTStatus ) );
-        }
-    }
-
-    return returnStatus;
-}
-
-/*-----------------------------------------------------------*/
-
-BaseType_t xUnsubscribeFromTopic( const char * pcTopicFilter,
-                                  uint16_t usTopicFilterLength )
-{
-    BaseType_t returnStatus = pdTRUE;
-    MQTTStatus_t xMQTTStatus;
-    MQTTContext_t * pxMqttContext = &mqttContext;
-    MQTTSubscribeInfo_t pSubscriptionList[ 1 ];
-
-    configASSERT( pxMqttContext != NULL );
-    configASSERT( pcTopicFilter != NULL );
-    configASSERT( usTopicFilterLength > 0 );
-
-    /* Start with everything at 0. */
-    ( void ) memset( ( void * ) pSubscriptionList, 0x00, sizeof( pSubscriptionList ) );
-
-    /* This example subscribes to only one topic and uses QOS1. */
-    pSubscriptionList[ 0 ].qos = MQTTQoS1;
-    pSubscriptionList[ 0 ].pTopicFilter = pcTopicFilter;
-    pSubscriptionList[ 0 ].topicFilterLength = usTopicFilterLength;
-
-    /* Generate packet identifier for the UNSUBSCRIBE packet. */
-    globalUnsubscribePacketIdentifier = MQTT_GetPacketId( pxMqttContext );
-
-    /* Send UNSUBSCRIBE packet. */
-    xMQTTStatus = MQTT_Unsubscribe( pxMqttContext,
-                                    pSubscriptionList,
-                                    sizeof( pSubscriptionList ) / sizeof( MQTTSubscribeInfo_t ),
-                                    globalUnsubscribePacketIdentifier );
-
-    if( xMQTTStatus != MQTTSuccess )
-    {
-        LogError( ( "Failed to send UNSUBSCRIBE packet to broker with error = %u.",
-                    xMQTTStatus ) );
-        returnStatus = pdFAIL;
-    }
-    else
-    {
-        LogInfo( ( "UNSUBSCRIBE sent topic %.*s to broker.\n\n",
-                   usTopicFilterLength,
-                   pcTopicFilter ) );
-
-        /* Process the incoming packet from the broker. */
-        xMQTTStatus = MQTT_ProcessLoop( pxMqttContext, mqttexamplePROCESS_LOOP_TIMEOUT_MS );
-
-        if( xMQTTStatus != MQTTSuccess )
-        {
-            returnStatus = pdFAIL;
-            LogError( ( "MQTT_ProcessLoop returned with status = %u.",
-                        xMQTTStatus ) );
-        }
-    }
-
-    return returnStatus;
-}
-
-/*-----------------------------------------------------------*/
-
-BaseType_t xPublishToTopic( const char * pcTopicFilter,
-                            int32_t topicFilterLength,
-                            const char * pcPayload,
-                            size_t payloadLength )
-{
-    BaseType_t returnStatus = pdPASS;
-    MQTTStatus_t xMQTTStatus = MQTTSuccess;
-    uint8_t ucPublishIndex = MAX_OUTGOING_PUBLISHES;
-    MQTTContext_t * pxMqttContext = &mqttContext;
-
-    configASSERT( pxMqttContext != NULL );
-    configASSERT( pcTopicFilter != NULL );
-    configASSERT( topicFilterLength > 0 );
-
-    /* Get the next free index for the outgoing publish. All QoS1 outgoing
-     * publishes are stored until a PUBACK is received. These messages are
-     * stored for supporting a resend if a network connection is broken before
-     * receiving a PUBACK. */
-    returnStatus = prvGetNextFreeIndexForOutgoingPublishes( &ucPublishIndex );
-
-    if( returnStatus == pdFAIL )
-    {
-        LogError( ( "Unable to find a free spot for outgoing PUBLISH message.\n\n" ) );
-    }
-    else
-    {
-        LogInfo( ( "the published payload:%s \r\n ", pcPayload ) );
-        /* This example publishes to only one topic and uses QOS1. */
-        outgoingPublishPackets[ ucPublishIndex ].pubInfo.qos = MQTTQoS1;
-        outgoingPublishPackets[ ucPublishIndex ].pubInfo.pTopicName = pcTopicFilter;
-        outgoingPublishPackets[ ucPublishIndex ].pubInfo.topicNameLength = topicFilterLength;
-        outgoingPublishPackets[ ucPublishIndex ].pubInfo.pPayload = pcPayload;
-        outgoingPublishPackets[ ucPublishIndex ].pubInfo.payloadLength = payloadLength;
-
-        /* Get a new packet id. */
-        outgoingPublishPackets[ ucPublishIndex ].packetId = MQTT_GetPacketId( pxMqttContext );
-
-        /* Send PUBLISH packet. */
-        xMQTTStatus = MQTT_Publish( pxMqttContext,
-                                    &outgoingPublishPackets[ ucPublishIndex ].pubInfo,
-                                    outgoingPublishPackets[ ucPublishIndex ].packetId );
-
-        if( xMQTTStatus != MQTTSuccess )
-        {
-            LogError( ( "Failed to send PUBLISH packet to broker with error = %u.",
-                        xMQTTStatus ) );
-            vCleanupOutgoingPublishAt( ucPublishIndex );
-            returnStatus = pdFAIL;
-        }
-        else
-        {
-            LogInfo( ( "PUBLISH sent for topic %.*s to broker with packet ID %u.\n\n",
-                       topicFilterLength,
-                       pcTopicFilter,
-                       outgoingPublishPackets[ ucPublishIndex ].packetId ) );
-
-            /* Calling MQTT_ProcessLoop to process incoming publish echo, since
-             * application subscribed to the same topic the broker will send
-             * publish message back to the application. This function also
-             * sends ping request to broker if MQTT_KEEP_ALIVE_INTERVAL_SECONDS
-             * has expired since the last MQTT packet sent and receive
-             * ping responses. */
-            xMQTTStatus = MQTT_ProcessLoop( &mqttContext, mqttexamplePROCESS_LOOP_TIMEOUT_MS );
-
-            if( xMQTTStatus != MQTTSuccess )
-            {
-                LogWarn( ( "MQTT_ProcessLoop returned with status = %u.",
-                           xMQTTStatus ) );
-                returnStatus = pdFAIL;
-            }
-        }
-    }
-
-    return returnStatus;
-}
-/*-----------------------------------------------------------*/
-
-static uint32_t prvGetTimeMs( void )
-{
-    TickType_t xTickCount = 0;
-    uint32_t ulTimeMs = 0UL;
-
-    /* Get the current tick count. */
-    xTickCount = xTaskGetTickCount();
-
-    /* Convert the ticks to milliseconds. */
-    ulTimeMs = ( uint32_t ) xTickCount * MILLISECONDS_PER_TICK;
-
-    /* Reduce ulGlobalEntryTimeMs from obtained time so as to always return the
-     * elapsed time in the application. */
-    ulTimeMs = ( uint32_t ) ( ulTimeMs - ulGlobalEntryTimeMs );
-
-    return ulTimeMs;
-}
-
-/*-----------------------------------------------------------*/
diff --git a/FreeRTOS-Plus/Demo/AWS/Device_Shadow_Windows_Simulator/Device_Shadow_Demo/DemoTasks/shadow_demo_helpers.h b/FreeRTOS-Plus/Demo/AWS/Device_Shadow_Windows_Simulator/Device_Shadow_Demo/DemoTasks/shadow_demo_helpers.h
deleted file mode 100644
index cf7ad1e91..000000000
--- a/FreeRTOS-Plus/Demo/AWS/Device_Shadow_Windows_Simulator/Device_Shadow_Demo/DemoTasks/shadow_demo_helpers.h
+++ /dev/null
@@ -1,104 +0,0 @@
-/*
- * FreeRTOS V202011.00
- * Copyright (C) 2020 Amazon.com, Inc. or its affiliates.  All Rights Reserved.
- *
- * Permission is hereby granted, free of charge, to any person obtaining a copy of
- * this software and associated documentation files (the "Software"), to deal in
- * the Software without restriction, including without limitation the rights to
- * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
- * the Software, and to permit persons to whom the Software is furnished to do so,
- * subject to the following conditions:
- *
- * The above copyright notice and this permission notice shall be included in all
- * copies or substantial portions of the Software.
- *
- * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
- * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
- * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
- * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
- * IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
- * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
- */
-
-#ifndef SHADOW_DEMO_HELPERS_H
-#define SHADOW_DEMO_HELPERS_H
-
-/* MQTT API header. */
-#include "core_mqtt.h"
-
-/* Transport interface implementation include header for TLS. */
-#include "using_mbedtls.h"
-
-/*-----------------------------------------------------------*/
-
-/**
- * @brief Establish a MQTT connection.
- *
- * @param[in] eventCallback The callback function used to receive incoming
- * publishes and incoming acks from MQTT library.
- *
- * @return The status of the final connection attempt.
- */
-BaseType_t xEstablishMqttSession( MQTTEventCallback_t eventCallback );
-
-/**
- * @brief Handle the incoming packet if it's not related to the device shadow.
- *
- * @param[in] pxPacketInfo Packet Info pointer for the incoming packet.
- * @param[in] usPacketIdentifier Packet identifier of the incoming packet.
- */
-void vHandleOtherIncomingPacket( MQTTPacketInfo_t * pxPacketInfo,
-                                 uint16_t usPacketIdentifier );
-
-/**
- * @brief Close the MQTT connection.
- *
- * @return pdPASS if DISCONNECT was successfully sent;
- * pdFAIL otherwise.
- */
-BaseType_t xDisconnectMqttSession( void );
-
-/**
- * @brief Subscribe to a MQTT topic filter.
- *
- * @param[in] pcTopicFilter Pointer to the shadow topic buffer.
- * @param[in] usTopicFilterLength Indicates the length of the shadow
- * topic filter.
- *
- * @return pdPASS if SUBSCRIBE was successfully sent;
- * pdFAIL otherwise.
- */
-BaseType_t xSubscribeToTopic( const char * pcTopicFilter,
-                              uint16_t usTopicFilterLength );
-
-/**
- * @brief Sends an MQTT UNSUBSCRIBE to unsubscribe from the shadow
- * topic.
- *
- * @param[in] pcTopicFilter Pointer to the shadow topic buffer.
- * @param[in] usTopicFilterLength Indicates the length of the shadow
- * topic filter.
- *
- * @return pdPASS if UNSUBSCRIBE was successfully sent;
- * pdFAIL otherwise.
- */
-BaseType_t xUnsubscribeFromTopic( const char * pcTopicFilter,
-                                  uint16_t usTopicFilterLength );
-
-/**
- * @brief Publish a message to a MQTT topic.
- *
- * @param[in] pcTopicFilter Points to the topic.
- * @param[in] topicFilterLength The length of the topic.
- * @param[in] pcPayload Points to the payload.
- * @param[in] payloadLength The length of the payload.
- *
- * @return pdPASS if PUBLISH was successfully sent;
- * pdFAIL otherwise.
- */
-BaseType_t xPublishToTopic( const char * pcTopicFilter,
-                            int32_t topicFilterLength,
-                            const char * pcPayload,
-                            size_t payloadLength );
-
-#endif /* ifndef SHADOW_DEMO_HELPERS_H */
diff --git a/FreeRTOS-Plus/Demo/AWS/Device_Shadow_Windows_Simulator/Device_Shadow_Demo/WIN32.vcxproj b/FreeRTOS-Plus/Demo/AWS/Device_Shadow_Windows_Simulator/Device_Shadow_Demo/WIN32.vcxproj
index b8940c63b..456d99a37 100644
--- a/FreeRTOS-Plus/Demo/AWS/Device_Shadow_Windows_Simulator/Device_Shadow_Demo/WIN32.vcxproj
+++ b/FreeRTOS-Plus/Demo/AWS/Device_Shadow_Windows_Simulator/Device_Shadow_Demo/WIN32.vcxproj
@@ -58,7 +58,7 @@
     </Midl>

     <ClCompile>

       <Optimization>Disabled</Optimization>

-      <AdditionalIncludeDirectories>..\..\..\..\..\Source\FreeRTOS-Plus-Trace\Include;..\..\..\..\..\FreeRTOS-Plus\Source\FreeRTOS-Plus-TCP\include;..\..\..\..\..\FreeRTOS-Plus\Source\FreeRTOS-Plus-TCP\portable\BufferManagement;..\..\..\..\..\FreeRTOS-Plus\Source\FreeRTOS-Plus-TCP\portable\Compiler\MSVC;..\..\..\..\..\FreeRTOS-Plus\Source\Utilities\logging;..\common\WinPCap;..\..\..\..\..\FreeRTOS\Source\include;..\..\..\..\..\FreeRTOS\Source\portable\MSVC-MingW;..\..\..\..\Source\Application-Protocols\coreMQTT\source\include;..\..\..\..\Source\Application-Protocols\coreMQTT\source\interface;..\..\..\..\Source\Utilities\exponential_backoff;..\..\..\..\Source\Application-Protocols\network_transport\freertos_plus_tcp;..\..\..\..\Source\Application-Protocols\network_transport\freertos_plus_tcp\using_mbedtls;..\..\..\..\Source\Utilities\mbedtls_freertos;..\..\..\..\..\Source\mbedtls_utils;..\..\..\..\ThirdParty\mbedtls\include;..\..\..\..\Source\AWS\device-shadow\source\include;..\..\..\..\Source\coreJSON\source\include;.;%(AdditionalIncludeDirectories)</AdditionalIncludeDirectories>

+      <AdditionalIncludeDirectories>..\..\..\..\..\Source\FreeRTOS-Plus-Trace\Include;..\..\..\..\..\FreeRTOS-Plus\Source\FreeRTOS-Plus-TCP\include;..\..\..\..\..\FreeRTOS-Plus\Source\FreeRTOS-Plus-TCP\portable\BufferManagement;..\..\..\..\..\FreeRTOS-Plus\Source\FreeRTOS-Plus-TCP\portable\Compiler\MSVC;..\..\..\..\..\FreeRTOS-Plus\Source\Utilities\logging;..\common\WinPCap;..\..\..\..\..\FreeRTOS\Source\include;..\..\..\..\..\FreeRTOS\Source\portable\MSVC-MingW;..\..\..\..\Source\Application-Protocols\coreMQTT\source\include;..\..\..\..\Source\Application-Protocols\coreMQTT\source\interface;..\..\..\..\Source\Utilities\exponential_backoff;..\..\..\..\Source\Application-Protocols\network_transport\freertos_plus_tcp;..\..\..\..\Source\Application-Protocols\network_transport\freertos_plus_tcp\using_mbedtls;..\..\..\..\Source\Utilities\mbedtls_freertos;..\..\..\..\..\Source\mbedtls_utils;..\..\..\..\ThirdParty\mbedtls\include;..\..\..\..\Source\AWS\device-shadow\source\include;..\..\..\..\Source\coreJSON\source\include;..\..\Mqtt_Demo_Helpers;.;%(AdditionalIncludeDirectories)</AdditionalIncludeDirectories>

       <PreprocessorDefinitions>MBEDTLS_CONFIG_FILE="mbedtls_config.h";WIN32;_DEBUG;_CONSOLE;_WIN32_WINNT=0x0500;WINVER=0x400;_CRT_SECURE_NO_WARNINGS;%(PreprocessorDefinitions)</PreprocessorDefinitions>

       <MinimalRebuild>false</MinimalRebuild>

       <BasicRuntimeChecks>EnableFastChecks</BasicRuntimeChecks>

@@ -490,7 +490,7 @@
     <ClCompile Include="..\..\..\..\..\FreeRTOS-Plus\Demo\Common\Logging\windows\Logging_WinSim.c" />

     <ClCompile Include="..\Common\main.c" />

     <ClCompile Include="DemoTasks\ShadowDemoMainExample.c" />

-    <ClCompile Include="DemoTasks\shadow_demo_helpers.c" />

+    <ClCompile Include="..\..\Mqtt_Demo_Helpers\mqtt_demo_helpers.c" />

   </ItemGroup>

   <ItemGroup>

     <ClInclude Include="..\..\..\..\..\FreeRTOS\Source\include\event_groups.h" />

diff --git a/FreeRTOS-Plus/Demo/AWS/Device_Shadow_Windows_Simulator/Device_Shadow_Demo/demo_config.h b/FreeRTOS-Plus/Demo/AWS/Device_Shadow_Windows_Simulator/Device_Shadow_Demo/demo_config.h
index c0b6ec636..f20a12cb2 100644
--- a/FreeRTOS-Plus/Demo/AWS/Device_Shadow_Windows_Simulator/Device_Shadow_Demo/demo_config.h
+++ b/FreeRTOS-Plus/Demo/AWS/Device_Shadow_Windows_Simulator/Device_Shadow_Demo/demo_config.h
@@ -67,6 +67,17 @@ extern void vLoggingPrintf( const char * pcFormatString,
 
 /************ End of logging configuration ****************/
 
+/**
+ * @brief The Thing resource registered on your AWS IoT account to use in the demo.
+ * A Thing resource is required to communicate with the AWS IoT Device Shadow service.
+ *
+ * @note The Things associated with your AWS account can be found in the
+ * AWS IoT console under Manage/Things, or using the ListThings REST API (that can
+ * be called with the AWS CLI command line tool).
+ *
+ * #define democonfigTHING_NAME    "...insert here..."
+ */
+
 #ifndef democonfigCLIENT_IDENTIFIER
 
 /**
@@ -83,16 +94,11 @@ extern void vLoggingPrintf( const char * pcFormatString,
 #endif
 
 /**
- * @brief Endpoint of the MQTT broker to connect to.
- *
- * This demo application can be run with any MQTT broker, that supports mutual
- * authentication.
- *
- * For AWS IoT MQTT broker, this is the Thing's REST API Endpoint.
+ * @brief The AWS IoT broker endpoint to connect to in the demo.
  *
  * @note Your AWS IoT Core endpoint can be found in the AWS IoT console under
- * Settings/Custom Endpoint, or using the describe-endpoint REST API (with
- * AWS CLI command line tool).
+ * Settings/Custom Endpoint, or using the DescribeEndpoint REST API (that can
+ * be called with AWS CLI command line tool).
  *
  * #define democonfigMQTT_BROKER_ENDPOINT    "...insert here..."
  */
@@ -113,8 +119,8 @@ extern void vLoggingPrintf( const char * pcFormatString,
 /**
  * @brief AWS root CA certificate.
  *
- * For AWS IoT MQTT broker, this certificate is used to identify the AWS IoT
- * server and is publicly available. Refer to the link below.
+ * This certificate is used to identify the AWS IoT server and is publicly available.
+ * Refer to the link below.
  * https://www.amazontrust.com/repository/AmazonRootCA1.pem
  *
  * @note This certificate should be PEM-encoded.
@@ -124,7 +130,6 @@ extern void vLoggingPrintf( const char * pcFormatString,
  * "...base64 data...\n"\
  * "-----END CERTIFICATE-----\n"
  *
- * #define democonfigROOT_CA_PEM    "...insert here..."
  */
 
 #define democonfigROOT_CA_PEM                                            \
@@ -152,7 +157,7 @@ extern void vLoggingPrintf( const char * pcFormatString,
 /**
  * @brief Client certificate.
  *
- * For AWS IoT MQTT broker, refer to the AWS documentation below for details
+ * Please refer to the AWS documentation below for details
  * regarding client authentication.
  * https://docs.aws.amazon.com/iot/latest/developerguide/client-authentication.html
  *
@@ -169,7 +174,7 @@ extern void vLoggingPrintf( const char * pcFormatString,
 /**
  * @brief Client's private key.
  *
- * For AWS IoT MQTT broker, refer to the AWS documentation below for details
+ * Please refer to the AWS documentation below for details
  * regarding clientauthentication.
  * https://docs.aws.amazon.com/iot/latest/developerguide/client-authentication.html
  *
@@ -187,7 +192,7 @@ extern void vLoggingPrintf( const char * pcFormatString,
  * @brief The username value for authenticating client to the MQTT broker when
  * username/password based client authentication is used.
  *
- * For AWS IoT MQTT broker, refer to the AWS IoT documentation below for
+ * Please refer to the AWS IoT documentation below for
  * details regarding client authentication with a username and password.
  * https://docs.aws.amazon.com/iot/latest/developerguide/custom-authentication.html
  * An authorizer setup needs to be done, as mentioned in the above link, to use
@@ -200,7 +205,7 @@ extern void vLoggingPrintf( const char * pcFormatString,
  * @brief The password value for authenticating client to the MQTT broker when
  * username/password based client authentication is used.
  *
- * For AWS IoT MQTT broker, refer to the AWS IoT documentation below for
+ * Please refer to the AWS IoT documentation below for
  * details regarding client authentication with a username and password.
  * https://docs.aws.amazon.com/iot/latest/developerguide/custom-authentication.html
  * An authorizer setup needs to be done, as mentioned in the above link, to use