Simplify the mqtt multitasking demo a little (#398)

2 files changed, 235 insertions, 205 deletions

diff --git a/FreeRTOS-Plus/Demo/coreMQTT_Windows_Simulator/MQTT_Multitask/DemoTasks/MultitaskMQTTExample.c b/FreeRTOS-Plus/Demo/coreMQTT_Windows_Simulator/MQTT_Multitask/DemoTasks/MultitaskMQTTExample.c
index 3cad2831d..088d71352 100644
--- a/FreeRTOS-Plus/Demo/coreMQTT_Windows_Simulator/MQTT_Multitask/DemoTasks/MultitaskMQTTExample.c
+++ b/FreeRTOS-Plus/Demo/coreMQTT_Windows_Simulator/MQTT_Multitask/DemoTasks/MultitaskMQTTExample.c
@@ -24,26 +24,44 @@
  */
 
 /*
- * Demo for showing use of the managed MQTT API shared between multiple tasks.
- * This demo uses a thread safe queue to hold commands for interacting with the
- * MQTT API. There are four tasks to note in this demo:
- *  - A command (main) task for processing commands from the command queue while
- *    other tasks enqueue them. This task enters a loop, during which it processes
- *    commands from the command queue. If a termination command is received, it
- *    will break from the loop.
- *  - A publisher task for synchronous publishes. This task creates a series of
- *    publish operations to push to the command queue, which are then executed
- *    by the command task. This task uses synchronous publishes, meaning it will
- *    wait for each publish to complete before scheduling the next one.
- *  - A publisher task for asynchronous publishes. The difference between this
- *    task and the previous is that it will not wait for completion before
- *    scheduling the next publish, and checks them after all publishes have been
- *    enqueued. Note that the distinction between synchronous and asynchronous
- *    publishes is only in the behavior of the task, not in the actual publish
- *    command.
- *  - A subscriber task that creates an MQTT subscription to a topic filter
- *    matching the topics published on by the publishers. It loops while waiting
- *    for publish messages to be received.
+ * This demo shows how to use coreMQTT in a multithreaded environment - it does not
+ * yet go as far as encapsulating the MQTT library within its own agent (or daemon)
+ * task - although the prvCommandLoop() function demonstrates how that might be done.
+ * In this task prvCommandLoop() is only executed from a single thread and is the
+ * only function that is allowed to use the coreMQTT API directly.  Anything else
+ * needing to interact with the coreMQTT API does so by posting commands to
+ * prvCommandLoop() via a queue.  Future coreMQTT releases will build an agent into
+ * the library itself, and then encapsulate the queues into the implementation of a
+ * thread safe coreMQTT API.
+ *
+ * To use this demo with TLS set democonfigUSE_TLS to 1.  To use this demo without
+ * TLS (so plain text) set democonfigUSE_TLS to 0.  democonfigUSE_TLS is defined
+ * in demo_config.h.
+ *
+ *!!! Plain text connections are only used for ease of demonstration.  Do not send
+ *!!! sensitive data on unencrypted connections.  Production devices should used
+ *!!! mutually authenticated and encrypted connections.
+ *
+ * There are four tasks to note in this demo:
+ *  - prvMQTTDemoTask() manages multiple iterations of the demo.  Each iteration
+ *    creates the other tasks, calls prvCommandLoop() to handle the MQTT traffic,
+ *    then cleans up ready for the next iteration.
+ *  - prvSyncPublishTask() which demonstrates synchronous publishes. The task creates
+ *    a series of publish operations that are sent over the command queue to be
+ *    processed by prvCommandLoop(), waiting for each publish to complete before
+ *    sending the next.
+ *  - prvAsyncPublishTask() which demonstrates asynchronous publishes. Like
+ *    prvSyncPublishTask(), the task creates a series of publish operations that are
+ *    sent over the command queue to be processed by prvCommandLoop(), but unlike
+ *    prvSyncPublishTask() this task does not wait for each publish to be complete
+ *    until after all the publish commands are sent.  Note that the distinction
+ *    between synchronous and asynchronous publishes is only in the behavior of the
+ *    task, not in the actual publish command.
+ *  - prvSubscribeTask() which creates an MQTT subscription to a topic filter
+ *    matching the topics published on by the two publishing tasks, and in doing so,
+ *    ensures the demo received a publish command back for each publish command it
+ *    sends. It loops while waiting for publish messages to be received.
+ *
  * Tasks can have queues to hold received publish messages, and the command task
  * will push incoming publishes to the queue of each task that is subscribed to
  * the incoming topic.
@@ -83,70 +101,6 @@
 /**
  * These configuration settings are required to run the demo.
  */
-#ifndef democonfigCLIENT_IDENTIFIER
-
-/**
- * @brief The MQTT client identifier used in this example.  Each client identifier
- * must be unique so edit as required to ensure no two clients connecting to the
- * same broker use the same client identifier.
- *
- * @note Appending __TIME__ to the client id string will reduce the possibility of a
- * client id collision in the broker. Note that the appended time is the compilation
- * time. This client id can cause collision, if more than one instance of the same
- * binary is used at the same time to connect to the broker.
- */
-    #define democonfigCLIENT_IDENTIFIER    "testClient"__TIME__
-#endif
-
-/* Compile time error for some undefined configs, and provide default values
- * for others. */
-#ifndef democonfigMQTT_BROKER_ENDPOINT
-    #error "Please define democonfigMQTT_BROKER_ENDPOINT in demo_config.h."
-#endif
-
-#if defined( democonfigUSE_TLS ) && ( democonfigUSE_TLS == 1 )
-    #ifndef democonfigROOT_CA_PEM
-        #error "Please define Root CA certificate of the MQTT broker(democonfigROOT_CA_PEM) in demo_config.h."
-    #endif
-
-/* If no username is defined, then a client certificate/key is required. */
-    #ifndef democonfigCLIENT_USERNAME
-
-/*
- *!!! Please note democonfigCLIENT_PRIVATE_KEY_PEM in used for
- *!!! convenience of demonstration only.  Production devices should
- *!!! store keys securely, such as within a secure element.
- */
-
-        #ifndef democonfigCLIENT_CERTIFICATE_PEM
-            #error "Please define client certificate(democonfigCLIENT_CERTIFICATE_PEM) in demo_config.h."
-        #endif
-        #ifndef democonfigCLIENT_PRIVATE_KEY_PEM
-            #error "Please define client private key(democonfigCLIENT_PRIVATE_KEY_PEM) in demo_config.h."
-        #endif
-    #else
-
-/* If a username is defined, a client password also would need to be defined for
- * client authentication. */
-        #ifndef democonfigCLIENT_PASSWORD
-            #error "Please define client password(democonfigCLIENT_PASSWORD) in demo_config.h for client authentication based on username/password."
-        #endif
-
-/* AWS IoT MQTT broker port needs to be 443 for client authentication based on
- * username/password. */
-        #if defined( democonfigUSE_AWS_IOT_CORE_BROKER ) && democonfigMQTT_BROKER_PORT != 443
-            #error "Broker port(democonfigMQTT_BROKER_PORT) should be defined as 443 in demo_config.h for client authentication based on username/password in AWS IoT Core."
-        #endif
-    #endif /* ifndef democonfigCLIENT_USERNAME */
-
-    #ifndef democonfigMQTT_BROKER_PORT
-        #define democonfigMQTT_BROKER_PORT    ( 8883 )
-    #endif
-#else /* if defined( democonfigUSE_TLS ) && ( democonfigUSE_TLS == 1 ) */
-    #ifndef democonfigMQTT_BROKER_PORT
-        #define democonfigMQTT_BROKER_PORT    ( 1883 )
-    #endif
-#endif /* if defined( democonfigUSE_TLS ) && ( democonfigUSE_TLS == 1 ) */
 
 /**
  * @brief The size to use for the network buffer.
@@ -155,73 +109,6 @@
     #define mqttexampleNETWORK_BUFFER_SIZE    ( 1024U )
 #endif
 
-/**
- * @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 This is the ALPN (Application-Layer Protocol Negotiation) string
- * required by AWS IoT for password-based authentication using TCP port 443.
- */
-#define AWS_IOT_CUSTOM_AUTH_ALPN    "\x04mqtt"
-
-/**
- * Provide default values for undefined configuration settings.
- */
-#ifndef democonfigOS_NAME
-    #define democonfigOS_NAME    "FreeRTOS"
-#endif
-
-#ifndef democonfigOS_VERSION
-    #define democonfigOS_VERSION    tskKERNEL_VERSION_NUMBER
-#endif
-
-#ifndef democonfigHARDWARE_PLATFORM_NAME
-    #define democonfigHARDWARE_PLATFORM_NAME    "WinSim"
-#endif
-
-#ifndef democonfigMQTT_LIB
-    #define democonfigMQTT_LIB    "core-mqtt@1.0.0"
-#endif
-
-/**
- * @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 ) )
-
-#ifdef democonfigCLIENT_USERNAME
-
-/**
- * @brief Append the username with the metrics string if #democonfigCLIENT_USERNAME is defined.
- *
- * This is to support both metrics reporting and username/password based client
- * authentication by AWS IoT.
- */
-    #define CLIENT_USERNAME_WITH_METRICS    democonfigCLIENT_USERNAME AWS_IOT_METRICS_STRING
-#endif
-
-/**
- * @brief Length of client identifier.
- */
-#define democonfigCLIENT_IDENTIFIER_LENGTH           ( ( uint16_t ) ( sizeof( democonfigCLIENT_IDENTIFIER ) - 1 ) )
-
-/**
- * @brief Length of MQTT server host name.
- */
-#define democonfigBROKER_ENDPOINT_LENGTH             ( ( uint16_t ) ( sizeof( democonfigMQTT_BROKER_ENDPOINT ) - 1 ) )
 
 /**
  * @brief Timeout for receiving CONNACK packet in milliseconds.
@@ -533,13 +420,6 @@ static BaseType_t prvSocketDisconnect( NetworkContext_t * pxNetworkContext );
 static void prvMQTTClientSocketWakeupCallback( Socket_t pxSocket );
 
 /**
- * @brief Initialize context for a command.
- *
- * @param[in] pxContext Context to initialize.
- */
-static void prvInitializeCommandContext( CommandContext_t * pxContext );
-
-/**
  * @brief Track an operation by adding it to a list, indicating it is anticipating
  * an acknowledgment.
  *
@@ -768,6 +648,14 @@ static void prvMQTTDemoTask( void * pvParameters );
  */
 static uint32_t prvGetTimeMs( void );
 
+/**
+ * @brief Cleans any persistent sessions that may already exist
+ * This demo uses a persistent session that can be re-connected if disconnected.
+ * Clean any lingering sessions that may exist from previous executions of the
+ * demo.
+ */
+static void prvCleanExistingPersistentSession( void );
+
 /*-----------------------------------------------------------*/
 
 /**
@@ -1049,7 +937,7 @@ static MQTTStatus_t prvResumeSession( bool xSessionPresent )
         /* Resubscribe if needed. */
         if( j > 0 )
         {
-            prvInitializeCommandContext( &xResubscribeContext );
+            memset( ( void * ) &xResubscribeContext, 0x00, sizeof( xResubscribeContext ) );
             xResubscribeContext.pxSubscribeInfo = pxResendSubscriptions;
             xResubscribeContext.ulSubscriptionCount = j;
             /* Set to NULL so existing queues will not be overwritten. */
@@ -1221,18 +1109,6 @@ static void prvMQTTClientSocketWakeupCallback( Socket_t pxSocket )
 
 /*-----------------------------------------------------------*/
 
-static void prvInitializeCommandContext( CommandContext_t * pxContext )
-{
-    pxContext->xIsComplete = false;
-    pxContext->pxResponseQueue = NULL;
-    pxContext->xReturnStatus = MQTTSuccess;
-    pxContext->pxPublishInfo = NULL;
-    pxContext->pxSubscribeInfo = NULL;
-    pxContext->ulSubscriptionCount = 0;
-}
-
-/*-----------------------------------------------------------*/
-
 static bool prvAddAwaitingOperation( uint16_t usPacketId,
                                      Command_t * pxCommand )
 {
@@ -1742,7 +1618,6 @@ static void prvCommandLoop( void )
 {
     Command_t xCommand;
     Command_t xNewCommand;
-    Command_t * pxCommand;
     MQTTStatus_t xStatus = MQTTSuccess;
     static int lNumProcessed = 0;
     bool xTerminateReceived = false;
@@ -1758,9 +1633,7 @@ static void prvCommandLoop( void )
             continue;
         }
 
-        pxCommand = &xCommand;
-
-        xStatus = prvProcessCommand( pxCommand );
+        xStatus = prvProcessCommand( &xCommand );
 
         /* Add connect operation to front of queue if status was not successful. */
         if( xStatus != MQTTSuccess )
@@ -1778,15 +1651,17 @@ static void prvCommandLoop( void )
 
         /* Delay after sending a subscribe. This is to so that the broker
          * creates a subscription for us before processing our next publish,
-         * which should be immediately after this. */
-        if( pxCommand->xCommandType == SUBSCRIBE )
+         * which should be immediately after this.  Only required because the
+         * subscribe and publish commands are coming from separate tasks, which
+         * would not normally be the case. */
+        if( xCommand.xCommandType == SUBSCRIBE )
         {
             LogDebug( ( "Sleeping for %d ms after sending SUBSCRIBE packet.", mqttexampleSUBSCRIBE_TASK_DELAY_MS ) );
             vTaskDelay( mqttexampleSUBSCRIBE_TASK_DELAY_MS );
         }
 
         /* Terminate the loop if we receive the termination command. */
-        if( pxCommand->xCommandType == TERMINATE )
+        if( xCommand.xCommandType == TERMINATE )
         {
             xTerminateReceived = true;
             break;
@@ -1800,8 +1675,7 @@ static void prvCommandLoop( void )
     configASSERT( xTerminateReceived == true );
 
     LogInfo( ( "Creating Disconnect operation." ) );
-    prvCreateCommand( DISCONNECT, NULL, NULL, &xNewCommand );
-    prvProcessCommand( &xNewCommand );
+    MQTT_Disconnect( &globalMqttContext );
     LogInfo( ( "Disconnected from broker." ) );
 }
 
@@ -1873,7 +1747,7 @@ void prvSyncPublishTask( void * pvParameters )
         snprintf( topicBuf, mqttexampleDEMO_BUFFER_SIZE, mqttexamplePUBLISH_TOPIC_FORMAT_STRING, "sync", i + 1 );
         xPublishInfo.topicNameLength = ( uint16_t ) strlen( topicBuf );
 
-        prvInitializeCommandContext( &xContext );
+        memset( ( void * ) &xContext, 0x00, sizeof( xContext ) );
         xContext.xTaskToNotify = xTaskGetCurrentTaskHandle();
         xContext.ulNotificationBit = 1 << i;
         xContext.pxPublishInfo = &xPublishInfo;
@@ -1935,7 +1809,7 @@ void prvAsyncPublishTask( void * pvParameters )
     for( int i = 0; i < mqttexamplePUBLISH_COUNT / 2; i++ )
     {
         pxContexts[ i ] = ( CommandContext_t * ) pvPortMalloc( sizeof( CommandContext_t ) );
-        prvInitializeCommandContext( pxContexts[ i ] );
+        memset( ( void * ) pxContexts[ i ], 0x00, sizeof( pxContexts[ i ] ) );
         pxContexts[ i ]->xTaskToNotify = xTaskGetCurrentTaskHandle();
 
         /* Set the notification bit to be the publish number. This prevents this demo
@@ -2023,7 +1897,7 @@ void prvSubscribeTask( void * pvParameters )
     LogInfo( ( "Topic filter: %.*s", xSubscribeInfo.topicFilterLength, xSubscribeInfo.pTopicFilter ) );
 
     /* Create the context and subscribe command. */
-    prvInitializeCommandContext( &xContext );
+    memset( &xContext, 0x00, sizeof( xContext ) );
     xContext.pxResponseQueue = xSubscriberResponseQueue;
     xContext.xTaskToNotify = xTaskGetCurrentTaskHandle();
     xContext.ulNotificationBit = mqttexampleSUBSCRIBE_COMPLETE_BIT;
@@ -2097,7 +1971,7 @@ void prvSubscribeTask( void * pvParameters )
 
     LogInfo( ( "Finished receiving\n" ) );
     prvCreateCommand( UNSUBSCRIBE, &xContext, prvCommandCallback, &xCommand );
-    prvInitializeCommandContext( &xContext );
+    memset( ( void * ) &xContext, 0x00, sizeof( xContext ) );
     xContext.pxResponseQueue = xSubscriberResponseQueue;
     xContext.xTaskToNotify = xTaskGetCurrentTaskHandle();
     xContext.ulNotificationBit = mqttexampleUNSUBSCRIBE_COMPLETE_BIT;
@@ -2131,12 +2005,38 @@ void prvSubscribeTask( void * pvParameters )
 
 /*-----------------------------------------------------------*/
 
+static void prvCleanExistingPersistentSession( void )
+{
+    BaseType_t xNetworkStatus = pdFAIL;
+    MQTTStatus_t xMQTTStatus;
+
+    /* Connect to the broker. We connect here with the "clean session" flag set
+     * to true in order to clear any prior state in the broker. We will disconnect
+     * and later form a persistent session, so that it may be resumed if the
+     * network suddenly disconnects. */
+    xNetworkStatus = prvSocketConnect( &xNetworkContext );
+    configASSERT( xNetworkStatus == pdPASS );
+    LogInfo( ( "Creating a clean session to clear any broker state information." ) );
+    xMQTTStatus = prvMQTTInit( &globalMqttContext, &xNetworkContext );
+    configASSERT( xMQTTStatus == MQTTSuccess );
+    xMQTTStatus = prvMQTTConnect( &globalMqttContext, true );
+    configASSERT( xMQTTStatus == MQTTSuccess );
+
+    /* Disconnect. */
+    xMQTTStatus = MQTT_Disconnect( &globalMqttContext );
+    configASSERT( xMQTTStatus == MQTTSuccess );
+    xNetworkStatus = prvSocketDisconnect( &xNetworkContext );
+    configASSERT( xNetworkStatus == pdPASS );
+}
+
+/*-----------------------------------------------------------*/
+
 static void prvMQTTDemoTask( void * pvParameters )
 {
     BaseType_t xNetworkStatus = pdFAIL;
+    MQTTStatus_t xMQTTStatus;
     BaseType_t xResult = pdFALSE;
     uint32_t ulNotification = 0;
-    MQTTStatus_t xMQTTStatus;
     uint32_t ulExpectedNotifications = mqttexamplePUBLISHER_SYNC_COMPLETE_BIT |
                                        mqttexampleSUBSCRIBE_TASK_COMPLETE_BIT |
                                        mqttexamplePUBLISHER_ASYNC_COMPLETE_BIT;
@@ -2156,23 +2056,10 @@ static void prvMQTTDemoTask( void * pvParameters )
      * synchronization primitives. */
     xDefaultResponseQueue = xQueueCreate( 1, sizeof( PublishElement_t ) );
 
-    /* Connect to the broker. We connect here with the "clean session" flag set
-     * to true in order to clear any prior state in the broker. We will disconnect
-     * and later form a persistent session, so that it may be resumed if the
-     * network suddenly disconnects. */
-    xNetworkStatus = prvSocketConnect( &xNetworkContext );
-    configASSERT( xNetworkStatus == pdPASS );
-    LogInfo( ( "Creating a clean session to clear any broker state information." ) );
-    xMQTTStatus = prvMQTTInit( &globalMqttContext, &xNetworkContext );
-    configASSERT( xMQTTStatus == MQTTSuccess );
-    xMQTTStatus = prvMQTTConnect( &globalMqttContext, true );
-    configASSERT( xMQTTStatus == MQTTSuccess );
-
-    /* Disconnect. */
-    xMQTTStatus = MQTT_Disconnect( &globalMqttContext );
-    configASSERT( xMQTTStatus == MQTTSuccess );
-    xNetworkStatus = prvSocketDisconnect( &xNetworkContext );
-    configASSERT( xNetworkStatus == pdPASS );
+    /* This demo uses a persistent session that can be re-connected if disconnected.
+     * Clean any lingering sessions that may exist from previous executions of the
+     * demo. */
+    prvCleanExistingPersistentSession();
 
     for( ; ; )
     {
@@ -2188,8 +2075,9 @@ static void prvMQTTDemoTask( void * pvParameters )
         configASSERT( xMQTTStatus == MQTTSuccess );
         configASSERT( globalMqttContext.connectStatus == MQTTConnected );
 
-        /* Give subscriber task higher priority so the subscribe will be processed before the first publish.
-         * This must be less than or equal to the priority of the main task. */
+        /* Give subscriber task higher priority so the subscribe will be processed
+         * before the first publish.  This must be less than or equal to the priority of
+         * the main task. */
         xResult = xTaskCreate( prvSubscribeTask, "Subscriber", democonfigDEMO_STACKSIZE, NULL, tskIDLE_PRIORITY + 1, &xSubscribeTask );
         configASSERT( xResult == pdPASS );
         xResult = xTaskCreate( prvSyncPublishTask, "SyncPublisher", democonfigDEMO_STACKSIZE, NULL, tskIDLE_PRIORITY, &xSyncPublisherTask );
@@ -2218,7 +2106,7 @@ static void prvMQTTDemoTask( void * pvParameters )
         xNetworkStatus = prvSocketDisconnect( &xNetworkContext );
         configASSERT( xNetworkStatus == pdPASS );
 
-        LogInfo( ( "prvMQTTDemoTask() completed an iteration successfully. Total free heap is %u.\r\n", xPortGetFreeHeapSize() ) );
+        LogInfo( ( "\r\n\r\nprvMQTTDemoTask() completed an iteration successfully. Total free heap is %u.\r\n", xPortGetFreeHeapSize() ) );
         LogInfo( ( "Demo completed successfully.\r\n" ) );
         LogInfo( ( "Short delay before starting the next iteration.... \r\n\r\n" ) );
         vTaskDelay( mqttexampleDELAY_BETWEEN_DEMO_ITERATIONS );
diff --git a/FreeRTOS-Plus/Demo/coreMQTT_Windows_Simulator/MQTT_Multitask/demo_config.h b/FreeRTOS-Plus/Demo/coreMQTT_Windows_Simulator/MQTT_Multitask/demo_config.h
index 9da7745a0..4b075a4d5 100644
--- a/FreeRTOS-Plus/Demo/coreMQTT_Windows_Simulator/MQTT_Multitask/demo_config.h
+++ b/FreeRTOS-Plus/Demo/coreMQTT_Windows_Simulator/MQTT_Multitask/demo_config.h
@@ -259,4 +259,146 @@ extern void vLoggingPrintf( const char * pcFormatString,
  */
 #define democonfigDEMO_STACKSIZE            configMINIMAL_STACK_SIZE
 
+
+
+
+
+
+
+/**********************************************************************************
+ * Error checks and derived values only below here - do not edit below here. -----*
+ **********************************************************************************/
+
+
+/* Compile time error for some undefined configs, and provide default values
+ * for others. */
+#ifndef democonfigMQTT_BROKER_ENDPOINT
+    #error "Please define democonfigMQTT_BROKER_ENDPOINT in demo_config.h."
+#endif
+
+#ifndef democonfigCLIENT_IDENTIFIER
+    /**
+     * @brief The MQTT client identifier used in this example.  Each client identifier
+     * must be unique so edit as required to ensure no two clients connecting to the
+     * same broker use the same client identifier.  Using a #define is for convenience
+     * of demonstration only - production devices should use something unique to the
+     * device that can be read from software - such as a production serial number.
+     */
+     #error  "Please define democonfigCLIENT_IDENTIFIER in demo_config.h to something unique for this device."
+#endif
+
+
+#if defined( democonfigUSE_TLS ) && ( democonfigUSE_TLS == 1 )
+    #ifndef democonfigROOT_CA_PEM
+        #error "Please define Root CA certificate of the MQTT broker(democonfigROOT_CA_PEM) in demo_config.h."
+    #endif
+
+/* If no username is defined, then a client certificate/key is required. */
+    #ifndef democonfigCLIENT_USERNAME
+
+        /*
+         *!!! Please note democonfigCLIENT_PRIVATE_KEY_PEM in used for
+         *!!! convenience of demonstration only.  Production devices should
+         *!!! store keys securely, such as within a secure element.
+         */
+
+        #ifndef democonfigCLIENT_CERTIFICATE_PEM
+            #error "Please define client certificate(democonfigCLIENT_CERTIFICATE_PEM) in demo_config.h."
+        #endif
+        #ifndef democonfigCLIENT_PRIVATE_KEY_PEM
+            #error "Please define client private key(democonfigCLIENT_PRIVATE_KEY_PEM) in demo_config.h."
+        #endif
+    #else
+
+/* If a username is defined, a client password also would need to be defined for
+ * client authentication. */
+        #ifndef democonfigCLIENT_PASSWORD
+            #error "Please define client password(democonfigCLIENT_PASSWORD) in demo_config.h for client authentication based on username/password."
+        #endif
+
+/* AWS IoT MQTT broker port needs to be 443 for client authentication based on
+ * username/password. */
+        #if defined( democonfigUSE_AWS_IOT_CORE_BROKER ) && democonfigMQTT_BROKER_PORT != 443
+            #error "Broker port(democonfigMQTT_BROKER_PORT) should be defined as 443 in demo_config.h for client authentication based on username/password in AWS IoT Core."
+        #endif
+    #endif /* ifndef democonfigCLIENT_USERNAME */
+
+    #ifndef democonfigMQTT_BROKER_PORT
+        #define democonfigMQTT_BROKER_PORT    ( 8883 )
+    #endif
+#else /* if defined( democonfigUSE_TLS ) && ( democonfigUSE_TLS == 1 ) */
+    #ifndef democonfigMQTT_BROKER_PORT
+        #define democonfigMQTT_BROKER_PORT    ( 1883 )
+    #endif
+#endif /* if defined( democonfigUSE_TLS ) && ( democonfigUSE_TLS == 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 This is the ALPN (Application-Layer Protocol Negotiation) string
+ * required by AWS IoT for password-based authentication using TCP port 443.
+ */
+#define AWS_IOT_CUSTOM_AUTH_ALPN    "\x04mqtt"
+
+/**
+ * Provide default values for undefined configuration settings.
+ */
+#ifndef democonfigOS_NAME
+    #define democonfigOS_NAME    "FreeRTOS"
+#endif
+
+#ifndef democonfigOS_VERSION
+    #define democonfigOS_VERSION    tskKERNEL_VERSION_NUMBER
+#endif
+
+#ifndef democonfigHARDWARE_PLATFORM_NAME
+    #define democonfigHARDWARE_PLATFORM_NAME    "WinSim"
+#endif
+
+#ifndef democonfigMQTT_LIB
+    #define democonfigMQTT_LIB    "core-mqtt@1.0.0"
+#endif
+
+/**
+ * @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 ) )
+
+#ifdef democonfigCLIENT_USERNAME
+
+/**
+ * @brief Append the username with the metrics string if #democonfigCLIENT_USERNAME is defined.
+ *
+ * This is to support both metrics reporting and username/password based client
+ * authentication by AWS IoT.
+ */
+    #define CLIENT_USERNAME_WITH_METRICS    democonfigCLIENT_USERNAME AWS_IOT_METRICS_STRING
+#endif
+
+/**
+ * @brief Length of client identifier.
+ */
+#define democonfigCLIENT_IDENTIFIER_LENGTH           ( ( uint16_t ) ( sizeof( democonfigCLIENT_IDENTIFIER ) - 1 ) )
+
+/**
+ * @brief Length of MQTT server host name.
+ */
+#define democonfigBROKER_ENDPOINT_LENGTH             ( ( uint16_t ) ( sizeof( democonfigMQTT_BROKER_ENDPOINT ) - 1 ) )
+
+
 #endif /* DEMO_CONFIG_H */