Configurations of the MQTT Library.

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Configuration settings are C pre-processor constants. They can be set with a #define in the config file (mqtt_config.h) or by using a compiler option such as -D in gcc.

MQTT_STATE_ARRAY_MAX_COUNT

Determines the maximum number of MQTT PUBLISH messages, pending acknowledgment at a time, that are supported for incoming and outgoing direction of messages, separately. QoS 1 and 2 MQTT PUBLISHes require acknowledgment from the server before they can be completed. While they are awaiting the acknowledgment, the client must maintain information about their state. The value of this macro sets the limit on how many simultaneous PUBLISH states an MQTT context maintains, separately, for both incoming and outgoing direction of PUBLISHes.

Note: The MQTT context maintains separate state records for outgoing and incoming PUBLISHes, and thus, 2 * MQTT_STATE_ARRAY_MAX_COUNT amount of memory is statically allocated for the state records.

Possible values: Any positive 32 bit integer.
Default value: 10

MQTT_PINGRESP_TIMEOUT_MS

Number of milliseconds to wait for a ping response to a ping request as part of the keep-alive mechanism. If a ping response is not received before this timeout, then MQTT_ProcessLoop will return MQTTKeepAliveTimeout.

Possible values: Any positive integer up to SIZE_MAX.
Default value: 500

MQTT_MAX_CONNACK_RECEIVE_RETRY_COUNT

The number of retries for receiving CONNACK. The MQTT_MAX_CONNACK_RECEIVE_RETRY_COUNT will be used only when the timeoutMs parameter of MQTT_Connect is passed as 0 . The transport receive for CONNACK will be retried MQTT_MAX_CONNACK_RECEIVE_RETRY_COUNT times before timing out. A value of 0 for this config will cause the transport receive for CONNACK to be invoked only once.

Possible values: Any positive 16 bit integer.
Default value: 5

LogError

Macro that is called in the MQTT library for logging "Error" level messages. To enable error level logging in the MQTT library, this macro should be mapped to the application-specific logging implementation that supports error logging.

Note: This logging macro is called in the MQTT library with parameters wrapped in double parentheses to be ISO C89/C90 standard compliant. For an example implementation of the logging macros, refer to mqtt_config.h files in the MQTT demo folder and the reference implementation of the logging-stack in demos.

Default value: Error logging is turned off, and no code is generated for calls to the macro in the MQTT library on compilation.

LogWarn

Macro that is called in the MQTT library for logging "Warning" level messages. To enable warning level logging in the MQTT library, this macro should be mapped to the application-specific logging implementation that supports warning logging.

Note: This logging macro is called in the MQTT library with parameters wrapped in double parentheses to be ISO C89/C90 standard compliant. For an example implementation of the logging macros, refer to mqtt_config.h files in the MQTT demo folder and the reference implementation of the logging-stack in demos.

Default value: Warning logs are turned off, and no code is generated for calls to the macro in the MQTT library on compilation.

LogInfo

Macro that is called in the MQTT library for logging "Info" level messages. To enable info level logging in the MQTT library, this macro should be mapped to the application-specific logging implementation that supports info logging.

Note: This logging macro is called in the MQTT library with parameters wrapped in double parentheses to be ISO C89/C90 standard compliant. For an example implementation of the logging macros, refer to mqtt_config.h files in the MQTT demo folder and the reference implementation of the logging-stack in demos.

Default value: Info logging is turned off, and no code is generated for calls to the macro in the MQTT library on compilation.