IotMqtt_SerializeDisconnect

Generate a DISCONNECT packet.

IotMqttError_t IotMqtt_SerializeDisconnect( uint8_t * pBuffer,
                                            size_t bufferSize );

Parameters

[in,out]	pBuffer	User provide buffer where the DISCONNECT packet is written.
[in]	bufferSize	Size of the buffer pointed to by pBuffer.

Returns

returns IOT_MQTT_SUCCESS or IOT_MQTT_BAD_PARAMETER

Note

This call is part of serializer API used for implementing light-weight MQTT client.

Example

// Example below shows how IotMqtt_SerializeDisconnect() should be used.

#define mqttexampleSHARED_BUFFER_SIZE 100
static ucSharedBuffer[mqttexampleSHARED_BUFFER_SIZE];
void sendDisconnectRequest( int xMQTTSocket )
{
    size_t xSentBytes = 0;

   // Disconnect is fixed length packet, therefore there is no need to calculate the size,
   // just makes sure static buffer can accommodate disconnect request.
   IotMqtt_Assert( MQTT_PACKET_DISCONNECT_SIZE <= mqttexampleSHARED_BUFFER_SIZE );

   // Serialize Disconnect packet into static buffer (dynamically allocated buffer can be used as well)
   xResult = IotMqtt_SerializeDisconnect( ucSharedBuffer, MQTT_PACKET_DISCONNECT_SIZE );
   IotMqtt_Assert( xResult == IOT_MQTT_SUCCESS );

   // xMQTTSocket here is posix socket created and connected to MQTT broker outside of this function.
   xSentByte = send( xMQTTSocket, ( void * ) ucSharedBuffer, MQTT_PACKET_DISCONNECT_SIZE, 0 );
   IotMqtt_Assert( xSentByte == MQTT_PACKET_DISCONNECT_SIZE );
}