MQTT C Client Libraries Internals
Data Structures
Here are the data structures with brief descriptions:
 CAckData for one of the ack packets
 CAckRequest
 CClientsData related to one client
 CClientStatesConfiguration data related to all clients
 Ccond_type_struct
 CConnackData for a connack packet
 CConnectData for a connect packet
 CframeDataBuilds a websocket frame for data transmission
 CHeaderBitfields for the MQTT header byte
 Cheap_infoInformation about the state of the heap
 CListStructure to hold all data for one list
 CListElementStructStructure to hold all data for one list element
 CLog_nameValue
 CMessagesClient publication message data
 CMQTTAsync_command
 CMQTTAsync_connectDataThe connect options that can be updated before an automatic reconnect
 CMQTTAsync_connectOptionsMQTTAsync_connectOptions defines several settings that control the way the client connects to an MQTT server
 CMQTTAsync_createOptionsOptions for the ::MQTTAsync_createWithOptions call
 CMQTTAsync_disconnectOptionsOptions for the ::MQTTAsync_disconnect call
 CMQTTAsync_failureDataThe data returned on completion of an unsuccessful API call in the response callback onFailure
 CMQTTAsync_failureData5The data returned on completion of an unsuccessful API call in the response callback onFailure
 CMQTTAsync_init_optionsInitialization options
 CMQTTAsync_messageA structure representing the payload and attributes of an MQTT message
 CMQTTAsync_nameValueUtility structure where name/value pairs are needed
 CMQTTAsync_queuedCommand
 CMQTTAsync_responseOptionsStructure to define call options
 CMQTTAsync_SSLOptionsMQTTAsync_sslProperties defines the settings to establish an SSL/TLS connection using the OpenSSL library
 CMQTTAsync_struct
 CMQTTAsync_successDataThe data returned on completion of a successful API call in the response callback onSuccess
 CMQTTAsync_successData5The data returned on completion of a successful API call in the response callback onSuccess
 CMQTTAsync_willOptionsMQTTAsync_willOptions defines the MQTT "Last Will and Testament" (LWT) settings for the client
 CMQTTClient_connectOptionsMQTTClient_connectOptions defines several settings that control the way the client connects to an MQTT server
 CMQTTClient_createOptionsOptions for the MQTTClient_createWithOptions call
 CMQTTClient_init_optionsInitialization options
 CMQTTClient_messageA structure representing the payload and attributes of an MQTT message
 CMQTTClient_nameValueMQTTClient_libraryInfo is used to store details relating to the currently used library such as the version in use, the time it was built and relevant openSSL options
 CMQTTClient_persistenceA structure containing the function pointers to a persistence implementation and the context or state that will be shared across all the persistence functions
 CMQTTClient_SSLOptionsMQTTClient_sslProperties defines the settings to establish an SSL/TLS connection using the OpenSSL library
 CMQTTClient_willOptionsMQTTClient_willOptions defines the MQTT "Last Will and Testament" (LWT) settings for the client
 CMQTTClients
 CMQTTLenStringThe data for a length delimited string
 CMQTTPacketData for a packet with header only
 CMQTTPersistence_message
 CMQTTPersistence_qEntry
 CMQTTPropertiesMQTT version 5 property list
 CMQTTPropertyStructure to hold an MQTT version 5 property of any type
 CMQTTProtocol
 CMQTTResponseMQTT version 5.0 response information
 CMQTTSubscribe_optionsThe MQTT V5 subscribe options, apart from QoS which existed before V5
 CnameToType
 CnetworkHandles
 CNodeStructStructure to hold all data for one list element
 CPacketBuffers
 Cpending_write
 Cpending_writes
 Cprops_rc_parms
 CPublicationsStored publication data to minimize copying
 CPublishData for a publish packet
 CqEntry
 CSHA_CTX_S
 Csocket_queue
 CSocketsStructure to hold all socket data for the module
 CstackEntry
 CstorageElementEach item on the heap is recorded with this structure
 CSubackData for a suback packet
 CthreadEntry
 Ctrace_settings_type
 CtraceEntry
 CTreeStructure to hold all data for one tree
 CUnsubackData for an MQTT V5 unsuback packet
 CwillMessagesClient will message data
 Cws_frameRaw websocket frame data