MQTTAsync_createOptions - Man Page

char struct_id [4]
int struct_version
int sendWhileDisconnected
int maxBufferedMessages
int MQTTVersion
int allowDisconnectedSendAtAnyTime
int deleteOldestMessages
int restoreMessages
int persistQoS0

The eyecatcher for this structure. must be MQCO.

The version number of this structure. Must be 0, 1, 2 or 3 0 means no MQTTVersion 1 means no allowDisconnectedSendAtAnyTime, deleteOldestMessages, restoreMessages 2 means no persistQoS0

Whether to allow messages to be sent when the client library is not connected.

The maximum number of messages allowed to be buffered. This is intended to be used to limit the number of messages queued while the client is not connected. It also applies when the client is connected, however, so has to be greater than 0.

Whether the MQTT version is 3.1, 3.1.1, or 5. To use V5, this must be set. MQTT V5 has to be chosen here, because during the create call the message persistence is initialized, and we want to know whether the format of any persisted messages is appropriate for the MQTT version we are going to connect with. Selecting 3.1 or 3.1.1 and attempting to read 5.0 persisted messages will result in an error on create.

Allow sending of messages while disconnected before a first successful connect.