Which CleanStart and Session Expiry Interval setting is equivalent to CleanSession 0 in v3.1.1 ?

[Takatoshi Kondo]

Hi,

In the MQTT v5 specification, Session Expiry Interval and Clean Start are introduced.

The MQTT v5 spec said as follows:

https://docs.oasis-open.org/mqtt/mqtt/v5.0/os/mqtt-v5.0-os.html#_Toc3901048

> Non-normative comment

> Setting Clean Start to 1 and a Session Expiry Interval of 0, is equivalent to setting CleanSession to 1 in the MQTT Specification Version 3.1.1. Setting Clean Start to 0 and no Session Expiry Interval, is equivalent to setting CleanSession to 0 in the MQTT Specification Version 3.1.1.

 

I understand "Setting Clean Start to 1 and a Session Expiry Interval of 0, is equivalent to setting CleanSession to 1 in the MQTT Specification Version 3.1.1. ".

But I don't understand why "Setting Clean Start to 0 and no Session Expiry Interval, is equivalent to setting CleanSession to 0 in the MQTT Specification Version 3.1.1.".

I think that "no Session Expiry Interval" means equivalent to 0.

The spec said as follos:

> If the Session Expiry Interval is absent the value 0 is used. If it is set to 0, or is absent, the Session ends when the Network Connection is closed.

> If the Session Expiry Interval is 0xFFFFFFFF (UINT_MAX), the Session does not expire.

So I think that "Setting Clean Start to 0 and no Session Expiry Interval, is equivalent to setting CleanSession to 0 in the MQTT Specification Version 3.1.1." is wrong.

It should be "Setting Clean Start to 0 and setting Session Expiry Interval to 0xFFFFFFFF, is equivalent to setting CleanSession to 0 in the MQTT Specification Version 3.1.1." 

Am I missing something?

Thanks,

Takatoshi