[OASIS Issue Tracker] (MQTT-263) Simplified State Management

[OASIS Issues Tracker <workgroup_mailer@lists.oasis-open.org>]

     [ https://issues.oasis-open.org/browse/MQTT-263?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Andrew Banks updated MQTT-263:
------------------------------

    Proposal: 
1) Update the CONNECT packet variable header to replace the 
   Clean Session flag with a Clean Start flag in the same 
   position in the Connect flags. 

   Clean Session is renamed to Clean Start. If set to 1 this causes
   any existing Session State to be deleted on CONNECT
   but not on DISCONNECT. Consequently the Session Present
   flag in CONNACK is always set to 0 if Clean Start is set to 1 
   on CONNECT.

   This bit specifies whether the Session state is deleted when
   a connection is made. Jira 249 - Session State Expiry interval
   contains the definition of the Session State. 

 Non normative comment 
     To ensure consistent state in the event of a failure during connect, 
     where SessionPresent=1, is unexpectedly received, 
     the Client should repeat its attempts to connect with a 
     Clean Start set to 1, until it connects successfully. 
  
 Non Normative comment 
     Setting a Session Expiry interval of 0 and Clean Start to 1, 
     is equivalent to setting Clean Session to 1 in the 
     MQTT Specification Version 3.1.1. 
     Setting no Session Expiry interval and setting Clean Start to 0
     is equivalent to setting Clean Session to 0 in the 
     MQTT Specification Version 3.1.1. 

  was:
1) Update the CONNECT packet variable header to replace the 
   Clean Session flag with a Clean Start flag in the same 
   position in the Connect flags. 

   Clean Session is renamed to Clean Start. If set to 1 this causes
   any existing Session State to be deleted on CONNECT
   but not on DISCONNECT. Consequently the Session Present
   flag in CONNACK is always set to 0 if Clean Start is set to 1 
   on CONNECT.

   This bit specifies whether the Session state is deleted when
   a connection is made. Jira 249 - Session State Expiry interval
   contains the definition of the Session State. 

 Non normative comment 
     To ensure consistent state in the event of a failure during connect, 
     the Client should repeat its attempts to connect with a 
     Clean Start set to 1, until it connects successfully. 
  
 Non Normative comment 
     Setting a Session Expiry interval of 0 and Clean Start to 1, 
     is equivalent to setting Clean Session to 1 in the 
     MQTT Specification Version 3.1.1. 
     Setting no Session Expiry interval and setting Clean Start to 0
     is equivalent to setting Clean Session to 0 in the 
     MQTT Specification Version 3.1.1. 


> Simplified State Management
> ---------------------------
>
>                 Key: MQTT-263
>                 URL: https://issues.oasis-open.org/browse/MQTT-263
>             Project: OASIS Message Queuing Telemetry Transport (MQTT) TC
>          Issue Type: Improvement
>          Components: futures
>    Affects Versions: 5
>            Reporter: Peter Niblett
>
> There could be some more things we do in CONNECT and DISCONNECT to make it easier for client applications to manage stateful Sessions. For example we could consider an option on DISCONNECT that requests an immediate destruction of server state (e.g. pending messages and subscriptions)



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