Re: [paho-dev] question from IRC

[Dave Locke <locke@xxxxxxxxxx>]

When a client publishes a message and the
client app, network connection or server drop while the message is being
delivered the client holds onto the message. It will deliver the message
when connectivity is re-established as long as, the client connected with
cleansession set to false and the message was published at a quality of
service greater than zero.  One method to track the delivery status
of a message is to use a delivery token. As the delivery may complete across
restarts of the client or connection the delivery token has a life across
client and connection instances. 

In the case where connectionLost is
driven and then the connection is re-stablished the original deliveyToken
for messages still to be delivered can be used to track the delivery of
the message,

In the case where the MQTT client instance
is closed (maybe the process is terminated) and the MQTT client is reinstantiated
the set of delivery tokens for messages that were previously published
but delivery had not completed can be obtained by using the  getPendingDeliveryTokens()
method prior to connecting,   


All the best 
Dave
  



From:      
 Andy Piper <andypiperuk@xxxxxxxxx>
To:      
 General development
discussions for paho project <paho-dev@xxxxxxxxxxx>
Date:      
 04/06/2013 23:40
Subject:    
   [paho-dev] question
from IRC
Sent by:    
   paho-dev-bounces@xxxxxxxxxxx

---

From #mqtt on freenode, something I was asked but
missed responding to
last week:

16:56:01] <g00s> andypiper if you are around, the paho java docs
say
about IMqttDeliveryToken "Unlike instances of IMqttToken delivery
tokens can be used across connection and client restarts." … can
you
explain this? i dont follow

Dave - any comments? Sounds like something that could be clarified. NB
we also need to update the online Javadoc asap.


--
Andy Piper | Farnborough, Hampshire (UK)
blog: http://andypiper.co.uk
  |   skype: andypiperuk
twitter: @andypiper  |  images: http://www.flickr.com/photos/andypiper
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