[OASIS Issue Tracker] (MQTT-256) Message Format indication

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    [ https://issues.oasis-open.org/browse/MQTT-256?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=59230#comment-59230 ] 

Rick Bullotta commented on MQTT-256:
------------------------------------

Yup.  I agree with your points.  We've addressed that with different (and extensible) serialization and deserialization.  Currently, for example, we have binary, "lean" binary (drops some of the metadata), JSON, compressed JSON (uses tokenization), and XML.  All of the above can be run through a compressor/decompressor as well.  The general metadata and data concepts are serialization agnostic, which is where the power comes in.  

> Message Format indication
> -------------------------
>
>                 Key: MQTT-256
>                 URL: https://issues.oasis-open.org/browse/MQTT-256
>             Project: OASIS Message Queuing Telemetry Transport (MQTT) TC
>          Issue Type: Bug
>          Components: futures
>            Reporter: Peter Niblett
>
> MQTT 3.1.1 does not provide an architected way of indicating the format of the payload that is passed in a PUBLISH packet. We need to avoid the risk of spec or data bloat, and I'm not advocating adding a complicated header structure that passes schemas, messageType indicators, MIME type strings or the like, but at the moment there is no standard way for a receiver even to be able to tell whether the payload is binary or string. 
> There are three ways that this can be dealt with today:
> 1. The Receiver already knows. It's implementing some bigger standard or program design which has dictated the encoding format (e.g. someone decides that all messages will be JSON)
> 2. There is an indicator embedded somewhere in the Topic name (The Topic name is  the only header we have in MQTT 3.1.1). There isn't a standard convention for this, so topic space designers have to choose their own way of doing it.
> 3. The Receiver assumes one format and has a go parsing it. If that doesn't look right it tries another



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