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Subject: Re: [mqtt-comment] Comments on mqtt-v3.1.1-cos01

On 2014-08-12 19:34, Roger Light wrote:
Hi Nick,

2) I was quite surprised to discover that an additional byte had been
inserted in front of the return code byte in the Connack packet type

The byte in question containing the "session present" flag just
replaces the already existing "reserved" byte of the CONNACK packet,
so there is no break in compatibility.

Ah, whoops. Yes. Phew!

8) I do wish that leading and trailing slashes were forbidden. I think topic
names should either have structure and semantic meaning, or not. The
half-way house of 'use the topic name however you want' and slashes being
significant for pattern-matching is confusing.

Not that I'm disagreeing with you, but the leading/trailing slashes
just create zero length topic hierarchy element at the beginning/end
of the topic. So the topic "/mqtt//comment/" would be split into five
levels, '', 'mqtt', '', 'comment' and ''. The only inconsistency that
I am aware of is that although leading slashes allow you to produce a
topic that starts with a zero length element, there is no way to
address that zero length element itself because zero length topics are
forbidden for some reason.

Hm, interesting. Although it is logical, I doubt many users would immediately understand that.


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