We are pleased to announce that MQTT Version 5.0 from the MQTT TC  is now available for public review and comment. This release has been updated based on feedback from the previous public review. The comments received in that review and their resolution can be found at http://docs.oasis-open.org/mqtt/mqtt/v5.0/csprd01/mqtt-v5.0-csprd01-comment-resolution-log.doc.
MQTT is a Client Server publish/subscribe messaging transport protocol. It is light weight, open, simple, and designed to be easy to implement. These characteristics make it ideal for use in many situations, including constrained environments such as for communication in Machine to Machine (M2M) and Internet of Things (IoT) contexts where a small code footprint is required and/or network bandwidth is at a premium.
The protocol runs over TCP/IP, or over other network protocols that provide ordered, lossless, bi-directional connections. Its features include:
– Use of the publish/subscribe message pattern which provides one-to-many message distribution and decoupling of applications.
– A messaging transport that is agnostic to the content of the payload.
– Three qualities of service for message delivery:
– “At most once”, where messages are delivered according to the best efforts of the operating environment. Message loss can occur. This level could be used, for example, with ambient sensor data where it does not matter if an individual reading is lost as the next one will be published soon after.
– “At least once”, where messages are assured to arrive but duplicates can occur.
– “Exactly once”, where messages are assured to arrive exactly once. This level could be used, for example, with billing systems where duplicate or lost messages could lead to incorrect charges being applied.
– A small transport overhead and protocol exchanges minimized to reduce network traffic.
– A mechanism to notify interested parties when an abnormal disconnection occurs.
The documents and related files are available here:
MQTT Version 5.0
Committee Specification Draft 02 / Public Review Draft 02
26 October 2017
Editable source (Authoritative):
For your convenience, OASIS provides complete packages of the prose specifications and related files in ZIP distribution files. You can download the ZIP files at:
How to Provide Feedback
OASIS and the MQTT TC value your feedback. We solicit feedback from potential users, developers and others, whether OASIS members or not, for the sake of improving the interoperability and quality of its technical work.
This public review starts 17 November 2017 at 00:00 UTC and ends 02 December 2017 at 11:59 UTC.
This specification was previously submitted for public review . Changes are highlighted in red-lined file included in the package . Comments for this draft is limited to the changes from the previous public review.
Comments on the work may be submitted to the TC by following the instructions located at:
Feedback submitted by TC non-members for this work and for other work of this TC is publicly archived and can be viewed at:
All comments submitted to OASIS are subject to the OASIS Feedback License, which ensures that the feedback you provide carries the same obligations at least as the obligations of the TC members. In connection with the public review of these works, we call your attention to the OASIS IPR Policy  applicable especially  to the work of this technical committee. All members of the TC should be familiar with this document, which may create obligations regarding the disclosure and availability of a member’s patent, copyright, trademark and license rights that read on an approved OASIS specification.
OASIS invites any persons who know of any such claims to disclose these if they may be essential to the implementation of the above specification, so that notice of them may be posted to the notice page for this TC’s work.
Additional information about this specification and the MQTT TC may be found on the TC’s public home page.
========== Additional references:
 OASIS Message Queuing Telemetry Transport (MQTT) TC
 Previous public reviews:
– 30-day public review, 10 August 2017:
– Comment resolution log:
 Red-lined copy of the specification: