{"id":2667,"date":"2017-07-02T17:41:16","date_gmt":"2017-07-02T15:41:16","guid":{"rendered":"http:\/\/www.jensd.de\/wordpress\/?p=2667"},"modified":"2017-07-03T11:31:11","modified_gmt":"2017-07-03T09:31:11","slug":"unveiled-why-mqtt-v4-0-will-never-be-released","status":"publish","type":"post","link":"https:\/\/www.jensd.de\/wordpress\/?p=2667","title":{"rendered":"“Secret” unveiled: Why MQTT v4.0 will never be released"},"content":{"rendered":"

In 2010 MQTT version 3.1 was released to the public.
\nAbout 4 years later MQTT 3.1.1 became an OASIS Standard.
\nBy end of this year (likely) the next version of the MQTT specification will be released: MQTT v5.0.
\nBut wait! MQTT v3.1.1 and now v5.0? Why isn’t the next release v4.0?<\/p>\n

Well, the root cause lies in the variable header of the MQTT CONNECT Control Packet.
\nThe protocol version or to be more precise, the protocol revision level is set in byte #7<\/a>:<\/p>\n

“The 8 bit unsigned value that represents the revision level of the protocol used by the Client. The value of the Protocol Level field for the version 3.1.1 of the protocol is 4 (0x04).”<\/em><\/strong><\/p>\n

\"\"
MQTT v3.1.1 CONNECT message<\/figcaption><\/figure>\n

 <\/p>\n

The protocol level of v3.1 is defined as 3<\/em> and v3.1.1 is 4<\/em>.
\nHence the next protocol level is 5<\/em>.
\nTo avoid inconsistency the specification group has agreed to name the next MQTT version accordingly<\/a>:<\/p>\n

“The\u00a0value of the Protocol Level field for the version 5.0 of the protocol is 5 (0x05).”<\/em><\/strong><\/p>\n

That\u2019s it ;-)!<\/p>\n

<\/div>\n","protected":false},"excerpt":{"rendered":"

In 2010 MQTT version 3.1 was released to the public. About 4 years later MQTT 3.1.1 became an OASIS Standard. By end of this year (likely) the next version of the MQTT specification will be released: MQTT v5.0. But wait! MQTT v3.1.1 and now v5.0? Why isn’t the next release v4.0? Well, the root cause… <\/span>Continue Reading “Secret” unveiled: Why MQTT v4.0 will never be released<\/span><\/i><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"jetpack_post_was_ever_published":false,"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":true,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"footnotes":"","_jetpack_memberships_contains_paid_content":false,"jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":true,"jetpack_social_options":{"image_generator_settings":{"template":"highway","enabled":false},"version":2}},"categories":[22,42,30,45,4,46,50,57],"tags":[88,101,91,76,102,106,86],"jetpack_publicize_connections":[],"aioseo_notices":[],"jetpack_featured_media_url":"","jetpack_shortlink":"https:\/\/wp.me\/p38FCL-H1","jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/www.jensd.de\/wordpress\/index.php?rest_route=\/wp\/v2\/posts\/2667"}],"collection":[{"href":"https:\/\/www.jensd.de\/wordpress\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.jensd.de\/wordpress\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.jensd.de\/wordpress\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.jensd.de\/wordpress\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=2667"}],"version-history":[{"count":12,"href":"https:\/\/www.jensd.de\/wordpress\/index.php?rest_route=\/wp\/v2\/posts\/2667\/revisions"}],"predecessor-version":[{"id":2681,"href":"https:\/\/www.jensd.de\/wordpress\/index.php?rest_route=\/wp\/v2\/posts\/2667\/revisions\/2681"}],"wp:attachment":[{"href":"https:\/\/www.jensd.de\/wordpress\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=2667"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.jensd.de\/wordpress\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=2667"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.jensd.de\/wordpress\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=2667"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}