Info on mqtt5 release.

www/posts/2019/02/mqtt5-test-release.md

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+<!--
+.. title: MQTT 5 Test Release
+.. slug: mqtt5-test-release
+.. date: 2019-02-14 10:30:00 UTC
+.. tags: Releases
+.. category:
+.. link:
+.. description:
+.. type: text
+-->
+
+The work on MQTT v5 support in Mosquitto has reached a point where it may be of interest to a range of people. It is not yet complete, but wider testing and feedback would be appreciated.
+
+The source is available at [mosquitto-mqtt5-test1.tar.gz] and can be compiled as normal.
+
+## Supported features
+
+* Session expiry
+* Message expiry
+* Reason code on all ACKs (not all reason codes are used)
+* Reason string on all ACKs (no reason strings are provided by the broker however)
+* Payload format and content type
+* Request / response pattern
+* Subscription ID
+* Topic alias
+* Flow control
+* User properties
+* Optional server feature availability
+* Subscription options
+* Server keep alive
+* Assigned Client ID
+
+
+## Unsupported features
+
+* Shared subscriptions
+* Extended authentication
+* Server reference
+* Not all reason codes are used by the broker
+* Bridges do not use MQTT v5
+* On disk persistence does not include MQTT 5 property support
+* The broker will not create topic aliases
+
+
+[mosquitto-mqtt5-test1.tar.gz]: https://mosquitto.org/files/source/test/mosquitto-mqtt5-test1.tar.gz