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--- tut:mqtt [2018-06-22 16:59]
jk created
+++ tut:mqtt [2018-07-20 18:31] (current)
jk
@@ Line 3: / Line 3: @@
 ... see [[https://en.wikipedia.org/wiki/MQTT|Wikipedia]]
+... see [[https://www.hivemq.com/blog/mqtt-essentials-part-1-introducing-mqtt]]
+... see [[https://blog.doubleslash.de/mqtt-fuer-dummies/]]
 ===== MQTT Data Flow by Examples =====
@@ Line 15: / Line 18: @@
 {{ :tut:mqtt:mqtt1.svg?600x0 }}
-If Client X publishes any data with Topic 1 and nobody is listening (nobody has subscribed Topic 1) the data is lost.
+If Client X publishes any data with Topic 1 and nobody is listening (nobody has subscriped Topic 1) the data is lost.
 (Exception: see Topics with Retain Flag)
@@ Line 22: / Line 25: @@
   * Client A connected
-  * Client B connected and subscribes Topic 2
+  * Client B connected and subscripes Topic 2
 {{ :tut:mqtt:mqtt2.svg?600x0 |}}
@@ Line 31: / Line 34: @@
   * Client A, C, E connected
-  * Client B connected and subscribes Topic 2
+  * Client B connected and subscripes Topic 2
-  * Client F connected and subscribes Topic 3
+  * Client F connected and subscripes Topic 3
 {{ :tut:mqtt:mqtt3.svg?600x0 }}
-Any Client can publish any data with any Topic at anytime. The subscriping Clients are notified instantly about change of the Topics they subscripes and only that.
+Any Client can publish any data with any Topic at anytime. The subscribing Clients are notified instantly about change of the Topics they subscripes and only that.
 ==== Example: Many Publisher, 1 Subscriber with Wildcard ====
   * Client A, C, E connected
-  * Client D connected and subscribes Topic with '#'
+  * Client D connected and subscripes Topic with '#'
 {{ :tut:mqtt:mqtt4.svg?600x0 }}
@@ Line 49: / Line 52: @@
 ==== Example: Request and Answer ====
-  * Client E connected and subscribes Topic 4
+  * Client E connected and subscripes Topic 4
-  * Client F connected and subscribes Topic 3
+  * Client F connected and subscripes Topic 3
 {{ :tut:mqtt:mqtt5.svg?600x0 }}
-Every Client can be publisher and subscriper. For sneding a request/command one Topic can be used. For the answer an other Topic is used.
+Every Client can be publisher and subscriber. For sneding a request/command one Topic can be used. For the answer an other Topic is used.
 Note: This can be solved with only one Tpoic but the publisher would receive his own request/command.
@@ Line 61: / Line 64: @@
   * Client G connected
-  * Client H connected and subscribes Topic 5 with QoS
+  * Client H connected and subscripes Topic 5 with QoS
 {{ :tut:mqtt:mqtt6.svg?600x0 }}
@@ Line 74: / Line 77: @@
 |2|garantee that data arrives only once|
-Note: Each publisher and each subscriper can user the QoS flag without affecting the others.
+Note: Each publisher and each subscriber can user the QoS flag without affecting the others.
 ==== Example: Remain-Flag ====
   * Client Y was connected long time ago
-  * Client Z connects now and subscribes Topic 6
+  * Client Z connects now and subscripes Topic 6
 {{ :tut:mqtt:mqtt7.svg?600x0 }}
@@ Line 90: / Line 93: @@
 |0|fire and forget|
 |1|saved on broker|
+===== Topic Wording =====
+There is no law that you have to name your topics in a special way. So the following names are (principle) correct:
+  * /MyHome/Kitchen/Temperature
+  * /MYHOME/KITCHEN/TEMPERATURE
+  * MyHome/Kitchen/Temperature
+  * MyHome.Kitchen.Temperature
+  * MyHomeKitchenTemperature
+  * MHKT
+  * /Temperature/Kitchen/MyHome
+  * 42
+But there are some guidelines for names that all clinets can filter and handle subscriptions in an easy way:
+  * The topic begins with a '/'
+  * The topic do NOT end with a '/'
+  * A '/' seperates topic levels
+  * The topic levels starts with the most commen level
+So the recommented name is:
+  * /MyHome/Kitchen/Temperature
+===== Subscription Wildcard Examples =====
+==== Exact Match ====
+On subscribing **"/MyHome/Kitchen/Temperature"** you get:
+  * **/MyHome/Kitchen/Temperature**
+  * <del>/MyHome/Kitchen/Humity</del>
+  * <del>/MyHome/Kitchen/Fridge/Temperature</del>
+  * <del>/MyHome/Livingroom/Temperature</del>
+  * <del>/MyHome/Livingroom/Humity</del>
+  * <del>/MyGarden/Air/Temperature</del>
+  * <del>/MyGarden/Pool/Temperature</del>
+==== # Wildcard ====
+On subscribing **"/#"** you get:
+  * /MyHome/Kitchen/Temperature
+  * /MyHome/Kitchen/Humity
+  * /MyHome/Kitchen/Fridge/Temperature
+  * /MyHome/Livingroom/Temperature
+  * /MyHome/Livingroom/Humity
+  * /MyGarden/Air/Temperature
+  * /MyGarden/Pool/Temperature
+On subscribing **"/MyHome/#"** you get:
+  * **/MyHome/**Kitchen/Temperature
+  * **/MyHome/**Kitchen/Humity
+  * **/MyHome/**Kitchen/Fridge/Temperature
+  * **/MyHome/**Livingroom/Temperature
+  * **/MyHome/**Livingroom/Humity
+  * <del>/MyGarden/Air/Temperature</del>
+  * <del>/MyGarden/Pool/Temperature</del>
+On subscribing **"/MyHome/Kitchen/#"** you get:
+  * **/MyHome/Kitchen/**Temperature
+  * **/MyHome/Kitchen/**Humity
+  * **/MyHome/Kitchen/**Fridge/Temperature
+  * <del>/MyHome/Livingroom/Temperature</del>
+  * <del>/MyHome/Livingroom/Humity</del>
+  * <del>/MyGarden/Air/Temperature</del>
+  * <del>/MyGarden/Pool/Temperature</del>
+==== + Wildcard ====
+On subscribing **"/MyHome/+/Temperature"** you get:
+  * **/MyHome/**Kitchen**/Temperature**
+  * <del>/MyHome/Kitchen/Humity</del>
+  * <del>/MyHome/Kitchen/Fridge/Temperature</del>
+  * **/MyHome/**Livingroom**/Temperature**
+  * <del>/MyHome/Livingroom/Humity</del>
+  * <del>/MyGarden/Air/Temperature</del>
+  * <del>/MyGarden/Pool/Temperature</del>
+On subscribing **"/+/+/Temperature"** you get:
+  * /MyHome/Kitchen**/Temperature**
+  * <del>/MyHome/Kitchen/Humity</del>
+  * <del>/MyHome/Kitchen/Fridge/Temperature</del>
+  * /MyHome/Livingroom**/Temperature**
+  * <del>/MyHome/Livingroom/Humity</del>
+  * /MyGarden/Air**/Temperature**
+  * /MyGarden/Pool**/Temperature**
+On subscribing **"/+/+/+/Temperature"** you get:
+  * <del>/MyHome/Kitchen/Temperature</del>
+  * <del>/MyHome/Kitchen/Humity</del>
+  * /MyHome/Kitchen/Fridge**/Temperature**
+  * <del>/MyHome/Livingroom/Temperature</del>
+  * <del>/MyHome/Livingroom/Humity</del>
+  * <del>/MyGarden/Air/Temperature</del>
+  * <del>/MyGarden/Pool/Temperature</del>

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