Software Engineering 2 A practical course in software engineering

Ekkart Kindler

Tutorial 5:

M2M Interaction with openHAB

Ekkart Kindler Task

Based on task from Tutorial 5,

develop an Android App, which triggers a

switch in openHAB when the mobile enters or

exits the proximity of DTU or your home

e.g. using a Mosquito server, MQTT client on

the mobile side, and the openHAB MQTT

bindings

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Ekkart Kindler

Concepts

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Ekkart Kindler Overview

MQTT (MQ Telemetry Transport):

Lightweight pub/sub messaging protocol

MQTT: servers and (Java) clients

openHAB MQTT binding:

Items receiving and sending MQTT messages

openHAB Rules:

Event Condition Action-like rule enigne

openHAB REST API

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Ekkart Kindler MQ Telemetry Transport

Publication and subscription service (pub/sub) for

messages

Messages arranged in hierarchical topics: e.g.

dk.dtu.se2.e17.grA/home1/proximity

Message content is user defined

(technically an array of bytes)

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Ekkart Kindler MQ Telemetry Transport

Clients can publish messages on topics

Topics do not need to be explicitly defined

Clients can subscribe for topics and will be notified

when a message on the topic are published

Wildcards for subscription:

+ for an arbitrary level: e.g. dk.dtu.se2.e17.grA/+/proximity

# for a complete subtree: e.g. dk.dtu.se2.e17.grA/#

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Ekkart Kindler MQTT: server

There are different MQTT servers available:

Mosquitto

HiveMQ

For the task and project you can either install a

server on your VM or use an freely available server

(e.g. http://test.mosquitto.org/)

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Ekkart Kindler MQTT: clients

For programming clients (publish/subscribe), there

are different libraries available

For Java (including Android): e.g. Paho

For messages the client subscribed to, a listener

can be registered. This listener is invoked when a

message of the respective topic is received

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Ekkart Kindler MQTT: openHab binding

OpenHAB comes with an MQTT binding

The MQTT binding allows to configure openHAB

items to send (publish) and receive MQTT

messages (subscribe to)

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Ekkart Kindler MQTT Links

MQTT: http://mqtt.org/

Paho: https://www.eclipse.org/paho/clients/j

ava/

Paho API: http://www.eclipse.org/paho/files/java

doc/index.html

Paho Example (at Git Hub): https://github.com/eclipse/paho.mqtt.j

ava/tree/master/org.eclipse.paho.sampl

e.mqttv3app/src/main/java/org/eclipse/

paho/sample/mqttv3app 11 SE2 (02162 e17), T05

Ekkart Kindler MQTT Links

MQTT openHAB binding: http://docs.openhab.org/addons/binding

s/mqtt1/readme.html

HTTP openHAB binding: http://docs.openhab.org/addons/binding

s/http1/readme.html

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Ekkart Kindler Overview

MQTT (MQ Telemetry Transport):

Lightweight pub/sub messaging protocol

MQTT: servers and (Java) clients

openHAB MQTT binding:

Items receiving and sending MQTT messages

openHAB Rules:

Event Condition Action-like rule enigne

openHAB REST API

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Ekkart Kindler ECA-Rules

ECA (Event Condition Action) rule:

WHEN <event>

IF <condition>

DO <action>

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Ekkart Kindler openHAB rules

openHAB comes with a rule engine for ECA-rules

Rules can be set up in openHAB,

and will then be executed by the openHAB rule

engine

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Ekkart Kindler Example

rule "corLightOn"

when

Item corMotion changed

from OFF to ON or

Item corFrontDoor changed

from CLOSED to OPEN

then

if(corBright.state < 40) {

sendCommand(corLightCeil, ON) }

end

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Ekkart Kindler openHAB Rules

Events can refer to

item-events events

time

state changes of system

state changes of things

Actions formulated in Xtend, a language based on

and interoperable with Java

Actions can

change states

issue commands

use state

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Ekkart Kindler Links

More examples: https://github.com/openhab/openhab1-

addons/wiki/Samples-Rules

https://github.com/openhab/openhab1-

addons/wiki/Rule-example:-Combining-

different-items

Technical information and setup: http://docs.openhab.org/configuration/

rules-dsl.html

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Ekkart Kindler openHAB Rest API

openHAB can also be accessed from other

programs via a REST API

For details, see

http://docs.openhab.org/configuration/restdocs.html

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