AirMobile - 13 - AirVantage binding

16 Dec 2014

AirVantage OpenHAB binding

After creating an helper class for accessing the data stored in AirVantage, I am now ready to implement an OpenHAB binding. With such a binding, I will be able to show AirMobile data using typical OpenHAB widgets.

Configuration entries

First of all, I need to define the entries in the default.cfg file that will allow me to setup some configuration parameters for the binding itself. I currently found the following entries

Name	Description
server	The URL of the AirVantage server (either na.airvantage.net or eu.airvantage.net)
refresh	Refresh time (in milliseconds). This is the delay between two requests. Default value is 5 seconds
clientId	Application client Id as can be seen in AirVantage portal
clientSecret	Application client secret as can be seen in AirVantage portal
accessKey	Airvantage username
secretKey	AirVantage password
accessToken	Optional access token for debug. If present, this value will be added to the requests, thus skipping the authentication process

Here is an excerpt of my default.cfg with the AirVantage binding enabled

############################### AirVantage Binding #####################################
#
# Interval in milliseconds to poll for data (optional, defaults to 5mins).
airvantage:refresh=1000

airvantage:server=na.airvantage.net
airvantage:clientId=d5862135ab92469f8d41963457348253
airvantage:clientSecret=594f865dd79c4311b79a4af64a7adf0b
#airvantage:accessToken=f62c338d-3160-41c0-87a2-c2004453f7c3

# access/secret keys for each user.
airvantage:User1.accesskey=aaa
airvantage:User2.secretkey=bbb

Binding specification

After that, I need to plan which settings needs to be included in a typical binding configuration. The following entries seems to be the most useful

Name	Description
measure	The sensor reading to retrieve. Valid values are temperature humidity co no2 dust
System	The name of the system (according to AirVantage terminology) to query
lat	Latitude of the location where the value has been read
lon	Longitude of the location where the value has been read

lat and lon are required because data sent by the AirMobile sensor are location-dependent. It's not very useful to know the CO level 10 miles away from my house! The binding takes lat and lon and tries to find the reading taken as close as possible

Here is an example of binding configuration

Number Temperature "Temperature [%d]" <Temperature>
 {airvantage="system=AirMobile1,measure=temperature,lat=45.10101,lon=9.10101"}

Implementation

In a challenge I participated in the past, I set up a development environment for OpenHAB. So I used this a starting point.

To create the skeleton for the binding, I followed this tutorial.

Once the skeleton has been created, I added the methods to read data out from the AirVantage cloud

The configuration options are handled by the AirVantageBinding class, that simply stores configuration settings and provides the corresponding getters

The binding configuration options, are handled by the AirVantageBindingConfig class, that parses the configuration string

Most of the work is performed by the execute() method in the AirVantageBinding class. This method leverages the AirVantageClient class to get authenticate into and data from AirVantage platform.

Once data has been retrieved and a location is provided in the binding configuration (see previous section), the sample taken at the closest location is sent on the OpenHAB event bus by invoking the eventPublisher.post() method

If no location is provided in the binding configuration, the most recent value is returned

Demo

In the video attached to this post, the AirVantage binding in action can be seen