Python Read and Write

This tutorial is very simple we start two sripts mimicing two devices talking to each other one acting as a device with two values a PIR motion sensor and a RELAY that can toggle “true” “false”.

Two scripts talking

Preparations

you need an environment that can run python scripts.

Two friending JID’s

Setup two accounts on your favourite XMPP site for example jabber.se. Use any jabber client to test the accounts and make sure they are friends.

Get the python code

Clone the code from github. Soon released through SleekXMPP

>$ git clone -b xep_0323_325 https://github.com/joachimlindborg/SleekXMPP.git

start the server device

go down to the IoT example catalog. And start one script

>$ cd SleekXMPP/examples/IoT
>$ python IoT_TestDevice.py -j yourthing@jabber.se -p passwd -n test
INFO     Negotiating TLS
INFO     Using SSL version: 3
WARNING  Could not find pyasn1 and pyasn1_modules. SSL certificate COULD NOT BE VERIFIED.
INFO     JID set to: yourthing@jabber.se/544301500141697366520183
WARNING  Could not find pyasn1 and pyasn1_modules. SSL certificate expiration COULD NOT BE VERIFIED.

giving a - - debug flag would give more information

>$ python IoT_TestDevice.py -j yourthing@jabber.se -p passwd -n test --debug
DEBUG    Loaded Plugin: RFC 6120: Stream Feature: STARTTLS
DEBUG    Loaded Plugin: RFC 6120: Stream Feature: Resource Binding
DEBUG    Loaded Plugin: RFC 3920: Stream Feature: Start Session
DEBUG    Loaded Plugin: RFC 6121: Stream Feature: Roster Versioning
DEBUG    Loaded Plugin: RFC 6121: Stream Feature: Subscription Pre-Approval
DEBUG    Loaded Plugin: RFC 6120: Stream Feature: SASL
DEBUG    Loaded Plugin: XEP-0030: Service Discovery
DEBUG    Loaded Plugin: XEP-0323 Internet of Things - Sensor Data
DEBUG    Loaded Plugin: XEP-0325 Internet of Things - Control
DEBUG    Loaded Plugin: XEP-0199: XMPP Ping
DEBUG    Device object started nodeId test
DEBUG    fields{'Counter': {'dataType': None, 'type': 'numeric', 'unit': 'Count'}, 'Relay': {'dataType': None, 'type': 'numeric', 'unit': 'Bool'}}
DEBUG    momentary{}
DEBUG    momentary updated{'Counter': {'flags': {'momentary': 'true', 'automaticReadout': 'true'}, 'value': '0'}}
DEBUG    fields{'Counter': {'dataType': None, 'type': 'numeric', 'unit': 'Count'}, 'Relay': {'dataType': None, 'type': 'numeric', 'unit': 'Bool'}}
DEBUG    momentary{'Counter': {'flags': {'momentary': 'true', 'automaticReadout': 'true'}, 'value': '0'}}
DEBUG    momentary updated{'Counter': {'flags': {'momentary': 'true', 'automaticReadout': 'true'}, 'value': '0'}, 'Relay': {'flags': {'writable': 'true', 'momentary': 'true', 'automaticReadout': 'true'}, 'value': '0'}}

Reading a value from a device

We now start a script that every 6th seconde reads all values from the first.

>$ cd SleekXMPP/examples/IoT
>$ python IoT_TestDevice.py -j anotherthing@jabber.se -p passwd -g
yourthing@jabber.se --delay 6
INFO     Negotiating TLS
INFO     Using SSL version: 3
WARNING  Could not find pyasn1 and pyasn1_modules. SSL certificate COULD NOT BE VERIFIED.
INFO     JID set to: anotherthing@jabber.se/28
WARNING  Could not find pyasn1 and pyasn1_modules. SSL certificate
expiration COULD NOT BE VERIFIED.

INFO     IoT SEND 323 REQ <iq to="yourthing@jabber.se/98" from="anotherthing@jabber.se/28" id="2" type="get"><req xmlns="urn:xmpp:iot:sensordata" seqnr="2" momentary="true" /></iq>
INFO     IoT RECIEVE <message to="anotherthing@jabber.se/28" from="yourthing@jabber.se/28" xml:lang="en"><fields xmlns="urn:xmpp:iot:sensordata" seqnr="2" done="true"><node nodeId="test"><timestamp value="2015-02-10T03:26:26"><numeric unit="Count" automaticReadout="true" name="Counter" value="3" momentary="true" /><boolean writable="true" automaticReadout="true" name="relay" value="False" momentary="true" /></timestamp></node></fields></message>
INFO     we got fields from yourthing@jabber.se/28 on node test
INFO     (test Counter 3) Count [momentary,automaticReadout,]
INFO     (test relay False) [writable,momentary,automaticReadout,]

Writing a value to a device

keep the two scripts above running and start a third one sending a value change True on the “Toggle” field every 10th second

>$ cd SleekXMPP/examples/IoT
>$ python IoT_TestDevice.py -j anotherthing@jabber.se -p passwd -c
yourthing@jabber.se --field "Toggle" --value "True" --delay 10
INFO     Negotiating TLS
INFO     Using SSL version: 3
WARNING  Could not find pyasn1 and pyasn1_modules. SSL certificate COULD NOT BE VERIFIED.
INFO     JID set to: anotherthing@jabber.se/28
WARNING  Could not find pyasn1 and pyasn1_modules. SSL certificate
expiration COULD NOT BE VERIFIED.

INFO     IoT will set Toggle to True on to {u'28': {'status': u'',
'priority': 0, 'show': u''}}
INFO     Control callback from yourthing@jabber.se/98 result OK error None
INFO     IoT will set Toggle to True on to {u'28': {'status': u'',
'priority': 0, 'show': u''}}
INFO     Control callback from yourthing@jabber.se/98 result OK error None

You now see the value of the relay changing once in a while in script reading values from the first instance.

What have you done?

You have now sent standardized calls between to endpoints that can be on any federated xmpp server on internet there are several https://xmpp.net/directory.php. Just imagin how devices now can talk between companies in a defined way.

Joachim Lindborg

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