Here, you will probably need to request a specific URL content using a GET request. Then you will need to parse the received result, which is probably in JSON or XML. Take a look at http://stackoverflow.com/questions/4216455/get-page-content-from-url
All of this will be implemented in the onRun() method of your plugin.
This method is already threaded so there is no need to create additional execution threads. It can be executed just one time or in a loop with some delay between the calls. To do this, just call this method in your plugin constructor:
setPollingWait(2000);
This way the onRun() method is executed in a dedicated thread every 2
seconds. To disable the loop execution, just set it with a negative
value:
setPollingWait(-1);
We want it to the read temperature value for London using Weather Underground’s APIs.
This event changes the temperature value of a thing on the map configured with protocol “weather-underground” and address “london”. The temperature value is stored into a java variable “londonTemperature”.
//This value should be read from weather underground APIs in a real use case
int londonTemperature=21;
//Change the 'London Thermometer' object value
ProtocolRead event = new ProtocolRead(this, "weather-underground", "london");
//specify a freedomotic object type and name for the autodiscovery feature
event.addProperty("object.class", "Thermometer");
event.addProperty("object.name", "London Thermometer");
//set the 'temperature' behavior of 'LondonThermometer' object to 21
event.addProperty("behavior.name", "temperature");
event.addProperty("behaviorValue", londonTemperature);
//send the event to freedomotic
notifyEvent(event);
If you just want to notify an event which is not directly related to the object’s states, it can be done in the following way: Events are published by plugins on messaging channels. A series of useful events is predefined in Freedomotic but you can create your own or simply use the GenericEvent class.
Every action in the real environment and every interaction with Freedomotic (eg: a click on the GUI) is mapped to an event. Events can be intercepted by triggers, and you can assign one or more commands to a trigger, changing the behavior of the system at runtime.
GenericEvent knowItAll = new GenericEvent(this);
//42 is the answer to the Ultimate Question of Life, the Universe, and Everything
//http://en.wikipedia.org/wiki/Answer_to_Life,_the_Universe,_and_Everything
event.addProperty("ultimate.question.answer", 42);
//set a channel on which this event should be sent
event.setDestination("app.event.sensor.deepthought");
//sends the event on the messaging bus
notifyEvent(event);
Now a trigger can listen to app.event.sensor.deepthought this way
<trigger>
<name>You know the right answer to Life</name>
<channel>app.event.sensor.deepthought</channel>
<payload>
<payload>
<statement>
<logical>AND</logical>
<attribute>ultimate.question.answer</attribute>
<operand>EQUAL</operand>
<value>42</value>
</statement>
</payload>
</payload>
</trigger>
and then you can create automations like WHEN [You know the right answer to Life] THEN [send me an email]
Besides the all purpose GenericEvent, some useful events are predefined in freedomotic. Look at this list http://freedomotic.com/javadoc/it/freedomotic/events/package-frame.html
Note
If your plugin’s main purpose is to change the state of an object on the map (eg: set thermometer object value to the value read from Google Weather) then you should follow option 1.
A trigger can listen on an events channel and filter the event content.
If your event notifies about the outdoor temperature, then you can have a trigger
called Outside is cold which fires if temperature is less than 10°C.
You should provide this trigger along with your plugin in its data/trg
folder. To know more about triggers definition take a look at this page
/content/triggers.
TODO