Phonebot developer's reference/Object reference/Using Phonebot services

Services are non-visual components that monitor different environment states and trigger an event when the state changes. The available services are:

• http - Make web requests
• sensor - Monitor hardware sensors
• timer - Alert at specific intervals

When a service is updated, its OnUpdate event fires, then the application's OnService event fires, and finally the current module's OnService event fires.

Each Service stores its update data in a queue. The methods get_event() and pop_event() access the next event in the queue and event_size returns how many events exist.

The maximum number of sensor events that will be retained in the queue is controlled by the "Sensor buffer" Phonebot property. The "Sensor buffer" value, the sensor service's "Minimum update frequency" value, and the amount of script within each OnUpdate and OnService event will determine how responsive your application is when reading sensor data. If updates are sluggish, try reducing the buffer size.

Service lifecycle

A service's properties, methods, and the application state affect that service's lifetime as the following diagram illustrates:

A service will start running:

• When its start() method is called
• If its autostart property is set to true, immediately after the application starts

A service will stop running:

• When its stop() method is called
• If its system property is set to false, when the application loses focus
• If its system property is set to true, when the application exits

Object reference

Properties

Syntax	Description
auto_start	Read-only.
event_size	Read-only. The number of events in the queue. When monitoring multiple services, this property can be used in on_service events to determine which service was updated.
name	Read-only.
text	Read-only.

Methods

Syntax	Description
size = clear_events()	Delete all events and return how many were deleted.
event = get_event()	Retrieve the next event in the queue.
value = get_property(name)	Retrieve a service property.
event = pop_event()	Retrieve and delete the next event in the queue.
set_property(name, value)	Set a service property.
start()	Start the service.
stop()	Stop the service.

Events

Syntax	Description
on_service

In addition to the common properties, methods, and events, each service may have custom properties:

Service	Properties	Description
http	url	Makes a GET request to a URL. Returns a single event in the queue containing the response.
sensor	sensors - array of sensor names update_frequency - time between updates in milliseconds	Monitors one or more hardware sensors. Returns an event containing a comma-delimited list of values beginning with the sensor name (e.g. orientation,60.0,-28.0,3.0). The range of each value is dependent on the sensor.
timer	duration - time between updates, formatted as h:m:s, m:s, or s	Fire the update events at regular intervals. The event will first fire immediately after the service is started. Returns an event containing the datetime value when the update happened.

Events can be accessed and parsed in the following manner:

HTTP:

event = http_service.pop_event()
// query with XPath
items = event:xml.query("//root/item")
// read json data
root = event:json.get_element("root")
items = event:json.get_element("item")

Sensor:

event = sensor_service.pop_event()
event = event:string.split(",")
name = event:array.get_element(0)
// get values from index 1 and greater

Timer:

event = timer_service.pop_event()
event = event:datetime.format("HH:mm:ss")

The sensor service can be configured to return any combination of sensor types. Each type has its own name and data format as described below:

Name	Structure of event value (actual values are prefixed with the name, i.e. name,value1,value2,...)	Description
accelerometer	x,y,z	Acceleration in meters/second^2
gps	latitude,longitude,accuracy,altitude,bearing,speed
gravity	x,y,z	Gravity in meters/second^2
gyroscope	x,y,z	Angular speed in radian/second
light	l	Ambient light in lux units
linear_acceleration		Acceleration in meters/second^2
magnetic_field	x,y,z	Magnetic field in micro-Teslas
orientation	azimuth,pitch,roll	Measured in degrees. 0=North, 90=East, 180=South, 270=West; -180..180; -90..90
pressure	p	Atmospheric pressure in millibars
proximity	p	Proximity in centimeters
rotation_vector
temperature

--SensorEvent values