Data Processor URI Scheme

An alternative to configuring data processors is to use a string URI. The configuration URI is a combination of a scheme and query string. The scheme and query string are separated by a question mark (?) and the query fields are separated by an ampersand (&).

"[scheme]?[field1=value1]&[field2=value2]...&[fieldN=valueN]"

The following tables provide a brief overview of the available transformers and filters and their scheme string. Further details about each scheme is given in the below sections.

Processor	Type	Description	Scheme
Accumulator	transformer	Computes a running sum of all data received	accumulator
Average	transformer	Calculates a running average of the input data over a given sample size	average
Comparison	filter	Only allow data through that satisfies the comparison	comparison
Counter	transformer	Counts the number of data samples that pass through	counter
Delta	both	Only allow data through that exceeds a relative offset from a reference value	delta
Math	transformer	Performs a mathematical operation on the input	math
Passthrough	filter	A gate that users can manually control	passthrough
Pulse	transformer	Detects and quantifies a pulse over a set of data	pulse
Rms	transformer	Combines multi-component data by computing root mean square	rms
Rss	transformer	Combines multi-component data by computing root sum square	rss
Sample	filter	Only allow every Nth data sample through	sample
Threshold	both	Only allow data through that crosses a boundary	threshold
Time	both	Periodically allow data through	time

Accumulator

Field	Description	Required
output	Output size of the running sum. If not specified, it will infer the output size based on the input	No

///< equivalent to: process(new Accumulator((byte) 4))
///< accumulate input and allocate 4 bytes for the output regardless of input
process("accumulator?output=4")

///< equivalent to: fromSwitch().process(new Accumulator())
///< accumulate input and infer the output size based in the input signal
///< will implicitly allocate 1 byte because switch data is only 1 byte
fromSwitch().process("accumulator")

Average

Field	Description	Required
sampleSize	How many data samples to compute a running average of	Yes

///< equivalent to: process(new Average((byte) 16))
///< Compute a running average over the past 16 samples
process("average?sampleSize=16")

Comparison

Field	Description	Required
operation	Sets the comparison used to filter data	Yes
reference	Value on the right hand side of the operation the input data is compared to	Yes
signed	Force a signed or unsigned comparison. If not specified, this field will be inferred from the input signal	No

Operation	Description	Value
Equals	True if input and reference are equivalent	eq
Not equals	Opposite result of equals to comparison	neq
Less than	True if input is less than the reference	lt
Less than or Equals	True if input is less than or equal to the reference	lte
Greater Than	True if input is greater than the reference	gt
Greater Than Or Equals	True if input is greater than or equal to the reference	gte

///< equivalent to: process(new Comparison(Comparison.Operation.EQ, 511))
///< Only allow data that is equal to 511 to pass, infer signed or unsigned based on input
process("comparison?operation=eq&reference=511")

///< equivalent to: process(new Comparison(Comparison.Operation.LTE, 511, true))
///< Only allow data less than or equal to 511 to pass, use a signed comparison
process("comparison?operation=lte&reference=511&signed=true")

Counter

Field	Description	Required
size	Size of the counter, between [1, 4] bytes. If not specified, defaults to 1 byte (counts to 255)	No

///< equivalent to: process(new Counter((byte) 2))
///< Count number of samples, up to 65535
process("counter?size=2")

///< equivalent to: process(new Counter())
///< Count number of samples, up to 255
process("counter")

Delta

Field	Description	Required
mode	Sets the operation mode of the delta processor	Yes
threshold	The limit that the relative distance between the current and reference values must exceed	Yes

Mode	Description	Value
Absolute	Output the value as is	abs
Differential	Opposite the difference between the current and reference values	diff
Binary	1 for positive difference, -1 for negative difference	bin

///< Equivalent to: fromTemperature().process(new Delta(Delta.Mode.DIFFERENTIAL, 2.f))
///< Only allow data through that is 2 degrees or higher from a reference value 
///< and output the difference
fromTemperature().process("delta?mode=diff&threshold=2.0")

///< Equivalent to: fromTemperature().process(new Delta(Delta.Mode.BINARY, 4.f))
///< Only allow data through that is 4 degrees or higher from a reference value 
///< and output 1 or -1 to signify positive or negative difference, respectively
fromTemperature().process("delta?mode=bin&threshold=4.0")

Math

Field	Description	Required
operation	Sets the mathematical operation to perform on the data	Yes
rhs	Value on the right hand side of the operation	Depends, yes if operation requires 2 inputs, no otherwise
signed	Force a signed or unsigned operation, If not specified, this field will be inferred from the input signal	No

Operation	Description	Value	# Operands
Addition	Adds the input data with an offset	add	2
Multiplication	Multiplies the input data by a scale factor	mult	2
Division	Divides the input data by a scale factor	div	2
Modulus	Computes the remainder of the input data and a divisor	mod	2
Exponent	Computes exponentiation using the input as the base, and the rhs value as the exponent	exp	2
Square Root	Computes square root of the data	sqrt	1
Left Shift	Performs a left shift of the data	lshift	2
Right Shift	Performs a right shift of the data	rshift	2
Subtraction	Subtracts the input data with an offset	sub	2
Absolute Value	Computes the absolute value of the ipnut	abs	1

///< equivalent to: fromTemperature().process(new Math(Math.Operation.ADD, 273.15))
///< Add 273.15 to the input, infer signed operation based on input
fromTemperature().process("math?operation=add&rhs=273.15")

///< equivalent to: fromTemperature().process(new Math(Math.Operation.ADD, 273.15, true))
///< Add 273.15 to the input with signed addition
fromTemperature().process("math?operation=add&rhs=273.15&signed=true")

Passthrough

Field	Description	Required
mode	Sets the operation mode	Yes
value	Sets the value or condition corresponding to the passthrough mode	Depends, yes for conditional and count modes, no otherwise

Mode	Description	Value
All	Allow all data to pass through	all
Conditional	If value is 0, unconditionally block all data. If value is 1, allow all data through	conditional
Count	Only allow a fixed number of data samples through	count

///< equivalent to: process(new Passthrough())
///< passthrough filter allowing all data through
process("passthrough?mode=all")

///< equivalent to: process(new Passthrough(Passthrough.Mode.CONDITIONAL, (short) 0))
///< do not allow data through for now
process("passthrough?mode=conditional&value=0")

///< equivalent to: process(new Passthrough(Passthrough.Mode.COUNT, (short) 4))
///< only allow 4 samples through
process("passthrough?mode=count&value=4")

Pulse

Field	Description	Required
mode	Sets the output mode of the processor	Yes
threshold	Value the sensor data must exceed for a valid pulse	Yes
width	Number of samples that exceed the threshold	No

Mode	Description	Value
area	Output sum of all data samples in the pulse	area
peak	Output max value in the pulse	peak
width	Output number of samples in the pulse	width

///< equivalent to: process(new Pulse(Pulse.OutputMode.AREA, 1.f, (short) 16))
///< pulse detector looking for a pulse above 1g consisting of min 16 samples
fromXAxis().process("pulse?mode=area&threshold=1.0&width=16")

Rms

No query string required for rms.

///< equivalent to: fromAccelAxis().process(new Rms())
///< Compute RMS value of the accelerometer XYZ axis data
fromAccelAxis().process("rms")

Rss

No query string required for rss.

///< equivalent to: fromAccelAxis().process(new Rss())
///< Compute RSS value of the accelerometer XYZ axis data i.e. vector magnitude
fromAccelAxis().process("rss")

Sample

Field	Description	Required
binSize	Number of elements to	Yes

///< Equivalent to: process(new Sample((byte) 4))
///< Only let every 4th sample through
process("sample?binSize=4")

Threshold

Field	Description	Required
hysteresis	Minimum distance between the limit and value to signal a successful crossing. Use with data that may frequently oscillate around the threshold limit.	No
limit	Boundary the data must cross	Yes
mode	Processor output mode	Yes

Mode	Description	Value
Absolute	Output the value as is	abs
Binary	1 if data rose above the limit, -1 if data fell below the limit	bin

///< Equivalent to: fromTemperature().process(new Threshold(30.f, Threshold.Mode.ABSOLUTE))
///< Only allow data through that crosses the 30 degree limit
fromTemperature().process("threshold?limit=30.0&mode=abs")

///< Equivalent to: fromTemperature().process(new Threshold(30.f, Threshold.Mode.BINARY))
///< Only allow data through that crosses the 30 degree limit, convert the data to 
///< a 1 if higher, or -1 if lower than the limit
fromTemperature().process("threshold?limit=30.0&mode=bin")

Time

Field	Description	Required
mode	Processor output mode	Yes
period	How often to allow data through. Specify value in milliseconds	Yes

Mode	Description	Value
Absolute	Output the value as is	abs
Differential	Output the difference between the current and previous value	diff

///< equivalent to: process(new Time(10000, Time.Mode.DIFFERENTIAL))
///< Allow the difference between the current and previous value through every 10 seconds
process("time?period=10000?mode=diff")

///< equivalent to: process(new Time(15000, Time.Mode.ABSOLUTE))
///< Allow data through every 15 seconds
process("time?period=15000?mode=abs")