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Scripting

Joule provides a flexible and extendable model of component development which includes executing external scripts or defined expression within the use case DSL. 
Currently only Javascript is supported with additonal languages being added with respect to roadmap commitments. 
Example
The below Javascript expression calculations the total compensation using StreamEvent fields which are passed in to the processing context.
scripting:
    expression: salary + bonus + pensionContribution
    expand all: true
Attributes
Attribute
Description
Data Type
Required
expression
Expression to evaluate against the passed event
String
script
Name and location of script to be used
String
method
Method to call within script
String
Default: processEvent
response attribute
Name of attribute to be used when adding the result in to the StreamEvent object.
​
If the processor is set as stateful this value is also added to the processing context.
String
Default: result
response datatype
Response data type returned from either the expressoin or script method.
​
Supported data types: DOUBLE, FLOAT, LONG, INTEGER, SHORT, BYTE, BOOLEAN, STRING
String
Default: DOUBLE
expand all
Expand all StreamEvent attributes within the scripting process context to enable access
Boolean
Default:
stateful
Cache and reuse the response attribute for further processing.
Boolean
Default: false
External scripts
The processor can also load external javascript script which may have complex set of functions that can be leveraged. 
Example
The below DSL definition will load totalCompensationCalc.js file in to the scripting engine, execute the totalCompensationCalc with the result as totalCompensation being added to the the StreamEvent object.
scripting:
    method: totalCompensationCalc
    response attribute: totalCompensation
    script: /var/joule/scripts/totalCompensationCalc.js
Example Javascript file
Simple example which demostrates the key capability.
function totalCompensationCalc(){
    return salary + bonus + pensionContribution;
}
Language Support
The following languages are supported using external file execution. Currently only a single langauge is supported, however there is work underway to extend this to more languages.
Javascript

Attribute	Description	Data Type
expression	Expression to evaluate against the passed event	String
script	Name and location of script to be used	String
method	Method to call within script	String Default: processEvent
response attribute	Name of attribute to be used when adding the result in to the StreamEvent object. If the processor is set as stateful this value is also added to the processing context.	String Default: result
response datatype	Response data type returned from either the expressoin or script method. Supported data types: DOUBLE, FLOAT, LONG, INTEGER, SHORT, BYTE, BOOLEAN, STRING	String Default: DOUBLE
expand all	Expand all StreamEvent attributes within the scripting process context to enable access	Boolean Default:
stateful	Cache and reuse the response attribute for further processing.	Boolean Default: false

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Last modified 10mo ago