Problem with DSL and Business Rules creation in Drools
- by jillika iyer
Hi,
I am using Eclipse with the Drools plugin to create rules.
I want to create business rules and main aim is to try and provide the user a set of options which he can use to create rules.
For eg:If an Apple can have only 3 colors: I want to provide an option like a drop down so that the user can know before hand which are the options he can use in his rules.
Is it possible?
I am creating a dsl but unable to still provide the above functionality for a business rule.
I am having an error implementing a basic dsl also.
The code to add the dsl is as follows in my RuleRunner class()
InputStream ruleSource = RuleRunner.class.getClassLoader().getResourceAsStream("/Rule1.dslr");
InputStream dslSource = RuleRunner.class.getClassLoader().getResourceAsStream("/sample-dsl.dsl");
//Load the rules , using DSL
addRulesToThisPackage.addPackageFromDrl(
new InputStreamReader(ruleSource),new InputStreamReader(dslSource));
I have both the sample-dsl .dsl and Rule1.dslr in my working directory.
Error encountered at adding the dsl to the package (last line)
Error stack:
Exception in thread "main" java.lang.NullPointerException
at java.io.Reader.<init>(Unknown Source)
at java.io.InputStreamReader.<init>(Unknown Source)
at com.org.RuleRunner.loadRuleFile(RuleRunner.java:96)
at com.org.RuleRunner.loadRules(RuleRunner.java:48)
at com.org.RuleRunner.runStatelessRules(RuleRunner.java:109)
at com.org.RulesTest.main(RulesTest.java:41)
my dsl file has basic mapping as per the online documentations.
The dsl rule I created is:
expander sample-dsl.dsl
rule "A status changes B status"
when
There is an A
- has an address
There is a B
- has name
then
- print updated A and Aaddress
End
I have created DSL in eclipse.
Is the code I added for it to be loaded to my package correct?? Or am I missing something????
It seems like my program is unable to find the dsl?
Please help. Can you point me towards the right direction to create a user friendly business rule ??
Thanks.
J
