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@evacchi
Created June 26, 2021 12:24
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jbang drools.java
///usr/bin/env jbang "$0" "$@" ; exit $?
//DEPS org.drools:drools-engine:7.56.0.Final
//DEPS org.drools:drools-mvel:7.56.0.Final
//DEPS org.drools:drools-mvel:7.56.0.Final
//DEPS org.slf4j:slf4j-nop:1.7.31
//DEPS com.fasterxml.jackson.core:jackson-databind:2.12.3
// example
// jbang <url> '{ "name":"Mario", "age":40 }' '{ "name":"Mark", "age":37 }'
package org.kie.example;
import static java.lang.System.*;
import org.kie.api.*;
import org.kie.api.builder.*;
import org.kie.api.runtime.*;
import com.fasterxml.jackson.databind.ObjectMapper;
public class drools {
public static record Person(String name, int age) {}
final static String drl = """
package org.kie.example;
import org.kie.example.drools.*;
rule MyRule when
$mark: Person(name == "Mark")
$older: Person(name != "Mark" && age > $mark.age)
then
System.out.printf("%s is older than %s", $older.name(), $mark.name());
System.out.println();
end
""";
public static void main(String... args) throws Exception {
var mapper = new ObjectMapper();
var kieSession = makeSession();
for (var s: args) {
var person = mapper.readValue(s, Person.class);
kieSession.insert(person);
}
kieSession.fireAllRules();
kieSession.dispose();
}
static KieSession makeSession() {
var kieServices = KieServices.Factory.get();
var kfs = kieServices.newKieFileSystem();
kfs.write("src/main/resources/rules.drl",
kieServices.getResources().newReaderResource(new java.io.StringReader(drl)));
var kieBuilder = kieServices.newKieBuilder(kfs).buildAll();
var results = kieBuilder.getResults();
if(results.hasMessages(Message.Level.ERROR)){
err.println("Errors building the rule base.");
err.println(results.getMessages());
System.exit(-1);
}
return kieServices
.newKieContainer(kieBuilder.getKieModule().getReleaseId())
.newKieSession();
}
}
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