How to replace .drl file dynamically while using drools in mule esb? - mule

Question

what i need is to replace the .drl file dynamically. through some nasty code i am able to load the .drl file and change the content but it seems that drools holds on to its initial file.
these are my config files (just in case):
mule-config.xml
<?xml version="1.0" encoding="UTF-8"?>
<mule xmlns:http="http://www.mulesoft.org/schema/mule/http"
xmlns="http://www.mulesoft.org/schema/mule/core"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:spring="http://www.springframework.org/schema/beans"
xmlns:quartz="http://www.mulesoft.org/schema/mule/quartz"
xmlns:vm="http://www.mulesoft.org/schema/mule/vm"
xmlns:jms="http://www.mulesoft.org/schema/mule/jms"
xmlns:scripting="http://www.mulesoft.org/schema/mule/scripting"
xmlns:bpm="http://www.mulesoft.org/schema/mule/bpm"
xmlns:client="http://www.mulesoft.org/schema/mule/client"
xmlns:tracking="http://www.mulesoft.org/schema/mule/ee/tracking"
xmlns:doc="http://www.mulesoft.org/schema/mule/documentation"
xmlns:context="http://www.springframework.org/schema/context"
xmlns:management="http://www.mulesoft.org/schema/mule/management"
xsi:schemaLocation="
http://www.mulesoft.org/schema/mule/http http://www.mulesoft.org/schema/mule/http/current/mule-http.xsd
http://www.mulesoft.org/schema/mule/core http://www.mulesoft.org/schema/mule/core/3.2/mule.xsd
http://www.mulesoft.org/schema/mule/quartz http://www.mulesoft.org/schema/mule/quartz/3.2/mule-quartz.xsd
http://www.mulesoft.org/schema/mule/vm http://www.mulesoft.org/schema/mule/vm/3.2/mule-vm.xsd
http://www.mulesoft.org/schema/mule/jms http://www.mulesoft.org/schema/mule/jms/3.2/mule-jms.xsd
http://www.mulesoft.org/schema/mule/scripting http://www.mulesoft.org/schema/mule/scripting/3.2/mule-scripting.xsd
http://www.mulesoft.org/schema/mule/bpm http://www.mulesoft.org/schema/mule/bpm/3.2/mule-bpm.xsd
http://www.mulesoft.org/schema/mule/client http://www.mulesoft.org/schema/mule/client/3.2/mule-client.xsd
http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
http://www.mulesoft.org/schema/mule/ee/tracking http://www.mulesoft.org/schema/mule/ee/tracking/current/mule-tracking-ee.xsd
http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.0.xsd
http://www.mulesoft.org/schema/mule/management http://www.mulesoft.org/schema/mule/management/current/mule-management.xsd
">
<bpm:jbpm />
<bpm:drools />
<!-- Define EMC Routing facts bean -->
<spring:bean name="NoFactsBean" class="java.util.ArrayList"/>
<jms:activemq-connector
name="jms-connector"
brokerURL="tcp://localhost:61616"
disableTemporaryReplyToDestinations="true"
specification="1.1"/>
<jms:endpoint name="UnsortedOrders" queue="UnsortedOrders"/>
<jms:endpoint name="DestinationEMC" queue="DestinationEMC"/>
<jms:endpoint name="DestinationOriginal" queue="DestinationOriginal"/>
<vm:endpoint name="DroolsEndpoint" path="drools"/>
<!-- GOLI -->
<spring:beans>
<spring:bean id="dto-convertor" class="com.hamgam.hit.esb.XMLToDTO" scope="singleton" />
<spring:bean id="rule-convertor" class="com.hamgam.hit.esb.RuleXMLToDRL" scope="singleton" />
</spring:beans>
<http:listener-config name="HTTP_Listener" host="localhost" port="8084" doc:name="HTTP Listener Configuration" />
<!-- /GOLI -->
<flow name="RestEtryPoint">
<http:listener config-ref="HTTP_Listener" path="/{name}" doc:name="HTTP" />
<set-variable variableName="name" value="#[message.inboundProperties['http.uri.params']['name']]" />
<set-variable variableName="msg" value="#[payload]"/>
<expression-component>
app.registry['dto'] = app.registry['dto-convertor'].convert(flowVars['name']);
</expression-component>
<set-payload value="#[app.registry['dto']]"/>
<jms:outbound-endpoint ref="UnsortedOrders"/>
<logger level="INFO" doc:name="Logger" message="***************Entry***************" />
</flow>
<flow name="jBPMProcess">
<composite-source>
<vm:inbound-endpoint path="in" exchange-pattern="request-response"/>
<jms:inbound-endpoint ref="UnsortedOrders"/>
</composite-source>
<!-- TODO streaming="false"Transform XML to object -->
<bpm:process processName="DecisionRouting" processDefinition="routing-process.jpdl.xml"/>
<logger level="INFO" doc:name="Logger" message="***************JBPM Process***************" />
</flow>
<flow name="DroolsFlow">
<vm:inbound-endpoint ref="DroolsEndpoint" exchange-pattern="request-response"/>
<bpm:rules rulesDefinition="emcRoutingRules.drl" initialFacts-ref="NoFactsBean" />
<expression-transformer evaluator="groovy" expression="message.getPayload().getObject()"/>
<logger level="INFO" doc:name="Logger" message="***************Drools Flow***************" />
</flow>
<flow name="ConsumeEmcQ">
<jms:inbound-endpoint ref="DestinationEMC"/>
<logger level="INFO" doc:name="Logger" message="*************Consume Q4 DestinationEMC*****************" />
<logger level="INFO" doc:name="Logger" message="#[payload]" />
</flow>
<flow name="ConsumeOrigQ">
<jms:inbound-endpoint ref="DestinationOriginal"/>
<logger level="INFO" doc:name="Logger" message="*************Consume Q4 DestinationOriginal*****************" />
</flow>
</mule>
this is routing-process.jpdl.xml:
<?xml version="1.0" encoding="UTF-8"?>
<process description="routing example" name="DecisionRouting" xmlns="http://jbpm.org/4.3/jpdl">
<mule-receive name="unsortedOrder" endpoint="UnsortedOrders" type="com.hamgam.hit.esb.XMLDTO" var="order">
<transition to="sendToDrools" />
</mule-receive>
<mule-send name="sendToDrools" expr="#{order}" endpoint="DroolsEndpoint" exchange-pattern="request-response" var="order">
<transition to="defineDestination" />
</mule-send>
<decision name="defineDestination">
<transition to="sendToEMC">
<condition expr="#{order.destination == 'EMC'}" />
</transition>
<transition to="sendToOriginalDest">
<condition expr="#{order.destination == 'ORIG'}" />
</transition>
<transition to="routingFailed" />
</decision>
<mule-send name="sendToEMC"
expr="#{order}" endpoint="DestinationEMC" exchange-pattern="one-way">
<transition to="routingSuccessful" />
</mule-send>
<mule-send name="sendToOriginalDest"
expr="#{order}" endpoint="DestinationOriginal" exchange-pattern="one-way">
<transition to="routingSuccessful" />
</mule-send>
<end name="routingSuccessful" />
<end name="routingFailed" />
</process>
and this is emcRoutingRules.drl that originally placed in resource folder :
package com.hamgam.hit.esb
import com.hamgam.hit.esb.*;
import org.mule.MessageExchangePattern
global org.mule.module.bpm.MessageService mule;
# default dialect for the semantic code will be MVEL
dialect "mvel"
declare XMLDTO
#role( event )
end
rule "Select Emc"
lock-on-active
when
$x:XMLDTO(inputXML == "moien")
then
modify( $x ) { setDestination("EMC") }
end
rule "Select Original Destination"
lock-on-active
when
$x:XMLDTO( inputXML == "goli" )
then
modify( $x ) { setDestination("ORIG") }
end
and this is how i am replacing the .drl file :
private void generateFile(String rule) throws IOException{
PrintWriter writer;
try {
ClassLoader classLoader = RuleXMLToDRL.class.getClassLoader();
File file =
new File(classLoader.getResource("emcRoutingRules.drl").getFile());
writer = new PrintWriter(file, "UTF-8");
writer.println(""
+ "package com.hamgam.hit.esb "
+ "import com.hamgam.hit.esb.*; "
+ "import org.mule.MessageExchangePattern "
+ "global org.mule.module.bpm.MessageService mule; "
+ "dialect \"mvel\" declare XMLDTO #role( event ) end");
writer.println(rule);
writer.close();
} catch (FileNotFoundException | UnsupportedEncodingException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}

Answer 1

I am not proud, but i came up with a hacker solution:
as i mentioned before any change on mule-config.xml file will lead to mules rebuild, so after changing .drl file i am making a dummy change to mule-config.xml file too.
PrintWriter out = new PrintWriter(new BufferedWriter(new FileWriter("mule-config.xml", true)));
out.println("<!-- -->");
out.flush();
note that the solution wont work if you lunch from Anypoint studio. but deploy it in mule standalone and it will work.
Till i find a better solution, this works just fine ;)