Enterprise Service Bus 4.5.1

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  • Sample 600 : Simple Message Transformation - Rule Mediator for Message Transformation

This documentation is for WSO2 ESB version 4.5.1. View documentation for the latest release.

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Objective: Introduction to simple rule based routing.

<!-- Simple rule based routing  of messages - same as filter mediator -->
<definitions xmlns="http://ws.apache.org/ns/synapse">
    <in>
        <rule>
            <ruleset >
                <source>
                    <package name="SimpleRoutingRules"
                             xmlns="http://drools.org/drools-5.0"
                             xmlns:xs="http://www.w3.org/2001/XMLSchema-instance"
                             xs:schemaLocation="http://drools.org/drools-5.0 drools-4.0.xsd">
                        <import name="org.apache.synapse.MessageContext"/>
                        <rule name="Invoke IBM ">
                            <lhs>
                                <pattern object-type="MessageContext" identifier="mc"></pattern>
                                <pattern object-type="String" identifier="symbol"></pattern>
                                <eval>symbol.equals("IBM")</eval>
                            </lhs>
                            <rhs>mc.setProperty("execute_children","true");</rhs>
                        </rule>
                    </package>
                </source>
                <creation>
                    <property name="source" value="xml"/>
                </creation>
            </ruleset>
            <session type="stateless"/>
            <facts>
                <fact name="mc" type="context"/>
                <fact name="symbol" type="java.lang.String"
                      expression="//m0:getQuote/m0:request/m0:symbol/child::text()"
                      xmlns:m0="http://services.samples"/>
            </facts>
            <childMediators>
                <send>
                    <endpoint>
                        <address uri="http://localhost:9000/services/SimpleStockQuoteService"/>
                    </endpoint>
                </send>
                <drop/>
            </childMediators>
        </rule>
    </in>
    <out>
        <send/>
    </out>

</definitions>

Prerequisites:

  • Start the Synapse configuration numbered 600: (i.e. ./wso2esb-samples.sh -sn 600)
  • Start the Axis2 server and deploy the SimpleStockQuoteService if not already deployed.

Run the client as

ant stockquote -Daddurl=http://localhost:9000/services/SimpleStockQuoteService -Dtrpurl=http://localhost:8280/

Or as

ant stockquote -Daddurl=http://localhost:9000/services/SimpleStockQuoteService -Dtrpurl=http://localhost:8280/ -Dsymbol=IBM

Then, you will get stock quote price in the client side.

In this sample , with in the rule mediator , the value, which is extracted from the SOAP envelope using XPath '//m0:getQuote/m0:request/m0:symbol', is added to the rule engine as a string fact . The message context property named "execute_children" is to indicate it is need to execute the child mediators of rule mediator. That property is set only if the symbol is IBM.

Now use following commands

ant stockquote -Daddurl=http://localhost:9000/services/SimpleStockQuoteService -Dtrpurl=http://localhost:8280/ -Dsymbol=SUN

and

ant stockquote -Daddurl=http://localhost:9000/services/SimpleStockQuoteService -Dtrpurl=http://localhost:8280/ -Dsymbol=MSFT

Then , you will get errors . This is because , 'symbol' is not equal to "IBM".

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