This documentation is for WSO2 Enterprise Service Bus version 4.8.1 . View documentation for the latest release.

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Objective: Introduction to ESB Sequence Templates.

<?xml version="1.0" encoding="UTF-8"?>
    <definitions xmlns="http://ws.apache.org/ns/synapse">

        <proxy name="StockQuoteProxy">
            <target>
            <inSequence>
            <!--use sequence template to trasnform incoming request-->
            <call-template target="xslt_func">
                            <with-param name="xslt_key" value="xslt-key-req"/>
                    </call-template>
            <send>
                <endpoint>
                                  <address uri="http://localhost:9000/services/SimpleStockQuoteService"/>
                            </endpoint>
                    </send>
                </inSequence>

                <outSequence>
            <!--use sequence template to trasnform incoming response-->
            <call-template target="xslt_func">
                            <with-param name="xslt_key" value="xslt-key-back"/>
                    </call-template>
                    <send/>
                </outSequence>
            </target>
        </proxy>

        <!--this sequence template will trasnform requests with the given xslt local entry key And will log
        the message before and after. Takes Iterate local entry key as an argument-->
        <template xmlns="http://ws.apache.org/ns/synapse" name="xslt_func">
            <parameter name="xslt_key"/>
            <sequence>
                    <log level="full">
                <property name="BEFORE_TRANSFORM" value="true" />
            </log>
                 <xslt key="{$func:xslt_key}"/>
            <log level="full">
                <property name="AFTER_TRANSFORM" value="true" />
            </log>
            </sequence>
        </template>

        <localEntry key="xslt-key-req" src="file:repository/samples/resources/transform/transform.xslt"/>
        <localEntry key="xslt-key-back" src="file:repository/samples/resources/transform/transform_back.xslt"/>
    </definitions>

Prerequisites:

  • Start the Synapse configuration numbered 750: i.e. wso2esb-samples -sn 750
  • Start the Axis2 server and deploy the SimpleStockQuoteService if not already done

Execute the stock quote client by requesting for a stock quote on the proxy service as follows:

ant stockquote -Daddurl=http://localhost:8280/services/StockQuoteProxy -Dmode=customquote

ESB Sequence Template can act a reusable function. Here proxy service reuses template xslt_func which will transform requests with the given xslt local entry key And will log the message before and after. It takes xslt transformation corresponding to local entry key as an argument (for insequence this key is xslt-key-req and out sequence it is xslt-key-back). We use call-template mediator for passing the xslt key parameter to a sequence template. ESB console will display how the custom stockquote is transformed and the transformed response from the service.

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