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<document>
    <properties>
        <title>Apache Synapse - Sample 850</title>
    </properties>
    <body>
        <section name="Sample 850: Introduction to Synapse Callout Block function template">
            <div class="xmlConf">&lt;!-- Introduction to Synapse Callout Block function template --&gt;
&lt;definitions xmlns="http://ws.apache.org/ns/synapse"&gt;
&lt;import xmlns="http://ws.apache.org/ns/synapse" name="EipLibrary" package="synapse.lang.eip" /&gt;
   &lt;sequence name="main"&gt;
    &lt;call-template target="synapse.lang.eip.callout_block"&gt;
        &lt;with-param name="action" value="urn:getQuote"/&gt;
        &lt;with-param name="service_URL" value="http://localhost:9000/services/SimpleStockQuoteService"/&gt;
        &lt;with-param xmlns:s11="http://schemas.xmlsoap.org/soap/envelope/" xmlns:s12="http://www.w3.org/2003/05/soap-envelope" name="source_xpath" value="{{s11:Body/child::*[fn:position()=1] | s12:Body/child::*[fn:position()=1]}}"/&gt;
        &lt;with-param xmlns:s11="http://schemas.xmlsoap.org/soap/envelope/" xmlns:s12="http://www.w3.org/2003/05/soap-envelope" name="target_xpath" value="{{s11:Body/child::*[fn:position()=1] | s12:Body/child::*[fn:position()=1]}}"/&gt;
    &lt;/call-template&gt;
     &lt;respond/&gt;
&lt;/sequence&gt;
&lt;/definitions&gt;</div>
            <subsection name="Objective">
                <p>
This pattern is pretty much identical to the Routing slip pattern and this blocks external service invocation during mediation. And useful in scenarios such as service chaining. As default values are assigned to source and target xpaths, one can simply utilize this pattern by just defining serviceURL. This sample is an introduction to Synapse Callout Block function template. 
                </p>
            </subsection>
            <subsection name="Pre-requisites">
                <p>
                    <ul>
                        <li>
                            Deploy the SimpleStockQuoteService in the sample Axis2 server and start Axis2
                        </li>
                        <li>
                            Start Synapse using the configuration numbered 850 (repository/conf/sample/synapse_sample_850.xml)
                            <div class="command">
                                Unix/Linux: sh synapse.sh -sample 850<br/>
                                Windows: synapse.bat -sample 850
                            </div>
                        </li>
                    </ul>
                </p>
            </subsection>
            <subsection name="Executing the Client">
<p>
                    In this sample, the callout block pattern does a synchronized service invocation to the
                    StockQuoteService using the client request, gets the response and then using the send mediator, the message
                    is sent back to the client.
                </p>
                <p>
                    Invoke the client as follows.
                </p>
                <div class="command">ant stockquote -Daddurl=http://localhost:9000/services/SimpleStockQuoteService -Dtrpurl=http://localhost:8280/</div>
            </subsection>
        </section>
        <p><a href="../samples.html">Back to Catalog</a></p>        
    </body>
</document>
