Mashup Code Sample - Mashup to convert a zipcode into Lat/Long data via a REST service

Have you ever wanted to translate zip codes to Lat/Long to display in Google Maps? Here's the example to do it!  [Don’t forget that this code requires a REST service in Presto named "geonames": http://ws.geonames.org/postalCodeSearch?postalcode=06700&country=MX.] 

      <mashup xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
            xsi:schemalocation="http://www.jackbe.com/2008-03-01/EMMLSchema ../src/schemas/EMMLSpec.xsd"
            xmlns="http://www.jackbe.com/2008-03-01/EMMLSchema" xmlns:macro="http://www.jackbe.com/2008-03-01/EMMLMacro"
            name="zip2lat">
        <operation
                name="invoke"> <!-- Here are our variables. Zipcode and Country are the variables in our REST. They have default variables to avoid sending it empty and receive an unexpected result -->
            <input name="zipcode" type="string" default="06700"     />
            <input name="country" type="string" default="MX"     />
            <output name="result" type="document"></output>
            <!-- We will be saving the lat/lng in these variables to have them in our constructor. Perhaps just a way to keep things organized since for later usage it could become a huge code if not modularized -->
            <variables>
                <variable name="lat" type="string"></variable>
                <variable name="lng" type="string"></variable>
            </variables>
            <!-- Here we invoke the REST we published in service explorer and send the previous inputs to it -->
            <invoke operation="getData" service="geonames" inputvariables="zipcode,country"
                    outputvariable="preliminary"></invoke>
            <assign fromexpr="$preliminary//lat/string()" outputvariable="lat"></assign>
            <assign fromexpr="$preliminary//lng/string()" outputvariable="lng"></assign>
            <!-- Building the output -->
            <constructor outputvariable="result"     />
        </operation>
    </mashup>