applications/product/servicedef/services_uom.xml

<?xml version="1.0" encoding="UTF-8"?>
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<services xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
        xsi:noNamespaceSchemaLocation="http://ofbiz.apache.org/dtds/services.xsd">
    <description>Unit of Measure Conversion Services - Formula based on Product data</description>
    <vendor>OFBiz</vendor>
    <version>1.0</version>

    <!-- UOM Formulas -->
    <service name="interfaceUomFormula" engine="interface" location="" invoke="">
        <attribute mode="IN" name="arguments" optional="false" type="java.util.Map"/>
        <attribute mode="OUT" name="convertedValue" optional="true" type="BigDecimal"/>
    </service>
    <service name="convertUomProduct" engine="simple" auth="false"
        location="component://product/minilang/product/product/ProductUomFormulas.xml" invoke="convertUomProduct">
        <description>UoM conversion based on product attributes</description>
        <implements service="interfaceUomFormula"/>
    </service>
</services>