SAPUI5 is loaded using the standard procedure. The following code requests SAPUI5 to run your main function as soon as SAPUI5 has finished its initialization:
<script id="sap-ui-bootstrap" src="/sap/public/bc/ui5_ui5/resources/sap-ui-core.js" data-sap-ui-evt-oninit="main();" data-sap-ui-libs="sap.ui.commons" data-sap-ui-theme="sap_goldreflection"> </script>