Custom XMP schema - add programatically

Hi,

I am trying to create custom XMP schema programatically and insert some properties with values there. Not completely sure if it’s possible, but this is how I try to do it:

    var namespace = "http://ns.adobe.com/MyName/1.0/";
    var prefix = "MyNameShort";
    var registered = XMPMeta.registerNamespace(namespace, prefix);

    var projectItem = app.project.rootItem.children[0];
    if (projectItem) {
        if (ExternalObject.AdobeXMPScript === undefined) {
            ExternalObject.AdobeXMPScript = new ExternalObject('lib:AdobeXMPScript');
        }
        if (ExternalObject.AdobeXMPScript !== undefined) {
            var xmpBlob = projectItem.getXMPMetadata();
            var xmp = new XMPMeta(xmpBlob);

            xmp.setProperty(namespace, "creator", "Team");
            xmp.setProperty(namespace, "fruit", "apple");

            var xmpAsString = xmp.serialize();
            projectItem.setXMPMetadata(xmpAsString);
        }
    }

This does not do anything obvious to me, doesn’t throw an error, but I don’t find a new schema with the given namespace or the new properties. What am I doing wrong?

Additionaly - if this is possible and the custom schema is created and new properties are inserted - on second attempt to use it - how will I check if the schema does already exist or should be created?

Thank you in advance!