Demo WMS 1.1.1 due to question https://groups.google.com/forum/?#!msg/ol3-dev/D-I_zmVZKP8/7r7yiwJeHE4J

<!doctype html>
<html lang="en">
  <head>
    <meta charset="UTF-8">
    <title>Jsonix WMS</title>
    <script src="https://cdn.jsdelivr.net/gh/highsource/jsonix@master/dist/jsonix-min.js"></script>
    <script src="https://cdn.jsdelivr.net/gh/highsource/w3c-schemas@master/scripts/lib/xlink_1_0.js"></script>
    <script src="https://cdn.jsdelivr.net/gh/highsource/ogc-schemas@master/scripts/lib/wms_1_1_1.js"></script>
  </head>
  <body>
    <script>
        // Trick for demo to manage Cors 
        (function() {
            var cors_api_host = 'cors-anywhere.herokuapp.com';
            var cors_api_url = 'https://' + cors_api_host + '/';
            var slice = [].slice;
            var origin = window.location.protocol + '//' + window.location.host;
            var open = XMLHttpRequest.prototype.open;
            XMLHttpRequest.prototype.open = function() {
                var args = slice.call(arguments);
                var targetOrigin = /^https?:\/\/([^\/]+)/i.exec(args[1]);
                if (targetOrigin && targetOrigin[0].toLowerCase() !== origin &&
                    targetOrigin[1] !== cors_api_host) {
                    args[1] = cors_api_url + args[1];
                }
                return open.apply(this, args);
            };
        })();

var context = new Jsonix.Context([XLink_1_0, WMS_1_1_1], {
            // Not required but recommended
            namespacePrefixes: {
                'https://www.w3.org/1999/xlink': 'xlink',
                'https://www.opengis.net/wms': 'wms'
            }
        });

var unmarshaller = context.createUnmarshaller();

unmarshaller.unmarshalURL('https://demo.mapserver.org/cgi-bin/wms?SERVICE=WMS&VERSION=1.1.1&REQUEST=GetCapabilities', function(result) {
            console.log(JSON.stringify(result, null, 2));
        });
    </script>
  </body>
</html>

Updated missing url https://cdn.jsdelivr.net/gh/highsource/jsonix@master/dist/Jsonix-min.js to https://cdn.jsdelivr.net/gh/highsource/jsonix@master/dist/jsonix-min.js

Updated missing url https://cdn.jsdelivr.net/gh/highsource/w3c-schemas@master/scripts/lib/XLink_1_0.js to https://cdn.jsdelivr.net/gh/highsource/w3c-schemas@master/scripts/lib/xlink_1_0.js

Updated missing url https://cdn.jsdelivr.net/gh/highsource/ogc-schemas@master/scripts/lib/WMS_1_1_1.js to https://cdn.jsdelivr.net/gh/highsource/ogc-schemas@master/scripts/lib/wms_1_1_1.js

https://cdn.jsdelivr.net/gh/highsource/jsonix@master/dist/Jsonix-min.js

https://cdn.jsdelivr.net/gh/highsource/w3c-schemas@master/scripts/lib/XLink_1_0.js

https://cdn.jsdelivr.net/gh/highsource/ogc-schemas@master/scripts/lib/WMS_1_1_1.js