OpenLayers WFS Layer with OpenLayers.Request.Get

HTML

<script src="http://cdnjs.cloudflare.com/ajax/libs/openlayers/2.11/OpenLayers.js"></script>
<body onload="init()">
    <p>OpenLayers WFS with invisible 10px stroke to make selection easier
        <div id="map"></div>
</body>

CSS

#map {
    width: 100%;
    height: 500px;
}

JavaScript

var map;
var layer, wms, selectControl;

function init() {

   map = new OpenLayers.Map({
      div: "map"
    });
    
 		wms = new OpenLayers.Layer.WMS(
        "OpenLayers WMS", "http://vmap0.tiles.osgeo.org/wms/vmap0", {
        layers: 'basic'
    });

		var points = [
      new OpenLayers.Geometry.Point(121.515, 25.0278),
      new OpenLayers.Geometry.Point(121.515, 25.0272),
      new OpenLayers.Geometry.Point(121.516, 25.0278),
      new OpenLayers.Geometry.Point(121.516, 25.0272)
    ];
    
    var ring = new OpenLayers.Geometry.LineString(points);
    
    var linestring_feature = new OpenLayers.Layer({
                                    geometry: ring
                                });
                                
  var vector_layer = new OpenLayers.Layer.Vector({
    source: new OpenLayers.Layer.Vector({
      features: linestring_feature
    })
  })

   /*layer = new OpenLayers.Layer.Vector("Custom WFS", {
                    strategies: [new OpenLayers.Strategy.Fixed()],
                    protocol: new OpenLayers.Protocol.WFS({
                        version: "1.0.0",
                        url: "http://210.241.18.213/GIS/wfs?UNIT=ME&SEC=0521&service=wfs&request=GetFeature&version=1.0.0&TYPENAME=ME0521"
                    }),
                    styleMap: new OpenLayers.StyleMap({
                        strokeColor: "red",
                        strokeWidth: 3
                    })
                });*/

//http://210.241.18.213/SOAWS/wfs.ashx?D=3&LD=QB&SCNO=0388&PO=02530000&service=WFS&Version=1.0.0&request=GetFeature

    //map.addLayers([wms, layer]);
    map.addLayers([wms,vector_layer]);
    map.setCenter(new OpenLayers.LonLat(121.515, 25.0278), 15);
    //map.setCenter(new OpenLayers.LonLat(120.9476, 23.7989), 10);

	 /*map.setCenter(new OpenLayers.LonLat(120.9476, 23.7989) // Center of the map
              .transform(
                new OpenLayers.Projection("EPSG:4326"), // transform from WGS 1984
                new...