Improve stability by allowing multiple (3) tries to load results.

www/app/results.js

@@ -6,30 +6,46 @@ xhttp.send("");
 return xhttp.responseXML;
 }
 
-function render(content)
+function render(err, content)
 {
-  style = loadXMLDoc("style/material.xsl");
-  if (document.implementation && document.implementation.createDocument)
-    {
-    xsltProcessor = new XSLTProcessor();
-    xsltProcessor.importStylesheet(style);
-    resultDocument = xsltProcessor.transformToFragment(content, document);
-    document.body.replaceWith(resultDocument);
-    }
+	if (err) {
+
+	} else {
+	  style = loadXMLDoc("style/material.xsl");
+	  if (document.implementation && document.implementation.createDocument)
+	    {
+	    xsltProcessor = new XSLTProcessor();
+	    xsltProcessor.importStylesheet(style);
+	    resultDocument = xsltProcessor.transformToFragment(content, document);
+	    document.body.replaceWith(resultDocument);
+	    }
+	}
 }
 
 /**
- * Returns OpenSearch responseXML for the given query.
+ * Delivers OpenSearch responseXML to callback for the given query.
  */
-function search(query,focus) {
+function search(query,focus,callback, tries) {
   query = query || "eingabe=";
   focus = focus || "focus=web";
-  return loadXMLDoc("https://metager3.de/meta/meta.ger3?"+focus+"&"+query+"&encoding=utf8&out=atom10&appversion=0.1.0");
+	let doc;
+	tries = tries || 3;
+	try {
+		doc = loadXMLDoc("https://metager3.de/meta/meta.ger3?"+focus+"&"+query+"&encoding=utf8&out=atom10&appversion=3.0.0");
+		callback(null, doc);
+	} catch (e) {
+		if(--tries) {
+			console.log("search error, tries left: "+tries);
+			search(query, focus, callback, tries);
+		} else {
+			callback(e);
+		}
+	};
 }
 
 function boot()
 {
-  render(search(getParameter('eingabe'),getParameter('focus')));
+  search(getParameter('eingabe'),getParameter('focus'),render);
 }
 
 function getParameter(parameterName) {