Implemented methods on backend

Backend/tools-services/src/main/java/com/r11/tools/xml/Saxon.java

@@ -39,6 +39,28 @@ public class Saxon implements XmlEngine{
         throw new UnsupportedOperationException();
     }
 
+    /**
+     * This method evaluates XQuery exporession on given xml
+     * @param data xml
+     * @param xquery expression
+     * @return
+     * @throws Exception
+     */
+    @Override
+    public String executeXQuery(String data, String xquery) throws Exception {
+        Processor processor = new Processor(false);
+
+        XQueryCompiler compiler = processor.newXQueryCompiler();
+
+        XQueryExecutable executable = compiler.compile(xquery);
+
+        XQueryEvaluator evaluator = executable.load();
+        evaluator.setSource(new StreamSource(new StringReader(data)));
+
+        XdmValue result = evaluator.evaluate();
+        return result.toString();
+    }
+
     /**
      * Process xpath and return either node or wrapped atomic value
      * @param data xml to be querried

Backend/tools-services/src/main/java/com/r11/tools/xml/Xalan.java

@@ -133,4 +133,9 @@ public class Xalan implements XmlEngine{
         validator.validate(dataSource);
         return "XML file is valid";
     }
+
+    @Override
+    public String executeXQuery(String data, String xquery) throws Exception {
+        throw new UnsupportedOperationException("Xalan doesn't support XQuery evaluation");
+    }
 }

Backend/tools-services/src/main/java/com/r11/tools/xml/XmlEngine.java

@@ -7,6 +7,8 @@ public interface XmlEngine {
     String processXSLT(String data, String transform) throws Exception;
     String validate(String data, String xsd) throws Exception;
 
+    String executeXQuery(String data, String xquery) throws Exception;
+
     public String getVersion();
 
 }