diff --git a/Backend/tools-services/src/main/java/com/r11/tools/xml/Saxon.java b/Backend/tools-services/src/main/java/com/r11/tools/xml/Saxon.java
index 4cb2835..f9f330b 100644
--- a/Backend/tools-services/src/main/java/com/r11/tools/xml/Saxon.java
+++ b/Backend/tools-services/src/main/java/com/r11/tools/xml/Saxon.java
@@ -11,7 +11,7 @@ import java.io.StringWriter;
  * Handler for Saxon engine
  * @author Wojciech Czop
  */
-public class Saxon {
+public class Saxon implements XmlEngine{
 
     /**
      * Transforms string containing xml document via xslt
@@ -20,7 +20,7 @@ public class Saxon {
      * @return transformed xml
      * @throws SaxonApiException thrown on stylesheet or transformation errors
      */
-    public static String processXSLT(String data, String transform) throws SaxonApiException {
+    public String processXSLT(String data, String transform) throws SaxonApiException {
         Processor processor = new Processor(false);
         XsltCompiler compiler = processor.newXsltCompiler();
         XsltExecutable stylesheet = compiler.compile(new StreamSource(new StringReader(transform)));
@@ -34,6 +34,11 @@ public class Saxon {
         return sw.toString();
     }
 
+    @Override
+    public String validate(String data, String xsd) {
+        throw new UnsupportedOperationException();
+    }
+
     /**
      * Process xpath and return either node or wrapped atomic value
      * @param data xml to be querried
@@ -42,7 +47,7 @@ public class Saxon {
      * @return string xml representation of the node
      * @throws Exception thrown on node building errors or invalid xpath
      */
-    public static XPathQueryResult processXPath(String data, String query, String version) throws Exception {
+    public XPathQueryResult processXPath(String data, String query, String version) throws Exception {
         Processor p = new Processor(false);
         XPathCompiler compiler = p.newXPathCompiler();
         DocumentBuilder builder = p.newDocumentBuilder();
@@ -70,7 +75,7 @@ public class Saxon {
      * Returns version of the processor
      * @return version of the processor
      */
-    public static String getVersion() {
+    public String getVersion() {
         return new Processor(false).getSaxonProductVersion();
     }
 }
diff --git a/Backend/tools-services/src/main/java/com/r11/tools/xml/Xalan.java b/Backend/tools-services/src/main/java/com/r11/tools/xml/Xalan.java
index 1caad08..d9cf805 100644
--- a/Backend/tools-services/src/main/java/com/r11/tools/xml/Xalan.java
+++ b/Backend/tools-services/src/main/java/com/r11/tools/xml/Xalan.java
@@ -24,7 +24,7 @@ import java.io.*;
  * Handler for Xalan engine
  * @author Wojciech Czop
  */
-public class Xalan {
+public class Xalan implements XmlEngine{
 
     /**
      * Transforms string containing xml document via xslt
@@ -33,7 +33,7 @@ public class Xalan {
      * @return transformed xml
      * @throws Exception thrown on stylesheet or transformation errors
      */
-    public static String processXSLT(String data, String transform) throws Exception{
+    public String processXSLT(String data, String transform) throws Exception {
         DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
         DocumentBuilder builder = factory.newDocumentBuilder();
         Document document = builder.parse(new InputSource(new StringReader(data)));
@@ -51,7 +51,7 @@ public class Xalan {
         return sw.toString();
     }
 
-    private static boolean isTextNode(Node n) {
+    private boolean isTextNode(Node n) {
         if (n == null)
             return false;
         short nodeType = n.getNodeType();
@@ -65,7 +65,7 @@ public class Xalan {
      * @return xml processed using given xpath
      * @throws Exception thrown on node building errors or invalid xpath
      */
-    public static XPathQueryResult processXPath(String data, String transform) throws Exception {
+    public XPathQueryResult processXPath(String data, String transform, String version) throws Exception {
 
         // Set up a DOM tree to query.
         InputSource in = new InputSource(new StringReader(data));
@@ -112,7 +112,7 @@ public class Xalan {
      * Returns version of the processor
      * @return version of the processor
      */
-    public static String getVersion(){
+    public String getVersion(){
         return org.apache.xalan.Version.getVersion();
     }
 
@@ -123,7 +123,7 @@ public class Xalan {
      * @return statement of validity
      * @throws Exception thrown on invalid xsd schema or xml
      */
-    public static String validate(String data, String xsd) throws Exception{
+    public String validate(String data, String xsd) throws Exception {
         Source dataSource = new StreamSource(new StringReader(data));
         Source xsdSource = new StreamSource(new StringReader(xsd));
         SchemaFactory schemaFactory = SchemaFactory
diff --git a/Backend/tools-services/src/main/java/com/r11/tools/xml/XmlEngine.java b/Backend/tools-services/src/main/java/com/r11/tools/xml/XmlEngine.java
index 7c5b546..5742073 100644
--- a/Backend/tools-services/src/main/java/com/r11/tools/xml/XmlEngine.java
+++ b/Backend/tools-services/src/main/java/com/r11/tools/xml/XmlEngine.java
@@ -3,9 +3,9 @@ package com.r11.tools.xml;
 import com.r11.tools.controller.internal.XPathQueryResult;
 
 public interface XmlEngine {
-    XPathQueryResult processXPath(String data, String query, String version);
-    String processXSLT(String data, String transform);
-    String validate(String data, String xsd);
+    XPathQueryResult processXPath(String data, String query, String version) throws Exception;
+    String processXSLT(String data, String transform) throws Exception;
+    String validate(String data, String xsd) throws Exception;
 
     public String getVersion();