simplified XML processing and eliminated helper classes

Author: aoberoi

src/main/java/com/opentok/api/OpenTok.java

@@ -10,13 +10,17 @@
 
 package com.opentok.api;
 
+import java.io.StringReader;
 import java.io.UnsupportedEncodingException;
 import java.util.Collection;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
 
 import javax.xml.bind.DatatypeConverter;
+import javax.xml.xpath.XPath;
+import javax.xml.xpath.XPathExpressionException;
+import javax.xml.xpath.XPathFactory;
 
 import com.opentok.api.constants.TokenOptions;
 import org.codehaus.jackson.JsonNode;
@@ -29,7 +33,7 @@
 import com.opentok.exception.OpenTokInvalidArgumentException;
 import com.opentok.exception.OpenTokRequestException;
 import com.opentok.exception.OpenTokSessionNotFoundException;
-import com.opentok.util.TokBoxXML;
+import org.xml.sax.InputSource;
 
 /**
 * Contains methods for creating OpenTok sessions and generating tokens.
@@ -270,7 +274,7 @@ public String generateToken(String sessionId) throws OpenTokException {
      */
     public Session createSession(SessionProperties properties) throws OpenTokException {
         Map<String, Collection<String>> params;
-        Session session = null;
+        String xpathQuery = "/sessions/Session/session_id";
 
         // NOTE: doing this null check twice is kind of ugly
         if(properties != null) {
@@ -279,14 +283,18 @@ public Session createSession(SessionProperties properties) throws OpenTokExcepti
             params = null;
         }
 
-        TokBoxXML xmlResponse = new TokBoxXML(this.client.createSession(params));
+        String xmlResponse = this.client.createSession(params);
 
 
         // NOTE: doing this null check twice is kind of ugly
-        if (properties != null) {
-            return new Session(xmlResponse.getElementValue("session_id", "Session"), apiKey, apiSecret, properties);
-        } else {
-            return new Session(xmlResponse.getElementValue("session_id", "Session"), apiKey, apiSecret);
+        try {
+            if (properties != null) {
+                return new Session(readXml(xpathQuery, xmlResponse), apiKey, apiSecret, properties);
+            } else {
+                return new Session(readXml(xpathQuery, xmlResponse), apiKey, apiSecret);
+            }
+        } catch (XPathExpressionException e) {
+            throw new OpenTokException("Cannot create session. Could not read the response: "+xmlResponse);
         }
     }
 
@@ -306,6 +314,13 @@ private static String repeatString(String str, int times){
         for(int i = 0;i < times;i++) ret.append(str);
         return ret.toString();
     }
+
+    private static String readXml(String xpathQuery, String xml) throws XPathExpressionException {
+        XPathFactory xpathFactory = XPathFactory.newInstance();
+        XPath xpath = xpathFactory.newXPath();
+        InputSource source = new InputSource(new StringReader(xml));
+        return xpath.evaluate(xpathQuery, source);
+    }
 
     /**
      * Gets an {@link Archive} object for the given archive ID.