Executing XPath Expressions in a Beanshell Post-Processor

[Noel O'Brien]

Hi, 

I have to extract an correlate many values from an XML feed. I then need to 
sort the entries, store them, and compare them against subsequent feeds. 

Given the complexity of the task, I decided to do it with a Beanshell 
Post-Processor. I first spiked the code in Java and everything worked. However 
when I moved it into JMeter/Beanshell, the evaluation of the XPath expressions 
always returns 0 nodes. Making the Document namespace-aware makes no 
difference. The document parses fine, and printing out "new String(data, 
"UTF-8")" displays the correct data returned by the sampler. 

Can anyone think of any reasons why this could be happening? 

Here's the code: 

>>>>>>>>>>>>>>>>>>>> 

import org.w3c.dom.*; 
import javax.xml.xpath.*; 
import javax.xml.parsers.*; 
import java.io.*; 
import java.nio.*; 
import java.nio.channels.*; 
import org.xml.sax.*; 


log.info("Starting "+getSourceFileInfo()); 
log.debug("Parameters: " + Parameters); 
startTime = System.currentTimeMillis(); 

params = Parameters.split("\\|"); 

sns = params[0]; 

// Method for retrieving Node text value 
public static String getNodeValue(Node node) 
{ 
if(!node.hasChildNodes()) return ""; 
else return node.getFirstChild().getNodeValue(); 
} 

// Build XML document from the response 
DocumentBuilderFactory domFactory = DocumentBuilderFactory.newInstance(); 
domFactory.setNamespaceAware(false); 
DocumentBuilder builder = domFactory.newDocumentBuilder(); 
InputSource inStream = new InputSource(); 
inStream.setCharacterStream(new StringReader(new String(data, "UTF-8"))); 
Document doc = builder.parse(inStream); 
XPath xpath = XPathFactory.newInstance().newXPath(); 


// Create XPath Expressions 
XPathExpression updatedExpr = xpath.compile("/feed/entry/updated"); 
XPathExpression displayNameExpr = xpath.compile("/feed/entry/author/name"); 
XPathExpression statusExpr = xpath.compile("/feed/entry/summary"); 
XPathExpression snsExpr = xpath.compile("/feed/entry/source/author/name"); 

// Evaluate XPath Expressions 
NodeList updatedNodes = (NodeList)updatedExpr.evaluate(doc, 
XPathConstants.NODESET); 
NodeList displayNameNodes = (NodeList)displayNameExpr.evaluate(doc, 
XPathConstants.NODESET); 
NodeList statusNodes = (NodeList)statusExpr.evaluate(doc, 
XPathConstants.NODESET); 
NodeList snsNodes = (NodeList)snsExpr.evaluate(doc, XPathConstants.NODESET); 

System.out.println("updatedNodes: "+updatedNodes.getLength()); 
System.out.println("displayNameNodes: "+displayNameNodes.getLength()); 
System.out.println("statusNodes: "+statusNodes.getLength()); 
System.out.println("snsNodes: "+snsNodes.getLength()); 

// Create data types 
/* HashSet<List> set = new HashSet<List>(); 
TreeMap<Date, HashSet<List>> tree = new TreeMap<Date, HashSet<List>>();*/ 

// Put values in data structure 
for(int i =0; i < updatedNodes.getLength(); i++) 
{ 
String u = getNodeValue(updatedNodes.item(i)); 
String d = getNodeValue(displayNameNodes.item(i)); 
String s1 = getNodeValue(statusNodes.item(i)); 
String s2 = getNodeValue(snsNodes.item(i)); 

// do more stuff 
} 


// Store tree in Object variable 
//vars.putObject("individual.friends.statuses.tree", tree); 

finishTime = System.currentTimeMillis(); 
log.info("Finished "+getSourceFileInfo()+" (" + (finishTime-startTime) + 
"ms)"); 

<<<<<<<<<<<<<<<<<<<< 

JMeter: 2.3.2 
Java 1.6.0_12 
OS: Linux 

Regards, 
Noel