simple web service client

[pranav modi]

Hi all,

I have written a very simple client for a web service. all i want it to do is connect to a website, get a xml document and print some elements of the document. It creates the url correctly, but on printing the document it gives :
[#document = null]
also it does not print the element which i coded it for. can someone point out the error for me?
thanks!
the code goes as follows:

import java.io.*;

import org.w3c.dom.*;
import org.xml.sax.SAXException;
import javax.xml.parsers.*;
import javax.xml.xpath.*;
import java.net.HttpURLConnection;
import java.net.URL;



public class Iapp
{
public static void main(String[] args)
throws IOException, ParserConfigurationException,
SAXException, XPathExpressionException
{
String lang = "lang="+args[0];
String country = "&country="+ args[1];
URL url = new URL("http://irrepressible.info/query?"+lang+country);
System.out.println(url);
HttpURLConnection huc = (HttpURLConnection) url.openConnection();
huc.setRequestMethod("GET");
huc.connect();
InputStream is = huc.getInputStream();
//System.out.println(is);
//int code = huc.getResponseCode();

// Turn the response entity-body into an XML document.
DocumentBuilderFactory docBuilderFactory = DocumentBuilderFactory.newInstance();
System.out.println(docBuilderFactory);

DocumentBuilder docBuilder = docBuilderFactory.newDocumentBuilder();
System.out.println(docBuilder);
Document doc = docBuilder.parse(is);



huc.disconnect();

System.out.println(doc);

XPath xpath = XPathFactory.newInstance().newXPath();
NodeList bookmarks = (NodeList)xpath.evaluate("/irrepressible:info/fragments/fragment/fragmentText", doc, XPathConstants.NODESET);
//Iterate over the bookmarks and print out each one.
for (int i = 0; i < bookmarks.getLength(); i++)
{
NamedNodeMap bookmark = bookmarks.item(i).getAttributes();
String description = bookmark.getNamedItem("description")
.getNodeValue();
String uri = bookmark.getNamedItem("href").getNodeValue();
System.out.println(description + ": " + uri);
}

System.exit(0);
}

}

[William Brogden]

[#document = null]

This is the expected result for a Document object.

See the excellent table in the JavaDocs for the Node Interface org.w3c.dom package. A Document object has the name "#document" and the toString() node value of null.

All Java programmers working with the standard toolkit should become very familiar with this table.

As to why the xpath statement is not working as expected, I could not say since you don't include an example of the XML structure.

Bill

[pranav modi]

oops...here is the xml document :

XML file does not appear to have any style information associated with it. The document tree is shown below.

−
<irrepressible:info>
−
<fragments count="10" query="http://irrepressible.info/api?lang=en&limit=10&country=china%20iran" language="en">
−
<fragment href="http://irrepressible.info?lang=en&fragment=1" id="1">
<country>China</country>
<domain>http://hrichina.org/</domain>;
<organisation>Human Rights in China</organisation>
<siteDescription>HRIC is a Chinese human rights organisation</siteDescription>
−
<url>
http://www.hrichina.org/public/contents/article?revision%5fid=10853&item%5fid=3759
</url>
−
<fragmentText>
With incredible bravery, she has broken through much of the fear and isolation imposed upon other victims' families.
</fragmentText>
</fragment>
+
<fragment href="http://irrepressible.info?lang=en&fragment=2" id="2">
<country>China</country>
<domain>http://hrichina.org/</domain>;
<organisation>Human Rights in China</organisation>
<siteDescription>HRIC is a Chinese human rights organisation</siteDescription>
−
<url>
http://www.hrichina.org/public/contents/article?revision%5fid=10853&item%5fid=3759
</url>
−
<fragmentText>
Her dedication and perseverance has gained her wide admiration,
</fragmentText>
</fragment>
+
<fragment href="http://irrepressible.info?lang=en&fragment=3" id="3">
<country>China</country>
<domain>http://hrichina.org/</domain>;
<organisation>Human Rights in China</organisation>
<siteDescription>HRIC is a Chinese human rights organisation</siteDescription>
−
<url>
http://www.hrichina.org/public/contents/article?revision%5fid=1894&item%5fid=1893
</url>
−
<fragmentText>
Several scholars and outspoken journalists have lost their jobs or been warned by the government.
</fragmentText>
</fragment>
+
<fragment href="http://irrepressible.info?lang=en&fragment=4" id="4">
<country>China</country>
<domain>http://www.amnesty.org/</domain>;
<organisation>Amnesty International</organisation>
−
<siteDescription>
Amnesty International is a movement of ordinary people standing for humanity and human rights.
</siteDescription>
<url>http://news.amnesty.org/index/ENGAMR510802006</url>;
−
<fragmentText>
They also need to allow independent medical experts into the camp
</fragmentText>
</fragment>
+
<fragment href="http://irrepressible.info?lang=en&fragment=5" id="5">
<country>China</country>
<domain>http://www.amnesty.org/</domain>;
<organisation>Amnesty International</organisation>
−
<siteDescription>
Amnesty International is a movement of ordinary people standing for humanity and human rights.
</siteDescription>
−
<url>
http://web.amnesty.org/pages/deathpenalty-index-eng
</url>
−
<fragmentText>
With 20,000 people on death row across the world, over 2,148 people were executed in 22 countries in 2005.
</fragmentText>
</fragment>
+
<fragment href="http://irrepressible.info?lang=en&fragment=6" id="6">
<country>China</country>
<domain>http://www.bbc.co.uk/</domain>;
<organisation>British Broadcasting Corporation</organisation>
<siteDescription>The BBC is a public service broadcaster</siteDescription>
<url>http://www.bbc.co.uk/weather/5day.shtml</url>;
−
<fragmentText>
so if a day is forecast to be sunny with the possibility of a brief shower,
</fragmentText>
</fragment>
+
<fragment href="http://irrepressible.info?lang=en&fragment=7" id="7">
<country>China</country>
<domain>http://www.bbc.co.uk/</domain>;
<organisation>British Broadcasting Corporation</organisation>
<siteDescription>The BBC is a public service broadcaster</siteDescription>
<url>http://news.bbc.co.uk/1/hi/sci/tech/default.stm</url>;
−
<fragmentText>
A US-British team challenges the idea that the tiny skeleton dubbed the ""Hobbit"" is a human new to science.
</fragmentText>
</fragment>
+
<fragment href="http://irrepressible.info?lang=en&fragment=8" id="8">
<country>China</country>
<domain>http://www.bbc.co.uk/</domain>;
<organisation>British Broadcasting Corporation</organisation>
<siteDescription>The BBC is a public service broadcaster</siteDescription>
−
<url>
http://news.bbc.co.uk/1/hi/entertainment/4994564.stm
</url>
−
<fragmentText>
Star Trek fans are being offered a "once in a lifetime" opportunity to buy props, models and sets from the show
</fragmentText>
</fragment>
+
<fragment href="http://irrepressible.info?lang=en&fragment=9" id="9">
<country>China</country>
<domain>http://www.freetibet.org/</domain>;
<organisation>Free Tibet Campaign</organisation>
−
<siteDescription>
Free Tibet Campaign stands for the Tibetans' right to determine their own future
</siteDescription>
<url>http://www.freetibet.org/events/climbfortibet.html</url>;
−
<fragmentText>
In the last few years the Climb for Tibet team has sent out thousands of Peace Messages
</fragmentText>
</fragment>
+
<fragment href="http://irrepressible.info?lang=en&fragment=10" id="10">
<country>China</country>
<domain>http://www.freetibet.org/</domain>;
<organisation>Free Tibet Campaign</organisation>
−
<siteDescription>
Free Tibet Campaign stands for the Tibetans' right to determine their own future
</siteDescription>
<url>http://www.freetibet.org/events/diary.html</url>;
−
<fragmentText>
The Healing Chod is an ancient enchanting ceremony and is a wonderful opportunity to deeply relax ones body, speech and mind.
</fragmentText>
</fragment>
</fragments>
</irrepressible:info>

[William Brogden]

Do you get the expected number of elements when the following is executed?

  NodeList bookmarks = (NodeList)xpath.evaluate("/irrepressible:info/fragments/fragment/fragmentText", doc, XPathConstants.NODESET);  

If so, then the XPath part is working correctly and your problem is with the extraction of the Text Node from the fragmentText Element.

Exactly what are you expecting the following code to do?

 NamedNodeMap bookmark = bookmarks.item(i).getAttributes();
String description = bookmark.getNamedItem("description")
.getNodeValue();
String uri = bookmark.getNamedItem("href").getNodeValue();
System.out.println(description + ": " + uri);