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HTTP Status Code 500 Returned - HttpURLConnection to Connect to Web Server Cluster Nodes
Submitted by dthanki on Mon, 10/05/2009 - 11:32.
Presently, I am attempting to use the HttpURLConnection to make web server calls across multiple nodes participating in a web server cluster. I have a web application 'MyWebAppl' that is running/deployed on 'WebServerA' (Node #1) and the same web application 'MyWebAppl' that is running/deployed on 'WebServerB' (Node #2). From 'WebServerA' I am attempting to open/establish a HttpURLConnection with 'WebServerA' and 'WebServerB' which results in IOException with an HTTP Status Code of 500. I would like to know whether anyone has attempted something similar wherein the client and the server co-exist within the same web application and the the client is trying to connect to itself. Are there any restrictions / limitations to this? I have tried to investigate and search if similar issues have been experienced or reported or if there are any limitations within HttpURLConnection, however I haven't found anything specific that suggests whether or not this is possible. I would appreciate any inputs or proposed approaches in this regard. I am also providing below the code snippet (convenience method) that is being used to make the web server calls.
/**
* <p>Invoke the URL</p>
*/
public boolean invokeUrl(String urlLink, String sessionId)
throws ClusterException
{
URL url;
HttpURLConnection urlConn = null;
PrintWriter outputWriter;
BufferedReader bufferedReader;
InputStream inputStream = null;
boolean success = false;
try
{
// Make the URL invocation for generating the report
url = new URL(urlLink);
urlConn = (HttpURLConnection) url.openConnection();
// Set the Cookie for the web server cluster node's session-id.
urlConn.setRequestProperty("Cookie", sessionId);
urlConn.setDoInput(true);
urlConn.setDoOutput(true);
urlConn.setUseCaches(false);
// Obtain the Input Stream for the URL connection. In case the session on the web server node
// has been terminated, HTTP status code '401' will be returned by the reporting server resulting
// into an IOException. In this situation the logged in user should be reauthenticated once again
// on the reporting server and reporting request must be reattempted.
try
{
inputStream = urlConn.getInputStream();
}
catch (IOException ioe)
{
urlConn.disconnect();
// If HTTP response code '401' is returned then try to resume the expired
// session on the reporting server by obtaining a new HTTP URL Connection.
if (urlConn.getResponseCode() == HttpURLConnection.HTTP_UNAUTHORIZED)
{
throw new ClusterException("The access to the requested resource was denied; the request may have been made without authorization credentials.");
}
// If response code other than '401' is returned then propagate the IOException to the next level.
else
{
throw new ClusterException(ioe.getMessage());
}
}
// HTTP Response message status is OK, then proceed with generating/displaying the response
if (urlConn.getResponseCode() == HttpURLConnection.HTTP_OK)
{
success = true;
}
}
catch (MalformedURLException murle)
{
throw new ClusterException(murle.getMessage());
}
catch (IOException ioe)
{
throw new ClusterException(ioe.getMessage());
}
finally
{
if (urlConn != null)
{
urlConn.disconnect();
}
return success;
}
}