Why did my application stop connecting using HTTP, and how can I debug it?

Question

I have a program that includes HTTP connection to a PLM application that runs on SQL Server. The program is scheduled to run daily. It collects data from few sources, then issues a query to the PLM to store the data, and finally reads the PLM's reply to verify if the data was properly stored.

The application ran OK, until we upgraded both the DB (into SQL Server 2012) and the PLM.

Since then the upgrade, when the program establishes the connection it receives OK status; however, the data setting query does not affect the data base, and there is no answer received. There are no error messages - just malfunction.

My major question is - how to debug it. I know whet I send and what I receive. How can I get more data on what happens in between?

I attach the code for review. What I didn't add here is the query itself, which is WML-like string. The PLM should fire an answer regardless the query it receives, even if it is an error message. However, I get only NULL.

public Boolean amlArasCommunication (String data , int targetDbType, String passWord)
{
        final String url = "http://plm-srv/InnovatorServer/Server/InnovatorServer2012.aspx";
        final String schemeUrl = "'http://schemas.xmlsoap.org/soap/envelope/'";
        String answer =””;
        String dataBase = data base name;
        Writer wout;
        HttpURLConnection amlConnection = null;

        try 
        {
// instantiate the HttpURLConnection with the URL object - A new connection is 
// opened every time by calling the openConnection method of the protocol 
// handler for this URL. This is the point where the connection is opened.
            amlConnection = (HttpURLConnection) new URL(url).openConnection();
            amlConnection.setDoOutput(true);
            amlConnection.setDoInput(true);
            amlConnection.setRequestMethod("POST");
            amlConnection.setRequestProperty("SOAPAction", "ApplyAML");
            amlConnection.setConnectTimeout(10000);
            amlConnection.setReadTimeout(10000);
            amlConnection.setRequestProperty("AUTHUSER", "Admin");
            amlConnection.setRequestProperty("AUTHPASSWORD", calcMD5(passWord));
            amlConnection.setRequestProperty("DATABASE", dataBase);

            String query = "<?xml version='1.0'?>\r\n" + 
                "<SOAP-ENV:Envelope xmlns:SOAP-ENV=" + schemeUrl + ">\r\n" + 
                "  <SOAP-ENV:Body>\r\n" + 
                data  + 
                "  </SOAP-ENV:Body>\r\n" + 
                "</SOAP-ENV:Envelope>\r\n";

// instantiate OutputStreamWriter using the output stream, returned from getOutputStream, that writes
// to this connection. If an I/O error occurs while creating the output stream, IOException will be fired.
            wout = new OutputStreamWriter(amlConnection.getOutputStream());
            wout.write (query);
            wout.close();

// At this point, we've sent all the data. The outputStream was closed, while the connection is still open
            int result;
            if ((result = amlConnection.getResponseCode()) == HttpURLConnection.HTTP_OK)
            {
// Get the communication results from the PLM
                InputStream ac = amlConnection.getInputStream();
                InputStreamReader isr = new InputStreamReader (ac);
                BufferedReader in = new BufferedReader(isr);
                String readResult = in.readLine ();
                int count = 0;
                while (readResult != null)
                {
                    answer += readResult + "\n";
                    readResult = in.readLine ();
                    count++;
                }
                in.close();
                if (answer.contains("fault"))
                    System.out.println ("Error message: " + answer + "\nQuery: " + query);
                else 
                    log.message ("Lines count=" + count + "; com status=" + result + "; reply: " + answer, false);
            }
            else
 // Error code is returned, or no status code is returned, do stuff in the else block
                System.out.println("Connection failed with the following code: " + result);
        }
        catch (IOException e) { ; }

        if (amlConnection != null)
            amlConnection.disconnect ();
        return true;
}

Answer 1

I think you will have to look into the log files of the PLM application to find out why you do not get an HTTP response. There might be a number of possible reasons why the application is not working anymore after the upgrade.

I guess that it will be difficult to debug the problem based on the client code only. As the server seems to accept your HTTP, I would expect that this event and errors would be written to a log file somewhere. You might also want to try some graphical tool like SOAP UI to test the SOAP service.