Reading from an InputStream of a SocketConnection hangs on Nokia N70 phones

[onestepahead]

Hi folks,

I've been browsing this and also other discussion boards for days in order to find a solution or helpful answer for my following problem. My searches were without success and I hope that some Nokia guy (or any other expert) will read this thread and take care of this.

I'm developing a J2ME application for my Nokia N70 smartphone (firmware version V 2.0536.0.2 12-09-05 RM-84) an run into trouble opening and using a plain socket connection. The midlet runs very well both on Sun's WTK Wireless Toolkit Version 2.2 and Nokia's Prototype SDK 2.2 for J2ME emulator.

Here's what I'm doing step by step:

I'm opening a socket connection to a local web server which runs on a well defined tcp port (say 8888) - other than port 80 in order to bypass midlet signment:

SocketConnection conn = (SocketConnection)Connector.open("socket://server.my.domain:8888");

After setting some socket options I retrieve the input and output streams associated with that socket:

DataInputStream input = conn.openDataInputStream();
DataOutputStream output = conn.openDataOutputStream();

Then I send a simple http request to my server as follows:

String webRequest = "GET / HTTP/1.1\n\n";
output.write(webRequest.getBytes());

Having sent the request to the server I simply read from the input stream in a loop:

byte[] inbuf = new byte[512];      
do {
    int nCount = input.read(inbuf);
    result.append(new String(inbuf, 0, nCount));
}
while (input.available() > 0);

As I said before this application runs well on both Sun's and Nokia's emulators - I'm getting the expected answer from the server. As soon as I run the midlet on the Nokia N70 the application seams to hang right at the statement "input.read()". Using the network protocol analyzer ethereal I can clearly see my request arriving at the web server and the expected result beeing sent to my phone. But the phone does not return from the read() method.

My provider's GPRS setting are fine since the very same midlet runs properly on my old Siemens S65 cell phone using the very same SIM card. Can anyone (Nokia experts, do you hear me?) explain this weird behaviour? Does anyone out there use socket connections on a Nokia N70 phone?

Here is the full midlet sample code which opens a TextBox in order to view the result read from the server. Any help is appreciated.

public class SocketMidlet extends MIDlet
{
  private static final String socketURL = "socket://server.my.domain:8888"; 
  private static final String webRequest = "GET / HTTP/1.1\n\n";
  private TextBox viewer = null;  

  public SocketMidlet()   {}

  public void pauseApp()  {}

  public void startApp()
  {
    viewer = new TextBox("SocketMidlet Test", null, 1024, TextField.ANY );
    viewer.setString("SocketMidlet:");
    Display.getDisplay(this).setCurrent(viewer);
    connect(socketURL);
  }

  public void destroyApp(boolean cond)
  {
    notifyDestroyed();
  }

  void connect(String url)
  {
    try
    {
      SocketConnection conn = (SocketConnection)Connector.open(url);
      conn.setSocketOption(SocketConnection.LINGER, 5);
      
      DataInputStream input = conn.openDataInputStream();
      DataOutputStream output = conn.openDataOutputStream();
 
      output.write(webRequest.getBytes());

      StringBuffer result = new StringBuffer("Content:\n");

      byte[] inbuf = new byte[512];      
      do
      {
        int nCount = input.read(inbuf);
        result.append(new String(inbuf, 0, nCount));
      }
      while (input.available() > 0);

      viewer.setString(viewer.getString()+result.toString());

      output.close();
      input.close();
      conn.close();
    }
    catch (IOException e)
    {
      e.printStackTrace();
    }
    
    Display.getDisplay(this).setCurrent(viewer);
  }
}

[springwood64]

Nokia have implemented 'read' as 'readfully'. The method call will terminate when it has read enough bytes to fill your buffer.

If you are reading HTTP then you will have to read it one byte at a time and cease reading when you detect the end of the response.

[onestepahead]

Hi springwood64,

the problem remains even reading byte by byte from a data input stream extracted from a http connection. Look at the following code snipplet. Even that the web server returns a valid HTML response (simple ascii text) the statement "input.available()" return 0 and no data is read at all.

HttpConnection con = null;
try
{
  con = (HttpConnection)Connector.open("http://server.my.domain:8888");
}
catch (IOException e)
{
   e.printStackTrace();
}

DataInputStream input = con.openDataInputStream();
try 
{        
  StringBuffer buf = new StringBuffer();
  while (input.available() > 0)  // == 0 (!)
  {
    buf.append((char)input.read());          
  }
  String content = buf.toString();
  int len = content.length();
}
catch (Exception e)
{
  e.printStackTrace();
}
input.close();

Any idea? Thanx.

[allike]

I met the same problem right now, Waitting for your response!

[springwood64]

I'm afraid that you cannot rely on available(). Instead you could read one byte at a time - each read will block until a single byte is available:

boolean dataFound = false;
while(!dataFound)
{
    byte next = input.read();
    // add 'next' to the data, check if you've got it all and set 'dataFound' to true
}

[onestepahead]

Hello, I'm back
Here is one working solution for the Nokia socket input stream problem:

1. Use POST, not GET (!)
2. Read from the input stream chunk by chunk (!!)

Sample code:

   // your URL
   String url = "http://server.my.domain:8888";
   // data buffer (chunk)
   byte[] readBuffer = new byte[8192];
   InputStream input = null;
   HttpConnection trafficConnection = null;
    try
    {
      // open http connection to server and POST request, do NOT use GET as request method
      conn = (HttpConnection)Connector.open(url);      
      conn.setRequestMethod(HttpConnection.POST);

      // return if we don't get response code 200 (HTTP OK)
      int rc = conn.getResponseCode();
      if (rc != HttpConnection.HTTP_OK)
      {
        // do something with error code "rc" and then
        return;
      }
      input = conn.openDataInputStream();
    }
    catch (IOException e)
    {
      // HTTP connection failure
      e.printStackTrace();
      return;
    }

    try
    {
      // read chunk by chunk
      ByteArrayOutputStream baos = new ByteArrayOutputStream();
      int count;
      while ((count = input.read(readBuffer, 0, readBuffer.length)) > 0)
        baos.write(readBuffer, 0, count);

      // do something with your data ...
      String result = new String(baos.toByteArray());
    }
    catch (ConnectionNotFoundException e)
    {
      e.printStackTrace();
    }
    catch (IOException e)
    {
      e.printStackTrace();
    }
    finally
    {
      try
      {
        // clean up resources
        if (input != null)
          input.close();
        if (conn != null)
          conn.close();
      }
      catch (IOException e)
      {
      }
    }

[unugurn]

i am facing same problem with HttpConnection. my phone is Nokia 6630.

may be this may solve your problem;

i notice that this happens when http resposnse length is -1. when i changed the code on the server side and set length to appropriate value everyting goes fine on both simulator and phone.

change your code as follows on

c = (HttpConnection) Connector.open(url);

int rc = c.getResponseCode();

if (rc != HttpConnection.HTTP_OK)
throw new IOException("HTTP response code: " + rc);

is = c.openInputStream();

int length = (int) c.getLength();

if (length > 0) {

int actual = 0;
int bytesread = 0;
byte[] data = new byte[length];
while ((bytesread != length) && (actual != -1)) {
actual = is.read(data, bytesread, length - bytesread);
bytesread += actual;
}

}

[stevejanko]

Hi

I am having a similar problem, and also can not get an answer. One thing I have found as that once the connection is established I press the menu key on the phones keypad, the menu is displayed and then my app receives an answer and the phone switches back to the J2ME app.

I dont know why the N70 behaves differently to the 6600, 6670 and 6680 on which my app runs perfectly.

What happens when you press the phone's menu key ?
Steve

[juarezjunior]

Hello there,

You should not rely on the available() method. Check the thread below:

http://discussion.forum.nokia.com/fo...ad.php?t=76112

BR

[stevejanko]

Thanks BR

I had already tried this, with the same result, any other ideas

Regards
Steve

[DanielNovy]

Hi guys. Just would like to share the solution to this issue. It's as simple as it looks like: just add a outputstream.flush() command after write. In my Nokia E50 it worked!

I know it's an very old thread but I search for the solution all over the net and couldn't find it! Hope my post can help other ones.

[huss81]

Hi,

Many thanks for posting your solution "myOutputStream.flush". I had the problem for some days that i was able to send data via bluetooth using SPP Probile with "myInputStream.write(..)", but trying to receive some data was always blocking for my application although the other bluetooth device was sending. Thank to your suggestion i now flush the outputstream AFTER writing and BEFORE reading --> everthying works fine :-).

[djbuan]

Hi,

Many thanks for posting your solution "myOutputStream.flush". I had the problem for some days that i was able to send data via bluetooth using SPP Probile with "myInputStream.write(..)", but trying to receive some data was always blocking for my application although the other bluetooth device was sending. Thank to your suggestion i now flush the outputstream AFTER writing and BEFORE reading --> everthying works fine :-).

This was a pretty good solution! it worked for me as well! Thanks for whoever posted the solution!