Exception sending serialised data from servlet to applet

Question

Hello,
I have a servlet that sends periodically a serialised object to an applet, under a http get request. it works fine, but if I force the comunication not waiting too much between requests, I am getting this anoying exception:
java.io.StreamCorruptedException:EOFException while reading stream header
This is a piece of code:
SERVLET--------
(called within the doGet)
public void sendSerialisedData(HttpServletResponse response, PlatformData dataToSend)
ObjectOutputStream outputToApplet;
try
outputToApplet = new ObjectOutputStream(response.getOutputStream());
response.setContentType("application/x-java-serialized-object");
outputToApplet.writeObject(dataToSend);
outputToApplet.flush();
outputToApplet.close();
catch (IOException e)
e.printStackTrace();
APPLET--------
HttpURLConnection servletConnection = (HttpURLConnection)url.openConnection();
servletConnection.setDoOutput(false);
servletConnection.setDoInput(true);
servletConnection.setRequestMethod("GET");
servletConnection.setUseCaches(false);
servletConnection.setDefaultUseCaches(false);
servletConnection.setRequestProperty("Content-type","application/x-java-serialized-object");
ObjectInputStream inputToServlet = new ObjectInputStream(servletConnection.getInputStream());
setTheData( (PlatformData) inputToServlet.readObject());
inputToServlet.close();
servletConnection=null;
The method that receives the refresh petitions in the client is synchronized, that means that I have ensured that no petition will be processed until the method on charge of processing it has finished.
I have spent 3 days with this problem, but I have not been lucky. Does anyone have an idea of what is happening?
thank you very much
carlos
[email protected]

Answer 1

the
communication works fine until you force a more
frequent communication... Ok.
I had a similar problem a while back while implementing an applet-servlet pipeline. I remember solving it by writing the objs in byte arrays and sending the byte arrays instead. The only other difference is that I was using POST instead of GET.
In your servlet :
// first
con.setRequestProperty("Content-type","application/octet-stream");
// method
private byte[] convertObjectToByteArray( Object obj ) throws IOException
ByteArrayOutputStream b = new ByteArrayOutputStream();
ObjectOutputStream out = new ObjectOutputStream( b );
out.writeObject( obj );
return b.toByteArray();
// code
byte[] b = convertObjectToByteArray( obj );
ObjectOutputStream out = new ObjectOutputStream( resp.getOutputStream() );
out.writeObject( b );
out.close();And in your applet, get the byte array and convert that to objects.:
// method
private Object convertByteArrayToObject( byte[] b ) throws Exception
ObjectInputStream in = new ObjectInputStream( new ByteArrayInputStream➥
( b ) );
return in.readObject();
// code
ObjectInputStream in = new ObjectInputStream( con.getInputStream() );
byte[] b = (byte[])in.readObject();
in.close();
// then call convertByteArrayToObject( b );If the above does not make a difference, I'm afraid I can't be of further help...