Servlet- applet serial'n

Question

Hi and thanks in advance if you can help.
I'm trying to serialize an object in a servlet and send it to an applet. The applet is giving me a ClassCastExecption: Bad magic number error, but I'm pretty sure that's a time-out error--the servlet appears to be hanging at the writeObject(myObj) statement. The code follows the straightforward examples I've found. Before I post the code, note that the following tests have succeeded:
-- using the same methods, sending a serialized String to the applet.
-- serializing my object to disk, then de-serializing it.
Also, please note that myObj can range in size from about half a Mb on up to nearly 3Mb, at least for now.
SERVLET SNIP
//res is the ServletResponse instance
res.setContentType("application/x-java-serialized-object");
oos = new ObjectOutputStream(res.getOutputStream());
oos.writeObject(myObj);
oos.flush();
oos.close();APPLET SNIP
private URL servletURL;
private HttpURLConnection con;
servletURL = new URL( getCodeBase(), "AppletMinder" );
con = (HttpURLConnection)servletURL.openConnection();
con.setDoInput(true);
con.setDoOutput(true);
con.setDefaultUseCaches(false);
con.setUseCaches(false);
//set content type for serialized objects
con.setRequestProperty("Content-Type","application/x-java-serialized-object");
//params sent to servlet, servlet populates a myObj instance -- all working.
//showing that it's threaded just for completeness
Thread t = new Thread(new Runnable() {
     public void run() {
          sendToServlet(params);
          myObj= receiveFromServlet();
t.start();
//from the receiveFromServlet() method...
input =     new ObjectInputStream(con.getInputStream());
myObj = (MyObj)input.readObject();
input.close();Okay, so to repeat, everything worked when I substituted a String for myObj.
Also when I serialized to disk as follows...
File test = new File("C:/test.bin");
ObjectOutputStream oos;
oos = new ObjectOutputStream(
     new BufferedOutputStream(
          new DeflaterOutputStream(
               new FileOutputStream(test, false), new Deflater(Deflater.BEST_COMPRESSION)), 4096));...then de-serialize and read it back in it works, so I know myObj is truly serializable. The problem seems to be with wrapping the ServletOutputStream in the ObjectOutputStream because the servlet appears to hang there.

Answer 1

An update:
MyObj has a number of primitive instance variables, an ImageIcon, and two vectors of other objects (myObjA and myObjB). In a typical populated myObj instance, the ImageIcon is by far the largest variable, so I tried serializing and sending just the ImageIcon instead of the whole myObj, and it worked.
However, when I try to serialize and send either of the vectors it fails (on the applet side) in the same way as when I tried sending the whole myObj (ClassFormatError: Bad magic number--I mistated the error above--it's a ClassFormatError, not a ClassCastException).
So I was wrong, the problem seems to be on the client/applet side. Is this possibly related to the plug-in vs. the VM? At compile time both the applet and servlet use the same environment within my IDE. I'm using 1.4.1_01.