reason for EOF exception?

[Lukas Benberg]

hi all,
maybe someone can give me a hint where to start searching my problem?

i send a http post request to a remote server. that server then reads a url (a file) on my server and processes the text in it. as a result i get a response. here is my code:

 
 // create http connection
HttpClient httpClient = new HttpClient();
PostMethod postMethod = new PostMethod("http://www.remoteserver.net/notification.php" );
// post request
postMethod.setRequestBody(data);
int responseCode = httpClient.executeMethod(postMethod);
...
// Read the response body.
String responseBody = inputStreamAsString(postMethod.getResponseBodyAsStream());       
System.out.println(responseBody);

the remote script obviously does read and processes my data, some output is generated. but it stops at some point and throws this exception:

java.io.EOFException
at java.io.ObjectInputStream$BlockDataInputStream.peekByte(ObjectInputStream.java:2502)
at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1267)
at java.io.ObjectInputStream.readObject(ObjectInputStream.java:339)
...

what could be the reason for this exception? the file on my server is intact. does the script on the remote server not work properly?

thanks for your help! l

[Joe Ess]

Can you perform the same operation with a browser?
Where is this ObjectInputStream? I would not expect HttpClient to use one. Are you using one in code you aren't showing us?

[Dawei Li]

at java.io.ObjectInputStream$BlockDataInputStream.peekByte(ObjectInputStream.java:2502)
at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1267)
at java.io.ObjectInputStream.readObject(ObjectInputStream.java:339)
hey 2502,1267,339 has relation with which line in your source?

[Lukas Benberg]

hi,
you are right, i use some more code and i guess that's where the problem is. i actually have two servlet classes: a "broker"-servlet who sends a http-message to a "communication"-servlet i mentioned above. the second one does the actual communication to the remote server. i think the communication between my own servlets fails. the exception refers to the broker-servlet.

broker-servlet:

private void brokeRequest(Properties props, URL servletURL){
try {
// create com.oreilly.servlet.HttpMessage 
HttpMessage msg = new HttpMessage(servletURL);

// Send a POST message to the servlet
InputStream in = msg.sendPostMessage(props);
 
// Get the response as an ObjectInputStream
ObjectInputStream result = new ObjectInputStream(in);
 
// Read the object from the stream
Object obj = result.readObject();   // Exception is thrown here!!
System.out.println("Result: "+(String)obj);

} catch (Exception e) {
e.printStackTrace();
}
}

communication-servlet:

private static void doRemoteRequest(NameValuePair[] data){
      
 HttpClient httpClient = new HttpClient();
      PostMethod postMethod = new PostMethod("http://www.remoteserver.net/notification.php" );
      postMethod.setRequestBody(data);
      
  try {
  // Execute the method.
 int responseCode = httpClient.executeMethod(postMethod);
      if (responseCode != HttpStatus.SC_OK) {
        System.err.println("Method failed: " + postMethod.getStatusLine());
      }
      // Read the response body.
      String responseBody = inputStreamAsString(postMethod.getResponseBodyAsStream());       
      System.out.println("Result remoteRequest: "+responseBody); 
 
  } catch (Exception e) {
  e.printStackTrace();
  } finally {
      // Release the connection.
  postMethod.releaseConnection();
  } 
  }

obviously the ObjectInputStream in brokeRequest is the problem. do i have to create an ObjectOutputStream in doRemoteRequest? i would like to let the broker know if the request succeeded. how would i do this?

thanks! l

[Joe Ess]

In order to use an ObjectInputStream to read an object, you must use an ObjectOutputStream to write an object (see here for a tutorial). What exactly does your URL reference?
Also, you say broker-servlet and communication-servlet are servlets, but they do not appear to implement the Servlet interface or its sub-interfaces. Do you understand how HTTP and Servlets work?

[Lukas Benberg]

yes, the classes do extend HttpServlet, i only left out the irrelevant stuff. i think i understand what servlets do, though i am certainly not an expert. i'm not that familiar with http. thanks for the tutorial. i'll try to understand the ObjectOutputStreams. L